EP1127344A1 - Aid for driving a motor vehicle driving and implementing system - Google Patents

Abstract

The invention concerns a method for providing aid for driving a motor vehicle equipped with a system comprising an electronic computer, receiving data delivered by a vehicle speed sensor and by a distance finder detecting target vehicles located ahead of the vehicle, performing the following: determining a situation for stopping behind a non-moving vehicle, for a minimum time interval; determining a clear way in front of the stopped equipped vehicle if the distance, or the relative speed or acceleration of the target vehicle are higher than their respective thresholds; signalling to the driver said clear way information. The system further comprises a self-releasing friction point on the accelerator pedal during the stop situation, when the vehicle is equipped therewith.

Description

 ASSISTANCE METHOD FOR DRIVING A MOTOR VEHICLE AND IMPLEMENTATION SYSTEM

The invention relates to a method of assisting in driving a motor vehicle, in particular in the event of a restart in a line of stationary vehicles, as well as an implementation system.

In a situation of heavy road traffic, in a traffic jam for example, the motorist has to stop and restart repeatedly. During the stopping phases of the vehicle, which can sometimes be quite long, the driver may wish to use the time available to adjust or interrogate his navigation system, consult a map to find another route, in other words take his eyes off the vehicle which precedes it in the queue. Unable to foresee the moment when the latter restarts, the driver is forced to monitor it very often to restart as quickly as possible behind him, so as not to displease the drivers of the vehicles following him and in turn waiting to be able to move forward.

There is currently an ACC (Adaptive Cruise Control) system on board the vehicle which monitors the previous target vehicle, with the aim of automatically keeping a safety distance between it and this target. Above a minimum speed, fixed at around 40 km / h, the driver can select a cruising speed, via a manual steering wheel control. The vehicle speed then stabilizes on this setpoint. The vehicle being equipped with a radar, intended to detect the vehicles which are located in front of it, if a slower vehicle is detected on the same traffic lane, the system automatically modulates the speed of the equipped vehicle to adapt its distance to the target vehicle . For this, this information is sent to a control computer which controls the air intake throttle, the gearbox and possibly the brakes in order to act on the acceleration of the vehicle. The driver is informed at any time about the state of the system via a dedicated interface.

The drawback of such an ACC system lies in the fact that it is only operational beyond a speed limit, around 40 km / h, for reasons of technical constraints. In addition, its use is limited to one type of road network, motorways, where the radii of curvature of turns are greater than 500 meters. Indeed, among the different targets detected by the radar at the front of the vehicle, the system must choose only those located on the vehicle traffic lane. This therefore requires making a prediction of the trajectory of the vehicle. The current limits of the sensors used, i.e. gyrometers or steering angle sensors for example, prevent the use of an ACC system on another type of road.

Thus, a current ACC system does not make it possible to warn the driver, whose vehicle is stationary in a queue, as soon as the road is clear to restart, and who therefore does not optimally have these "dead times".

The present invention aims to resolve these drawbacks by proposing a driving assistance method which automatically detects the situations of stopping of the vehicle equipped behind another vehicle, then then detects, also automatically, the actions of the preceding vehicle to authorize restart by the driver.

To this end, a first object of the invention is a method of assisting in driving a motor vehicle equipped with a system comprising an electronic control computer, receiving information delivered by a vehicle speed sensor, by a rangefinder detecting target vehicles located at the front of the vehicle, and intended to carry out the steps of the method, characterized in that it comprises the following steps:

- determination of a stop situation for the equipped vehicle, behind a target vehicle;

- determination of "clear lane" information in front of the stopped equipped vehicle; - signaling to the driver of "free lane" information.

According to another characteristic of the invention, the determination of a stop situation for the equipped vehicle, behind a target vehicle, is obtained from the zero speed state of the equipped vehicle, the distance and the speed relative between the two following vehicles, and their immobilization time. According to another characteristic of the invention, the determination of clear lane information is obtained by detection of a displacement of the target vehicle beyond a predetermined threshold, or else by detection of both a relative speed and a relative acceleration of the target vehicle with respect to the immobilized equipped vehicle above predefined thresholds.

According to another characteristic of the invention, the vehicle being equipped with a driving assistance system comprising a device for immobilizing the accelerator pedal in an inactive position, the driving assistance method comprises following steps: - determination of a stop situation for the equipped vehicle, behind a target vehicle;

- activation of a disengageable hard point on the accelerator pedal;

- determination of "clear lane" information in front of the stopped equipped vehicle;

- deactivation of said hard point on the accelerator pedal;

- signaling to the driver of said "clear lane" information.

A second object of the invention is a system for implementing said driving assistance method.

Other characteristics and advantages of the invention will appear on reading the description of an example of implementation of the driving assistance method according to the invention, illustrated by the following figures which are: - Figure 1: a block diagram of a driving assistance system, during restart phases, according to the invention;

- Figure 2: a flowchart of the different stages fulfilled by the driving assistance method according to

1 * invention.

According to the invention and as shown diagrammatically in FIG. 1, the vehicle must be equipped with a system comprising an electronic control computer 5 receiving information from a vehicle speed sensor 1, which makes it possible to detect the stop or the starting of the vehicle, and of a range finder 2 which detects target vehicles situated in front of the equipped vehicle and determines the position, the speed and the relative acceleration of the target vehicles with respect to the equipped vehicle which follows them.

The method according to the invention consists first of all in determining, under certain conditions, whether the vehicle thus equipped with the driving assistance system is stopped behind another vehicle, said system being activated.

Then the rangefinder tracks the movements of the previous vehicle, so that the electronic computer determines, according to certain conditions of distance, speed and relative acceleration between the two vehicles, if the traffic lane has become clear again, authorizing a restart of the equipped vehicle .

In the case of a free lane determination, the process signals this to the driver who can thus restart safely. The system can be put into service or out of service, from a selection interface 3 by the driver or automatically. It may further comprise a device 4 for immobilizing the accelerator pedal, as described in French patent application No. 96 13944 in the name of RENAULT, controlled by the computer 5.

This device immobilizes the pedal in an inactive situation, where the control member for the admission of gases into the engine can be placed directly under the control of the control computer of the driving assistance system, on board the vehicle. . For this, this device comprises a movable element connected to the pedal, which is moved by the latter between a first position in which the pedal is immobilized in its inactive position, kept as long as the driver's thrust on the pedal remains less than one pre-established effort threshold, and a second position for disabling the assistance system where the pedal has no particular resistance. This last position is joined as soon as said force threshold is exceeded by the driver who can again control the opening of the gases.

In a driving assistance system by speed or distance regulation, such a device performs a footrest function, by creating a hard point in the travel of the accelerator pedal, this function of course being disengageable.

In this mode of implementation, when the method has determined a stop situation for the equipped vehicle, in a queue of vehicles, it activates the disengageable hard point function in the stroke of the accelerator pedal to immobilize it.

Then, in the case of a clear lane detection, the method deactivates the hard point position for the accelerator pedal, whether the driver has his foot on it or not. If the driver actually has his foot on the pedal in the footrest position when this function is disengaged, he will feel an effect under the foot signaling that the way is clear.

FIG. 2 is an example of a flow diagram of execution of the different steps of the method according to the invention.

The first step (a) concerns the activation of the driver assistance system. This activation can be done by the driver of the vehicle via a manual interface, for example a button, dedicated to this function. It can also be obtained from the activation commands of a speed or distance regulation system when the vehicle is equipped with it. In this case, the two distance and speed regulation functions being active only beyond a speed threshold of 40 km / h for example, it is considered that the method according to the invention constitutes the extension of their use for zero speeds.

According to another alternative embodiment of step (a), the activation of the system is automatic from operating conditions of the vehicle observed in the following step (c).

With the system activated, step (b) of initializing the process consists in zeroing a counter, of which the role will be to count down the time during which the equipped vehicle is stopped behind a vehicle.

The following step (c) makes it possible to recognize whether the vehicle is in a stop situation, by reading the speed of the wheels delivered by a sensor. If the vehicle is not stopped, the method returns to step (b) of zeroing the counter.

If the equipped vehicle is effectively immobilized, the following step (d) detects the presence of a target in front of said vehicle, on its lane. For this, the rangefinder delivers relative distance and speed information which are then compared respectively to two predetermined thresholds S _d and S _v .

The method therefore compares the relative distance between the equipped vehicle and the target vehicle detected to a maximum threshold S ^, of the order of 6 meters for example, below which the system is sure not to take account of erroneous obstacles such as a roundabout or a parked vehicle behind which the equipped vehicle parks. The method relates only to driving in line. The method also compares the speed relative to a maximum threshold S _γ , to ensure that the target vehicle is itself stopped, or even reverses slightly.

These two conditions being fulfilled, it is considered that there is detection of a stop situation behind a lined up vehicle.

If this is not the case, the method returns to step (b) for resetting the counter to zero. When a stop situation is detected in step (d), step (e) counts the time spent at a stop behind a target vehicle itself immobilized. This count is obtained by incrementing the counter, which will be compared in the following step (f) with a minimum time value _m ^ _n , which can be configured and adapted, to be observed in order to determine a real stopping situation behind a vehicle. This minimum time is of the order of 1.5 seconds, necessary to activate the assistance offered by the process.

Step (g) relates to the determination of a stopping situation, as soon as the conditions for stopping in line behind a target vehicle have been met for a period defined in step (f). Thus, the vehicle is immobilized, until the computer restarts.

During this immobilization time, the method ensures monitoring of the previous target vehicle, that is to say notes whether it has moved sufficiently forward to allow or necessitate a bringing together of the equipped vehicle. In fact, when the distance between these two vehicles is too great, this can hinder the other following vehicles in the queue or allow the insertion of a new vehicle between them. Step (h) for this purpose consists in measuring the distance between these two vehicles and in comparing it with a minimum distance threshold S _D , of the order of 8 meters for example. This minimum distance threshold S _D can be calibrated according to the driving style of the driver of the vehicle thus equipped and the state of road traffic.

If the distance measured is greater than this threshold Sp, the method proceeds to step (i) of determining "free lane" information for the equipped vehicle. In step (k), the driver is warned that the way is clear, and that he can restart safely, in particular by a man / machine interface, such as an audible signal, light information or tactile information. noticeable by the driver at the steering wheel.

On the other hand, if the distance measured is always less than the threshold S _D , the method performs in step (j) two comparisons, one of the relative speed of the two vehicles and the other of the acceleration of the target vehicle by compared to the equipped vehicle. It first checks whether the relative speed is greater than a minimum calibratable Sy threshold, of the order of 1.5 m / s, corresponding to the distance from the target car at a speed greater than Sy.

In addition, it checks whether the relative acceleration is greater than a calibrated minimum threshold S _A , of the order of 2.6 m / s ² , so that the driver reacts without delay to the restart of the vehicle in front, depending of its starting acceleration. If these two comparisons are positive, the method proceeds to step (i) already described previously and then signals to step (k).

In the variant implementation of the method according to the invention, from a driving assistance system comprising a device for immobilizing the accelerator pedal, step (g) corresponds to activation a disengageable hard point immobilizing the accelerator pedal in the high position, when the conditions for stopping in line behind a vehicle have been observed for a sufficient time, defined in step (f). This hard point position allows the driver rest your foot on the pedal without affecting the control of the air intake in the engine.

If the driver wishes to regain control of his vehicle, he only needs to exert sufficient pressure on the accelerator pedal to disengage the hard spot and for this pedal to no longer exhibit any particular resistance.

In step (i) of determining free lane information in front of the stopped equipped vehicle, the method performs deactivation of the hard point in the travel of the accelerator pedal. This automatic disengagement of the hard point makes it possible to warn the driver that he can again move his vehicle forward, since his lane is clear.

The method according to the invention thus makes it possible to assist the driver in a traffic jam situation, in road traffic, by signaling to him that the lane becomes free to restart without the need to constantly monitor the road scene. For vehicles equipped with a distance or speed regulation system, necessarily including a rangefinder, radar for example, the invention can be incorporated into it without additional cost or additional specific means.

The invention also makes it possible to perform a footrest function for the driver, at the disengageable hard point of the accelerator pedal. It applies to any type of vehicle, automobile or industrial, utility, bus or truck.

Claims

1. Method for assisting in driving a motor vehicle equipped with a system comprising an electronic control computer, receiving information delivered by a vehicle speed sensor, by a range finder detecting target vehicles located at the front of the vehicle, and intended to carry out the steps of the method, characterized in that it comprises the following steps: - determination of a stop situation for the equipped vehicle, behind a target vehicle; - determination of "clear lane" information in front of the stopped equipped vehicle; - signaling to the driver of "clear lane" information. 2 driving assistance method according to claim 1, characterized in that, the vehicle being equipped with a driving assistance system comprising a device for immobilizing the accelerator pedal in an inactive position, where the air intake control member can be directly placed under the control of the electronic computer, the driving assistance process comprises the following steps: - determination of a stop situation for the equipped vehicle, behind a target vehicle; - activation of a disengageable hard point on the accelerator pedal; - determination of "clear lane" information in front of the stopped equipped vehicle; - deactivation of said hard point on the accelerator pedal; - signaling to the driver of 1 ^• "clear lane" information. 3. A driving assistance method according to one of claims 1 or 2, characterized in that the determination of a stopping situation of the vehicle equipped behind a target vehicle is obtained from the following steps: (c): recognition of the stopping of the equipped vehicle by reading the speed of the wheels, delivered by the sensor and of zero value; (d): detection of a target vehicle, in front of the equipped vehicle, by the range finder which delivers their relative distance and speed, then comparison of the distance relative to a maximum threshold (S _d ) and comparison of the speed relative to a maximum threshold (S _v ) below which the target vehicle is considered to be stopped; (e): accounting of the time spent at a stop behind the target vehicle itself immobilized; (f): comparison of this time spent with a minimum duration (T _min ). 4. A driving assistance method according to one of claims 1 or 2, characterized in that the determination of free lane information in front of the equipped vehicle is obtained from the following steps: (h): measurement of the distance between the equipped vehicle and the target vehicle which precedes it and comparison of this distance with a minimum threshold (S _D ) which can be calibrated, above which the insertion of a third vehicle is possible between the two precedents; (i): determination of clear lane information if the distance measured between the two vehicles is greater than the threshold (S _D ), or if both the relative speed and the relative acceleration of these two vehicles are greater at the respective thresholds (S _y and s _A ); (j): in the case where the distance measured between the two vehicles is less than said threshold (S _n ), comparison of their speed relative to a minimum threshold (Sy), which can be calibrated, corresponding to the distance from the target vehicle at a speed greater than (Sy) and comparison of their acceleration relative to a calibrated minimum threshold (S _A ). 5. A driving assistance method according to one of claims 1 or 2, characterized in that step (k) of signaling the information "free lane" to the driver of the equipped vehicle is performed by a human interface / machine, such as an audible signal, light information or tactile information perceptible to the driver at the steering wheel. 6. A driving assistance method according to one of claims 1 or 2, characterized in that it is activated automatically from the operating conditions of the vehicle concerning its distance to a detected target vehicle, its speed and its acceleration. relative. 7. Driving assistance method according to one of claims 1 or 2, characterized in that it is activated by the driver of the equipped vehicle, via a manual interface dedicated to this function, such as 'a button. 8. Driving assistance method according to one of claims 1 or 2, characterized in that it is activated from the activation commands of a speed and / or distance regulation system when said vehicle is equipped with it. 9. Driving assistance system, on board a motor vehicle, implementing the method according to one of claims 1 to 8, characterized in that it comprises an electronic control computer (5), receiving information a vehicle speed sensor (1) and a rangefinder (2) detecting the relative position, speed and acceleration of the target vehicles with respect to the equipped vehicle following them. 10. Driving assistance system according to claim 9, characterized in that it further comprises a device (4) for immobilizing the accelerator pedal in an inactive position, where the control member of the The air intake can be directly placed under the control of the electronic computer (5). 11. Driving assistance system according to one of claims 8 or 9, characterized in that it further comprises a man / machine interface, such as an audible signal, light information or tactile information perceptible by the driver at the steering wheel.