WO2003038387A1 - Vehicle control method - Google Patents

Vehicle control method Download PDF

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Publication number
WO2003038387A1
WO2003038387A1 PCT/ES2002/000509 ES0200509W WO03038387A1 WO 2003038387 A1 WO2003038387 A1 WO 2003038387A1 ES 0200509 W ES0200509 W ES 0200509W WO 03038387 A1 WO03038387 A1 WO 03038387A1
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WO
WIPO (PCT)
Prior art keywords
wheels
motors
load torque
wheel
torque
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PCT/ES2002/000509
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Spanish (es)
French (fr)
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WO2003038387B1 (en
Inventor
Teodor Akinfiev
Manuel Angel ARMADA RODRÍGUEZ
Roemi FERNÁNDEZ
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Consejo Superior De Investigaciones Científicas
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Publication of WO2003038387A1 publication Critical patent/WO2003038387A1/en
Publication of WO2003038387B1 publication Critical patent/WO2003038387B1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60LPROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/12Recording operating variables ; Monitoring of operating variables
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/60Other road transportation technologies with climate change mitigation effect
    • Y02T10/64Electric machine technologies in electromobility

Definitions

  • the invention pertains to control engineering and mechanical engineering and can be used particularly in vehicles and mobile robots with wheels.
  • a third solution is known [Arrangement for improved vehicle traction control. Patent Number: GB2354496. Publication date: 2001-03-28. Inventor (s): BURROWS ANDREW JULI ⁇ N (GB)] in which the vehicle's engine is connected to each wheel and a mechanical transmission is used for the distribution of the pairs.
  • the defect of this system is related to insufficient quality of traction control and the possibility of sliding conditions on one or more wheels during movement.
  • the vehicle control method is performed with electric motors on more than one wheel, measuring the angular speed on each of the wheels with motors and the current in the motors for the calculation of the load torque of the motors in the wheels, and these pairs are controlled with the help of a control system that varies the value of the voltage of the motors.
  • the disadvantage of this solution is related to the possibility of sliding on one or more wheels. If the vehicle moves on inclined surfaces or is subjected to external lateral forces, the wheel slip condition may cause a deviation from the vehicle's trajectory. In addition, if slippage occurs, it is impossible to calculate the position of the vehicle according to the angle of rotation of the wheels.
  • the vehicle control method is performed with engines on more than one wheel, measuring the angular speed on each of the wheels with engines and calculating the load torque of the engines on the wheels, and these pairs are controlled with the help of a control system that is distinguished by the fact that the speed control of the first wheel is done in such a way as to minimize as much as possible the difference between the actual speed of this wheel at that time and the predetermined speed therein moment while checking whenever the load torque T t does not exceed the limit load torque T * and the control of the torque of the different remaining wheels is carried out in such a way that the load torque T ⁇ is less than the torque limit load T and in
  • the objective of the invention is to increase the tensile force, but in any case, to prevent the sliding of the wheels when the vehicle moves on curved and / or irregular surfaces, when it is subjected to external forces, and especially if the coefficient of friction between the wheels and the surface is not very large.
  • the present invention can be used in vehicles with wheels driven by any type of motor, such as DC motors, AC motors, hydraulic motors, gasoline engines or diesel engines.
  • the robot (FIG. 1) includes a main body, three or four independent wheels with direct current electric motors assembled to said body, a control system connected to the motors, with sensors to calculate the wheel speeds and current sensors in the motors.
  • Each of the motors is attached on a separate shaft and its rotor is mechanically coupled by means of conventional reductions.
  • the control system will be responsible for modifying the voltage of each of the traction motors.
  • the current sensors will be used to measure the currents in the stator of each of the motors.
  • the sensors for calculating angular speeds in each of the wheels with motors can be for example optical encoders. System works this way:
  • one of the functions carried out in the control method is to always verify that the load pairs of the traction motors T t (for i - ⁇ - n, where n is the number of wheels with motors) do not exceed the established limit load pairs T t (see FIG. 2 for the load torque T t ).
  • the limit load torque of each motor T l must be determined previously and for example, experimentally. This torque of limit load is related to the frictional force and could be defined as the torque from which sliding begins to occur, therefore, any torque greater than the limit load torque would cause the wheel to slide.
  • a limit load torque T l lower than the real T ⁇ so that it works with a certain reserve margin.
  • the limit load pairs may be the same for all traction motors, in which case they would be equal to the smallest experimentally measured limit torque multiplied by a coefficient ⁇ , or different, in which case they would be equal to the respective experimentally measured limit torque, multiplied by the coefficient ⁇ .
  • the coefficient ⁇ can take values between 0.1 and 1, and the choice of its value will depend on the external forces to which the vehicle is subjected, such as the action of the gravitational force. In this way, if external forces act on the vehicle or if the surrounding conditions are poorly understood, it is recommended to work with a larger reserve, so a small value of ⁇ must be selected. If, on the contrary, the vehicle moves in environments with well-known conditions, it is not necessary to have a lot of reserve, so it can work with a large value of ⁇ .
  • one of the wheels is chosen as a reference, for example a front wheel.
  • the actual speed of this wheel is measured, compared with a predetermined speed, and with the help of the control system the motor voltage varies, so that the difference between the two is minimized as much as possible (as much as the limit load torque T * allows).
  • a current sensor is used to measure the current in the stator of the traction motor. With this current, the load torque of the motor T x is calculated (for example as it is carried out in US Pat. No. 4,243,927) and is verified as long as it does not exceed the limit load torque T * previously set.
  • the voltage at the motor terminals may be varied interchangeably as necessary for speed control.
  • the motor load torque T x begins to equalize or exceed the limit, it will be necessary to reduce the motor voltage until the motor load torque T equals the value of the limit load torque set T ⁇ regardless of the conditions established by the speed control and maintain it until such time that the voltage necessary to maintain the speed is less than the voltage necessary to withstand the torque limit.
  • force sensors can be placed on the supports of some or each of the wheels with motors and connected to the control system.
  • T ⁇ is the limit load torque for each of the traction motors N
  • N is the normal force on each of the wheels with ⁇ motors
  • R is the radius of the wheels
  • is the coefficient that can take a value between 0.1 and 1.
  • FIG. 3 one of these sensors is shown, characterized by being a small curved piece of the same wheel material (10), rubber for example, and which will be continuously sliding in contact with the surface; of a spring (11) that will deform adapting to surface irregularities if they exist; an elbow-shaped aluminum or steel bar (12) that will connect the sensor to the wheel support (15); and two strain gauges used as force sensors, one placed on the spring (13), and another placed on the bar (14). The coefficient of Friction is then measured, determining the force required to produce the movement of an object through a surface.
  • is the coefficient of friction of the wheel i F FR S , is the frictional force on the wheel sensor i
  • N is the normal force on the wheel sensor /
  • N will be constant and can be determined experimentally. If, on the contrary, the surface is irregular, the spring will deform adapting to the irregularities and N. will be equal to the force measured by the force sensor (13) placed in the spring. On the other hand, the frictional force of the F FR S sensor will be given by the measurement of the second force sensor (14) placed on the bar. Then, the resulting values ⁇ are used in the formula
  • the equivalent inertia that is, the inertia of the assembly formed by the motor rotor, gearbox, axles and wheels
  • the equivalent inertia that is, the inertia of the assembly formed by the motor rotor, gearbox, axles and wheels
  • FIG. 1 is a simplified diagram of the main components of the control system installed in the mobile robot.
  • FIG. 2 shows the load torque T t of the one wheel drive motor.
  • FIG. 3 shows the main components of the sensor used to calculate the coefficient of friction.
  • FIG. 4 is a graph of angular velocity with respect to time.
  • FIG. 5 is a simplified diagram of the main components of the control system installed in the mobile robot of example 1.
  • FIG. 6 is a simplified diagram of the main components of the control system installed in the mobile robot of example 2.
  • the present invention is described herein applied to an underwater climber robot intended for cleaning ship hulls.
  • the robot of FIG. 4 includes a main body, three independent wheels with DC motors assembled to said body, a front (1) and two rear (3-4), a control system (5) connected to the motors, with C1-C3 sensors to calculate the speeds in each of the wheels and 11-13 current sensors in the motors.
  • the front wheel (1) can carry another M4 electric motor that allows the robot to rotate.
  • Each of the motors is attached on a separate shaft and its rotor is mechanically coupled by means of conventional reductions.
  • the control system (5) may independently modify the voltage of each of the M1-M3 traction motors.
  • one of the functions carried out in the control method is to verify that the load torque of the traction motors T x , T 2 , T 3 does not exceed the established limit load pairs T * , T 2 * , T 3 , that is, T x ⁇ T * ,
  • T 3 55 Nm.
  • the front wheel is chosen as a reference.
  • the Cl sensor the actual speed is measured or, at this moment, this wheel is compared with a predetermined speed r r ⁇ , and with the help of the control system the motor voltage is varied, so as to minimize as much as possible the difference between the two (as much as the limit load torque T x allows).
  • the current sensor II is used to measure the current in the stator of the traction motor MI. With this current, the load torque of the motor T is calculated and verified as long as it does not exceed the limit torque T * previously set. In FIG. 5 it is appreciated that the speed can be varied interchangeably as necessary while the engine load torque T x is within the limit.
  • the control of the M2 and M3 traction motors is based on the tracking of the reference wheel.
  • the procedure for the M2 motor is described below:
  • the control system uses the current measured in the M2 motor stator with the current sensor 12 and acceleration of the wheel 2 derived from the actual speed co. measured with the C2 sensor to calculate the load torque T 2 , which will be given by the difference between the current multiplied by the torque constant and the acceleration multiplied by the equivalent inertia.
  • the present invention is described herein applied to an underwater climber robot intended for cleaning ship hulls.
  • the robot (FIG. 6) includes a main body, four independent wheels with DC motors assembled to said body, two front (1, 2) and two rear (3, 4), a control system (5) connected to the motors, with C1-C4 sensors to calculate the speeds in each of the wheels, current sensors 11-14 in the motors, force sensors N1-N4 placed in the wheel supports and sensors that allow to calculate the coefficient of friction on each of the CF1-CF4 wheels.
  • the front wheel (1) can carry another M5 electric motor that allows the robot to rotate.
  • Each of the motors is fastened on a separate shaft and its rotor is mechanically coupled by means of conventional reductions.
  • the control system may independently modify the voltage of each of the M1-M4 traction motors.
  • the CF1-CF4 sensors consist of a small curved piece of the same wheel material and that is continuously sliding in contact with the surface; of a spring that deforms adapting to surface irregularities if they exist; of an elbow-shaped aluminum bar that joins the sensor with the wheel support; and two strain gauges used as force sensors.
  • the first gauge placed on the spring that deforms adapting to the irregularities of the surface measures the normal force of the sensors on each of the wheels N x s , N 2 S , N 3 and N 4 5 .
  • the second gauge placed on the bar measures the frictional force of the sensors on each of the wheels F FR S ⁇ , F FR S 2, F FR S ⁇ and E ⁇ S 4.
  • the obtained values allow to calculate the coefficient of friction in each of the wheels ⁇ , ⁇ . ,, during the movement process as follows:
  • N is the normal force on each of the wheels with motors ⁇ is the coefficient of friction on each of the wheels R is the radius of the wheels ⁇ is the coefficient that can take a value between 0.1 and 1.
  • the control system always checks that the load torques of the traction motors T x , T 2 , T 3 , T 4 do not exceed the limit load torques T ⁇ * , T * , T * , T 4 * that is, T ⁇ ⁇ T x , T 2 ⁇ T 2 , T 3 ⁇ T * and T 4 ⁇ T 4 .
  • the front wheel (1) is chosen as a reference.
  • the Cl sensor the actual speed is measured or, at this moment, this wheel is compared with a predetermined speed ⁇ ref , and with the help of the control system the motor voltage is varied, so that it is minimized as much as possible the difference between the two (as much as the limit load torque T x allows).
  • the current sensor II is used to measure the current in the stator of the traction motor MI. With this current, the load torque of the motor 7 is calculated and verified whenever the calculated limit load torque T * is not exceeded.
  • the control of the M2, M3 and M4 traction motors is based on the tracking of the reference wheel.
  • the procedure for the M2 motor is described below:
  • the control system uses the current measured in the stator of the M2 motor with the current sensor 12 and acceleration of the wheel 2 derived from the actual speed c ⁇ measured with the C2 sensor for Calculate the load torque T 2 , which will be given by the difference between the current multiplied by the torque constant and the acceleration multiplied by the equivalent inertia.
  • the inertia of the assembly formed by the motor rotor, gearbox, axles and wheels is not very large compared to the inertia of the robot, the external torque or motor load torque is approximately equal to the internal torque.
  • the internal torque is in turn proportional to the current in the motor stator, so it is possible to work directly with the currents, without the need to calculate the torques, achieving a simplification in the control.

Abstract

The invention relates to a vehicle control method. The inventive method consists in: placing motors in more than one wheel; measuring the angular velocity in each of said wheels with motors; and calculating the load torque of the motors in said wheels. The aforementioned load torques are controlled using a control system in which the velocity of the first wheel is controlled such as to minimise the difference between the velocity of said wheel at a given moment and the pre-determined velocity at the same moment, while ensuring that load torque TI does not exceed limit load torque TI. The torque of the various remaining wheels is controlled such that load torqueTI is less than limit load torque TI* and, in these conditions, TI-TI(TI*/TI), wherein i=2-n and n is the number of wheels with motors, is minimised as much as possible.

Description

TÍTULOTITLE
MÉTODO DE CONTROL DE VEHÍCULOSVEHICLE CONTROL METHOD
SECTOR DE LA TÉCNICA La invención pertenece a la ingeniería de control y a la ingeniería mecánica y se puede utilizar particularmente en vehículos y robots móviles con ruedas.SECTOR OF THE TECHNIQUE The invention pertains to control engineering and mechanical engineering and can be used particularly in vehicles and mobile robots with wheels.
ESTADO DE LA TÉCNICASTATE OF THE TECHNIQUE
Se conoce una solución [(Work space control of a mobile robot using range and contact forcé sensing. D.S. Necsulescu, B. Kim, H. Reynaud. lst IFAC International Workshop. Intelligent Autonomous Nehicles. University of Southampton, Hampshire, United Kingdom. 18-21 april 1993.) (Odometry in determination of the position of an autonomous mobile vehicle. I. Povazan, D. Janglová, L. Uher. Proc. of the Fourth International Symposium on Measurement and Control in Robotics, Smolenice 1995, str. 425-429)] en la que el vehículo utiliza sólo una rueda con motor de tracción. La misma rueda lleva además un motor para el giro. El defecto de esta solución es que con una sola rueda motorizada es posible que no se tenga suficiente fuerza de tracción.A solution is known [(Work space control of a mobile robot using range and contact force sensing. DS Necsulescu, B. Kim, H. Reynaud. L st IFAC International Workshop. Intelligent Autonomous Nehicles. University of Southampton, Hampshire, United Kingdom. April 18-21, 1993.) (Odometry in determination of the position of an autonomous mobile vehicle. I. Povazan, D. Janglová, L. Uher. Proc. Of the Fourth International Symposium on Measurement and Control in Robotics, Smolenice 1995, str 425-429)] in which the vehicle uses only one wheel with traction motor. The same wheel also has a motor for rotation. The defect of this solution is that with a single motorized wheel it is possible that there is not enough traction force.
Se conoce otra solución [(Odometry in determination of the position of an autonomous mobile vehicle. I. Povazan, D. Janglová, L. Uher. Proc. of the Fourth International Symposium on Measurement and Control in Robotics, Smolenice. 1995, str. 425-429), ( Sliding mode control for trajectory tracking of nonholonomic wheeled mobile robots. Jun-Min Yang, Jong-Hwan Kim. IEEE Transactions on Robotics and Automation, Nolume 15 (1999) number 3, pp. 578-587.)] en la que el vehículo utiliza dos ruedas con motores de tracción. Para cambiar la dirección de movimiento del vehículo se utilizan diferentes velocidades en las ruedas con motores. Al igual que en la solución anterior, esta configuración también puede presentar el defecto de fuerza de tracción insuficiente. Se conoce una tercera solución [Arrangement for improved vehicle traction control. Patent Number: GB2354496. Publication date: 2001-03-28. Inventor(s): BURROWS ANDREW JULIÁN (GB)] en la que el motor del vehículo está conectado con cada rueda y se utiliza una transmisión mecánica para la distribución de los pares. El defecto de este sistema se relaciona con una calidad insuficiente del control de la tracción y con la posibilidad de tener condiciones de deslizamiento en una o más ruedas durante el movimiento.Another solution is known [(Odometry in determination of the position of an autonomous mobile vehicle. I. Povazan, D. Janglová, L. Uher. Proc. Of the Fourth International Symposium on Measurement and Control in Robotics, Smolenice. 1995, str. 425-429), (Sliding mode control for trajectory tracking of nonholonomic wheeled mobile robots. Jun-Min Yang, Jong-Hwan Kim. IEEE Transactions on Robotics and Automation, Nolume 15 (1999) number 3, pp. 578-587.) ] in which the vehicle uses two wheels with traction motors. To change the direction of movement of the vehicle, different speeds are used on the wheels with motors. As in the previous solution, this configuration may also have an insufficient tensile force defect. A third solution is known [Arrangement for improved vehicle traction control. Patent Number: GB2354496. Publication date: 2001-03-28. Inventor (s): BURROWS ANDREW JULIÁN (GB)] in which the vehicle's engine is connected to each wheel and a mechanical transmission is used for the distribution of the pairs. The defect of this system is related to insufficient quality of traction control and the possibility of sliding conditions on one or more wheels during movement.
En la solución propuesta más cercana [Traction vehicle/wheel slip and slide control Patent Number: US6152546. Publication date: 2000-11-28. Inventor(s): DAIGLEIn the nearest proposed solution [Traction vehicle / wheel slip and slide control Patent Number: US6152546. Publication date: 2000-11-28. Inventor (s): DAIGLE
JEFFREY LOUIS (US). EC Classification: B60K28/16.] el método de control del vehículo se realiza con motores eléctricos en más de una rueda, midiendo la velocidad angular en cada una de las ruedas con motores y la corriente en los motores para el cálculo del par de carga de los motores en las ruedas, y estos pares se controlan con la ayuda de un sistema de control que varía el valor del voltaje de los motores. La desventaja de esta solución se relaciona con la posibilidad de tener deslizamientos en una o más ruedas. Si el vehículo se mueve sobre superficies inclinadas o se ve sometido a fuerzas externas laterales, la condición de deslizamiento de las ruedas puede provocar una desviación de la trayectoria del vehículo. Además, si se produce deslizamiento resulta imposible calcular la posición del vehículo de acuerdo al ángulo de rotación de las ruedas.JEFFREY LOUIS (US). EC Classification: B60K28 / 16.] The vehicle control method is performed with electric motors on more than one wheel, measuring the angular speed on each of the wheels with motors and the current in the motors for the calculation of the load torque of the motors in the wheels, and these pairs are controlled with the help of a control system that varies the value of the voltage of the motors. The disadvantage of this solution is related to the possibility of sliding on one or more wheels. If the vehicle moves on inclined surfaces or is subjected to external lateral forces, the wheel slip condition may cause a deviation from the vehicle's trajectory. In addition, if slippage occurs, it is impossible to calculate the position of the vehicle according to the angle of rotation of the wheels.
DESCRIPCIÓN DE L INVENCIÓNDESCRIPTION OF THE INVENTION
- Breve descripción de la invención. El método de control del vehículo se realiza con motores en más de una rueda, midiendo la velocidad angular en cada una de las ruedas con motores y calculando el par de carga de los motores en las ruedas, y estos pares se controlan con la ayuda de un sistema de control que se distingue por el hecho de que el control de velocidad de la primera rueda se hace de tal forma que se minimice lo más posible la diferencia entre la velocidad real de esta rueda en ese instante y la velocidad predeterminada en el mismo momento mientras se verifica siempre que el par de carga Tt no sobrepase el par de carga límite T* y el control del par de las diferentes ruedas restantes se realiza de tal manera que el par de carga T¡ sea menor al par de carga límite T y en- Brief description of the invention. The vehicle control method is performed with engines on more than one wheel, measuring the angular speed on each of the wheels with engines and calculating the load torque of the engines on the wheels, and these pairs are controlled with the help of a control system that is distinguished by the fact that the speed control of the first wheel is done in such a way as to minimize as much as possible the difference between the actual speed of this wheel at that time and the predetermined speed therein moment while checking whenever the load torque T t does not exceed the limit load torque T * and the control of the torque of the different remaining wheels is carried out in such a way that the load torque T ¡ is less than the torque limit load T and in
esta condición se intentará minimizar en lo posible Tt -Tx ~ f , donde i = 2- n , y n esThis condition will try to minimize as much as possible T t -T x ~ f, where i = 2- n, and n is
Ά el número de ruedas con motores.Ά the number of wheels with motors.
- Descripción detallada de la invención- Detailed description of the invention
El objetivo de la invención es incrementar la fuerza de tracción, pero en cualquier caso, prevenir el deslizamiento de las ruedas cuando el vehículo se mueve en superficies curvas y/o con irregulares, cuando se ve sometido a fuerzas externas, y especialmente si el coeficiente de fricción entre las ruedas y la superficie no es muy grande.The objective of the invention is to increase the tensile force, but in any case, to prevent the sliding of the wheels when the vehicle moves on curved and / or irregular surfaces, when it is subjected to external forces, and especially if the coefficient of friction between the wheels and the surface is not very large.
La presente invención se puede utilizar en vehículos con ruedas accionadas por cualquier tipo de motor, como por ejemplo, motores de corriente continua, motores de corriente alterna, motores hidráulicos, motores de gasolina o motores de diesel.The present invention can be used in vehicles with wheels driven by any type of motor, such as DC motors, AC motors, hydraulic motors, gasoline engines or diesel engines.
Con propósitos de ilustración, la presente invención se describe aquí aplicada a un robot escalador submarino destinado a la limpieza de los cascos de barcos. Ampliando la descripción, el robot (FIG. 1) incluye un cuerpo principal, tres o cuatro ruedas independientes con motores eléctricos de corriente continua ensambladas a dicho cuerpo, un sistema de control conectado a los motores, con sensores para calcular las velocidades en las ruedas y sensores de corriente en los motores. Cada uno de los motores está sujeto en un eje separado y su rotor está mecánicamente acoplado por medio de reducciones convencionales. El sistema de control será el encargado de modificar el voltaje de cada uno de los motores de tracción. Los sensores de corriente se utilizarán para medir las corrientes en el estator de cada uno de los motores. Los sensores para calcular las velocidades angulares en cada una de las ruedas con motores pueden ser por ejemplo codificadores ópticos. El sistema funciona de la siguiente manera:For purposes of illustration, the present invention is described herein applied to an underwater climber robot intended for cleaning ship hulls. Extending the description, the robot (FIG. 1) includes a main body, three or four independent wheels with direct current electric motors assembled to said body, a control system connected to the motors, with sensors to calculate the wheel speeds and current sensors in the motors. Each of the motors is attached on a separate shaft and its rotor is mechanically coupled by means of conventional reductions. The control system will be responsible for modifying the voltage of each of the traction motors. The current sensors will be used to measure the currents in the stator of each of the motors. The sensors for calculating angular speeds in each of the wheels with motors can be for example optical encoders. System works this way:
Para lograr el objetivo planteado, una de las funciones que se llevan a cabo en el método de control es verificar siempre que los pares de carga de los motores de tracción Tt (para i - \- n , donde n es el número de ruedas con motores) no sobrepasen los pares de carga límite establecidos Tt (véase en la FIG. 2 el par de carga Tt ). Por este motivo se debe determinar previamente y por ejemplo, de forma experimental, el par de carga límite de cada motor Tl . Este par de carga límite está relacionado con la fuerza de fricción y se podría definir como el par a partir del cual se empieza a producir deslizamiento, por lo cual, cualquier par de carga superior al par de carga límite provocaría un deslizamiento de la rueda. Sin embargo, para el control es preferible utilizar un par de carga límite Tl inferior al real T^ de manera que se trabaje con un cierto margen de reserva. Por tanto, para el control se utiliza un porcentaje del par de carga límite medido experimentalmente. Así pues, los pares de carga límites pueden ser iguales para todos los motores de tracción, en cuyo caso se igualarían al menor par límite medido experimentalmente multiplicado por un coeficiente λ, o diferentes, en cuyo caso se igualarían al par límite respectivo medido experimentalmente, multiplicado por el coeficiente λ. El coeficiente λ puede tomar valores entre 0.1 y 1, y la elección de su valor dependerá de las fuerzas externas a las que se encuentre sometido el vehículo, como por ejemplo la acción de la fuerza gravitatoria. De esta forma, si actúan fuerzas externas sobre el vehículo o si las condiciones del entorno son poco conocidas, se recomienda trabajar con una mayor reserva, por lo que se debe seleccionar un valor pequeño de λ. Si por el contrario, el vehículo se mueve en entornos con condiciones muy conocidas no es necesario contar con mucha reserva, por lo que se puede trabajar con un valor grande de λ .To achieve the stated objective, one of the functions carried out in the control method is to always verify that the load pairs of the traction motors T t (for i - \ - n, where n is the number of wheels with motors) do not exceed the established limit load pairs T t (see FIG. 2 for the load torque T t ). For this reason, the limit load torque of each motor T l must be determined previously and for example, experimentally. This torque of limit load is related to the frictional force and could be defined as the torque from which sliding begins to occur, therefore, any torque greater than the limit load torque would cause the wheel to slide. However, for the control it is preferable to use a limit load torque T l lower than the real T ^ so that it works with a certain reserve margin. Therefore, a percentage of the experimentally measured limit load torque is used for the control. Thus, the limit load pairs may be the same for all traction motors, in which case they would be equal to the smallest experimentally measured limit torque multiplied by a coefficient λ, or different, in which case they would be equal to the respective experimentally measured limit torque, multiplied by the coefficient λ. The coefficient λ can take values between 0.1 and 1, and the choice of its value will depend on the external forces to which the vehicle is subjected, such as the action of the gravitational force. In this way, if external forces act on the vehicle or if the surrounding conditions are poorly understood, it is recommended to work with a larger reserve, so a small value of λ must be selected. If, on the contrary, the vehicle moves in environments with well-known conditions, it is not necessary to have a lot of reserve, so it can work with a large value of λ.
A continuación, se elige una de las ruedas como referencia, por ejemplo una rueda delantera. Con uno de los sensores se mide la velocidad real de esta rueda, se compara con una velocidad predeterminada, y con la ayuda del sistema de control se varía el voltaje del motor, de manera que se minimice lo más posible la diferencia entre ambas (tanto como lo permita el par de carga límite T* ). Al mismo tiempo se utiliza un sensor de corriente para medir la corriente en el estator del motor de tracción. Con esta corriente se calcula el par de carga del motor Tx (por ejemplo como se lleva a cabo en U.S. Pat. No. 4,243,927) y se verifica siempre que no sobrepase el par de carga límite T* fijado previamente. Mientras el par de carga del motor -T- esté dentro del límite, el voltaje en las terminales del motor se podrá variar indistintamente según sea necesario para el control de velocidad. En el instante en el que el par de carga del motor Tx empiece a igualar o sobrepasar el límite será necesario reducir el voltaje del motor hasta que el par de carga del motor T iguale el valor del par de carga límite fijado T¡ sin importar las condiciones establecidas por el control de velocidad y mantenerlo hasta el momento en el que el voltaje necesario para mantener la velocidad sea menor al voltaje necesario para soportar el par límite.Next, one of the wheels is chosen as a reference, for example a front wheel. With one of the sensors, the actual speed of this wheel is measured, compared with a predetermined speed, and with the help of the control system the motor voltage varies, so that the difference between the two is minimized as much as possible (as much as the limit load torque T * allows). At the same time a current sensor is used to measure the current in the stator of the traction motor. With this current, the load torque of the motor T x is calculated (for example as it is carried out in US Pat. No. 4,243,927) and is verified as long as it does not exceed the limit load torque T * previously set. While the motor load torque -T- is within the limit, the voltage at the motor terminals may be varied interchangeably as necessary for speed control. When the motor load torque T x begins to equalize or exceed the limit, it will be necessary to reduce the motor voltage until the motor load torque T equals the value of the limit load torque set T ¡ regardless of the conditions established by the speed control and maintain it until such time that the voltage necessary to maintain the speed is less than the voltage necessary to withstand the torque limit.
El control de cualquiera de los motores de tracción de las ruedas restantes se basa en el seguimiento de la rueda de referencia y para ello se realiza el procedimiento que se describe a continuación:The control of any of the traction motors of the remaining wheels is based on the follow-up of the reference wheel and for this the procedure described below is performed:
Con un sensor de corriente se mide la corriente en el estator del motor para calcular el par de carga. Entonces, el control del par minimiza en lo posible la diferencia entre el par de carga del motor de tracción de la rueda a controlar y un porcentaje del par de carga del motor de tracción de la rueda de referencia. Dicho porcentaje vendrá dado por la relación entre el par de carga límite del motor de tracción de la rueda a controlar y el par de carga límite del motor de tracción de la rueda deWith a current sensor, the current in the motor stator is measured to calculate the load torque. Then, torque control minimizes as far as possible the difference between the load torque of the drive motor of the wheel to be controlled and a percentage of the load torque of the drive motor of the reference wheel. Said percentage will be given by the relationship between the torque limit of the traction motor of the wheel to be controlled and the torque limit load of the traction motor of the wheel of
referencia. Por lo tanto, se intentará minimizar en lo posible Tt -Tx -A , parareference. Therefore, we will try to minimize as much as possible T t -T x -A, to
i = 2- n , donde n es el número de ruedas con motores. De esta forma se logra una distribución uniforme de la reserva. Aquí también se puede verificar que el par de carga del motor Tl (para i = 2- n , donde n es el número de ruedas con motores) no sobrepase el par de carga límite r. fijado previamente, aunque en realidad no es necesario, ya que el par de carga del motor de la rueda a controlar tiende a seguir al par de carga del motor de la primera rueda (rueda de referencia), que ya ha sido limitado previamente. i = 2- n, where n is the number of wheels with motors. In this way a uniform distribution of the reserve is achieved. Here it can also be verified that the motor load torque T l (for i = 2- n, where n is the number of wheels with motors) does not exceed the limit load torque r. previously set, although in reality it is not necessary, since the load torque of the wheel motor to be controlled tends to follow the load torque of the first wheel motor (reference wheel), which has already been previously limited.
Adicionalmente, se puede contar con sensores de fuerza colocados en los soportes de algunas o de cada una de las ruedas con motores y conectados al sistema de control. Con la intención de mejorar la calidad del control se pueden utilizar las medidas de fuerza normal obtenidas con dichos sensores durante el proceso de movimiento para determinar el par de carga límite de las ruedas con motores de acuerdo a la siguiente fórmula: r,* = N, μRλ para i = l a /ι (4.2.1) donde T¡ es el par de carga límite para cada uno de los motores de tracción N, es la fuerza normal en cada una de las ruedas con motores μ, es el coeficiente de fricción correspondiente (un valor predeterminado, por ejemplo) R es el radio de las ruedas λ es el coeficiente que puede tomar un valor entre 0.1 y 1.Additionally, force sensors can be placed on the supports of some or each of the wheels with motors and connected to the control system. With the intention of improving the quality of the control, the normal force measurements obtained with these sensors can be used during the movement process to determine the limit load torque of the wheels with motors according to the following formula: r, * = N , μRλ for i = la / ι (4.2.1) where T ¡ is the limit load torque for each of the traction motors N, is the normal force on each of the wheels with μ motors, is the coefficient of corresponding friction (a predetermined value, for example) R is the radius of the wheels λ is the coefficient that can take a value between 0.1 and 1.
También se puede contar con sensores que permitan calcular el coeficiente de fricción durante el proceso de movimiento, colocados en algunas o en cada una de las ruedas con motores y conectados al sistema de control. En la FIG. 3 se muestra uno de estos sensores, que se caracterizan por estar constituidos por una pequeña pieza curva del mismo material de la rueda (10), caucho por ejemplo, y que estará continuamente deslizándose en contacto con la superficie; de un resorte (11) que se deformará adaptándose a las irregularidades de la superficie si existen; una barra de aluminio o de acero con forma de codo (12) que unirá al sensor con el soporte de la rueda (15); y de dos galgas extensiométricas utilizadas como sensores de fuerza, una colocada en el resorte (13), y otra colocada en la barra (14). El coeficiente de fricción se mide entonces, determinando la fuerza requerida para producir el movimiento de un objeto a través de una superficie. Por lo tanto,You can also have sensors that allow you to calculate the coefficient of friction during the movement process, placed on some or each of the wheels with motors and connected to the control system. In FIG. 3 one of these sensors is shown, characterized by being a small curved piece of the same wheel material (10), rubber for example, and which will be continuously sliding in contact with the surface; of a spring (11) that will deform adapting to surface irregularities if they exist; an elbow-shaped aluminum or steel bar (12) that will connect the sensor to the wheel support (15); and two strain gauges used as force sensors, one placed on the spring (13), and another placed on the bar (14). The coefficient of Friction is then measured, determining the force required to produce the movement of an object through a surface. Thus,
E s μ, = - A para ¡ = l a « (4.2.2)E s μ, = - A for ¡= the «(4.2.2)
donde μ, es el coeficiente de fricción de la rueda i FFR S, es la fuerza de fricción en el sensor de la rueda iwhere μ, is the coefficient of friction of the wheel i F FR S , is the frictional force on the wheel sensor i
N, es la fuerza normal en el sensor de la rueda /N, is the normal force on the wheel sensor /
Si la superficie es plana y regular, N, será constante y se podrá determinar experimentalmente. Si por el contrario, la superficie es irregular, el resorte se deformará adaptándose a las irregularidades y N. será igual a la fuerza medida por el sensor de fuerza (13) colocado en el resorte. Por otro lado, la fuerza de fricción del sensor FFR S, vendrá dada por la medida del segundo sensor de fuerza (14) colocado en la barra. Entonces, se utilizan los valores resultantes μ, en la fórmulaIf the surface is flat and regular, N will be constant and can be determined experimentally. If, on the contrary, the surface is irregular, the spring will deform adapting to the irregularities and N. will be equal to the force measured by the force sensor (13) placed in the spring. On the other hand, the frictional force of the F FR S sensor will be given by the measurement of the second force sensor (14) placed on the bar. Then, the resulting values μ are used in the formula
(4.2.2) para mejorar aún más la calidad del control.(4.2.2) to further improve the quality of control.
En algunos casos en los que la inercia equivalente (es decir, la inercia del conjunto formado por el rotor del motor, la caja de reducciones, los ejes y las ruedas) no es muy grande comparada con la inercia del cuerpo del vehículo es posible trabajar directamente con las corrientes, sin necesidad de calcular los pares, con lo que se logra una simplificación en el control.In some cases where the equivalent inertia (that is, the inertia of the assembly formed by the motor rotor, gearbox, axles and wheels) is not very large compared to the inertia of the vehicle body it is possible to work directly with the currents, without the need to calculate the pairs, thus achieving a simplification in the control.
EXPLICACIÓN DETALLADA DE LOS DD3UJOSDETAILED EXPLANATION OF THE DD3UJOS
A continuación se describe detalladamente la invención por medio de dos ejemplos y haciendo referencia a las figuras adjuntas, en las que FIG. 1 es un diagrama simplificado de los principales componentes del sistema de control instalado en el robot móvil. FIG. 2 muestra el par de carga Tt del motor de tracción de una rueda. FIG. 3 muestra los componentes principales del sensor utilizado para el cálculo del coeficiente de fricción.The invention is described in detail below by means of two examples and referring to the attached figures, in which FIG. 1 is a simplified diagram of the main components of the control system installed in the mobile robot. FIG. 2 shows the load torque T t of the one wheel drive motor. FIG. 3 shows the main components of the sensor used to calculate the coefficient of friction.
FIG. 4 es una gráfica de la velocidad angular con respecto al tiempo. FIG. 5 es un diagrama simplificado de los principales componentes del sistema de control instalado en el robot móvil del ejemplo 1.FIG. 4 is a graph of angular velocity with respect to time. FIG. 5 is a simplified diagram of the main components of the control system installed in the mobile robot of example 1.
FIG. 6 es un diagrama simplificado de los principales componentes del sistema de control instalado en el robot móvil del ejemplo 2.FIG. 6 is a simplified diagram of the main components of the control system installed in the mobile robot of example 2.
I . Primera rueda delantera 2. Segunda rueda delanteraI. First front wheel 2. Second front wheel
3. Primera rueda trasera3. First rear wheel
4. Segunda rueda trasera4. Second rear wheel
5. Sistema de control5. Control system
6. Algoritmos de control 7. Motor de tracción de una rueda6. Control algorithms 7. Single wheel drive motor
8. Eje del motor de tracción8. Drive motor shaft
9. Caja de reducción9. Reduction box
10. Pieza del mismo material de la rueda10. Part of the same wheel material
I I . Resorte 12. Barra con forma de codaI I. Spring 12. Coda-shaped bar
13. Primer sensor de fuerza13. First force sensor
14. Segundo sensor de fuerza14. Second force sensor
15. Soporte de la rueda 15. Wheel support
EJEMPLO DE REALIZACIÓN DE LA INVENCIÓN.EXAMPLE OF EMBODIMENT OF THE INVENTION.
Ejemplo 1Example 1
La presente invención se describe aquí aplicada a un robot escalador submarino destinado a la limpieza de los cascos de barcos. El robot de la FIG. 4 incluye un cuerpo principal, tres ruedas independientes con motores de corriente continua ensambladas a dicho cuerpo, una delantera (1) y dos traseras (3-4), un sistema de control (5) conectado a los motores, con sensores C1-C3 para calcular las velocidades en cada una de las ruedas y sensores de corriente 11-13 en los motores. Además de los motores para la tracción M1-M3, la rueda delantera (1) puede llevar otro motor eléctrico M4 que permita el giro del robot. Cada uno de los motores está sujeto en un eje separado y su rotor está mecánicamente acoplado por medio de reducciones convencionales. El sistema de control (5) podrá modificar independientemente el voltaje de cada uno de los motores de tracción M1-M3. Para lograrlo, una de las funciones que se llevan a cabo en el método de control es verificar siempre que los pares de carga de los motores de tracción Tx , T2 , T3 no sobrepasen los pares de carga límite establecidos T* , T2 * , T3 , es decir, Tx < T* ,The present invention is described herein applied to an underwater climber robot intended for cleaning ship hulls. The robot of FIG. 4 includes a main body, three independent wheels with DC motors assembled to said body, a front (1) and two rear (3-4), a control system (5) connected to the motors, with C1-C3 sensors to calculate the speeds in each of the wheels and 11-13 current sensors in the motors. In addition to the M1-M3 traction motors, the front wheel (1) can carry another M4 electric motor that allows the robot to rotate. Each of the motors is attached on a separate shaft and its rotor is mechanically coupled by means of conventional reductions. The control system (5) may independently modify the voltage of each of the M1-M3 traction motors. To achieve this, one of the functions carried out in the control method is to verify that the load torque of the traction motors T x , T 2 , T 3 does not exceed the established limit load pairs T * , T 2 * , T 3 , that is, T x <T * ,
T2 < T2 y T3 < T* . Por este motivo se determina previamente y de forma experimental, el par de carga límite de cada motor: TX E = 50Nm, T2 ε = 60Nm yT 2 <T 2 and T 3 <T * . For this reason, the limit load torque of each motor is determined previously and experimentally: T X E = 50Nm, T 2 ε = 60Nm and
T3 = 55 Nm. Sin embargo para el control es preferible utilizar un par límite inferior al real de manera que se trabaje con un cierto margen de reserva. Por tanto, para el control se utiliza un porcentaje del par límite medido experimentalmente. Así pues, los pares de carga límites pueden ser iguales para todos los motores de tracción, en cuyo caso se igualarían al menor par límite medido experimentalmente (Tx ε ) multiplicado por el coeficiente λ, T¡ =T2 =T3 =TX E - X (El .l) o diferentes, en cuyo caso se igualarían al par límite respectivo medido experimentalmente, multiplicado por el coeficiente λT 3 = 55 Nm. However, for the control it is preferable to use a lower limit than the real one so that it works with a certain reserve margin. Therefore, a percentage of the experimentally measured limit torque is used for the control. Thus, the limit load pairs can be the same for all traction motors, in which case they would be equal to the smallest experimentally measured limit torque (T x ε ) multiplied by the coefficient λ, T¡ = T 2 = T 3 = T X E - X (El .l) or different, in which case they would be equal to the respective experimentally measured limit pair, multiplied by the coefficient λ
Tx = TχA (El.2)T x = T χ A (El.2)
T2 =T2A τ; =τ3AT 2 = T 2 A τ; = τ 3 A
Debido a que el robot escalador submarino se encuentra sometido a varias fuerzas externas se selecciona λ= 0.5.Because the underwater climber robot is subjected to several external forces, λ = 0.5 is selected.
A continuación, se elige la rueda frontal como referencia. Con el sensor Cl se mide la velocidad real o, de esta rueda en ese instante, se compara con una velocidad predeterminada co , y con la ayuda del sistema de control se varía el voltaje del motor, de manera que se minimice lo más posible la diferencia entre ambas (tanto como lo permita el par de carga límite Tx ). Al mismo tiempo se utiliza el sensor de corriente II para medir la corriente en el estator del motor de tracción MI. Con esta corriente se calcula el par de carga del motor T y se verifica siempre que no sobrepase el par límite T* fijado previamente. En la FIG. 5 se aprecia que la velocidad se puede variar indistintamente según sea necesario mientras el par de carga del motor Tx esté dentro del límite. En el instante A en el que el par de carga del motor T¡ empieza a igualar o sobrepasar el par de carga límite fijado se hace necesario reducir el voltaje del motor hasta que el par de carga del motor Tx iguale el valor del par de carga límite fijado T* sin importar las condiciones establecidas por el control de velocidad y se mantiene hasta el momento B en el que el voltaje necesario para mantener la velocidad es menor al voltaje necesario para soportar el par límite establecido. El sistema de control se encargará además de avisar al operador de la reducción de velocidad llevada a cabo a partir del instante A. El hecho de que no se pueda seguir el patrón de velocidad predefinido no implica una desventaja o inconveniente, ya que para el robot escalador submarino destinado a la limpieza de cascos de barco, una velocidad menor a la establecida se traducirá en un mayor tiempo de limpieza de una misma superficie.Next, the front wheel is chosen as a reference. With the Cl sensor, the actual speed is measured or, at this moment, this wheel is compared with a predetermined speed r rε , and with the help of the control system the motor voltage is varied, so as to minimize as much as possible the difference between the two (as much as the limit load torque T x allows). At the same time the current sensor II is used to measure the current in the stator of the traction motor MI. With this current, the load torque of the motor T is calculated and verified as long as it does not exceed the limit torque T * previously set. In FIG. 5 it is appreciated that the speed can be varied interchangeably as necessary while the engine load torque T x is within the limit. At the instant A in which the load torque of the motor T ¡ begins to equal or exceed the set limit load torque, it is necessary to reduce the motor voltage until the motor load torque T x equals the torque value. fixed limit load T * regardless of the conditions established by the speed control and is maintained until the moment B in which the voltage necessary to maintain the speed is less than the voltage necessary to support the established limit torque. The control system will also be in charge of notifying the operator of the speed reduction carried out from the moment A. The fact that the predefined speed pattern cannot be followed does not imply a disadvantage or inconvenience, since for the robot Underwater climber intended for cleaning ship hulls, a lower speed than the established one will result in a longer cleaning time of the same surface.
El control de los motores de tracción M2 y M3 se basa en el seguimiento de la rueda de referencia. A continuación se describe el procedimiento para el motor M2: El sistema de control utiliza la corriente medida en el estator del motor M2 con el sensor de corriente 12 y aceleración de la rueda 2 derivada de la velocidad real co. medida con el sensor C2 para calcular el par de carga T2 , que vendrá dado por la diferencia entre la corriente multiplicada por la constante de par y la aceleración multiplicada por la inercia equivalente.The control of the M2 and M3 traction motors is based on the tracking of the reference wheel. The procedure for the M2 motor is described below: The control system uses the current measured in the M2 motor stator with the current sensor 12 and acceleration of the wheel 2 derived from the actual speed co. measured with the C2 sensor to calculate the load torque T 2 , which will be given by the difference between the current multiplied by the torque constant and the acceleration multiplied by the equivalent inertia.
Entonces, el control del par minimiza en lo posible T2 -Tx - • De esta forma seThen, the torque control minimizes as much as possible T 2 -T x - • This way
-* . logra una distribución uniforme de la reserva.- *. achieves a uniform distribution of the reserve.
Aquí también se puede verificar que el par de carga del motor T2 no sobrepase el par límite T * fijado previamente, aunque en realidad no es necesario, ya que el par de carga T2 tiende a seguir al par de carga de la primera rueda Tx , que ya ha sido limitado anteriormente. Para el control del motor de tracción M3 se realiza exactamente el mismo procedimiento.Here you can also verify that the load torque of the T 2 motor does not exceed the previously set limit torque T * , although in reality it is not necessary, since the load torque T 2 tends to follow the load torque of the first wheel T x , which has been previously limited. For the control of the M3 drive motor, exactly the same procedure is performed.
Ejemplo 2Example 2
La presente invención se describe aquí aplicada a un robot escalador submarino destinado a la limpieza de los cascos de barcos. El robot (FIG. 6) incluye un cuerpo principal, cuatro ruedas independientes con motores de corriente continua ensambladas a dicho cuerpo, dos delanteras (1, 2) y dos traseras (3, 4), un sistema de control (5) conectado a los motores, con sensores C1-C4 para calcular las velocidades en cada una de las ruedas, sensores de corriente 11-14 en los motores, sensores de fuerza N1-N4 colocados en los soportes de las ruedas y sensores que permiten calcular el coeficiente de fricción en cada una de las ruedas CF1-CF4. Además de los motores para la tracción M1-M4, la rueda delantera (1) puede llevar otro motor eléctrico M5 que permita el giro del robot. Cada uno de los motores está sujeto en un eje separado y su rotor está mecánicamente acoplado por medio de reducciones convencionales. El sistema de control podrá modificar independientemente el voltaje de cada uno de los motores de tracción M1-M4.The present invention is described herein applied to an underwater climber robot intended for cleaning ship hulls. The robot (FIG. 6) includes a main body, four independent wheels with DC motors assembled to said body, two front (1, 2) and two rear (3, 4), a control system (5) connected to the motors, with C1-C4 sensors to calculate the speeds in each of the wheels, current sensors 11-14 in the motors, force sensors N1-N4 placed in the wheel supports and sensors that allow to calculate the coefficient of friction on each of the CF1-CF4 wheels. In addition to the M1-M4 traction motors, the front wheel (1) can carry another M5 electric motor that allows the robot to rotate. Each of the motors is fastened on a separate shaft and its rotor is mechanically coupled by means of conventional reductions. The control system may independently modify the voltage of each of the M1-M4 traction motors.
Con los sensores de fuerza N1-N4 se mide la fuerza normal en cada una de las ruedas con motores Nx , N2 , N3 , N4 durante el proceso de movimiento del robot. Los sensores CF1-CF4 están constituidos por una pequeña pieza curva del mismo material de la rueda y que está continuamente deslizándose en contacto con la superficie; de un resorte que se deforma adaptándose a las irregularidades de la superficie si existen; de una barra de aluminio con forma de codo que une al sensor con el soporte de la rueda; y de dos galgas extensiométricas utilizadas como sensores de fuerza. La primera galga colocada en el resorte que se deforma adaptándose a las irregularidades de la superficie, mide la fuerza normal de los sensores en cada una de las ruedas Nx s , N2 S , N3 y N4 5. La segunda galga colocada en la barra, mide la fuerza de fricción de los sensores en cada una de las ruedas FFR Sι , FFR S2 , FFR S¡ y E Λ S4 . Los valores obtenidos permiten calcular el coeficiente de fricción en cada una de las ruedas μ , μ. , , durante el proceso del movimiento de la siguiente forma:With the N1-N4 force sensors, the normal force on each of the wheels is measured with N x , N 2 , N 3 , N 4 motors during the robot's movement process. The CF1-CF4 sensors consist of a small curved piece of the same wheel material and that is continuously sliding in contact with the surface; of a spring that deforms adapting to surface irregularities if they exist; of an elbow-shaped aluminum bar that joins the sensor with the wheel support; and two strain gauges used as force sensors. The first gauge placed on the spring that deforms adapting to the irregularities of the surface, measures the normal force of the sensors on each of the wheels N x s , N 2 S , N 3 and N 4 5 . The second gauge placed on the bar measures the frictional force of the sensors on each of the wheels F FR S ι, F FR S 2, F FR S ¡and E Λ S 4. The obtained values allow to calculate the coefficient of friction in each of the wheels μ, μ. ,, during the movement process as follows:
E s, μ = FR ' para i = 1 a 4E s , μ = FR 'for i = 1 to 4
N,s N, s
Las medidas de fuerza normal N, , N2 , N3 , N4 obtenidas con los sensores Ν1-Ν4 y los valores calculados μ , μ , μs , μ con ayuda de los sensores CF1-CF4 se utilizan para determinar el par de carga límite de cada una de las ruedas con motores de acuerdo a la fórmula: r,* = N,μRλ para í = l a 4 donde T* es el par de carga límite para cada uno de los motores M1-M4The normal force measurements N,, N 2 , N 3 , N 4 obtained with the sensors Ν1-Ν4 and the calculated values μ, μ, μ s , μ with the help of the CF1-CF4 sensors are used to determine the torque of limit load of each of the wheels with motors according to the formula: r, * = N, μRλ for í = 4 where T * is the torque limit for each of the M1-M4 engines
N, es la fuerza normal en cada una de las ruedas con motores μ es el coeficiente de fricción en cada una de las ruedas R es el radio de las ruedas λ es el coeficiente que puede tomar un valor entre 0.1 y 1.N, is the normal force on each of the wheels with motors μ is the coefficient of friction on each of the wheels R is the radius of the wheels λ is the coefficient that can take a value between 0.1 and 1.
Εl sistema de control verifica siempre que los pares de carga de los motores de tracción Tx , T2 , T3 , T4 no sobrepasen los pares de carga límite T¡ * , T * , T* , T4 * es decir, Tλ < Tx , T2 < T2 , T3 < T* y T4 < T4 . A continuación, se elige la rueda frontal (1) como referencia. Con el sensor Cl se mide la velocidad real o, de esta rueda en ese instante, se compara con una velocidad predeterminada ωref , y con la ayuda del sistema de control se varía el voltaje del motor, de manera que se minimice lo más posible la diferencia entre ambas (tanto como lo permita el par de carga límite Tx ). Al mismo tiempo se utiliza el sensor de corriente II para medir la corriente en el estator del motor de tracción MI. Con esta corriente se calcula el par de carga del motor 7¡ y se verifica siempre que no sobrepase el par de carga límite calculado T* .The control system always checks that the load torques of the traction motors T x , T 2 , T 3 , T 4 do not exceed the limit load torques T ¡ * , T * , T * , T 4 * that is, T λ <T x , T 2 <T 2 , T 3 <T * and T 4 <T 4 . Next, the front wheel (1) is chosen as a reference. With the Cl sensor, the actual speed is measured or, at this moment, this wheel is compared with a predetermined speed ω ref , and with the help of the control system the motor voltage is varied, so that it is minimized as much as possible the difference between the two (as much as the limit load torque T x allows). At the same time the current sensor II is used to measure the current in the stator of the traction motor MI. With this current, the load torque of the motor 7 is calculated and verified whenever the calculated limit load torque T * is not exceeded.
El control de los motores de tracción M2, M3 y M4 se basa en el seguimiento de la rueda de referencia. A continuación se describe el procedimiento para el motor M2: El sistema de control utiliza la corriente medida en el estator del motor M2 con el sensor de corriente 12 y aceleración de la rueda 2 derivada de la velocidad real c^ medida con el sensor C2 para calcular el par de carga T2 , que vendrá dado por la diferencia entre la corriente multiplicada por la constante de par y la aceleración multiplicada por la inercia equivalente.The control of the M2, M3 and M4 traction motors is based on the tracking of the reference wheel. The procedure for the M2 motor is described below: The control system uses the current measured in the stator of the M2 motor with the current sensor 12 and acceleration of the wheel 2 derived from the actual speed c ^ measured with the C2 sensor for Calculate the load torque T 2 , which will be given by the difference between the current multiplied by the torque constant and the acceleration multiplied by the equivalent inertia.
Entonces, el control del par minimiza en lo posible T2 -Tx - r* • De esta forma seThen, torque control minimizes as much as possible T 2 -T x - r * • This way you
- logra una distribución uniforme de la reserva. Aquí también se puede verificar que el par de carga del motor T2 no sobrepase el par límite T * fijado previamente, aunque en realidad no es necesario, ya que el par de carga T2 tiende a seguir al par de carga de la primera rueda Tx , que ya ha sido limitado anteriormente.- achieves a uniform distribution of the reserve. Here you can also verify that the load torque of the T 2 motor does not exceed the previously set limit torque T * , although in reality it is not necessary, since the load torque T 2 tends to follow the load torque of the first wheel T x , which has been previously limited.
Para el control de los motores de tracción M3 y M4 se realiza exactamente el mismo procedimiento.For the control of the M3 and M4 traction motors, exactly the same procedure is performed.
Como en este caso la inercia del conjunto formado por el rotor del motor, la caja de reducciones, los ejes y las ruedas no es muy grande comparada con la inercia del robot, el par extemo o par de carga del motor es aproximadamente igual al par interno. El par interno es a su vez proporcional a la corriente en el estator del motor, por lo que es posible trabajar directamente con las corrientes, sin necesidad de calcular los pares, lográndose una simplificación en el control. As in this case, the inertia of the assembly formed by the motor rotor, gearbox, axles and wheels is not very large compared to the inertia of the robot, the external torque or motor load torque is approximately equal to the internal torque. The internal torque is in turn proportional to the current in the motor stator, so it is possible to work directly with the currents, without the need to calculate the torques, achieving a simplification in the control.

Claims

REEWTNDICACIONES REEWTNDICATIONS
1. El método de control del vehículo se realiza con motores en más de una rueda midiendo la velocidad angular en cada una de las ruedas con motores, y calculando el par de carga de los motores en las ruedas, y estos pares se controlan con la ayuda de un sistema de control que se distingue por el hecho de que el control de velocidad de la primera rueda se hace de tal forma que se minimice lo más posible la diferencia entre la velocidad real de esta rueda en ese instante y la velocidad predeterminada en el mismo momento mientras se verifica siempre que el par de carga Tx no sobrepase el par de carga límite establecido 7¡* y el control del par de las diferentes ruedas restantes se realiza de tal manera que el par de carga Tl sea menor al par de carga límite establecido Tt 1. The vehicle control method is performed with engines on more than one wheel by measuring the angular speed on each of the wheels with engines, and calculating the load torque of the engines on the wheels, and these pairs are controlled with the help of a control system that is distinguished by the fact that the speed control of the first wheel is done in such a way as to minimize as much as possible the difference between the actual speed of this wheel at that moment and the predetermined speed in the same moment while verifying that the load torque T x does not exceed the established limit load torque 7¡ * and the control of the torque of the different remaining wheels is carried out in such a way that the load torque T l is less than set limit load torque T t
y en esta condición se intentará minimizar en lo posible T¡ -T - tL τ , dondeand in this condition an attempt will be made to minimize as much as possible T ¡ -T - t L τ , where
i = 2- n , y n es el número de ruedas con motores.i = 2- n, and n is the number of wheels with motors.
2. El método de control del vehículo descrito en el número 1 se distingue por el hecho de que se realiza la medición experimental del par de carga límite Tt E para cada una de las ruedas con motores y se elige Tt de manera que sea igual al menor Tι medido, multiplicado por un coeficiente cuyo valor no es mayor que 1 ni menor que 0.1, siendo i = l- n .2. The vehicle control method described in No. 1 is distinguished by the fact that the experimental measurement of the limit load torque T t E is performed for each of the wheels with motors and T t is chosen to be equal to the smallest T ι measured, multiplied by a coefficient whose value is not greater than 1 or less than 0.1, where i = l- n.
3. El método de control del vehículo descrito en el número 1 se distingue por el hecho de que T¡ se iguala a _T, multiplicado por un coeficiente cuyo valor no es mayor que 1 ni menor a 0.1 , siendo i = \- n .3. The control method of the vehicle described in item 1 distinguished by the fact that T It equals _T, multiplied by a coefficient whose value is greater than 1 or less than 0.1, where i = \ - n.
4. El método descrito en el número 1 se distingue por el hecho de que durante el proceso de movimiento del vehículo se supervisa la fuerza normal N, de cada una de las ruedas con motores y se utiliza para la limitación del par de acuerdo a la siguiente fórmula:4. The method described in No. 1 is distinguished by the fact that during the movement of the vehicle the normal force N of each of the wheels with motors is monitored and used to limit the torque according to the following formula:
T* = N,μRλ para ¿ = 1 a n donde T* es el par de carga límite para cada uno de los motores N. es la fuerza normal en cada una de las ruedas con motores μ, es el coeficiente de fricción correspondienteT * = N, μRλ for ¿= 1 an where T * is the limit load torque for each of the motors N. is the normal force on each of the wheels with μ motors, it is the corresponding coefficient of friction
R es el radio de las ruedas λ es el coeficiente que puede tomar un valor entre 0.1 y 1.R is the radius of the wheels λ is the coefficient that can take a value between 0.1 and 1.
5. El método descrito en el número 4 se distingue por el hecho de que durante el proceso de movimiento del vehículo se supervisa el coeficiente de fricción para cada rueda y el valor resultante μ se utiliza en la fórmula mencionada.5. The method described in No. 4 is distinguished by the fact that during the vehicle movement process the friction coefficient for each wheel is monitored and the resulting value μ is used in the aforementioned formula.
6. Los dispositivos necesarios para la realización de los métodos 1-5 son un vehículo con ruedas y no menos de 2 motores eléctricos conectados a estas ruedas, un sistema de control conectado a los motores y sensores de velocidad en las ruedas y sensores de corriente en los motores, y se distingue por el hecho de contar adicionalmente con sensores de fuerza normal y sensores de coeficiente de fricción para cada rueda con motor y conectados al sistema de control. 6. The devices necessary for performing the 1-5 methods are a vehicle with wheels and not less than 2 electric motors connected to these wheels, a control system connected to the motors and speed sensors on the wheels and current sensors in the engines, and it is distinguished by the fact of having additionally normal force sensors and friction coefficient sensors for each motor wheel and connected to the control system.
PCT/ES2002/000509 2001-11-02 2002-10-31 Vehicle control method WO2003038387A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5419624A (en) * 1990-11-24 1995-05-30 Mannesmann Aktiengesellschaft Arrangement for detecting a critical driving torque in a motor vehicle
EP0748730A1 (en) * 1995-06-14 1996-12-18 Japan Electronics Industry, Ltd. Control method for antilock braking systems with stress sensor
US6151546A (en) * 1997-08-07 2000-11-21 Robert Bosch Gmbh Method and device for controlling traction in motor vehicles
US6152546A (en) * 1997-02-12 2000-11-28 General Electric Company Traction vehicle/wheel slip and slide control
GB2354496A (en) * 1999-08-04 2001-03-28 Rover Group Arrangement for improved vehicle traction control

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5419624A (en) * 1990-11-24 1995-05-30 Mannesmann Aktiengesellschaft Arrangement for detecting a critical driving torque in a motor vehicle
EP0748730A1 (en) * 1995-06-14 1996-12-18 Japan Electronics Industry, Ltd. Control method for antilock braking systems with stress sensor
US6152546A (en) * 1997-02-12 2000-11-28 General Electric Company Traction vehicle/wheel slip and slide control
US6151546A (en) * 1997-08-07 2000-11-21 Robert Bosch Gmbh Method and device for controlling traction in motor vehicles
GB2354496A (en) * 1999-08-04 2001-03-28 Rover Group Arrangement for improved vehicle traction control

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