CN114620029A

CN114620029A - Method, apparatus and computer program product for adjusting speed during parking

Info

Publication number: CN114620029A
Application number: CN202111527743.0A
Authority: CN
Inventors: A·埃尔班
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-12-14
Filing date: 2021-12-14
Publication date: 2022-06-14
Also published as: DE102020215816A1

Abstract

The invention relates to a method for regulating the speed (v) during the parking of a vehicle (1)Method, wherein the distance(s) of the vehicle (1) from an end point of a trajectory (T) defining the parking process is sensed_dist) Wherein the vehicle (1) is stationary on the end of the trajectory (T), wherein the actual speed (v) of the vehicle (1) is sensed_ist) Wherein the distance(s) is processed in a control device (15)_dist) And said actual speed (v)_ist) And wherein a target speed (v) of the vehicle (1) is predefined along the trajectory (T)_soll) Wherein the control device (15) controls a drive device (21) and/or a brake device (22) of the vehicle (1) in order to follow the target speed (v) at least indirectly_soll). The invention also relates to a computer program product, a control device and a drive train for an electric vehicle.

Description

Method, apparatus and computer program product for adjusting speed during parking

Technical Field

The invention relates to a method for regulating the speed during a parking process, in particular an autonomous parking process, of a vehicle. Furthermore, the invention relates to a device for carrying out the inventive method and to a computer program product.

Background

DE 10343174 a1 discloses in the context of an automated parking process of a vehicle that the parking process is carried out in a speed-dependent manner along a trajectory, i.e. using the speed as a nominal predetermined value during the parking process and reducing the speed up to zero until the vehicle comes to a standstill on the end of the trajectory. Here, the disclosed method is used for the following docking procedure: during the parking process, the driver still controls the parking process by actuating the accelerator pedal or the brake pedal. In other words, this means that, although the disclosed method predetermines a speed value, the driver actively influences this speed value by actuating the accelerator pedal or the brake pedal. In particular, the cited document does not disclose a completely autonomous parking maneuver, in which the parking maneuver is performed completely autonomously, i.e., without a driver.

Disclosure of Invention

The method according to the invention for regulating the speed during the parking of a vehicle provides for the parking process to be carried out completely autonomously, i.e. without a driver. This method thus enables, for example, a so-called fully automated "valet parking", in which case the driver controls the parking process by means of his mobile telephone and a corresponding application (App) which is in active connection with the vehicle, i.e. the driver is not present in the vehicle. In particular in connection with electric vehicles, the method according to the invention also makes it possible to use regenerative braking processes for sensitive position control in an electric vehicle in a particularly advantageous manner.

In the context of the above description, the method according to the invention therefore proposes that the distance of the vehicle from the end of the trajectory defining the parking process is sensed, wherein the vehicle is stopped at the end of the trajectory, wherein the actual speed of the vehicle is sensed, wherein the distance and the actual speed are processed in the control device, wherein the target speed of the vehicle is specified along the trajectory, wherein the control device actuates the drive and/or brake of the vehicle in order to comply at least indirectly with the target speed, and wherein the actuation of the drive and/or brake takes place independently of the driver, i.e. completely autonomously, via the output interface of the control device.

Although not explained in further detail, in the case of a vehicle in which the driver is present, he is of course given the driver the decision whether to bring the speed or the vehicle to a standstill by, in particular, intervening on the braking device during the parking process, or to reduce the parking speed of the vehicle. Typically, however, manipulation of the accelerator pedal does not result in an increase in actual speed during the parking process.

In a preferred embodiment, an advantageous development of the method according to the invention for adjusting the speed during the parking of a vehicle is specified.

It is important for the speed to be regulated during the parking of the vehicle that the exact actual speed of the vehicle is sensed, since the regulation takes place on the basis of the actual speed and a possible deviation between the actual speed and the due speed. Against this background, a particularly preferred embodiment of the method according to the invention provides that the actual speed of the vehicle is sensed by determining the wheel speed at the wheels of the axle of the vehicle which are not coupled to the steering device, wherein an average wheel speed is determined, the average wheel speed is compared with a reference speed from a further data source of the vehicle, and the minimum of the reference speed and the average wheel speed is used as the actual speed for the adjustment.

The advantage of determining the wheel speed on the axle not coupled to the steering device is that the steering angle is taken into account when determining the wheel speed on the axle coupled to the steering device, since the steering angle influences the wheel speed of the wheels. It is further to be mentioned that the reference speed from another device or data source of the vehicle can be obtained, for example, from an acceleration sensor or the like, a driver assistance device or the like.

In order to determine the braking torque at the wheel of the brake device and/or the braking force at the wheel, it is preferably provided that a manipulated variable is first determined, wherein the manipulated variable takes into account a speed deviation between the actual speed and a target speed predetermined for the trajectory at a distance corresponding to the end of the trajectory, and wherein the manipulated variable is additionally influenced by the magnitude of the distance and the speed deviation by means of a PI adjustment of the manipulated variable.

In terms of driving comfort during parking, in particular to avoid sudden accelerations or decelerations, it is advantageous here to influence the magnitude of the predetermined control value additionally by means of a filter which specifies the maximum rate of change of the braking torque.

In addition, the quality of the regulation or the docking process is also influenced by other factors which are taken into account in the regulation according to the invention or in the method according to the invention. These further factors are taken into account, in particular, when actuating the drive and/or brake device of the vehicle, by additionally incorporating into the control algorithm the different friction ratios between the two wheels of the existing downhill or uphill slope of the roadway and/or the axle and the roadway and/or the drive torque, which is increased adaptively by the control, as a result of obstacles, such as curbs.

The control value for controlling the brake device, which is generated by means of the method described above, is preferably additionally influenced by: immediately before the end of the trajectory is reached, the braking torque is increased by generating an additional braking torque which is dependent on the downhill slope and the distance.

As mentioned above, the method of the invention is preferably, but not limitatively, used in the context of electric vehicles for the following vehicles: the vehicle is driven at least partially, preferably completely, by at least one electric motor, which is powered by a drive battery. Against this background, a further preferred embodiment of the method according to the invention provides that the drive device and/or the brake device is coupled at least indirectly to an electric motor for driving the vehicle, the energy released by the electric motor during deceleration of the vehicle being regenerated, and the regeneration taking place until a standstill of the vehicle. This last feature makes it possible to optimize the comfort during braking of the vehicle.

The invention further relates to a computer program product, in particular a data program or a data carrier, which is designed to carry out at least one of the steps of the method according to the invention.

The invention also comprises a control device which is designed to carry out the method according to the invention, and a drive train for an electric vehicle having a corresponding control device.

Further advantages, features and details of the invention emerge from the following description of a preferred embodiment of the invention and from the drawing.

Drawings

Figure 1 shows the vehicle at the beginning of a parking situation in a top view,

FIG. 2 shows a graph of the speed profile of a vehicle during a parking process, an

Fig. 3 shows a block diagram of a control device for actuating a drive and/or a brake of a vehicle to carry out a parking process.

Detailed Description

Identical elements or elements having an identical function are provided with the same reference symbols in the figures.

Fig. 1 shows a plan view of a vehicle 1 in a parking space, the parking space being delimited by a front vehicle 2 and a rear vehicle 3.

The vehicle 1 is preferably, but not restrictively, configured as an electric vehicle. However, the vehicle 1 may also be a hybrid vehicle using an electric motor as part of the drive device, or a vehicle 1 driven by an internal combustion engine.

The vehicle 1 is designed to carry out a completely autonomous, i.e. driver-independent, parking process. For example, the autonomous parking process can be a so-called "Valet" parking process, in which the driver initiates the parking process by his mobile phone outside the vehicle 1 and the vehicle 1 executes it completely autonomously.

The vehicle 1 has a wide range of driver assistance devices or environment recognition devices, which can comprise a plurality of sensors, for example distance sensors, radar sensors or cameras. By way of example and not limitation, vehicle 1 has in the region of its front and rear bumpers a distance sensor 11, which is designed to sense the distance of vehicle 1 from an obstacle located in front of or behind the vehicle 1 in the direction of travel, and which, as shown by way of example by distance sensor 11 being drawn in the region of the right front bumper, is able to sense the length of the parking space when driving through it, in order to be able to deduce therefrom the parking possibility for vehicle 1, for example, on the basis of ultrasound.

In addition, the vehicle 1 has a processing device 12, which is designed to process the signals sensed by the distance sensor 11 or to convert these signals into a corresponding distance s_dist. The processing means 12 are coupled to the control means 15. In particular, the distance s with respect to an obstacle located in the driving path of the vehicle 1_distFed as input variables by the processing means 12. In addition, the control device 15 is connected to a switch-on device 16 for actuating the control device 15 or for initiating the parking process in the case of a (completely) autonomous parking process. In addition, the control device 15 is operatively connected to the actuating device 17. The actuating device 17 comprises in particular a brake pedal and/or an accelerator pedal of the vehicle 1, which, in the case of a driver in the vehicle 1, makes it possible to influence a completely autonomous parking maneuver by actuating the brake pedal or the accelerator pedal by the driver.

The vehicle 1 further comprises a drive device 21 (in the form of at least one electric motor in the case of an electric car) for driving the vehicle 1 and a brake device 22 for braking the vehicle 1. Both the drive 21 and the brake 22 can be actuated by the control device 15 via corresponding interfaces in order to carry out the parking process. In the drive train of the electric vehicle, the drive device 21 and the brake device 22 may be constituted by electric motors.

In vehicle 1, two

wheel sensors

23, 24 are additionally provided in the rear axle region of the vehicle, which is not connected to the steering device, wherein the two vehiclesThe signals of the wheel sensors are fed as input variables to the control device 15, and these signals are converted into corresponding wheel speeds v of the left or right wheels of the vehicle 1_lAnd v_r. The vehicle 1 further comprises means for sensing a reference speed v_refAn additional device or data source 25. The data source 25 may be, for example, a navigation system of the vehicle 1, an inertial sensor, or the like. What matters is only for the data source 25: the low speed typical for a parking process can be sensed with sufficient accuracy.

Fig. 1 shows a trajectory T of the vehicle 1, along which the vehicle 1 is moved (backwards) indirectly by the control device 15 into a parking space between the two vehicles 2 and 3. The trajectory T is configured in such a way that it ends, for example, at a defined distance, for example, 30cm, in front of the rear vehicle 3.

Fig. 2 shows a speed profile v of vehicle 1 at time T during a parking process along trajectory T. It can be seen in particular that the vehicle 1 is stationary up to a time t₁Illustratively accelerating purely linearly. At a point in time t₁And t₂In between, the vehicle 1 has a constant speed v₁. At a point in time t₂And t₃During this time, a deceleration or reduction of the speed v of the vehicle 1 to a value of zero again occurs. It should be noted here that the speed profile of the vehicle 1 mentioned during the parking process is selected purely by way of example. In particular, it can be provided, for example for reasons of comfort, that no linear speed change is provided during the parking process. In principle, the speed profile can also be configured differently depending on the length of the trajectory T or the length of the parking space and/or the distance of the vehicle 1 from the parking space.

In fig. 3, the control device 15 and its functional blocks are shown in more detail in the form of a functional diagram. In particular, the control device 15 has an algorithm, for example in the form of a data program or a data carrier, which is designed to regulate or control the drive 21 and/or the brake 22 of the vehicle 1 at least indirectly via the output interfaces 50 and 51 during the parking procedure mentioned. For this purpose, a (positive) drive torque M is applied to the output interface 50 for the drive 21_PropIncAnd maximum allowable driveMoment M_PropDecAs an output value, this maximum permissible drive torque can also be negative (as drag torque or as regenerative torque). These values can be converted into the corresponding forces F on the driven wheel of the vehicle 1 by dividing by the wheel diameter in block 55_Prop. In a corresponding manner, a braking torque M (for the hydraulic brake system) is applied to the output connection 51 for the brake device 22_BrakeAnd a braking force F for the wheels of the vehicle 1_BrakeCan be used.

With reference to fig. 3, it is to be noted that the block diagram has two regulation loops a and B for generating values at the output interfaces 50 and 51. The control circuit a is associated with the output interface 51. In block 101, the actual speed v of the vehicle 1 during the parking process is first calculated_ist. To this end, in block 102, the control device 15 is fed with the reference speed v determined by the data source 25_ref. In block 103, the wheel speed v determined by the

wheel sensors

23, 24_lAnd v_rIs fed. Subsequently, the two speeds v are set_lAnd v_rAdded and divided by two in block 104. In other words, this means that the two wheel speeds v are determined by the block 104_lAnd v_rAverage wheel speed v of_whl. In block 101, a slave velocity v_whlAnd v_refThe smaller speed is selected. This smaller speed is taken as the actual speed v of the vehicle 1_istIs taken as the basis for the calculation or parking process.

By means of the block 106, a desired speed v is obtained along the trajectory T from a trajectory planner which is part of the driver assistance system_sollIs fed as an input variable to the control device 15. Such a desired speed v is predefined for each time point or for each point along the trajectory T in accordance with the above criteria, for example in accordance with the length of the trajectory T or the like_soll。

In the node 107, the actual speed v of the vehicle 1 is found by subtraction_istAnd due to velocity v_sollDeviation therebetween as d_vxAnd feeds this deviation as input variable to the block 108. Block 108 (this block is in this embodiment)In the exemplary embodiment, designed as a PI controller) is used to determine a braking torque manipulated variable MP for actuating the (hydraulic) brake device 22. The magnitude of the manipulated variable MP is influenced by means of a block 109 which is a component of the nonlinear PI controller and whose output value KP_BrakeAnd KI_BrakeAlso fed as input parameters to block 108. Block 109 is fed with the nominal speed v of vehicle 1_sollDistance s_distAnd due velocity v_sollWith the actual speed v_istSpeed deviation d between_vxAs input variables.

Proportional gain KP_BrakeThe dynamics of the regulation loop are influenced as an output value of block 109. The following are distinguished here: the current running ratio of the vehicle 1 has a speed v_sollFaster or slower. When approaching the target or end point of the trajectory T, the proportional gain KP_BrakeIs continuously subtracted or continuously reduced. By means of an integral gain KI as output value of block 109_BrakeIn block 108, the integral component MI is determined_Raw. This reflects the operating point of the adjustment and leads to the desired accuracy of the adjustment, wherein it is important, in particular toward the end of the parking maneuver, to reach the target or end point of the trajectory T as precisely as possible. For this purpose, the integral gain KI is increased towards the end of the parking process_Brake。

In parallel with block 108, block 110 is provided. Distance s_distAnd the value a of the vehicle 1_xIs fed as input parameter to the block 110. Value a_xConsider: whether the vehicle 1 is located in an area of a downhill slope or an uphill slope.

In block 111, the value MI generated in block 108_RawAnd the output value MI generated in block 110_PreThe (pre-control values) are fed as input variables. In this case, the maximum of the two values mentioned is generated as an output variable in block 111 and is fed as an input variable to filter 112. Filter 112 additionally takes into account, for example, distance s_distAnd an uphill or downhill slope of the roadway as input variables, the filter specifying an (integrated) output value MI of the braking torque, which is the maximum speed of change of the braking torqueAnd the output value is added to the proportional output value MP in node 113 to obtain the value M_PIBrake. Value M_PIBrakeIs used as input parameter in block 115. Block 115 applies the value MPI, if necessary_BrakeTo the actuators and drives of the hydraulic brakes. For this purpose, the increasing setpoint drive torque M is set_PropIncAnd the currently effective drive torque M_PropAnd (4) balancing. Block 115 provides for actuating the brake device 22 via the output interface 51.

In this case, the actuation value M for the hydraulic brake system 22 is also specified in advance_BrakeSuperimposing a value M generated in block 117_Stop. Value M_StopIs envisaged as an additional safety feature when approaching the target point of the trajectory T and takes into account, for example, the situation of an accidental crossing of the target point. A monitoring function is thus implemented which is independent of the adjustment of the drive device 21 and the brake device 22 and which progressively brakes the vehicle 1 when the target point is crossed. For this purpose, the distance s_distAnd a value a for uphill or downhill of a lane_xIs fed as input variable to the block 117.

In parallel to the first control circuit a described so far for actuating the brake device 22, a second control circuit B is provided for actuating the drive 21 of the vehicle 1 via the output interface 50. To this end, a pilot control value M for the drive torque is first generated in block 120_Proppre. For this purpose, the distance s_distAcceleration value a for an uphill or downhill slope of a roadway_xAnd the differential moment M occurring due to the different friction ratios between the wheels and the ground_DifIs fed as input variable to the block 120.

Pre-control value M_ProppreWith the (integrated) pre-control value MI generated in block 121_PropSummed in node 122 and smoothed in filter 123. Actual speed v of vehicle 1_istAnd due to velocity v_sollDeviation d between_vxAnd the value Kl_MotorIs used as input variable for block 121. Value Kl_MotorIs an integral component MI for a motor torque regulator_PropIs measured. The output value M generated from the filter 123_PropIncIs used asThe input parameters in block 125. In addition, the set Gear and the distance s_distSum value M_PIBrakeIs fed as input parameter to the block 125. Block 125 is used to obtain the torque M of the drive 21 mentioned_PropIncSum moment M_PropDec. In the case of an electric vehicle having a plurality of electric motors as drive units, the drive torque M should be_PropIncOf (A) M_PropDecOr F_PropCan be variably distributed between motors at the front or rear axle, with a normal distribution typically being 50: 50.

The method described so far or the control device 15 described so far can be modified or adapted in a number of ways without departing from the inventive concept.

Claims

1. Method for regulating the speed (v) during a parking process of a vehicle (1), wherein the distance(s) of the vehicle (1) from the end of a trajectory (T) defining the parking process is sensed_dist) Wherein the vehicle (1) stops at the end of the trajectory (T), wherein the actual speed (v) of the vehicle (1) is sensed_ist) Wherein the distance(s) is processed in a control device (15)_dist) And said actual speed (v)_ist) Wherein a target speed (v) of the vehicle (1) is predefined along the trajectory (T)_soll) Wherein the control device (15) controls a drive device (21) and/or a brake device (22) of the vehicle (1) in order to comply at least indirectly with the target speed (v)_soll) And wherein the drive device (21) and/or the brake device (22) are actuated independently of the driver, i.e. completely autonomously, via an output interface (50, 51) of the control device (15).

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

by determining the wheel speed (v) at the wheels of the axle of the vehicle (1) that are not coupled to the steering device_l、v_r) To sense the actual speed (v) of the vehicle (1)_ist) Wherein an average vehicle is obtainedWheel speed (v)_whl) Determining said average wheel speed (v)_whl) With a reference speed (v) from another data source (25) of the vehicle (1)_ref) Comparing and comparing the reference speeds (v)_ref) And said average wheel speed (v)_whl) Is used as the actual speed (v)_ist) For making said adjustments.

3. The method according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

in order to determine a braking torque (M) at a wheel of the braking device (22)_Brake) And/or the braking force (F) on the wheel_Brake) In a block (108), a manipulated variable (MP) for the braking torque is first determined, wherein the manipulated variable (MP) takes into account the actual speed (v)_ist) At a corresponding distance(s) from the end point of said trajectory (T)_dist) At a predetermined nominal speed (v) for the trajectory (T)_soll) Speed deviation (d) between_vx) And wherein the distance(s) is additionally adjusted by means of a PI adjustment of the adjustment variable by means of a block (109)_dist) And said speed deviation (d)_vx) Influences the manipulated variable (MP).

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the magnitude of the manipulated variable (MP) is additionally influenced by means of a filter (112) which specifies a maximum rate of change of the braking torque.

5. The method of any one of claims 1 to 4,

it is characterized in that the preparation method is characterized in that,

when actuating the drive (21) and/or the brake (22) of the vehicle (1), existing downhill or uphill slopes and/or different friction ratios between wheels and roadway and/or obstacles that increase the drive torque, such as curbs, are additionally taken into account.

6. The method according to any one of claims 3 to 5,

it is characterized in that the preparation method is characterized in that,

just before the end of the trajectory (T) is reached, an additional braking torque (M) is generated, which is dependent on the downhill slope and the distance_Stop) To increase said braking torque (M)_Brake)。

7. The method of any one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

the drive device (21) and/or the brake device (22) are coupled at least indirectly to at least one electric motor for driving the vehicle (1) and regenerate energy released by the electric motor when the vehicle (1) decelerates, and wherein regeneration takes place until a standstill of the vehicle (1).

8. Computer program product, in particular data program or data carrier, which is designed to carry out at least one step of the method according to one of claims 1 to 7.

9. Control device (15) configured for carrying out the method according to any one of claims 1 to 7.

10. Drive train for an electric vehicle, the drive train having a control device (15) according to claim 9.