DE4201142A1 - Vehicle speed controller for vehicle with navigation system - Google Patents

Abstract

The vehicle speed controller contains a vehicle speed sensor and a controller which receives information about the curve of the road along which the vehicle is moving as indicated by the navigation system. The controller computes the maximum speed at which the vehicle can safely take the curve taking account of the measured speed and curve information. The controller either gives a warning or reduces the vehicle speed when the speed exceeds the maximum safe value.

Description

The invention relates to a navigation system for motor vehicles witness and relates in particular to an automobile driving Tool navigation system, which has the feature that a vehicle speed when cornering is controlled.

In recent years, different types of automa table-controlled, electronic driving systems known which have been developed to enable drivers to move, drive safely and comfortably, independently of their driving technique and driving experience. For example automatically delay vehicle distance control devices a motor vehicle and give an alarm if that force vehicle a distance from the vehicle in front comes, which is shorter than a safety distance, which corresponds to a vehicle speed at which the Motor vehicle is currently driving. Such a vehicle distance Control device is for example from the Japanese Patent publication 57 (1982) -1 55 700 is known. The driving tool distance control device according to this publication the vehicle's own speed and the Distance between the vehicle and a vehicle in front Vehicle and compares the distance with a security distance, which is appropriate for the vehicle speed is.

To increase driving safety, the vehicles must be controlled in such a way that a safety speed depending on the road conditions as well as a safety distance between two vehicles are maintained. For example, if a vehicle is driving on a straight line at a relatively high speed before a sharp turn and wants to drive out of the curve, the vehicle speed should be reduced to a suitable approach speed before the vehicle enters the curve, which speed is below the cruising speed is corresponding to a radius of a sharp curve before a curve approach point is reached. If the vehicle enters the sharp curve 21 at a higher speed than the appropriate approach speed VB, it may be carried out of the curve by a centrifugal force which increases inversely in proportion to the curve radius with the square of the vehicle speed. However, if a curve on the way is confusing or blind, it is difficult to estimate the radius of the blind curve. If a curve is icy or wet on the way, even though it is clearly overlooked to estimate the radius of the curve, safe driving is only guaranteed if a vehicle enters the curve at a speed lower than that which can be estimated visually if only the curve radius is taken into account. Such an estimation of a radius and a speed is difficult to carry out with sufficient accuracy and speed while driving.

The invention is based on the disclosure of a vehicle speed control device for a vehicle create which is suitable for the vehicle speed automatically control when the vehicle is in a Entering the curve.  

This object is achieved according to the invention in that a vehicle speed control device for a Vehicle is created, which with the support ei Nes vehicle navigation system works to the location of a Display vehicle on a road map on a road map Screen is displayed while the vehicle is traveling with information about the street including Curves is delivered. The vehicle speed tax device receives information about a curve of a Road, for example over the radius of curvature, on wel cher the vehicle drives when the vehicle navigation system stem a vehicle location on a road before the curve shows, and it becomes a vehicle limit speed calculates with which the vehicle exits the curve and can drive safely through the curve. The calculation takes place based on the vehicle speed and the bend radius of the curve. If the vehicle speed is higher than the vehicle speed limit, the Vehicle speed control device a warning and / or brakes the vehicle automatically or closes auto matically a throttle valve of the vehicle, so that the driving speed below the limit speed is set.

The invention is described below, for example, using the Drawing described; in this show:

Fig. 1 is a block diagram of a vehicle speed control device according to a preferred embodiment of the invention;

FIG. 2 is a block diagram illustrating a vehicle navigation system using a global positioning satellite system in connection with the vehicle speed control device shown in FIG. 1;

Fig. 3 is a block diagram illustrating a Fahrzeugort- detector means;

Fig. 4 and Fig. 5 representations of the principles of the vehicle location;

FIG. 6 is a flowchart illustrating an operation sequence of the vehicle navigation system shown in FIG. 2;

Fig. 7 is a flowchart illustrating a vehicle speed control sequence of the vehicle speed control device shown in Fig. 1;

Fig. 8 is an illustration of the operation of the vehicle speed control device shown in Fig. 1 and

Fig. 9 is a block diagram of He illustrates a Fahrzeugge speed controller according to another preferred embodiment of the invention.

According to the drawing and in particular according to FIG. 1, a vehicle speed control device according to a preferred embodiment of the invention, which cooperates with a vehicle navigation system, has a vehicle speed control unit 23 . The vehicle speed control unit 23 receives signals which are representative of the road condition, for example the road temperature and the humidity as well as the vehicle speed, the signals being supplied by a temperature sensor 29 , a humidity sensor 25 and a speed sensor 24 . The vehicle speed control unit 23 also receives signals from a vehicle navigation system 22 so that the necessary information about the road, which is required to guide the vehicle to a desired destination, is displayed on a screen 6 , for example on a screen Liquid crystal display device which is arranged in an instrument panel of the vehicle. On the basis of the signals and information from the sensors 24 , 25 and 29 and from the vehicle navigation system 22 , the vehicle speed control unit 23 actuates various elements, for example a brake actuating element 26 , a throttle valve actuating element 27 and a warning device.

The vehicle navigation system 22 is shown in FIG. 2 Darge. USAGE The vehicle navigation system of FIG. 2 det a bottom-creeping Positioning System (grovel Positioning System), in which position data from a satellite ge be transmitting. The vehicle navigation system 22 has a navigation control unit 10 which has a central computer 11 (CPU), a read-only memory 12 (ROM) for receiving a control program and a memory with direct access 13 (RAM) for receiving various control data. The central computer 11 is connected via a matching device 14 to various external units, which will be described later, in order to be able to exchange information between them. As external or external units with the navigation control unit 10 in the vehicle, a CD player 2 , a control switch unit 3 , a vehicle sensor 4 , a liquid crystal display 6 and an audio unit 9 are connected. The CD turntable 2 , which is connected to the navigation control unit 10 via a decoder 8 , drives a disk 1 (CD-ROM) as a read-only memory in which a large number of road maps are stored, which are of different sizes and reduced scale are stored and have access to disk 1 (CD-ROM) at a predetermined address defined by a length Y and a width X so that a desired road map can be read from disk 1 (CD-ROM) and the data of the desired road map on the one hand to the central computer 11 via the decoder 8 and the adapting device 14 and on the other hand the audio unit 9 can be transmitted. The data for the central computer 11 are temporarily stored in the memory 13 with direct access. The control switch unit 3 , which is connected to the navigation control unit 10 via an encoder 16 , is used to set, reset and change a specific destination, change a desired route and to change the command to display a specific map . The audio unit 9 , which is connected to the CD turntable 2 via the decoder 8 , has an amplifier, an equalizer, a loudspeaker, etc. The liquid crystal display device 6 , which is connected to the navigation control unit 10 via a display driver circuit 5 with a video memory 7 , illustrates a video image of a card which is read by the CD player 2 from the disk 1 (CD-ROM) . The vehicle location sensor 4 , which is connected directly to the navigation control unit 10 , determines a point Pn in the sense of width Xn and length Yn, where the vehicle is currently located.

In disk 1 (CD-ROM), the data of details of, for example, about 30,000 colored road maps are stored, corresponding to 15,000 sets of colored road maps, each set of maps of different sizes being reduced. The road map data includes at least details of roads, for example in the form of radii for curves, curvatures, bends and the like, in contrast to colored images.

The display switch unit 3 , which can be arranged as a switch device on a screen or can be designed in any other known manner, has various switch functions, for example as a menu display, information display, destination reset, enlarged map display, normal sizes - Map display, point display and correction. Commands which are entered via the display switch unit 3 are encoded by the encoder 6 and then fed to the central computer 11 of the navigation control unit 10 via the adapter 14 . Depending on the commands, the central computer 11 carries out the necessary processing, for example to cause the display driver circuit 5 to display an image on the liquid crystal display device 6 .

As shown in FIG. 3 in detail, the vehicle location sensor 4 has an extrapolation navigation system in the form of a first location sensor device 4 A, which uses the earth's magnetism and a ground-creep-positioning navigation system in the form of a second location sensing means 4 B. the first vehicle location sensing means 4 a for example, has a terrestrial or geomagnetic sensor 41, for example, a flow gate to determine the terrestrial magnetism a location at which the vehicle is traveling, a vehicle speed sensor 42, which serves a To determine speed in the form of the rotation of a wheel, from which the vehicle speed and a covered distance can be determined, further a processing circuit 43 , the operation of which is explained below in connection with FIG. 4, and which serves to point Pn in Form of latitude Xn and longitude Yn to determine where the vehicle is currently in place by determining a distance D from a reference point Po (Xo, Yo) and a direction of the vehicle. This is done so that the position of a point in relation to another point can easily be determined from the exact distance between the two points and a direction in which the one point is oriented.

In order to understand the basic principle that is used to find a position of a point relative to another point, consider a vehicle A that considers the position of a point A 1 as the starting point or reference point Po is going to another point An as the target point Pn, namely via the points A 2 , A 3 ,. . ., A 9 , as shown in FIG. 4, where in one direction (d) through the geomagnetic sensor 41 at any predetermined distance (A 1 -A 2 , A 2 -A 3 , A 3 -A 4 ,. ., A 9 -An) of 5 m, for example, is determined, which is derived from the number of wheel revolutions, which is sensed by the vehicle speed sensor 42 . Because of the distance or the distance (D) and the direction (d) of each point A 2 , A 3 ,. . ., or On, a coordinate transformation is carried out relative to each preceding point in order to find the coordinates of the point in an orthogonal coordinate system, the east-west direction being the X coordinate axis and the north-south direction being the Y- Serve coordinate axis. A distance or a distance Dx between two adjacent points in the east-west direction is then determined from an equation Dx = Dcosd. Similarly, a distance or a distance Dy between two adjacent points in the north-south direction is calculated from an equation Dy = Dsind. The coordinates (Anx, Any) of the point An are determined by adding the distances Dx and Dy. In this way, the coordinates (Px, Py) of a target point Pn are determined.

The second location sensor device 4 B interacts with a global satellite positioning system, as illustrated in FIG. 5. Such a system is already in practical use. The global satellite positioning system has a ground control station 76 , which radiates a radio wave via a ground station antenna 75 , furthermore has at least 4, preferably 18 global positioning system satellites 77 A- 77 D, which serve to transmit the radio wave received, and further has a floor monitor station 85 to radio waves of the global Po sitionier sYSTEM satellites 77 a to receive 77 D, tungs- to rich or to determine bearing error coefficients may also be referred to as the azimuth error coefficient which indicate the magnitude of the bearing errors of the radio waves from the global positioning system satellites 77 A- 77 D. The bearing error coefficients are superimposed on the radio waves by the ground control station 76 .

As shown in FIG. 3, the second positioning is sensor means 4 B of the vehicle A, a radio wave receiving circuit 44, a second signal processing circuit 45, and a bearing error coefficient decision circuit 46. The second signal processing circuit 45 determines distances between the global positioning system satellites 77 A- 77 D and the vehicle A, a geographic latitude of the vehicle A and a time, based on radio waves from the global positioning system satellites 77 originate A- 77 D wherein the Ra diowellen 44 taken up by the radio wave receiving circuit to an absolute location to find Pn where the vehicle is currently located. The bearing error coefficient decision circuit 46 provides bearing error signals when the bearing error coefficients of the radio waves from the global positioning system satellites 77 A- 77 D are less than a predetermined value that is expected, for example due to an improper one arrangement of the global positioning system satellites 77 a, when the on-vehicle a in a tunnel 77 is D and / or un zureichender field strength of the radio waves which are received by the radio wave receiving circuit 44, which may be caused in the pitch. The bearing error coefficients are classified into four levels, for example, which are represented by four geographical latitudes of the bearing error signals, namely the smallest width 0, a medium-small width 1, a medium-sized width 2 and the largest width 3.

The bearing error discriminator circuit 20 selects the second location sensor device 4 B if no larger width or bearing error signals 2 and 3 are provided by the bearing error coefficient decision circuit 46 , or the first location sensor device 4 H if larger width or bearing error signals 2 and 3 are supplied by the bearing error coefficient decision circuit 46 . The information of a vehicle location, which is supplied by the selected location sensor device, is transmitted to the central computer 11 , which is also referred to as a central processing unit and forms part of the navigation control unit 10 . The selection of the location sensor device by the DF error discriminator 20 , which can also be referred to as a switching device, is only effected if a map adaptation (which is described below) is not introduced.

In general it can be said that a bearing error, the size of which depends on the accuracy of the positioning method, inevitably occurs. Since such a positioning error adds up, especially when an extrapolation navigation system is used, a location of the vehicle may be displayed on an incorrect road on a road map displayed on a screen, which does not correspond to the road on which the The vehicle in question practically drives. For this reason, the navigation system with which the vehicle control system interacts performs a "map adjustment" to properly indicate the location of the vehicle on a road on the road map that is most likely to be virtually real on that road moves. The map adaptation is carried out after predetermined intervals or predetermined times, so that a display error of the vehicle location is corrected. To perform the map adjustment, all roads in the vicinity of the vehicle are listed, and information about the roads is read out from the fixed memory 13 to thereby determine the likelihood of any road on which the vehicle is practically running. A card adaptation program is stored in the central processing unit or the central computer 11 . While the map adaptation is being carried out, the switching device 20 selects both the first and the second location sensor devices 4 A and 4 B, so that vehicle location information is fed to the central computer 11 . The vehicle location information is evaluated in a selective manner, depending on the levels 0, 1, 2 and 3 of the direction finding error signal, in order to carry out a map adjustment in a stable manner. The navigation control unit 10 guides the vehicle in such a manner that it always follows the best route based on a relationship between a predetermined destination Pend and a current vehicle location Pn which is determined and displayed on a road map is displayed on the screen 6 .

Referring to FIG. 6, which illustrates a flowchart, there is a proper route selection and a vehicle location display routine illustrating the first operation in the step S 1 in a disk 1 (CD-ROM) in the compact disk player 2 use and operate the CD turntable 2 in such a way that the road map information is provided for reading. Before the vehicle A is started, a target point Pend is entered via the control switch unit 3 and the vehicle location sensor 4 is activated to enter a starting point Po (Xo, Yo) in step S 2 in the direct access memory 13 . Thereafter, a desired route between the starting point Po and the destination point Pend is set, and a road map is illustrated on which the starting point and a street along the desired route are displayed on the screen 6 . While the vehicle is running, the navigation system 22 properly marks a vehicle location, which is determined by the first and the second location sensor devices 4 A and 4 B, on the road map, with a map adjustment being carried out.

Generally speaking, when the vehicle approaches a sharp curve or curvature 21 that has a small radius of curvature R, as illustrated in FIG. 8, on the way to the destination point Pend, the vehicle 90 must begin one Initiate deceleration or reduce its speed to a suitable vehicle limit speed VB, and this must be done at a suitable point A 1 before the sharp curve 21 so that the vehicle can safely enter the sharp curve 21 . After the sharp curve 21 has been safely passed, the vehicle 90 accelerates or sets its speed up again, specifically in the region of the exit from curve 21 , and the vehicle then leaves curve 21 . This is a fundamental driving behavior, which could be described as "slowly in and quickly out". However, if a sharp curve or curvature has a very small radius of curvature and is smooth or icy, it is difficult to negotiate the curve safely and there is a risk of the vehicle being carried out of the curve. For this reason, the vehicle 90 should reduce its speed to a suitable limit speed VB, which is determined by the radius of curvature of the curve or curvature of a road and by the state of the road. However, if a curve is blind or confusing, it is very difficult to even roughly estimate the radius of curvature of the curve, making it difficult to estimate a suitable safety speed for the curve.

In the following, reference is made again to FIG. 1. The navigation system 22 shown there reads information about the radius of curvature R of a curve of a road as a function of a travel location Pn, which is determined by the vehicle location sensor 4 , and sends this information to the vehicle speed control unit 23 . At the same time, the vehicle speed control unit 23 receives signals which are representative of the road condition, for example the road temperature T and the humidity W, and the vehicle speed VA, corresponding signals being determined by a temperature sensor 29 , a humidity sensor 25 and a speed sensor 24 . On the basis of all signals and information about the road including the curve, the vehicle speed control unit 23 calculates a vehicle limit speed VB, which is still permissible to safely enter the curve and the vehicle safely through the curve through and out of Driving out of the curve. If an actual vehicle speed VA is greater than the vehicle speed limit VB, the driver is given a warning signal by the warning device 28 or the brake actuation element 26 or the throttle valve actuation element 27 is actuated automatically, so that the vehicle speed VA is forced to the vehicle Limit speed VB is reduced. The operation of the vehicle speed control device can best be understood with reference to FIG. 7, which is a flowchart illustrating a vehicle speed control sequence. It is state of the art to program a computer. The following description is intended to enable a programmer with average skill and knowledge to write a suitable program. The specific details of such a program would of course depend on the structure of the specially selected computer.

The first operation at step S 1 is to input data of a vehicle location Pn (a point A 1 in FIG. 8) where the vehicle is currently and data of a radius of curvature R of a curve 21 which the vehicle is approaches from the vehicle location Pn, namely, this data is input into the vehicle speed control unit 23 from the vehicle navigation system 22 . After it has been indicated in step S 2 that the vehicle is approaching a curve, the vehicle speed control unit 23 receives a signal which is representative of the actual current vehicle speed VA, namely from the speed sensor 24 , and furthermore also data about the friction resisting Fdo state of the road surface from the vehicle a navigation system, 22 at step S3. Almost simultaneously, the vehicle speed control unit 23 receives signals representative of the temperature T of the road and the humidity W of the road, from the temperature sensor 29 and the humidity sensor 25 , respectively. This happens in step S 4 . Based on the temperature T of the road and the humidity or moisture W of the road and the frictional resistance Fdo of the road, the actual practical frictional resistance Fd is read out from a frictional resistance map. In the map, the frictional resistances are classified into, for example, three levels of practical frictional resistances Fd 1 , Fd 2 and Fd 3 depending on the road temperature T and the road humidity W, and taking into account the frictional resistance Fdo.

Then, in step S 6, a vehicle limit speed VB is determined from the following equation:

If the vehicle speed VB with which the vehicle approaches curve 21 has a radius of curvature R, an angular speed w is expressed as follows:

w = VB / R

If g and m are used for the gravitational acceleration and for the weight of the vehicle 90 , respectively, if the vehicle 90 , which is traveling at a vehicle speed VB at a point A 2 , is in dynamic equilibrium, the following equation is fulfilled:

Fd · m · g = m · R · (VB / R) ²

If this equation is solved for VB, the result is following relationship:

The vehicle limit speed VB, which was determined in accordance with the radius of curvature R and the road conditions in curve 21 , allows the vehicle to safely drive through curve 21 .

In step S 7 , a decision is made as to whether a vehicle speed deviation dV, which corresponds to the difference between the actual vehicle speed VA and the vehicle limit speed VB, is still positive. If the answer to this question is "no", it indicates that the vehicle 90 has already reduced its speed below the vehicle limit speed VB before the curve 21 has been reached. Then the vehicle 90 is given permission to continuously continue at the vehicle speed VA. If the answer to the question asked is "yes", this indicates that the vehicle 90 must be decelerated. A further decision is then made in step S 8 as to whether the vehicle speed deviation dV is greater than a predefined speed deviation dVo. The predefined speed deviation dVo has been set so that it can be eliminated by only closing the throttle valve of the machine. So if the answer to the decision in step S 8 is "no", this indicates that the vehicle speed VA can be reduced below the vehicle limit speed VB by only closing the throttle valve. Then, the control unit 23 causes Fahrzeuggeschwindigkeit- that the throttle actuator 27 is actuated to close the throttle valve in step S. 11 On the other hand, if the answer to the question in question in step S 8 is "yes", this indicates that the vehicle cannot be slowed to or below the vehicle limit speed VB by closing the throttle valve. Then the vehicle speed control unit causes the brake actuation element 26 to forcefully brake the vehicle 90 at step S 10 , so that the vehicle speed VA before curve 21 is reduced below the vehicle limit speed VB, immediately after via the warning device 28 at step S 9 a warning was issued. This leads to the result that the vehicle can enter curve 21 with a lower than the vehicle limit speed VB, which was determined in accordance with the radius of curvature R and the road condition Fd of the curve, so that curve 21 can be safely driven through.

The vehicle speed control device according to the Invention can also record road information from curves men who do not come from the vehicle navigation system but of tele-terminals and signposts leading to one Automobile traffic information communication system ren, which is already used in practice.  

According to FIG. 9, the car navigation system 22 receives road information about a traffic information receiving unit 93, which a tele-terminal information receiver 92 and a tele-guide-Informationsempfän ger 91 has, via a tele-terminal, and a sign of the automobile traffic information communication system. Road information including information about accidents, traffic jams or congestion, traffic restrictions, road conditions, e.g. B. curvatures, snowfall, frost, etc., are transmitted from a traffic control center via an information communication system to the tele-terminals. The tele-terminal information receiver 92 receives information about roads in a particular circular area defined by a radius of about 10 km within which the vehicle is currently traveling, via a tele-terminal in the particular Area, and forwards the road information to the vehicle control unit 23 so that it can be displayed on a map displayed on the screen 6 . The signpost information receiver 91 receives a location check signal which is emitted by the signpost in the special area, so that a vehicle location is exactly corrected on a road map shown, which was determined by the vehicle navigation system 2 .

The vehicle speed control unit 23 determines a vehicle location, which was determined on the basis of the precisely corrected vehicle location on the road map. If the determined vehicle location corresponds to a point A 1 (see FIG. 8) which lies in front of a sharp curve 21 , the vehicle speed control unit 23 controls the vehicle speed VA below a vehicle limit speed VB, which corresponds to the road information via the curve 21 was determined, the information was received by the traffic information receiving unit 93 via the tele-terminal and the signpost of the automobile traffic information communication system in the manner described above. As a result, the vehicle can take the curve 21 and safely pass the curve 21 at a speed which is automatically reduced below the vehicle limit speed VB.

Although the invention has been described in detail with respect to preferred it has to be pointed out that various other embodiments and variants for the expert are possible, which in the area and Fall within the spirit of the invention, and such other execution shapes and variants are intended by the following patent claims are included.

Claims (11)

1. Vehicle speed control means tion system for a vehicle for use with a vehicle-Naviga indicating the location of a vehicle on a road map that is displayed on a screen while the vehicle is running, and that information is supplied over the road, including curves, characterized characterized in that the vehicle speed control device has the following parts:
a speed sensor device to sense the speed of the vehicle,
a vehicle speed control device which serves to record information about a curve of a road on which the vehicle is traveling when the vehicle navigation system indicates that the vehicle location is before this curve to calculate a vehicle speed limit at which the vehicle can take the curve and safely drive through the curve, taking into account the vehicle speed determined by the speed sensor device and information about the curve, in order to compare the vehicle speed with the vehicle limit speed and to trigger an action in which at least either a warning or a reduction in the speed of the vehicle occurs if the vehicle speed is higher than the vehicle limit speed. 2. Vehicle speed control device after Claim 1 characterized, that the vehicle speed control device Vehicle brakes automatically when the vehicle speed is higher than the vehicle limit dizziness. 3. Vehicle speed control device after Claim 1 characterized, that the vehicle speed control device automatically closes a throttle valve of the vehicle, if the vehicle speed is higher than that Vehicle speed limit. 4. Vehicle speed control device after Claim 1 characterized, that the information about a curve at least the Contains radius of curvature. 5. Vehicle speed control device after Claim 4 characterized, that the information about a curve continues the Friction resistance of the curve indicates. 6. Vehicle speed control device according to claim 5, characterized in that the vehicle limit speed (VB) is determined from the following equation: where g is the acceleration due to gravity
where R is the radius of curvature of the curve and
where F is the frictional resistance of the road. 7. Vehicle speed control device after Claim 6 characterized, that a road condition sensing device is provided hen is a moisture and a temperature of Road to determine. 8. Vehicle speed control device after Claim 7 characterized, that the total frictional resistance of the road a frictional resistance, a temperature and one Moisture of the curve is determined. 9. Vehicle speed control device after Claim 1 characterized, that the vehicle has a vehicle location sensor points, which serves to make a radio wave from a to receive global positioning satellites, so that determines information about the vehicle location where the vehicle is currently traveling. 10. Vehicle speed control device after Claim 1 characterized, that the vehicle has a vehicle location sensor points to earth magnetism in one place mean that the vehicle is currently traveling on determine a vehicle location where the driving currently located.   11. Vehicle speed control device after Claim 1 characterized, that the vehicle is an information receiving device which serves to provide street information from a tele-terminal of an automobile traffic informa tion communication system in one area received in which the vehicle is currently traveling, so that a vehicle location can be determined at the the vehicle is currently running.