Rack position determination method and device and vehicle

Abstract

The embodiment of the invention provides a rack position determining method and device and a vehicle, and relates to the technical field of automobile control. The method comprises the steps of determining an original rack position corresponding to a target steering wheel angle of a vehicle at the current moment; acquiring a target rack position at the previous moment; based on the original rack position, the sampling time, the time constant, the damping coefficient, the reset mark and the target rack position at the previous moment, the target rack position at the current moment is obtained; wherein the time constant and the damping coefficient are respectively used for adjusting the change rate of the target rack position curve at the beginning stage and the end stage, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents a relation curve of the target rack position and the time. By means of the rack position determining method, the target rack position can be dynamically adjusted, then the actual steering wheel movement performance is controlled, and the driving experience of a driver is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of automobile control technology, and in particular to a method and device for determining a rack position and a vehicle. Background Art

[0002] In the intelligent driving scenario, the host computer requests the target steering wheel angle, while for EPS (Electric Power Steering, electric power steering system), the control object is the rack and the rack position needs to be obtained. Therefore, EPS needs to convert the target steering wheel angle requested by the host computer into the target rack position, where the conversion coefficient between the steering wheel angle and the rack position is related to the system hardware and is constant.

[0003] At present, if the converted target rack position is directly output to the PID controller for execution, since the target rack position is always changing suddenly, the target rack position transitions too quickly, causing the P-term torque to also change suddenly, and the controlled object is prone to "not being able to stop" at the target position, that is, overshoot. In addition, the target rack position always stops suddenly, forcing the rack of the controlled object to stop suddenly during the control process. Due to the inertia of the steering wheel, the steering wheel cannot stop suddenly during movement, which leads to the situation that the rack at the bottom of the steering system has stopped, while the steering wheel at the top is still moving. This situation will cause the torsion bar under the steering wheel to deform, and then cause the steering wheel to vibrate for a short time at the target angle, affecting the driver's driving experience. Summary of the invention

[0004] Embodiments of the present invention provide a rack position determination method, device and vehicle to dynamically adjust a target rack position, thereby controlling actual steering wheel motion performance and improving the driver's driving experience.

[0005] A first aspect of an embodiment of the present invention provides a method for determining a rack position, the method comprising:

[0006] Determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment;

[0007] Get the target rack position at the last moment;

[0008] Based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment, obtaining the target rack position at the current moment;

[0009] Among them, the time constant and the damping coefficient are used to adjust the change rate of the target rack position curve in the initial stage and the final stage respectively, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents the relationship curve between the target rack position and time.

[0010] A second aspect of an embodiment of the present invention provides a rack position determination device, the device comprising:

[0011] An original position determination module, used to determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment;

[0012] A position acquisition module is used to obtain the target rack position at the last moment;

[0013] A target position determination module, used to obtain a target rack position at a current moment based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at a previous moment;

[0014] Among them, the time constant and the damping coefficient are used to adjust the change rate of the target rack position curve in the initial stage and the final stage respectively, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents the relationship curve between the target rack position and time.

[0015] A third aspect of an embodiment of the present invention provides a vehicle, the vehicle comprising at least: a controller, the controller, when executed, implements the rack position determination method as described in the first aspect of the embodiment of the present invention.

[0016] In the rack position determination method provided by the embodiment of the present invention, after the original rack position is obtained based on the target steering wheel angle conversion at the current moment, the original rack position is no longer directly output to the controller for execution, but the original rack position is dynamically adjusted based on the sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment to obtain the target rack position at the current moment. In this method, the change rate of the target rack position curve in the initial stage and the final stage is adjusted respectively by the time constant and the damping coefficient, thereby avoiding the sudden stop and / or sudden change of the target rack position. The controller executes based on the target rack position obtained by this method, which can avoid the overshoot phenomenon and the torsion bar deformation causing the short-term vibration of the steering wheel as much as possible, thereby effectively controlling the actual steering wheel movement performance, thereby improving the driving experience of the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0018] Figure 1It is a schematic diagram of conversion of a steering wheel angle into a rack position shown in the related art;

[0019] Figure 2 is a flow chart of a method for determining a rack position according to an embodiment of the present invention;

[0020] Figure 3 is an integration schematic diagram of an integrator shown in one embodiment of the present invention;

[0021] Figure 4 is an integration schematic diagram of a first integrator shown in an embodiment of the present invention;

[0022] Figure 5 is an integration schematic diagram of a second integrator shown in an embodiment of the present invention;

[0023] Figure 6 It is a schematic diagram of a detection process of an integral reset flag shown in an embodiment of the present invention;

[0024] Figure 7 is a schematic diagram of the overall process of a method for determining a rack position according to an embodiment of the present invention;

[0025] Figure 8 is an adjustment comparison diagram of a target rack position curve shown in an embodiment of the present invention;

[0026] Fig. 9 It is a structural block diagram of a rack position determination device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] As mentioned above, EPS needs to convert the target steering wheel angle of the host computer into the target rack position, where the conversion coefficient is related to the system hardware and is constant. Figure 1 As shown, Figure 1 This is a conversion diagram of a steering wheel angle to a rack position shown in the related art. If the converted target rack position is directly output to the PID controller for execution, the following effects will occur:

[0029] 1. From Figure 1It can be seen that the target rack position on the right is always changing suddenly. The target rack position transitions too quickly, causing the P-term torque to change suddenly, and the controlled object is prone to "not being able to stop" at the target rack position, which is called overshoot. Overshoot will cause the steering wheel to be unable to stop immediately after turning to the target angle and exceed the target angle, and then return to the target angle. At this time, the steering wheel fluctuates up and down at the target angle.

[0030] 2. Since the target rack position always stops suddenly, the rack of the controlled object is forced to stop suddenly during the control process. Due to the inertia of the steering wheel, it is impossible for the steering wheel to stop suddenly during movement, which results in the situation where the rack at the bottom of the steering system has stopped, while the steering wheel at the top is still moving. This situation will cause the torsion bar under the steering wheel to deform, which in turn causes the steering wheel to vibrate for a short time at the target angle (deformation → recovery → deformation → recovery). Since the torsion bar itself is relatively soft and prone to relative deformation, this vibration is related to the characteristics of the torsion bar. At this moment, the rack has reached the target rack position and the rack has stopped moving, so it is impossible to eliminate the vibration by adjusting the PID controller parameters. (Note: Because the torsion bar will deform, the torque sensor can detect the driver's hand force based on the deformation variable.)

[0031] 3. Under different intelligent driving conditions, the expected steering wheel rotation performance is different. For example: APA (AutoParking Assist), because APA always requests the steering wheel at a large angle, APA hopes to slow down in advance to achieve a slow stop when the target angle is about to be reached. However, the angle request of LKA (Lane Keeping Assist) is smaller, and LKA hopes that the steering wheel will stop quickly when it reaches the target angle (but no inertial shaking of the steering wheel can be generated). Similar to this, the expected steering wheel movement performance under different working conditions is different, and closed-loop control based on the traditional target rack position is not achievable.

[0032] 4. Since the target rack position always changes suddenly, it brings challenges to the software development of position closed-loop control on the one hand, and puts pressure on calibration engineers to debug the steering wheel vibration on the other hand.

[0033] Therefore, in order to at least partially solve one or more of the above problems and other potential problems, an embodiment of the present invention proposes a rack position determination method. After determining the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment, the original rack position is dynamically adjusted based on the sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment to obtain the target rack position at the current moment. In this method, the change rate of the target rack position curve at the beginning and the end stage is adjusted respectively by the time constant and the damping coefficient, avoiding the sudden stop and / or sudden change of the target rack position, thereby avoiding the overshoot phenomenon and the short-term vibration of the steering wheel caused by the torsion bar deformation as much as possible, thereby effectively controlling the actual steering wheel movement performance and improving the driving experience of the driver.

[0034] Hereinafter, specific examples of the present solution will be described in more detail with reference to the accompanying drawings.

[0035] refer to Figure 2 , Figure 2 FIG. 1 is a flow chart of a method for determining a rack position according to an embodiment of the present invention. The method can be applied to a controller, such as an MCU (Microcontroller Unit). Figure 1 As shown, the rack position determination method of this embodiment may include the following steps:

[0036] Step S11: Determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment.

[0037] In this embodiment, the target steering wheel angle of the vehicle at the current moment can be obtained, which can be obtained by requesting the host computer. After obtaining the target steering wheel angle at the current moment, the target steering wheel angle at the current moment can be converted based on the conversion coefficient between the steering wheel angle and the rack position to obtain the original rack position at the current moment. In this embodiment, the original rack position is the rack position obtained by converting the target steering wheel angle.

[0038] Step S12: Obtain the target rack position at the previous moment.

[0039] In this embodiment, the target rack position is the rack position obtained by adjusting the original rack position based on at least the time constant and the damping coefficient. This embodiment also needs to obtain the target rack position at the previous moment, and the target rack position at the previous moment is the target rack position obtained by this rack position determination method at the previous moment.

[0040] Step S13: based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment, the target rack position at the current moment is obtained.

[0041] In this embodiment, after obtaining the original rack position at the current moment and the target rack position at the previous moment, the target rack position at the current moment can be obtained based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment. For example, in this embodiment, the original rack position at the current moment is adjusted based on the sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment to obtain the target rack position at the current moment.

[0042] This embodiment pre-sets a time constant and a damping coefficient, both of which are calibration quantities. The time constant is used to adjust the rate of change of the target rack position curve at the beginning stage, and the damping coefficient is used to adjust the rate of change of the target rack position curve at the end stage. Among them, the target rack position curve represents the relationship curve between the target rack position and time; the sampling time is the interval time between the current moment and the previous moment, that is, the sampling time of this embodiment is the time interval between two adjacent moments of obtaining the target steering wheel angle.

[0043] In this embodiment, the original rack position is dynamically adjusted by sampling time, time constant, damping coefficient, reset flag and target rack position at the previous moment to obtain the target rack position at the current moment. In this way, the change rate of the target rack position curve in the initial stage and the final stage is adjusted based on the time constant and the damping coefficient, respectively, to avoid sudden stops and / or sudden changes in the target rack position, thereby avoiding overshoot and short-term vibration of the steering wheel caused by torsion bar deformation as much as possible, thereby effectively controlling the actual steering wheel movement performance and improving the driver's driving experience.

[0044] In combination with the above embodiments, in one implementation manner, the time constant ≥ the sampling time.

[0045] In combination with the above embodiments, in one implementation, the present invention further provides a method for determining the position of a rack. Specifically, in this embodiment, the above step S13 may include steps S21 to S24:

[0046] Step S21: Determine the input of the first integrator at the current moment based on the original rack position, the target rack position at the previous moment and the time constant.

[0047] In this embodiment, the original rack position, sampling time, time constant, damping coefficient, reset flag and target rack position at the previous moment are processed by an integrator to obtain the target rack position at the current moment. Specifically, the reset flag of this embodiment includes: an integral reset flag, and the integrator includes: a first integrator and a second integrator, and the first integrator and the second integrator are connected in sequence.

[0048] In this embodiment, the internal algorithms of the first integrator and the second integrator are the same. The integration schematic diagram of the first integrator or the second integrator can be as follows: Figure 3 As shown, Figure 3 FIG. 1 is a schematic diagram of an integration of an integrator shown in an embodiment of the present invention. Figure 3 In the figure, u is the input of the integrator, SampleTime is the sampling time, Reset is the integral reset flag, ResetValue is the integral reset flag value, and y is the output of the integrator. The internal algorithm of the integrator is as follows:

[0049]

[0050] Among them, y t is the output of the integrator at the current moment, u t is the input of the integrator at the current moment, y t-1 is the output of the integrator at the previous moment.

[0051] And, in this embodiment, the input of the first integrator at the current moment can be determined based on the original rack position, the target rack position at the previous moment, and the time constant.

[0052] Step S22: obtaining the output of the first integrator at the current moment based at least on the integration reset flag, the sampling time and the input of the first integrator at the current moment.

[0053] In this embodiment, the first integrator can process the sampling time, the input of the first integrator at the current moment and the integration reset flag of the first integrator, and obtain the output of the first integrator at the current moment based at least on the integration reset flag of the first integrator, the sampling time and the input of the first integrator at the current moment.

[0054] Step S23: Determine the input of the second integrator at the current moment based on the output of the first integrator at the current moment, the damping coefficient, the target rack position at the previous moment, and the time constant.

[0055] In this embodiment, after obtaining the output of the first integrator at the current moment, the input of the second integrator at the current moment can be determined based on the output of the first integrator at the current moment, the damping coefficient, the target rack position at the previous moment, and the time constant.

[0056] Step S24: obtaining the target rack position at the current moment output by the second integrator based at least on the integration reset flag, the sampling time and the input of the second integrator at the current moment.

[0057] In this embodiment, the second integrator can process the sampling time, the input of the second integrator at the current moment, and the integration reset flag of the second integrator, and obtain the target rack position at the current moment output by the second integrator based at least on the integration reset flag of the second integrator, the sampling time, and the input of the second integrator at the current moment. Wherein, at the same moment, the integration reset flag of the first integrator can be the same as or different from the integration reset flag of the second integrator.

[0058] In this embodiment, the two integrators are set to make the time constant and the damping coefficient work at the same time, so as to adjust the change rate (i.e., the rate of increase or decrease) of the target rack position curve (i.e., tracking cancellation) at the beginning and end stages. In an optional example, the time constant can be a second-order filter time constant, represented by tau; the damping coefficient can be a second-order damping coefficient, represented by damp.

[0059] In combination with the above embodiments, in one implementation, the present invention also provides a method for determining the position of a rack. Specifically, in this method, the above step S22 may include step S31 and step S32:

[0060] Step S31: when the integral reset flag is set, determining the output of the first integrator at the current moment based on the input of the first integrator at the current moment, the sampling time, the damping coefficient and the target rack position at the previous moment.

[0061] In this embodiment, the first integrator can determine whether the integral reset flag of the first integrator is set or reset. When the integral reset flag is determined to be set, the output of the first integrator at the current moment can be determined based on the input of the first integrator at the current moment, the sampling time, the damping coefficient and the target rack position at the previous moment.

[0062] Step S32: when the integration reset flag is reset, determining the output of the first integrator at the current moment based on the input of the first integrator at the current moment, the sampling time and the output of the first integrator at the previous moment.

[0063] In this embodiment, when the integration reset flag is determined to be reset, the output of the first integrator at the current moment may be determined based on the input of the first integrator at the current moment, the sampling time, and the output of the first integrator at the previous moment.

[0064] like Figure 4 As shown, Figure 4 FIG. 1 is a schematic diagram of an integration of a first integrator shown in an embodiment of the present invention. Figure 4In the figure, integrator 1 is the first integrator, u1 is the input of the first integrator, SampleTime is the sampling time, Reset is the integration reset flag of the first integrator, ResetValue1 is the integration reset flag value of the first integrator, and y1 is the output of the first integrator.

[0065] In an optional embodiment, the input of the first integrator may be:

[0066]

[0067] Among them, u1 is the input of the first integrator, Raw is the original rack position, tau is the time constant, y old is the target rack position at the previous moment.

[0068] The output y1 of the first integrator can be:

[0069]

[0070] Where Reset is the integral reset flag, ResetValue1 is the integral reset flag value of the first integrator, ResetValue1 = u1*SampleTime+2*damp*y old ; SampleTime is the sampling time, damp is the damping coefficient, y1 t is the output of the first integrator at the current moment, u1 t is the input of the first integrator at the current moment, y1 t-1 is the output of the first integrator at the previous moment.

[0071] In combination with the above embodiments, in another implementation, the present invention also provides a method for determining the position of a rack. Specifically, in this embodiment, the above step S24 may include steps S41 to S43:

[0072] Step S41: when the integral reset flag is set, determining the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time and the target rack position at the previous moment.

[0073] In this embodiment, the second integrator can determine whether the integral reset flag of the second integrator is set or reset. When it is determined that the integral reset flag is set, the output of the second integrator at the current moment can be determined based on the input of the second integrator at the current moment, the sampling time and the target rack position at the previous moment.

[0074] Step S42: when the integration reset flag is reset, determining the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time and the output of the second integrator at the previous moment.

[0075] In this embodiment, when the integration reset flag is determined to be reset, the output of the second integrator at the current moment may be determined based on the input of the second integrator at the current moment, the sampling time, and the output of the second integrator at the previous moment.

[0076] Step S43: Determine the output of the second integrator at the current moment as the target rack position at the current moment.

[0077] In this embodiment, the output of the second integrator at the current moment may be determined as the target rack position at the current moment.

[0078] like Figure 5 As shown, Figure 5 FIG. 1 is a schematic diagram of the integration of the second integrator shown in one embodiment of the present invention. Figure 5 In the figure, integrator 2 is the second integrator, u2 is the input of the second integrator, SampleTime is the sampling time, Reset is the integration reset flag of the second integrator, ResetValue2 is the integration reset flag value of the second integrator, and y2 is the output of the second integrator.

[0079] In an optional embodiment, the input of the second integrator may be:

[0080]

[0081] Among them, u2 is the input of the second integrator, y1 is the output of the first integrator, tau is the time constant, and y old is the target rack position at the previous moment, and damp is the damping coefficient.

[0082] The output y2 of the second integrator can be:

[0083]

[0084] Where Reset is the integral reset flag, ResetValue2 is the integral reset flag value of the second integrator, ResetValue2 = u2*SampleTime+y old ; SampleTime is the sampling time, y2 t is the output of the second integrator at the current moment, u2 t is the input of the second integrator at the current moment, y2 t-1 is the output of the second integrator at the previous moment, y oldis the target rack position at the previous moment.

[0085] In combination with the above embodiments, in another implementation, an embodiment of the present invention further provides a method for determining a rack position. In this embodiment, the integral reset flag of the integrator indicates whether the integrator stops integration or resumes integration. When the integral reset flag is set, integration is stopped; when the integral reset flag is reset, integration is resumed.

[0086] Generally speaking, it is necessary to detect the rising edge of the position control activation flag and reset the integral reset flag at the moment the position control activation is detected. In other words, when the reset of the Reset (integral reset flag) is triggered by the position control activation, at the initial moment of the position control activation, the purpose is to capture the current actual rack position and the current target rack position to ensure that the integral process starts with the current state.

[0087] However, when the reset of Reset (integral reset flag) is caused by the change in the direction of the target rack position, such as when the steering wheel turns left or right, the size of the target rack position is positive and negative. When it is determined that the direction of the target rack position has changed, it is considered that the integral direction has changed and re-integration is required, otherwise an unexpected target rack position value will be output.

[0088] Specifically, in this embodiment, in addition to the above steps, steps S51 to S54 may also be included:

[0089] Step S51: input the target rack position at the previous moment into a delay device to obtain a delayed target rack position at the previous moment delayed by one sampling period.

[0090] In this embodiment, the target rack position at the previous moment needs to be input into the delay device, and the delayed target rack position at the previous moment delayed by one sampling cycle output by the delay device is obtained. The delayed target rack position is the target rack position delayed by one sampling cycle. Among them, the delay device of this embodiment plays a delay role.

[0091] Step S52: Determine the relationship between the first difference between the target rack position at the previous moment and the delayed target rack position at the previous moment and zero.

[0092] In this embodiment, a first difference between the target rack position at the last moment and the delayed target rack position at the last moment may be determined first. After the first difference is obtained, the relationship between the first difference and zero needs to be compared.

[0093] Step S53: when the first difference is greater than zero, determining whether the target rack position at the previous moment is greater than or equal to the original rack position.

[0094] In this embodiment, when it is determined that the first difference is greater than zero, that is, when it is determined that the target rack position at the previous moment is greater than the delayed target rack position at the previous moment, it is necessary to further determine the relationship between the target rack position at the previous moment and the original rack position at the current moment, and judge whether the target rack position at the previous moment is greater than or equal to the original rack position at the current moment.

[0095] Step S54: when the target rack position at the previous moment is greater than or equal to the original rack position, determine that the integral reset flag is reset; when the target rack position at the previous moment is less than the original rack position, determine that the integral reset flag is set.

[0096] In this embodiment, when it is determined that the target rack position at the previous moment is greater than or equal to the original rack position, the integral reset characteristic can be determined to be reset. When it is determined that the target rack position at the previous moment is less than the original rack position, the integral reset flag is determined to be set. It should be noted that in this embodiment, at the same time, the integral reset flag of the first integrator is the same as the integral reset flag of the second integrator.

[0097] In combination with the above embodiments, in one implementation, the present invention also provides a method for determining the position of a rack. Specifically, in addition to the above steps, the method may also include steps S61 to S63:

[0098] Step S61: when the first difference is equal to zero, determining that the integral reset flag is set.

[0099] In this embodiment, when it is determined that the first difference between the target rack position at the previous moment and the delayed target rack position at the previous moment is equal to zero, that is, the target rack position at the previous moment is equal to the delayed target rack position at the previous moment, it can be determined that the integral reset flag is set.

[0100] Step S62: when the first difference is less than zero, determining whether the original rack position is greater than or equal to the target rack position at the previous moment.

[0101] In this embodiment, when it is determined that the first difference between the target rack position at the previous moment and the delayed target rack position at the previous moment is less than zero, that is, the target rack position at the previous moment is less than the delayed target rack position at the previous moment, it is necessary to further determine the relationship between the original rack position and the target rack position at the previous moment, that is, to determine whether the original rack position is greater than or equal to the target rack position at the previous moment.

[0102] Step S63: When the original rack position is greater than or equal to the target rack position at the previous moment, determine that the integral reset flag is reset; when the original rack position is less than the target rack position at the previous moment, determine that the integral reset flag is set.

[0103] In this embodiment, when it is determined that the original rack position is greater than or equal to the target rack position at the previous moment, the integral reset flag of the integrator can be determined to be reset; when it is determined that the original rack position is less than the target rack position at the previous moment, the integral reset flag of the integrator can be determined to be set.

[0104] In one embodiment, if Figure 6 As shown, Figure 6 FIG. 1 is a schematic diagram of a detection process of an integral reset flag according to an embodiment of the present invention. Figure 6 In the figure, y_old represents the target rack position at the previous moment, delay(y_old) represents y_old delayed by one sampling period, that is, the delayed target rack position at the previous moment, Raw represents the original rack position, Reset is the integral reset flag, Reset = True represents that the integral reset flag is reset, and Reset = False represents that the integral reset flag is set.

[0105] In combination with the above embodiments, in one implementation, the present invention further provides a method for determining the position of a rack. Specifically, in this method, the above step S12 may include steps S71 to S73:

[0106] Step S71: Input the actual rack position at the current moment and the target rack position at the previous moment output by the second integrator into a delay device.

[0107] The delay device of this embodiment plays a delay role, and is mainly used to delay a sampling period so that the initial target rack position is consistent with the current actual rack position. Specifically, the delay device is deployed after the first integrator and the second integrator, and the delay device has two inputs, namely: the actual rack position at the current moment and the target rack position at the previous moment output by the second integrator. In other words, it is necessary to input the actual rack position at the current moment and the target rack position at the previous moment output by the second integrator into the delay device. Among them, the actual rack position at the current moment is: the current actual rack position, that is, the actual rack position obtained by multiplying the current actual steering wheel angle by the conversion relationship.

[0108] Step S72: when the current moment is the initial moment, the actual rack position at the current moment output by the delay device is determined as the target rack position at the previous moment.

[0109] In this embodiment, it is necessary to determine whether the current moment is the initial moment. The initial moment of this embodiment is the starting moment of determining the target rack position by the method of this embodiment. In the case of determining that the current moment is the initial moment, the delay device outputs the actual rack position at the current moment. At this time, the actual rack position at the current moment is determined as the target rack position at the previous moment and input into the first integrator and the second integrator. In this way, it can be ensured that the initial target rack position is consistent with the current actual rack position, and the change is based on the current actual rack position.

[0110] Step S73: When the current moment is not the initial moment, the target rack position at the previous moment output by the delay device is determined as the target rack position at the previous moment.

[0111] In this embodiment, when it is determined that the current moment is not the initial moment, the delay device outputs the target rack position of the previous moment output by the second integrator. At this time, the target rack position of the previous moment output by the delay device is determined as the target rack position of the previous moment to be input into the first integrator and the second integrator.

[0112] In one example, the internal algorithm of the delay timer is as follows:

[0113]

[0114] Among them, y is the output of the delay device, that is, the target rack position at the previous moment, Actpos is the actual rack position at the current moment, and y2 is the output of the second integrator.

[0115] In one embodiment, if Figure 7 As shown, Figure 7 FIG. 1 is a schematic diagram of the overall process of a method for determining the position of a rack according to an embodiment of the present invention. Figure 7 In this scheme, the internal integrators (the first integrator (integrator 1) and the second integrator (integrator 2)) and the delay device Delay. Among them, in this scheme, the external output is: Raw-original rack position, SampleTime-sampling time; tau-time constant (such as second-order filter time constant), is the calibration quantity, damp-damping coefficient (such as second-order damping coefficient), is the calibration quantity, Reset-integral reset flag, y_old-the target rack position y at the previous moment, and ActPos is the actual rack position at the current moment; the output is: y-the target rack position at the current moment, and y1 is the output of the first integrator, and y2 is the output of the second integrator. In Figure 7 In the process, the target rack position y output by the delay device Delay will be input into the integrator as the target rack position y_old at the previous moment.

[0116] In combination with the above embodiments, in one implementation, an embodiment of the present invention further provides a method for determining the position of a rack. Specifically, in addition to the above steps, the method may also include steps S81 to S83:

[0117] Step S81: Determine the current operating condition and current vehicle speed of the vehicle.

[0118] In this embodiment, the current working condition and current speed of the vehicle also need to be determined, wherein the current working condition is the intelligent driving working condition that the vehicle is currently in. For example, the intelligent driving working condition may include: APA (Auto Parking Assist, automatic parking assistance) working condition, LKA (Lane Keeping Assist, lane keeping assistance) working condition, ESS (Emergency Steering Support, emergency steering assistance) working condition, and the like.

[0119] Step S82: Determine the time constant based on the current operating condition, the current vehicle speed and the first mapping relationship.

[0120] In this embodiment, a first mapping relationship is set in advance, and the first mapping relationship is a mapping relationship between vehicle speeds and time constants under multiple preset working conditions. For example, the first mapping relationship at least includes: a mapping relationship between each vehicle speed and a time constant under an APA working condition, a mapping relationship between each vehicle speed and a time constant under an LKA working condition, and a mapping relationship between each vehicle speed and a time constant under an ESS working condition.

[0121] This embodiment may determine a time constant for determining the target rack position based on the acquired current operating condition, the current vehicle speed, and a first mapping relationship set in advance.

[0122] Step S83: Determine the damping coefficient based on the current operating condition, the current vehicle speed and the second mapping relationship.

[0123] In this embodiment, a second mapping relationship is also pre-set, and the second mapping relationship is a mapping relationship between vehicle speed and damping coefficient under multiple pre-set working conditions. For example, the second mapping relationship at least includes: a mapping relationship between each vehicle speed and damping coefficient under the APA working condition, a mapping relationship between each vehicle speed and damping coefficient under the LKA working condition, and a mapping relationship between each vehicle speed and damping coefficient under the ESS working condition.

[0124] This embodiment can determine the damping coefficient for determining the target rack position based on the acquired current working condition, the current vehicle speed and the pre-set second mapping relationship. Through the rack position determination method of this embodiment, the target rack position can be dynamically adjusted based on the working condition and the vehicle speed, thereby controlling the actual steering wheel movement performance.

[0125] In one embodiment, the original rack position Raw can be adjusted by two calibrated parameters, the time constant tau and the damping coefficient damp, so that the final determined target rack position y meets the expectation. Figure 8 As shown, Figure 8 FIG. 1 is an adjustment comparison diagram of a target rack position curve shown in an embodiment of the present invention. Figure 8 middle, Figure 8 The Raw on the left is the original rack position. Three different target rack position curves can be adjusted through three sets of calibration parameters (tau and damp), which are: Figure 8 y, y′, y″ on the right.

[0126] Among them, tau acts on the beginning stage of the target rack position curve, and damp acts on the end stage of the target rack position curve. By inputting damp, the actual rack position can be slowed down when it approaches the target rack position, thereby avoiding overshoot caused by too fast tracking speed. The larger the tau, the smoother the target rack position curve starts to change, and the smaller the rate of change; the smaller the tau, the more "rapid" the target rack position curve starts to change, and the faster the rate of change. The larger the damp, the smoother the target rack position curve changes at the end, and the smaller the rate of change; the smaller the damp, the more "rapid" the curve changes at the end, and the faster the rate of change. Therefore, the desired target curve can be set by calibrating tau and damp. Table 1 below shows the above Figure 8 The relationship between the various groups of parameters in (with y as the reference).

[0127] Table 1 Relationship between parameters in different target curves

[0128] Target curve number Parameter name Parameter Relationship y tau, damp y′ tau′, damp′ tau′>tau, damp>damp′ y″ tau″、damp″ tau″<tau、damp<damp″

[0129] Among them, it can be concluded from Table 1 that, with the target rack position curve y as a reference, the target rack position curve y′ changes more smoothly in the initial stage because the tau' corresponding to the target rack position curve y′ is greater than the tau corresponding to the target rack position curve y; the target rack position curve y′ changes more "rapidly" in the final stage because the damp' corresponding to the target rack position curve y′ is less than the damp corresponding to the target rack position curve y. Also, with the target rack position curve y as a reference, the target rack position curve y″ changes more "rapidly" in the initial stage because the tau" corresponding to the target rack position curve y″ is less than the tau corresponding to the target rack position curve y; the target rack position curve y″ changes more smoothly in the final stage because the damp" corresponding to the target rack position curve y″ is greater than the damp corresponding to the target rack position curve y.

[0130] In another embodiment, when setting the first mapping relationship and the second mapping relationship, from the perspective of response performance: when in the APA condition, since the steering wheel usually needs to be rotated at a large angle, tau and damp should be adjusted to be larger in order to make the target rack position curve smoother.

[0131] When in LKA and ESS conditions, the steering wheel rotation usually depends on the vehicle speed, so the tau and damp coefficients at low speeds are usually larger than those at high speeds; in addition, smaller tau and damp coefficients at high speeds will speed up the response, which is also a safer consideration.

[0132] When setting the first mapping relationship and the second mapping relationship, we start from the perspective of the torsion bar characteristics: if the rack stops quickly during movement, but the steering wheel generates inertial torque under the action of inertia, which in turn causes the torsion bar to deform, resulting in the steering wheel shaking at the target position even if the rack is stationary (the motor is no longer rotating at this time). Therefore, by adjusting the damp coefficient, specifically increasing the damp coefficient, the steering wheel can be effectively "braked" in advance to stop slowly, avoiding torsion bar deformation.

[0133] It should be noted that, for the sake of simplicity, the method embodiments are described as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0134] Based on the same inventive concept, an embodiment of the present invention provides a rack position determination device 900, which can be applied to a controller. Fig. 9 , Fig. 9 1 is a structural block diagram of a rack position determination device provided by an embodiment of the present invention. Fig. 9 As shown, the rack position determination device 900 includes:

[0135] The original position determination module 901 is used to determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment;

[0136] The position acquisition module 902 is used to acquire the target rack position at the last moment;

[0137] A target position determination module 903, configured to obtain a target rack position at a current moment based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at a previous moment;

[0138] Among them, the time constant and the damping coefficient are used to adjust the change rate of the target rack position curve in the initial stage and the final stage respectively, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents the relationship curve between the target rack position and time.

[0139] Optionally, the reset flag includes an integral reset flag; the target position determination module 903 includes:

[0140] A first input determination module, configured to determine an input of a first integrator at a current moment based on the original rack position, the target rack position at a previous moment, and the time constant;

[0141] A first output determination module, configured to obtain an output of the first integrator at a current moment based at least on the integration reset flag, the sampling time, and the input of the first integrator at a current moment;

[0142] a second input determination module, configured to determine an input of the second integrator at a current moment based on the output of the first integrator at the current moment, the damping coefficient, the target rack position at the previous moment, and the time constant;

[0143] The second output determination module is used to obtain the target rack position at the current moment output by the second integrator based at least on the integration reset flag, the sampling time and the input of the second integrator at the current moment.

[0144] Optionally, the first output determination module includes:

[0145] A first output determination submodule, configured to determine the output of the first integrator at the current moment based on the input of the first integrator at the current moment, the sampling time, the damping coefficient, and the target rack position at the previous moment, when the integral reset flag is set;

[0146] The second output determination submodule is used to determine the output of the first integrator at the current moment based on the input of the first integrator at the current moment, the sampling time and the output of the first integrator at the previous moment when the integration reset flag is reset.

[0147] Optionally, the second output determination module includes:

[0148] A third output determination submodule, configured to determine the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time and the target rack position at the previous moment, when the integral reset flag is set;

[0149] A fourth output determination submodule, configured to determine the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time, and the output of the second integrator at the previous moment when the integral reset flag is reset;

[0150] The fifth output determination submodule is used to determine the output of the second integrator at the current moment as the target rack position at the current moment.

[0151] Optionally, the rack position determining device 900 further includes:

[0152] A first input module is used to input the target rack position at the previous moment into a delay device to obtain a delayed target rack position at the previous moment delayed by one sampling period;

[0153] A first determining module, used to determine the relationship between a first difference between the target rack position at the previous moment and the delayed target rack position at the previous moment and zero;

[0154] A second determination module, configured to determine whether the target rack position at the previous moment is greater than or equal to the original rack position when the first difference is greater than zero;

[0155] The third determination module is used to determine that the integral reset flag is reset when the target rack position at the previous moment is greater than or equal to the original rack position; and to determine that the integral reset flag is set when the target rack position at the previous moment is less than the original rack position.

[0156] Optionally, the rack position determining device 900 further includes:

[0157] a fourth determining module, configured to determine that the integral reset flag is set when the first difference is equal to zero;

[0158] a fifth determination module, configured to determine, when the first difference is less than zero, whether the original rack position is greater than or equal to the target rack position at the previous moment;

[0159] The sixth determination module is used to determine that the integral reset flag is reset when the original rack position is greater than or equal to the target rack position at the previous moment; and to determine that the integral reset flag is set when the original rack position is less than the target rack position at the previous moment.

[0160] Optionally, the location acquisition module 902 includes:

[0161] A second input module, used for inputting the actual rack position at the current moment and the target rack position at the previous moment output by the second integrator into a delay device;

[0162] A seventh determination module, configured to determine, when the current moment is the initial moment, the actual rack position at the current moment output by the delay device as the target rack position at the previous moment;

[0163] An eighth determination module is used to determine the target rack position at a previous moment output by the delay device as the target rack position at the previous moment when the current moment is not the initial moment.

[0164] Optionally, the rack position determining device 900 further includes:

[0165] A ninth determination module, configured to determine a current operating condition and a current vehicle speed of the vehicle;

[0166] A time constant determination module, configured to determine the time constant based on the current operating condition, the current vehicle speed and a first mapping relationship;

[0167] a damping coefficient determination module, configured to determine the damping coefficient based on the current operating condition, the current vehicle speed and a second mapping relationship;

[0168] The first mapping relationship is a mapping relationship between the vehicle speed and the time constant under various preset working conditions, and the second mapping relationship is a mapping relationship between the vehicle speed and the damping coefficient under various preset working conditions.

[0169] Based on the same inventive concept, another embodiment of the present invention provides a vehicle, which at least includes: a controller, which, when executed, implements the steps in the rack position determination method described in any of the above embodiments of the present invention.

[0170] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0171] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0172] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, embodiments of the present invention may take the form of complete hardware embodiments, complete software embodiments, or embodiments combining software and hardware. Furthermore, embodiments of the present invention may take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0173] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0174] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0175] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0176] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0177] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0178] The rack position determination method, device and vehicle provided by the present invention are introduced in detail above. The principles and implementation methods of the present invention are explained in this article using specific examples. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for determining a rack position, characterized in that: The method comprises: Determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment; Get the target rack position at the last moment; Based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment, obtaining the target rack position at the current moment; Among them, the time constant and the damping coefficient are used to adjust the change rate of the target rack position curve in the initial stage and the final stage respectively, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents the relationship curve between the target rack position and time.

2. The rack position determination method according to claim 1, characterized in that: The reset flag includes an integral reset flag; the target rack position at the current moment is obtained based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at the previous moment, including: Determine an input of the first integrator at a current moment based on the original rack position, the target rack position at the previous moment, and the time constant; At least based on the integration reset flag, the sampling time and the input of the first integrator at the current moment, obtain the output of the first integrator at the current moment; determining an input of a second integrator at a current moment based on the output of the first integrator at the current moment, the damping coefficient, the target rack position at the previous moment, and the time constant; The target rack position at the current moment output by the second integrator is obtained based at least on the integration reset flag, the sampling time and the input of the second integrator at the current moment.

3. The rack position determination method according to claim 2, characterized in that: The step of obtaining the output of the first integrator at the current moment based at least on the integration reset flag, the sampling time and the input of the first integrator at the current moment comprises: When the integral reset flag is set, determining the output of the first integrator at the current moment based on the input of the first integrator at the current moment, the sampling time, the damping coefficient, and the target rack position at the previous moment; When the integration reset flag is reset, the output of the first integrator at the current moment is determined based on the input of the first integrator at the current moment, the sampling time, and the output of the first integrator at the previous moment.

4. The rack position determination method according to claim 2, characterized in that: The step of obtaining the target rack position at the current moment output by the second integrator based at least on the integral reset flag, the sampling time and the input of the second integrator at the current moment comprises: When the integral reset flag is set, determining the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time and the target rack position at the previous moment; When the integration reset flag is reset, determining the output of the second integrator at the current moment based on the input of the second integrator at the current moment, the sampling time and the output of the second integrator at the previous moment; The output of the second integrator at the current moment is determined as the target rack position at the current moment.

5. The rack position determination method according to claim 3 or 4, characterized in that: The method further comprises: Input the target rack position at the previous moment into the delay device to obtain the delayed target rack position at the previous moment delayed by one sampling period; Determine a relationship between a first difference between the target rack position at the last moment and the delayed target rack position at the last moment and zero; In the case where the first difference is greater than zero, determining whether the target rack position at the previous moment is greater than or equal to the original rack position; When the target rack position at the previous moment is greater than or equal to the original rack position, the integral reset flag is determined to be reset; when the target rack position at the previous moment is less than the original rack position, the integral reset flag is determined to be set.

6. The rack position determination method according to claim 5, characterized in that: The method further comprises: When the first difference is equal to zero, determining that the integral reset flag is set; When the first difference is less than zero, determining whether the original rack position is greater than or equal to the target rack position at the previous moment; When the original rack position is greater than or equal to the target rack position at the previous moment, the integral reset flag is determined to be reset; when the original rack position is less than the target rack position at the previous moment, the integral reset flag is determined to be set.

7. The rack position determination method according to any one of claims 2 to 4, characterized in that: The obtaining of the target rack position at the previous moment includes: Inputting the actual rack position at the current moment and the target rack position at the previous moment output by the second integrator into a delay device; In the case where the current moment is the initial moment, determining the actual rack position at the current moment output by the delay device as the target rack position at the previous moment; In the case that the current moment is not the initial moment, the target rack position at the previous moment output by the delay device is determined as the target rack position at the previous moment.

8. The rack position determination method according to any one of claims 1 to 4, characterized in that: The method further comprises: Determining a current operating condition and a current speed of the vehicle; Determining the time constant based on the current operating condition, the current vehicle speed and a first mapping relationship; Determining the damping coefficient based on the current operating condition, the current vehicle speed and a second mapping relationship; The first mapping relationship is a mapping relationship between the vehicle speed and the time constant under various preset working conditions, and the second mapping relationship is a mapping relationship between the vehicle speed and the damping coefficient under various preset working conditions.

9. A rack position determination device, characterized in that: The device comprises: An original position determination module, used to determine the original rack position corresponding to the target steering wheel angle of the vehicle at the current moment; A position acquisition module is used to obtain the target rack position at the last moment; A target position determination module, used to obtain a target rack position at a current moment based on the original rack position, sampling time, time constant, damping coefficient, reset flag and the target rack position at a previous moment; Among them, the time constant and the damping coefficient are used to adjust the change rate of the target rack position curve in the initial stage and the final stage respectively, the sampling time is the interval time between the current moment and the previous moment, and the target rack position curve represents the relationship curve between the target rack position and time.

10. A vehicle, characterized in that: The vehicle at least comprises: a controller, and when the controller is executed, the rack position determination method according to any one of claims 1 to 8 is implemented.

Images