Method and device for automatic speed adjustment in a vehicle

The present invention relates to a method and an apparatus for automatically setting the speed of a vehicle according to the preambles of claims 1 and 13, respectively.

[0002] German Patent Publication No. 41 00 993 A1 discloses a system for automatically controlling the vertical movement of a vehicle and the traveling following a vehicle traveling in front of the vehicle. .. According to this system, the distance and relative speed between the vehicle and the vehicle traveling in front are determined, the measurement signal is supplied to the control device, and the control device determines the actual speed of the vehicle and the set speed of the vehicle. The operating signal supplied to the operating element of the vehicle for automatic setting is generated from the value of the measured signal in consideration of a predetermined conversion relationship.

[0003] The system, which comprises a follow-up control device, can also drive the vehicle in a stop-and-go mode. In this mode, when the vehicle traveling ahead starts and the distance between the vehicles becomes shorter than the predetermined set vehicle distance, the following vehicle automatically starts from the stopped state. The vehicle speed of the following vehicle may temporarily exceed the speed of the vehicle traveling in front until the following vehicle accelerates from the stopped state and the set distance between the vehicles is restored. Even when the vehicle traveling ahead decelerates, the set distance between the vehicles is maintained. When the vehicle traveling ahead reaches a stopped state, the speed of the following vehicle is also reduced to zero.

[0004] [Problems to be Solved by the Invention] By using this system, it is possible to automatically follow a vehicle in which a vehicle is traveling in front of the vehicle. However, especially in the low speed range, starting from a stopped state to a different speed and applying a new brake to bring it to a stopped state are frequently performed, which may adversely affect comfort. There is. In addition, in stagnant traffic, it is easy to reach relatively high speeds in a row of vehicles, and in this situation, when the vehicle enters the distance between the vehicle that is following and the vehicle that is traveling in front, it is following. A dangerous situation can arise in which the vehicle system must initiate a relatively difficult braking operation with the risk of a rear-end collision. This problem also causes the following vehicle to start braking from a high speed level in certain situations, as the speed of the following vehicle can easily exceed the speed of the vehicle traveling ahead. It is also detailed by the fact that it must be.

[0005] An object of the present invention is to improve driving comfort and driving safety in a vehicle having an automatic speed setting.

[Means for Solving the Problems] This problem is solved by the present invention having the features of claims 1 and 13, respectively. Dependent terms also include preferred embodiments.

[0007] According to the method according to the invention, the maximum permissible speed limit is first predetermined or determined from the vehicle's current measurement and state variables. If the measurement reveals that an obstacle, such as a vehicle traveling in front, is moving away from the vehicle, it is to be applied to the vehicle and determines the vehicle set speed that the vehicle is not allowed to exceed. .. The set speed is set to the smaller of the set of values formed by the speed limit and obstacles, specifically the current speed of the vehicle traveling ahead. The actual speed of the vehicle is adjusted to the set speed.

[0008] This method ensures that the speed of the following vehicle must not exceed the maximum value, specifically the speed limit that is to be predetermined or determined. Even if the speed of the vehicle traveling ahead exceeds this speed limit, the following vehicle must not exceed this speed limit. In this case, the distance between this vehicle and the vehicle traveling in front increases, which specifically results in short-term acceleration operations and especially braking operations in stagnant traffic. It provides sufficient comfort to the occupants of the following vehicle, as it is reduced and the following vehicle follows at a constant speed in principle. Furthermore, the vehicle entering the interval between the following vehicle and the vehicle traveling in front of the following vehicle is no longer able to perform an unexpected braking operation of the following vehicle because the following vehicle is moving at a relatively low speed level. Since it does not cause a problem, safety is improved.

Maintaining a constant speed when the vehicle traveling ahead exceeds the speed limit is a vehicle that is being re-formed as the following vehicle moves at a continuous speed in stagnant traffic. Steadily approaching the rear of the line, leading to a situation where the vehicle is connected to the rear of a vehicle traveling in front. This steady movement method allows the vehicle to be violently accelerated from a stationary or very slow speed and then braked again to avoid the harmonica effect commonly formed in stagnant traffic. In addition to improving driving comfort and driving safety, this method also leads to reduced pollutant emissions.

[0010] In one preferred embodiment, if the distance between the vehicle and the vehicle traveling ahead is less than the proximity limit, automatic speed setting is activated. When driving in stagnant or heavy urban traffic, limiting the actual speed of the vehicle generally does not have a negative effect on such a journey, and in any case. Since the average speed is relatively low, this criterion can be set to a low level and used as a trigger to start the automatic speed setting together with the speed limit indicating the slowing speed. By automatically braking the vehicle until it is stopped, it is possible to avoid the risk of accidentally colliding with an obstacle traveling in front of the vehicle.

[0011] Further, this method can be used for obstacles other than vehicles. Specifically, this method can be used as a parking aid, in which case a fixed obstacle can be detected and braking of the vehicle to a stopped state can be induced.

[0012] Further, in one preferred embodiment, when the vehicle and the obstacle become less than the minimum distance after the automatic speed setting is activated, the obstacle traveling in front continues to move. However, it is stipulated that the vehicle is automatically braked until it is stopped. As a result, the minimum safe distance between the vehicle and the obstacle is ensured. As soon as the minimum distance is exceeded again, the vehicle will begin to move accordingly.

[0013] According to a more preferred embodiment, the minimum possible vehicle reaction time during the braking operation is minimized if appropriate over the entire operating time of the automatic speed setting, at least in predetermined driving conditions. Braking torque is generated by the vehicle's brakes. As a result, when the vehicle traveling ahead decelerates or a third vehicle enters the vehicle interval, the following vehicle can brake in the shortest time. It is convenient that this minimum braking torque is generated at all dynamic transition stages of the following vehicle, specifically at the acceleration and braking stages. However, if appropriate, braking torque can be applied even when the vehicle speed is constant. However, even when the speed is constant and in the acceleration stage, this braking torque is smaller than the driving torque.

[0014] Where appropriate, specifically, the braking torque can be reduced at least temporarily when the distance exceeds the distance threshold in order to prevent overloading of the braking device.

[0015] The automatic speed setting may be switched off if the driver so desires, for example, by excessively depressing the acceleration pedal in order to achieve a vehicle speed that exceeds the vehicle set speed. In this case, the driver's wishes take precedence over the automatic speed setting. Where appropriate, tolerances beyond the set speed can be considered, within which the driver can over-press the acceleration pedal without immediately switching off the automatic speed setting. Can be moved. In this case, the automatic speed setting is switched off only when this allowable range is exceeded. As a result, within the permissible range, the driver can follow the vehicle moving rapidly ahead by activating the acceleration pedal, but if the depressurization of the acceleration pedal is still reduced, the speed The automatic setting of is maintained.

[0016] When the system is switched off, the braking torque that is probably occurring is not suddenly reduced, but according to a given characteristic curve to avoid sudden shocks and possible driver discomfort. It is preferable to reduce the amount.

The device according to the invention for automatic speed setting includes a measuring device for determining the distance and relative speed between a vehicle and an obstacle, specifically, a vehicle traveling in front. The operating signal, which is used to set the operating element of the vehicle that automatically brings the actual speed of the vehicle closer to the vehicle set speed and is determined from the measurement signal according to a predetermined relationship, is recorded in the measuring device. It is equipped with a control device that is generated based on a measurement signal. Specifically, the operating signal acting on the braking device, engine management system and / or the operating device that regulates the air supply in the vehicle is a set speed that does not exceed the speed of the obstacle that is moving away, and at the same time, it is predetermined. It is generated to bring the actual speed of the vehicle closer to the set speed, which is limited by the speed limit that is set or determined. This device for automatic speed setting in a vehicle is particularly suitable for performing the aforementioned method having all steps.

Further preferred improvements will become apparent from further claims, illustrations and drawings.

[Embodiment of the Invention] The vehicle 1 shown in FIG. 1 is equipped with a device 2 for automatically setting a speed particularly in a low speed range. This device 2 includes a measuring device 3 having a distance sensor 4 in the front region of the vehicle, a control device 5, and specifically, a braking device 6 which is configured as an electrohydraulic brake and can be set by an operation signal. It includes a wheel speed sensor 7 and a pedal signal transmitter 8 for detecting the operation of the acceleration pedal. In order to automatically set the speed, the measurement signal from the distance sensor 4 that indicates the distance between the vehicle 1 and the obstacle located in front, specifically, the vehicle traveling in front, It is processed by the control device 5. The control device 5 also receives measurement signals from the braking device 6, the wheel speed sensor 7, and the pedal signal transmitter 8. Specifically, the distance from obstacles located in front, and the relative speed between the vehicle and obstacles located in front of or traveling in front, and, as appropriate, further safety. The vehicle set speed according to the relevant criterion is determined from the measurement signal based on the relationship stored in the control device.

[0020] The operation supplied to the braking device 6 for generating the braking torque on the brake of the vehicle, the engine management system for setting the ignition time and the fuel injection, and the operating element for adjusting the air supply to the cylinder. The signal is generated by the control device 5.

[0021] According to the flowchart shown in FIG. 2, the relative distance Δs and the relative speed between the vehicle equipped with the automatic speed setting and the obstacle in front, specifically, the vehicle traveling in front. Δv is first determined in step V1 of the first method. Measurements and determinations of relative distance Δs and relative velocity Δv are performed at regular time intervals regardless of the activation of automatic velocity setting or the current stage.

[0022] The query to be executed in the next method step V2 constitutes an operating condition for the operation of automatic speed setting. In step V2, the relative velocity Δs is the proximity limit S_NGIt is confirmed whether it is below. If this is not the case, the automatic speed setting will not work and the system will return to step V1 of the first method according to the branch line for "No". Relative distance Δs is proximity limit S_NGIf it is less than, the relative velocity Δv is the threshold v_SWIt is preferable to confirm whether or not it is less than the above as another condition to be further satisfied. If this is not the case, the system returns to the first method step V1 again according to the "No" branch line. On the other hand, the relative velocity Δv is the threshold value v_SWIf less, both conditions according to method step V2 are met. Then, the automatic speed setting is activated, and the system proceeds to the next method step V3 according to the "Yes" branch line.

Proximity limit S_NGAnd speed threshold V_SWIs a variable that is permanently predetermined and is stored in the control device as appropriate. However, as an alternative, these values may be derived from current events on the road, or the drivers may predefine these values. Finally, in method step V2, it may be sufficient that both of the above two conditions are not satisfied, but one of them is satisfied. In this case, the system moves from method step V2 to the next method step V3 if only one of the conditions in method step V2 is satisfied.

Next Method In step V3, braking torque M greater than 0_BrIs generated by the braking device of the vehicle. At the same time, drive engine torque M greater than 0_MIs generated and the braking torque M is to allow the vehicle to move automatically._BrIs engine torque M_MAn additional condition is defined that it is less than.

Further, in method step V3, the current speed v of the vehicle is the speed v of the obstacle._HAnd driving speed v_KrIt is set to the minimum value of the set of values formed by. In the controller, the measured or calculated relative velocity between the vehicle and the obstacle Δv and the velocity v of the vehicle itself to the velocity v of the obstacle_HCan be determined. Driving speed v_KrConsists of a speed limit that is predetermined as a fixed value and stored in the control device. Driving speed v the speed of the current vehicle_KrLimiting to allows the vehicle to follow obstacles in front of it at the same speed as the obstacles when the automatic speed setting is activated, but at most slow speed v_KrGuarantee that

Next Method In step V4, the relative distance Δs is a stop limit s that is a condition for braking the vehicle until it is stopped._SGIt is confirmed whether it becomes smaller. If this is not the case, the current state is maintained and the system iteratively checks the conditions of method step V4 according to the "No" branch line. This iterative check continues until the conditions of method step V4 are met.

[0027] The relative distance Δs is the stop limit s_SGIf less than, the system follows the Yes branch line in Method Step 4 to the next Method Step V5 (see Figure 3). Method In step V5, engine braking torque M_BrAnd drive engine torque M_MEngine braking torque M because the relationship with_BrIs engine torque M_MIs braked until the vehicle is stopped at speed v = 0.

Next Method In step V6, it is confirmed whether the vehicle can move forward automatically. Therefore, the relative velocity Δs between the vehicle and the obstacle is the distance threshold s._WGIt is confirmed whether it exceeds. If this is not the case, the system will return to method step V5 following the "No" branch line of method step V6 and the vehicle will still remain stationary. However, if the condition of method step V6 is met, this means that the distance from the obstacle in front is increased and the condition of forward movement is met. In this case, the system follows the "Yes" branch line to the next method step V7.

[0029] In method step V7, a confirmation is made to determine if the acceleration pedal is being actuated by the driver. If this is the case, the automatic speed setting ends because the driver's wishes are prioritized over the automatically controlled driving of the vehicle. However, here it is considered whether the acceleration pedal actuation generated by the driver is presumed to be faster than the predetermined speed by the automatic speed setting under the current external circumstances. Preferably, the system moves to the "Yes" branch only if this is the case.

If there is a corresponding actuation of the acceleration pedal, the system continues to method step V8 according to the Yes branch line of method step V7. Method In step V8, if appropriate, the engine braking torque M, taking into account the reduction characteristic curve._BrDecreases to zero. The method is then terminated and the system can return to the beginning of the entire sequence in method step V1.

If the acceleration pedal is not activated, the system continues to method step V9 according to the No branch line of method step V7. Now in the method step V9, the engine braking torque M to allow the condition to move forward and the vehicle to move again._BrIs the drive engine torque M_MSet to a smaller value. The current vehicle speed v is the speed of the obstacle v_HAnd driving speed_KrIt is set to the smaller value of.

Method In step V10, the relative distance Δs is then the stop limit s._SGA confirmation is made to determine if it exceeds. This confirmation is a stop limit s that represents a safe distance_SGIt ensures that the vehicle is automatically moved only if it exceeds. If this is not the case, the system returns to method step V5 following the "No" branch line and the vehicle is braked to a stopped state. Otherwise, the system proceeds to method step V7 following the "Yes" branch line. Method In step V7, a reconfirmation is performed to determine if the acceleration pedal has been activated.

[Brief Description of Drawings] [Fig. 1] Fig. 1 is a schematic view of a vehicle equipped with automatic speed setting.

FIG. 2 is a flow chart relating to individual steps of a method for automatically setting the speed of a vehicle following a vehicle traveling ahead.

FIG. 3 is a diagram showing a continuation of the flowchart shown in FIG.