Methods, apparatus, and computer programs for adjusting speed during berthing.

Abstract

This invention relates to a method for adjusting the speed (v) of a vehicle (1) during a parking process, wherein the distance (s) between the vehicle (1) and the endpoint of a trajectory (T) defining the parking process is sensed. dist ), wherein the vehicle (1) is stationary 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 the control device (15). dist ) and the actual speed (v) ist ), and wherein, along the trajectory (T), the expected speed (v) of the vehicle (1) is pre-given. soll The control device (15) manipulates the drive unit (21) and / or braking device (22) of the vehicle (1) to at least indirectly follow the expected speed (v). soll The present invention also relates to a computer program product, a control device, and a drive system for an electric vehicle.

Description

Technical Field

[0001] This invention relates to a method for adjusting speed during vehicle parking, particularly during autonomous parking. Furthermore, this invention relates to an apparatus for performing the method of the invention and a computer program product. Background Technology

[0002] DE 103 43 174 A1 discloses, in the context of automated parking processes for vehicles, a method for performing a parking process along a trajectory in a speed-dependent manner, whereby the speed is used as a predetermined, rated value during the parking process and the speed is reduced to zero until the vehicle comes to a stop at the end of the trajectory. Here, the disclosed method is used for parking processes in which the driver still controls the parking process by manipulating the accelerator pedal or brake pedal. In other words, this means that although the disclosed method predefines a speed value, the driver actively influences this speed value by manipulating the accelerator pedal or brake pedal. In particular, the mentioned document does not disclose a fully autonomous parking process, in which the parking process is performed completely autonomously, i.e., without a driver. Summary of the Invention

[0003] The method of the present invention for adjusting speed during vehicle parking proposes to perform the parking process completely autonomously, i.e., without a driver. Therefore, this method can, for example, realize so-called fully automated "valet parking," in which the driver controls the parking process via their mobile phone and a corresponding application (App) connected to the vehicle, i.e., the driver is not in the vehicle. Particularly in relation to electric vehicles, the method of the present invention also enables, in electric vehicles, the regenerative braking process to be used for sensitive position adjustment in a particularly advantageous manner.

[0004] Therefore, in the context of the above description, the method of the present invention proposes to sense the distance between the vehicle and the end point of a trajectory for a defined parking process, wherein the vehicle stops at the end point of the trajectory, wherein the actual speed of the vehicle is sensed, wherein the distance and the actual speed are processed in a control device, wherein a desired speed of the vehicle is pre-given along the trajectory, wherein the control device manipulates the vehicle's drive and / or braking devices to at least indirectly comply with the desired speed, and wherein the manipulation of the drive and / or braking devices is performed independently of the driver, i.e., completely autonomously, through the output interface of the control device.

[0005] Although not elaborated further, when the driver is in the vehicle, it is of course up to the driver to decide whether to bring the speed or vehicle to a standstill during the parking process, especially by intervening with the braking system, or to reduce the parking speed of the vehicle. However, typically, operation of the accelerator pedal does not result in an actual increase in speed during the parking process.

[0006] Advantageous extensions of the method of the present invention for adjusting speed during vehicle parking are described in the preferred embodiments.

[0007] For adjusting speed during vehicle parking, it is important to sense the vehicle's accurate actual speed, as the adjustment is based on the actual speed and any possible deviations between the actual speed and the expected speed. In this context, a particularly preferred configuration of the method of the present invention proposes sensing the vehicle's actual speed by calculating the wheel speeds on the wheels of the vehicle's axles that are not coupled to the steering mechanism, wherein an average wheel speed is calculated, the average wheel speed is compared with a reference speed from another data source of the vehicle, and the minimum of the reference speed and the average wheel speed is used as the actual speed for adjustment.

[0008] The advantage of determining the wheel speeds on axles not coupled to the steering system is that, when determining the wheel speeds on axles coupled to the steering system, steering rotation affects the wheel speeds and therefore the steering angle must be taken into account. It should also be mentioned that reference speeds from other devices or data sources within the vehicle can be obtained, for example, from acceleration sensors or similar sensors, driver assistance devices, or similar devices.

[0009] Preferably, in order to determine the braking torque and / or braking force on the wheels of the braking device, an adjustment parameter is first obtained, wherein the adjustment parameter takes into account the speed deviation between the actual speed and the expected speed pre-given for the trajectory at the corresponding distance from the end of the trajectory, and wherein, additionally, the adjustment parameter is affected by the magnitude of the distance and speed deviation through PI adjustment of the adjustment parameter.

[0010] Regarding driving comfort during parking, especially to avoid sudden acceleration or deceleration, it is advantageous to additionally use a filter to influence the magnitude of the pre-control value, which pre-sets the maximum rate of change of the customized torque.

[0011] In addition, other factors also influence the adjustment quality or parking process, and these other factors are taken into account in the adjustment or method of the present invention. These other factors are particularly considered when manipulating the vehicle's drive and / or braking systems by additionally incorporating the existing downhill or uphill slope of the lane and / or the different friction ratios between the two wheels of the axle and the lane, and / or the adaptively increased driving torque caused by obstacles, such as curbs, into the adjustment algorithm.

[0012] Preferably, the control values ​​for controlling the braking device generated by the above method are further influenced by increasing the braking torque by generating an additional braking torque related to the downhill slope and distance just before reaching the end of the track.

[0013] As described above, the method of the present invention is preferably, but not limited to, electric vehicles, used in vehicles whose driving is at least partially, preferably entirely, performed by at least one electric motor powered by a drive battery. In this context, another preferred configuration of the method of the present invention proposes that the drive unit and / or braking unit are at least indirectly coupled to the electric motor used to drive the vehicle, regenerating the energy released by the electric motor during vehicle deceleration, wherein regeneration continues until the vehicle comes to a standstill. This last feature enables the optimization of comfort during vehicle braking.

[0014] Additionally, the present invention also includes a computer program product, particularly a data program or data carrier, which is configured to perform at least one step of the method of the present invention.

[0015] The invention also includes a control device configured to perform the method of the invention, and a drive system for an electric vehicle having a corresponding control device.

[0016] Other advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Attached Figure Description

[0017] Figure 1 The top view shows the vehicle at the start of the parking situation.

[0018] Figure 2 A graph showing the vehicle's speed curve during the parking process, and

[0019] Figure 3 A block diagram of a control device for manipulating the drive and / or braking devices of a vehicle to achieve the parking process is shown. Detailed Implementation

[0020] Components that are identical or have the same function are given the same reference numerals in the accompanying drawings.

[0021] exist Figure 1 The image shows a top-down view of vehicle 1 parking in a parking space, where the parking space is defined by vehicle 2 in front and vehicle 3 behind.

[0022] Vehicle 1 is preferably, but not limited to, being constructed as an electric vehicle. However, vehicle 1 may also be a hybrid vehicle that uses an electric motor as part of its drive system, or a vehicle 1 driven by an internal combustion engine.

[0023] Vehicle 1 is configured to perform a fully autonomous, i.e., driver-independent, parking process. For example, the autonomous parking process could be a so-called "valet" parking process, in which the driver initiates the parking process outside of vehicle 1 via their mobile phone and vehicle 1 performs the parking process entirely autonomously.

[0024] Vehicle 1 has a wide range of driver assistance or environmental recognition devices, which may include multiple sensors, such as distance sensors, radar sensors, or cameras. Exemplarily, and not limitingly, vehicle 1 has distance sensors 11, for example, operating on an ultrasonic basis, in areas of its front and rear bumpers. These distance sensors are configured to sense the distance between vehicle 1 and obstacles observed in front of or behind it along the direction of travel of vehicle 1. As illustrated by the distance sensor 11 depicted in the area of ​​the right front bumper, this distance sensor can sense the length of a parking space as it passes by, thereby inferring the parking probability for vehicle 1.

[0025] Additionally, vehicle 1 has a processing device 12 configured to process signals sensed by distance sensor 11 or convert these signals into corresponding distances s. dist The processing device 12 is coupled to the control device 15. In particular, the distance s relative to an obstacle located in the driving path of the vehicle 1... dist The input parameters are fed to the processing device 12. Additionally, the control device 15 is connected to the activation device 16, which is used to operate the control device 15 or initiate the parking process in a (fully) autonomous manner. Furthermore, the control device 15 is operatively connected to the operating device 17. The operating device 17 includes, in particular, the brake pedal and / or accelerator pedal of the vehicle 1, which, when the driver is in the vehicle 1, allows the fully autonomous parking process to be influenced by the driver operating the brake pedal or accelerator pedal.

[0026] The vehicle 1 also includes a drive unit 21 (in the case of an electric vehicle, in the form of at least one electric motor) for driving the vehicle 1 and a braking device 22 for braking the vehicle 1. Both the drive unit 21 and the braking device 22 can be controlled by the control device 15 through corresponding interfaces to perform the parking process. In the drive system of an electric vehicle, the drive unit 21 and the braking device 22 can be configured as an electric motor.

[0027] In vehicle 1, two wheel sensors 23 and 24 are additionally installed in the rear axle area of ​​the vehicle that are not connected to the steering device. The signals from these two wheel sensors are fed to the control device 15 as input parameters, and these signals are converted into the corresponding wheel speed v of the left or right wheel of vehicle 1. l and v r Vehicle 1 also includes a system for sensing a reference speed v. ref The additional device or data source 25. The data source 25 may be, for example, the vehicle 1's navigation system, inertial sensors, or similar devices. For the data source 25, the only important thing is that it can sense the typical low speed for the parking process with sufficient accuracy.

[0028] exist Figure 1 The diagram shows the trajectory T of vehicle 1, which is indirectly controlled by control device 15 to move vehicle 1 (rearward) along the trajectory to the parking space between two vehicles 2 and 3. The trajectory T is configured such that it ends, for example, at a certain distance in front of the rear vehicle 3, for example, 30 cm.

[0029] exist Figure 2 The diagram illustrates the velocity curve v of vehicle 1 over time t during a parking process along trajectory T. It can be seen, in particular, that vehicle 1 accelerates linearly from a standstill up to time t1. Between time t1 and t2, vehicle 1 maintains a constant velocity v1. Between time t2 and t3, vehicle 1's velocity v decelerates or decreases until it reaches zero. It should be noted that the velocity curves mentioned for vehicle 1 during the parking process are purely exemplary. In particular, it is possible to configure the velocity curves without linear changes during the parking process, for example, for comfort reasons. In principle, the velocity curves can also be configured differently depending on the length of trajectory T or the length of the parking space and / or the distance between vehicle 1 and the parking space.

[0030] exist Figure 3The 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 data carrier, configured to regulate or control the drive unit 21 and / or braking unit 22 of the vehicle 1, at least indirectly, via output interfaces 50 and 51 during the aforementioned parking process. For this purpose, at the output interface 50 for the drive unit 21, the (positive) drive torque M... PropInc and the maximum permissible driving torque M PropDec As an output value, the maximum permissible driving torque can also be negative (as a drag torque or as a regenerative torque). These values ​​can be converted into the corresponding force F on the driven wheel of vehicle 1 by dividing by the wheel diameter in box 55. Prop In a corresponding manner, the braking torque M (for hydraulic braking devices) is applied to the output interface 51 for the braking device 22. Brake and the braking force F used for the wheels of vehicle 1 Brake Available for use.

[0031] Reference Figure 3 It should be noted that this block diagram has two control loops, A and B, for generating values ​​at output interfaces 50 and 51. Control loop A is associated with output interface 51. Here, in block 101, the actual speed v of vehicle 1 during the parking process is first calculated. ist Therefore, in block 102, the reference velocity v obtained from the data source 25 is fed to the control device 15. ref In box 103, the wheel speed v is obtained by wheel sensors 23 and 24. l and v r It is fed. Then, the two velocities v are... l and v r Add them together and divide by two in box 104. In other words, this means that box 104 calculates the two wheel velocities v. l and v r Average wheel speed v whl In box 101, from the velocity v whl and v ref Choose the smaller speed. This smaller speed will be taken as the actual speed v of vehicle 1. ist It is used as the basis for calculation or berthing process.

[0032] Through box 106, the expected speed v along trajectory T from the trajectory planner, which is part of the driver assistance system. soll The input parameter is fed to the control device 15. Corresponding to the aforementioned criteria, such as the length of the trajectory T or a similar pre-defined value, this expected velocity v is pre-defined for each time point, or for each point along the trajectory T.soll .

[0033] In node 107, the actual speed v of vehicle 1 is obtained by subtraction. ist With the expected speed v soll The deviation between them, as d vx The deviation is then fed as an input parameter to block 108. Block 108 (constructed as a PI controller in this embodiment) is used to determine the braking torque adjustment parameter MP for controlling the (hydraulic) braking device 22. The magnitude of the adjustment parameter MP is influenced by block 109, which is part of a non-linear PI controller, and the output value of this block is KP. Brake and KI Brake It is also fed as an input parameter to box 108. The expected speed v of vehicle 1 is fed to box 109. soll Distance s dist And the required speed v soll With actual speed v ist The speed deviation d between vx As an input parameter.

[0034] Proportional Gain KP Brake The output value of block 109 influences the dynamics of the control loop. Here, we distinguish: the current speed of vehicle 1 is greater than its expected speed v. soll Faster or slower. The proportional gain KP increases as the trajectory approaches its target point or endpoint. Brake Continuously reduce or decrease. This is achieved using the integral gain KI, which is the output value of box 109. Brake Find the integral component MI in box 108. Raw This reflects the operating point of the adjustment and leads to the desired adjustment accuracy, where it is particularly important, especially near the end of the parking process, to reach the target point or endpoint of trajectory T as accurately as possible. To this end, the integral gain KI is increased near the end of the parking process. Brake .

[0035] A box 110 is positioned parallel to box 108. Distance s dist And the value a of vehicle 1 x It is fed as an input parameter to box 110. Value a x Consider: Is vehicle 1 located in a downhill or uphill area?

[0036] The value MI generated in box 108 is in box 111. Raw and the output value MI generated in box 110 PreThe (pre-control value) is fed as an input parameter. Here, the maximum of the two values ​​mentioned is generated in block 111 as an output parameter, and this maximum value is fed as an input parameter to filter 112. Filter 112 additionally considers, for example, distance s. dist Taking the uphill or downhill slope of the lane as input parameters, the filter is pre-loaded with a custom (integral) output value MI, which is the maximum rate of change of the braking torque. This output value is then added to the proportional output value MP at node 113 to obtain the value M. PIBrake Value M PIBrake It is used as the input parameter in box 115. When needed, box 115 will assign the value MPI. Brake The torque is distributed to the actuators and drive units of the hydraulic brake. This causes the required driving torque M to increase. PropInc and the currently effective driving torque M Prop Balance. Block 115 is used to control the braking device 22 via output interface 51.

[0037] Here, the control value M of the hydraulic braking device 22 is also given in advance. Brake Overlay a value M generated in box 117 Stop Value M Stop This is conceived as an additional safety feature when approaching the target point on trajectory T, and also considers situations such as accidentally exceeding the target point. Therefore, a monitoring function, independent of adjustments to the drive unit 21 and braking unit 22, is implemented, which progressively brakes vehicle 1 when exceeding the target point. For this purpose, distance s... dist And the value a used for uphill or downhill sections of the lane. x It is fed into box 117 as an input parameter.

[0038] Parallel to the first regulating circuit A for controlling the braking device 22 described so far, a second regulating circuit B for controlling the drive device 21 of the vehicle 1 via the output interface 50 is provided. For this purpose, a pre-control value M of the drive torque is first generated in block 120. Proppre Therefore, the distance from s dist The acceleration value 'a' used for uphill or downhill driving lanes. x And the differential torque M due to the different friction ratios between the wheels and the ground Dif It is fed into box 120 as an input parameter.

[0039] Pre-control value M Proppre Compared with the (integral) pre-control value MI generated in box 121 Prop The sums are added at node 122 and smoothed in filter 123. The actual speed v of vehicle 1. ist With the expected speed v soll The deviation d betweenvx and value Kl Motor Used as the input parameter for box 121. Value Kl Motor It is the integral component MI used in motor torque regulators. Prop The gain parameter. The output value M generated from filter 123. PropInc This is used as the input parameter in box 125. Additionally, the gear position and distance s are already set. dist Sum M PIBrake It is fed as an input parameter to block 125. Block 125 is used to obtain the torque M mentioned by the drive unit 21. PropInc and torque M PropDec In the case of an electric vehicle with multiple electric motors as drive units, there should be a driving torque M. PropInc M PropDec or F Prop The value can be variably distributed between the motors at the front or rear axle, where a normal distribution is typically 50:50.

[0040] The method or control device 15 described herein can be modified or altered in various ways without departing from the inventive concept.

Claims

1. A method for adjusting speed (v) during parking of a vehicle (1), wherein, The distance (s) between the vehicle (1) and the endpoint of the trajectory (T) that defines 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 the control device (15). dist ) and the actual speed (v) ist ), wherein the expected speed (v) of the vehicle (1) is pre-given along the trajectory (T). soll The control device (15) operates the drive unit (21) and / or braking device (22) of the vehicle (1) to at least indirectly comply with the required speed (v). soll Furthermore, the operation of the drive unit (21) and / or the braking unit (22) is performed independently of the driver, i.e., entirely autonomously, through the output interfaces (50, 51) of the control unit (15), wherein the wheel speeds (v) of the axles of the vehicle (1) on the wheels not coupled to the steering device are determined. l v r ) to sense the actual speed (v) of the vehicle (1). ist ), where the average wheel speed (v) is calculated. whl The average wheel speed (v) whl ) and the reference speed (v) from another data source (25) of the vehicle (1). ref Compare the reference speed (v) with the reference speed (v). ref ) and the average wheel speed (v whl The minimum value in ) is used as the actual velocity (v) ist ) is used to perform the aforementioned adjustment.

2. The method according to claim 1, Its features are, In order to determine the braking torque (M) on the wheel of the braking device (22) Brake ) and / or braking force on the wheels (F Brake In the first functional module, the adjustment parameter (MP) for the braking torque is first determined, wherein the adjustment parameter (MP) takes into account the actual speed (v). ist ) and the corresponding distance (s) to the endpoint of the trajectory (T). dist The given velocity (v) at point (T) is the trajectory (T) given in advance. soll The speed deviation (d) between ) vx ), and wherein, additionally by means of a second functional module, the PI adjustment of the adjustment parameter is determined by the distance (s) dist ) and the speed deviation (d) vx The magnitude of ) affects the adjustment parameter (MP).

3. The method according to claim 2, Its features are, Additionally, the magnitude of the adjustment parameter (MP) is influenced by a filter (112), which pre-determines the braking torque (M) on the wheel. Brake The maximum rate of change of ).

4. The method according to any one of claims 1 to 3, Its features are, When operating the drive unit (21) and / or braking unit (22) of the vehicle (1), additional consideration is given to existing downhill or uphill slopes and / or different friction ratios between the wheels and the lane and / or obstacles that increase the driving torque.

5. The method according to claim 2 or 3, Its features are, Just before reaching the end of the trajectory (T), an additional braking torque (M) related to the downhill slope and distance is generated. Stop To increase the braking torque (M) on the wheels. Brake ).

6. The method according to any one of claims 1 to 3, Its features are, The drive unit (21) and / or the braking unit (22) are at least indirectly coupled to at least one electric motor for driving the vehicle (1), and regenerate the energy released by the electric motor when the vehicle (1) decelerates, wherein the regeneration continues until the vehicle (1) is stationary.

7. The method according to claim 4, Its features are, The obstacle is a curb.

8. A computer program product configured to perform at least one step of the method according to any one of claims 1 to 7.

9. The computer program product according to claim 8, characterized in that, The computer program product is a data program or a data carrier.

10. A control device (15) configured to perform the method according to any one of claims 1 to 7.

11. A drive system for an electric vehicle, the drive system having a control device (15) according to claim 10.

Images