Differential braking steering control method, drive-by-wire vehicle, storage medium and program product

Abstract

The invention relates to a differential braking steering control method, a drive-by-wire vehicle, a storage medium and a program product. The method comprises the following steps: acquiring a steer-by-wire parameter and an actual wheel speed; determining a target left and right wheel speed difference value according to the steer-by-wire parameters and the actual steering torque of the steering motor, and determining a target wheel speed by using the target left and right wheel speed difference value and the actual wheel speed; performing closed-loop control on the wheel speed difference value between the target wheel speed and the actual wheel speed to obtain the braking steering torque of the corresponding wheel; and compensating the actual steering torque of the steering motor by using the braking steering torque so as to perform steering compensation on wheels. By the adoption of the method, the braking steering torque can be provided for the wheels in a braking mode to compensate for the insufficient steering torque of the steering motor, so that the redundant backup design requirement and the steering capacity requirement for steering motor hardware are reduced, and the whole vehicle cost and the whole vehicle weight are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of steering control of a wire-controlled vehicle, and in particular to a differential braking steering control method, a wire-controlled vehicle, a storage medium, and a program product. Background Art

[0002] Because a by-wire chassis utilizes an electronic control system instead of mechanical connections, redundant backup designs must be implemented for key components in the vehicle to meet functional safety objectives. Specifically, since the by-wire steering system lacks an intermediate shaft connection, the required performance of the steering motor is higher than that of a standard steering motor.

[0003] A common solution currently is to achieve functional safety redundancy by increasing the capabilities of the motors themselves. For example, in a drive-by-wire vehicle, both motors can be configured to independently meet steering requirements, minimizing the impact of a single motor failure on the overall vehicle's functional safety. However, this functional safety redundancy approach increases vehicle cost and weight. Furthermore, even with dual motors configured for steering control, motor torque degradation may occur during actual operation, resulting in insufficient steering torque output.

[0004] With the further development of steering control technology, there is an urgent need for a low-cost steering control method that can provide sufficient steering torque. Summary of the Invention

[0005] Based on this, it is necessary to provide a differential braking steering control method, a wire-controlled vehicle, a chassis domain controller, a storage medium and a program product to address the above technical problems, which can reduce the cost and weight of the vehicle while meeting the functional safety requirements.

[0006] In a first aspect, the present application provides a differential braking steering control method, comprising:

[0007] Get steer-by-wire parameters and actual wheel speed;

[0008] determining a target left-right wheel speed difference based on the steer-by-wire parameter and the actual steering torque of the steering motor, and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed;

[0009] performing closed-loop control on a wheel speed difference between the target wheel speed and the actual wheel speed to obtain a braking steering torque for the corresponding wheel;

[0010] The braking steering torque is used to compensate the actual steering torque of the steering motor to perform steering compensation on the wheel.

[0011] In one embodiment, performing closed-loop control on the wheel speed difference between the target wheel speed and the actual wheel speed to obtain the braking steering torque of the corresponding wheel includes:

[0012] calculating a wheel speed difference between a target wheel speed and an actual wheel speed of the wheel;

[0013] The wheel speed difference and the proportional integral coefficient are used to perform calculation processing to obtain a proportional adjustment torque;

[0014] The wheel speed difference and the integral adjustment coefficient are used to perform calculation processing to obtain the integral adjustment torque;

[0015] The wheel speed difference and the differential coefficient are used to perform calculation processing to obtain a differential adjustment torque;

[0016] The proportional adjustment torque, the integral adjustment torque, and the differential adjustment torque are summed to obtain the braking steering torque.

[0017] In one embodiment, the steer-by-wire parameters include steering wheel parameters and rack motion parameters; determining a target left-right wheel speed difference based on the steer-by-wire parameters and an actual steering torque of a steering motor, and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed, comprises:

[0018] determining a target steering torque of the steering motor according to the steering wheel steering parameter and the rack motion parameter;

[0019] determining a torque difference between an actual steering torque of the steering motor and the target steering torque;

[0020] Querying and obtaining a target left-right wheel speed difference corresponding to the torque difference from a preset first mapping relationship;

[0021] Obtaining a speed-dependent coefficient corresponding to the actual wheel speed from a preset second mapping relationship;

[0022] The target left-right wheel speed difference is adjusted using the speed-following coefficient, and the target wheel speed is calculated based on the adjusted target left-right wheel speed difference and the actual wheel speed.

[0023] In one embodiment, the steering wheel parameters include a steering angle parameter and a rotation speed parameter; the rack motion parameters include a rack position parameter and a rack speed parameter;

[0024] The determining the target steering torque of the steering motor according to the steering wheel steering parameter and the rack motion parameter includes:

[0025] Querying and obtaining a target rack position corresponding to the rotation angle parameter from a preset third mapping relationship;

[0026] determining a position difference between the target rack position and the rack position parameter;

[0027] The position difference is processed by a preset position loop algorithm to obtain a target rack movement speed;

[0028] The target rack moving speed and the rack speed parameter are processed to obtain the target steering torque.

[0029] In one embodiment, the calculating and processing the target rack movement speed and the rack speed parameter to obtain the target steering torque includes:

[0030] Obtaining a feedforward coefficient corresponding to the speed parameter from a preset fourth mapping relationship;

[0031] Multiplying the target rack moving speed by the feedforward coefficient to obtain the feedforward rack moving speed;

[0032] determining a rack speed difference between the feedforward rack speed and the rack speed parameter;

[0033] The rack speed difference is processed by a preset speed loop algorithm to obtain the target steering torque.

[0034] In one embodiment, determining the target wheel speed using the target left and right wheel speed difference and the actual wheel speed includes:

[0035] Calculating an actual left and right wheel speed difference using the actual wheel speed;

[0036] When the target left-right wheel speed difference is greater than the actual left-right wheel speed difference, the actual wheel speed of the first wheel is used as the target wheel speed of the first wheel, and the difference between the actual wheel speed of the first wheel and the target left-right wheel speed difference is used as the target wheel speed of the second wheel;

[0037] When the target left-right wheel speed difference is not greater than the actual left-right wheel speed difference, the sum of the actual wheel speed of the second wheel and the target left-right wheel speed difference is used as the target wheel speed of the first wheel, and the actual wheel speed of the second wheel is used as the target wheel speed of the second wheel;

[0038] Wherein, the first wheel and the second wheel are both front wheels, or the first wheel and the second wheel are both rear wheels.

[0039] In one embodiment, before obtaining the steer-by-wire parameters and the actual wheel speed, the method further includes:

[0040] Get steering fault information;

[0041] detecting a working state of an electromechanical brake mechanism, which is used to provide the braking steering torque, when the steering fault information includes torque degradation of the steering motor;

[0042] Determine that the working state is normal working.

[0043] In the second aspect, the present application also provides a wire-controlled vehicle, including wheels, a steering motor, an electronic mechanical braking mechanism and a chassis domain controller, the chassis domain controller including a memory and a processor, the memory storing a computer program, the chassis domain controller being used to execute the computer program through the processor to implement the steps of the differential braking steering control method described in any one of the embodiments of the first aspect above to obtain a braking steering torque, and to compensate the actual steering torque of the steering motor based on the braking steering torque through the electronic mechanical braking mechanism to perform steering compensation on the wheels.

[0044] In a third aspect, the present application further provides a chassis domain controller. The chassis domain controller includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the differential braking steering control method described in any one of the embodiments of the first aspect.

[0045] In a fourth aspect, the present application further provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the differential braking steering control method described in any one of the embodiments of the first aspect.

[0046] In a fifth aspect, the present application further provides a program product, which includes a computer program that, when executed by a processor, implements the differential braking steering control method described in any one of the embodiments of the first aspect.

[0047] The above-mentioned differential braking steering control method obtains steer-by-wire parameters and actual wheel speeds; determines a target left-right wheel speed difference based on the steer-by-wire parameters and the actual steering torque of the steering motor; and determines a target wheel speed using the target left-right wheel speed difference and the actual wheel speed; performs closed-loop control on the wheel speed difference between the target wheel speed and the actual wheel speed to obtain a braking steering torque for the corresponding wheel; and uses the braking steering torque to compensate for the actual steering torque of the steering motor to compensate for the steering of the wheel. This method can utilize a differential braking optimization strategy to compensate for insufficient steering torque in the steering motor hardware, thereby reducing the redundant backup design requirements and steering capability requirements for the steering motor hardware, thereby reducing vehicle cost and reducing vehicle weight. Furthermore, compared to traditional technical means of achieving vehicle steering by driving, the above-mentioned differential braking steering control method can improve the safety and reliability of the differential braking steering control method by providing braking steering torque to the wheels to compensate for insufficient steering torque of the steering motor through braking, thereby achieving more precise steering control. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 1 is a flow chart of a differential braking steering control method according to an embodiment;

[0050] Figure 2 1 is a flow chart of a step of determining a braking steering torque in one embodiment;

[0051] Figure 3 is a schematic diagram of a method for calculating braking steering torque in one embodiment;

[0052] Figure 4 FIG1 is a flow chart of a target wheel speed determination step based on speed-dependent adjustment in one embodiment;

[0053] Figure 5 is a schematic diagram of a method for calculating target wheel speed in one embodiment;

[0054] Figure 6 FIG1 is a flow chart of a target steering torque determination step in one embodiment;

[0055] Figure 7 is a schematic diagram of a method for calculating target steering torque in one embodiment;

[0056] Figure 8 1 is a flow chart of target steering torque feedforward calculation steps in one embodiment;

[0057] Figure 9 FIG1 is a flow chart of a step of determining a target wheel speed based on left and right wheel speeds in one embodiment;

[0058] Figure 10 1 is a flow chart of differential braking compensation determination in one embodiment;

[0059] Figure 11 is a structural block diagram of a wire-controlled vehicle 1100 in one embodiment;

[0060] Figure 12 11 is a structural block diagram of the chassis domain controller 1110 in one embodiment. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0062] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0063] In one embodiment, Figure 1 As shown, a differential braking steering control method is provided. This embodiment uses the method applied to a chassis domain controller of a drive-by-wire vehicle as an example for illustration. It is understandable that the method can also be applied to other passenger vehicle steering control scenarios with insufficient steering capabilities. In this embodiment, the method includes the following steps S102 to S108. Among them:

[0064] Step S102: Obtaining steer-by-wire parameters and actual wheel speed.

[0065] Among them, steer-by-wire parameters can be used to characterize parameters such as the actual angle, position, and speed of the steering wheel and / or wheel rack during steering in a steer-by-wire system (SBW system, a control system that eliminates the mechanical connection between the steering wheel and wheels and uses the electrical energy generated by the steering motor to achieve steering). For example, steer-by-wire parameters may include, but are not limited to, steering wheel angle, steering wheel speed, front wheel rack position, and wheel rack displacement speed.

[0066] The actual wheel speed can be used to represent the current actual speed of the wheel. The wheel may include but is not limited to the left front wheel, right front wheel, left rear wheel, right rear wheel, etc. of the wire-controlled vehicle.

[0067] In an exemplary embodiment, when the actual steering torque output by the steering motor does not match the vehicle steering command of the driver, the wire-controlled steering parameters and the actual wheel speed of the wheel can be read from the wire-controlled steering system. For example, the chassis domain controller can determine the corresponding steering command parameters in response to the vehicle steering command triggered by the driver. The vehicle steering command is sent to the wire-controlled steering system for execution, and the actual steering torque output by its steering motor is monitored. In the event that the actual steering torque does not match the steering command parameters of the vehicle steering command, differential braking compensation for the steering motor with insufficient steering capability is triggered, and the operation of obtaining the wire-controlled steering parameters and the current actual wheel speed of the wheel is executed.

[0068] Step S104 , determining a target left-right wheel speed difference based on the steer-by-wire parameter and the actual steering torque of the steering motor, and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed.

[0069] The actual steering torque may be used to represent the torque actually output by the steering motor, and the torque output by the steering motor is used to drive the vehicle to steer.

[0070] The target left-right wheel speed difference may be used to represent a speed difference between the left front wheel and the right front wheel and / or a speed difference between the left rear wheel and the right rear wheel required for differential braking compensation.

[0071] The target wheel speed can be used to represent the wheel speed after differential braking compensation is applied to the wheels. In various embodiments of the differential braking steering control method provided herein, the wheel speed can be changed by controlling the braking force of the corresponding wheel through an electronic mechanical brake (EMB) mechanism to produce a target left-right wheel speed difference between the left front wheel and the right front wheel, and / or a target left-right wheel speed difference between the left rear wheel and the right rear wheel. The target left-right wheel speed difference is used to implement differential steering, thereby compensating for the actual steering torque output by the steering motor and addressing the problem of insufficient steering torque.

[0072] For example, the chassis domain controller can determine a target steering torque that matches the steer-by-wire parameters based on a conversion relationship between the preset steer-by-wire parameters and the steering torque. A torque difference is obtained by subtracting the target steering torque from the actual steering torque output by the steering motor. From a table pre-stored with torque differences and left and right wheel speed differences corresponding to the torque differences, the torque difference obtained by the current subtraction is used to obtain the left and right wheel speed difference corresponding to the torque difference obtained by the current subtraction by looking up the table as the target left and right wheel speed difference between the corresponding wheels. The current actual wheel speeds of the left front wheel and the right front wheel are processed, and / or the current actual wheel speeds of the left rear wheel and the right rear wheel are processed so that the left and right wheel speed difference after the processing reaches the target left and right wheel speed difference, and the wheel speed obtained after the processing is used as the target wheel speed corresponding to the wheel.

[0073] Step S106 , performing closed-loop control on the wheel speed difference between the target wheel speed and the actual wheel speed to obtain the braking steering torque of the corresponding wheel.

[0074] The braking steering torque can be used to characterize the braking torque required to achieve the target left and right wheel speed difference, and can be used to compensate for the torque difference between the actual steering torque output by the steering motor and the vehicle steering command.

[0075] For example, the chassis domain controller can calculate the wheel speed difference between the actual wheel speed and the desired target wheel speed. Based on preset closed-loop control logic, the wheel speed difference is processed using parameters such as differential, integral, and proportional coefficients to obtain the braking steering torque for the corresponding wheel.

[0076] Step S108 : Using the braking steering torque to compensate for the actual steering torque of the steering motor to perform steering compensation on the wheels.

[0077] For example, the chassis domain controller can output braking steering torque to the corresponding wheels to change their speeds, generating a target left-right wheel speed difference. Based on this target left-right wheel speed difference, differential steering is implemented to compensate for the steering motor's insufficient steering capability compared to the vehicle's steering command. This allows for coordinated control of wheel steering using the braking steering torque and the steering motor's actual steering torque, enabling the wheels to perform steering operations corresponding to the vehicle's steering command (e.g., lateral control operations such as steering or lane changing).

[0078] In the above-mentioned differential braking steering control method, by obtaining steer-by-wire parameters and actual wheel speeds; determining a target left-right wheel speed difference based on the steer-by-wire parameters and the actual steering torque of the steering motor; and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed; performing closed-loop control on the wheel speed difference between the target wheel speed and the actual wheel speed to obtain a braking steering torque for the corresponding wheel; and using the braking steering torque to compensate for the actual steering torque of the steering motor to compensate for the steering of the wheel. This method can utilize a differential braking optimization strategy to compensate for insufficient steering torque in the steering motor hardware, thereby reducing the redundant backup design requirements and steering capability requirements for the steering motor hardware, and achieving a reduction in vehicle cost and weight. Furthermore, compared to traditional technical means of achieving vehicle steering by driving, the above-mentioned differential braking steering control method can improve the safety and reliability of the differential braking steering control method by providing braking steering torque to the wheels to compensate for insufficient steering torque of the steering motor through braking, thereby achieving more precise steering control.

[0079] In addition, compared with the traditional method of requiring redundant backup design of two steering motors with 100% steering capability (that is, each can independently complete the steering capability requirements), the above-mentioned differential braking steering control method only requires each steering motor to have 50% steering capability. When any steering motor fails or has insufficient steering capability, the insufficient steering torque of the steering motor can be compensated by using differential braking with braking steering torque, which has more advantages in terms of low cost and light weight.

[0080] In an exemplary embodiment, Figure 2 As shown, the above step S106 may include the following steps S202 to S210. Among them:

[0081] Step S202 , calculating the wheel speed difference between the target wheel speed and the actual wheel speed.

[0082] In step S204, the wheel speed difference and the proportional integral coefficient are used to perform calculation processing to obtain the proportional adjustment torque.

[0083] Step S206 : performing calculations on the wheel speed difference and the integral adjustment coefficient to obtain the integral adjustment torque.

[0084] In step S208, the wheel speed difference and the differential coefficient are used for calculation processing to obtain the differential adjustment torque.

[0085] Step S210 , summing the proportional adjustment torque, the integral adjustment torque, and the differential adjustment torque to obtain the braking steering torque.

[0086] The proportional integral coefficient can be used to characterize the proportional relationship between the braking steering torque required for the differential braking wheel and the wheel speed difference required for differential braking. The integral adjustment coefficient can be used to characterize the integral relationship between the braking steering torque required for the differential braking wheel and the wheel speed difference required for differential braking. The differential coefficient can be used to characterize the differential relationship between the braking steering torque required for the differential braking wheel and the wheel speed difference required for differential braking.

[0087] Optionally, in some embodiments, the proportional-integral coefficient, the integral adjustment coefficient, and the differential coefficient may be obtained by simulating the wheel speed difference and the braking torque in an actual differential braking scenario.

[0088] For example, Figure 3 As shown, the chassis domain controller can calculate the difference between the target wheel speed and the actual wheel speed for each wheel. For each wheel speed difference, the following operations are performed: The wheel speed difference is multiplied by the proportional-integral coefficient to obtain the proportional control torque. The current wheel speed difference is multiplied by the integral control coefficient, and the product is integrated (cumulated) with the integral control torque at the previous moment. The resulting extreme value is used to determine the current integral control torque. The current wheel speed difference is differentiated from the previous wheel speed difference, and the differential control torque is multiplied by the differential coefficient to obtain the differential control torque. The proportional control torque, integral control torque, and differential control torque are summed to obtain the braking steering torque. The braking steering torque obtained from these calculation steps can then be used to compensate for the actual steering torque of the steering motor. The combined effect of the braking steering torque and the actual steering torque allows each wheel to complete the vehicle steering command.

[0089] In this embodiment, the wheel speed difference is processed by means of a proportional integral coefficient, an integral adjustment coefficient, and a differential coefficient to obtain the braking steering torque, which can improve the accuracy of determining the braking steering torque.

[0090] In an exemplary embodiment, the steer-by-wire parameters may include steering wheel parameters and rack motion parameters. Figure 4 As shown, the above step S104 may include the following steps S402 to S410. Among them:

[0091] Step S402 : determining a target steering torque of the steering motor according to the steering wheel steering parameter and the rack motion parameter.

[0092] Among them, the steering wheel parameters can be used to characterize working parameters such as the steering wheel angle and speed.

[0093] The rack motion parameters can be used to characterize information such as the position and displacement of the wheel rack.

[0094] For example, the chassis domain controller may store a preset conversion relationship between steering wheel parameters and rack motion parameters. Based on this conversion relationship, the steering wheel parameters are processed to obtain corresponding target rack motion parameters. Based on the preset conversion relationship between the rack motion parameters and the steering torque, a proportional-integral-derivative (PID) calculation is performed on the difference between the target rack motion parameters and the current actual rack motion parameters to calculate the target steering torque of the steer-by-wire system. Optionally, in some embodiments, the target rack motion parameters can be used to represent the target movement speed of the wheel rack that matches the current steering wheel angle. A rack speed difference between the target movement speed and the actual movement speed of the wheel rack can be obtained by subtraction. A proportional-integral-derivative (PID) calculation is performed on the rack speed difference, and the resulting data is used as the current target steering torque, thereby achieving closed-loop speed control.

[0095] Step S404 : determining a torque difference between the actual steering torque of the steering motor and the target steering torque.

[0096] Step S406: Query and obtain the target left and right wheel speed difference corresponding to the torque difference from a preset first mapping relationship.

[0097] The first mapping relationship may be used to represent the correspondence between the preset torque difference and the left and right wheel speed difference. The first mapping relationship may be stored in a table so that the required parameters can be obtained by looking up the table.

[0098] For example, Figure 5 As shown, the chassis domain controller can calculate the torque difference between the actual steering torque of the steering motor and the target steering torque by performing a difference calculation. From a preset first mapping relationship, the target left and right wheel speed difference corresponding to the torque difference is obtained by querying.

[0099] Step S408: Obtain a speed-dependent coefficient corresponding to the actual wheel speed from a preset second mapping relationship.

[0100] In step S410, the target left and right wheel speed difference is adjusted using a speed-dependent coefficient, and the target wheel speed is calculated based on the adjusted target left and right wheel speed difference and the actual wheel speed.

[0101] The second mapping relationship can be used to represent the correspondence between a preset vehicle speed and a speed-dependent coefficient. The second mapping relationship can be stored in a table to facilitate table lookup to obtain the required parameters. The speed-dependent coefficient is a parameter in a speed-dependent power steering system used to describe how the steering assist varies with vehicle speed. It is used to determine the corresponding steering assist gain or adjustment value based on the current vehicle speed, thereby achieving automatic adjustment of the steering assist.

[0102] For example, Figure 5 As shown, the chassis domain controller can query the speed-dependent coefficient corresponding to the current actual wheel speed from a preset second mapping relationship. The target left and right wheel speed difference is multiplied by the speed-dependent coefficient to obtain an adjusted target left and right wheel speed difference. The target wheel speed is determined based on the adjusted target left and right wheel speed difference and the actual wheel speed. The target wheel speed determination operation can be implemented by referring to the target wheel speed determination method provided in step S104 above and will not be further described here.

[0103] In this embodiment, the target wheel speed is determined by using a first mapping relationship to look up a table to obtain the target left-right wheel speed difference, and a second mapping relationship to look up a table to obtain a speed-dependent coefficient. This target wheel speed is then determined using this target left-right wheel speed difference, the speed-dependent coefficient, and the actual wheel speed. This improves the efficiency and accuracy of determining the target wheel speed. Furthermore, because the speed-dependent coefficient is used to adjust the target left-right wheel speed difference and then determines the target wheel speed based on this adjusted target left-right wheel speed difference and the actual wheel speed, the target wheel speed is more accurately aligned with speed variations in actual vehicle steering scenarios, thereby improving the reliability of the target wheel speed.

[0104] In an exemplary embodiment, the steering wheel parameters may include a steering angle parameter and a speed parameter. The rack motion parameters may include a rack position parameter and a rack speed parameter. Figure 6 As shown, step S402 may include the following steps S602 to S608.

[0105] Step S602: Query and obtain the target rack position corresponding to the rotation angle parameter from a preset third mapping relationship.

[0106] Step S604: determining the position difference between the target rack position and the rack position parameter.

[0107] Step S606 , using a preset position loop algorithm to perform calculation processing on the position difference to obtain a target rack movement speed.

[0108] The third mapping relationship can be used to represent the correspondence between the steering wheel angle and the rack position. Because the steering ratio of steer-by-wire is variable, the third mapping relationship between the steering wheel angle and the rack position is nonlinear. The third mapping relationship can be stored in a table to facilitate table lookup to obtain the required parameters.

[0109] The position loop algorithm can be used to represent an algorithm that performs a proportional-integral-derivative (PID) operation based on the difference between the target position and the actual position to obtain a target speed that matches the difference between the target position and the actual position.

[0110] For example, Figure 7 As shown, the chassis domain controller can query the target rack position corresponding to the current steering wheel angle parameter from a preset third mapping relationship. The desired target rack position is then subtracted from the rack position parameter to obtain a position difference. This position difference is then input into a position loop (a data processing structure that stores movement speed calculation logic, which includes proportional, differential, and integral coefficients derived from simulations of the rack position difference and rack movement speed). Proportional, differential, and integral operations are performed to generate a target rack movement speed corresponding to the position difference, achieving closed-loop position control.

[0111] Step S608 : performing calculation processing on the target rack movement speed and the rack speed parameter to obtain the target steering torque.

[0112] For example, the chassis domain controller may store a preset conversion relationship between rack speed difference and steering torque. The rack speed difference between the target rack movement speed and the rack speed parameter is calculated. Based on the conversion relationship between the rack speed difference and steering torque, the rack speed difference is processed to obtain the corresponding target steering torque.

[0113] In this embodiment, the target rack position is obtained by looking up a table using a third mapping relationship, the target rack movement speed is calculated using a position loop based on the deviation between the target rack position and the actual rack position parameters, and the target steering torque is calculated using the deviation between the actual rack speed parameters and the target rack movement speed. The preset stored mapping relationship can be used to quickly query and obtain the corresponding target rack position, thereby improving the efficiency of calculating the target steering torque.

[0114] In an exemplary embodiment, Figure 8 As shown, the above step S608 may further include the following steps S802 to S808. Among them:

[0115] Step S802: Obtain a feedforward coefficient corresponding to the speed parameter from a preset fourth mapping relationship.

[0116] Step S804: multiply the target rack moving speed by the feedforward coefficient to obtain the feedforward rack moving speed.

[0117] Step S806 , determining the rack speed difference between the feedforward rack speed and the rack speed parameter.

[0118] Step S808: Using a preset speed loop algorithm to calculate the rack speed difference to obtain a target steering torque.

[0119] The fourth mapping relationship can be used to represent the correspondence between the feedforward coefficient and the steering wheel speed. The fourth mapping relationship can be stored in a table format to facilitate table lookup to obtain the required parameters. The feedforward coefficient can be used to represent a parameter in vehicle steering control. Its function is to pre-adjust the steering motor torque so that the steering wheel angle more quickly tracks the target value corresponding to the wheel steering command, improving the vehicle's steering response speed and stability.

[0120] The speed loop algorithm can be used to represent an algorithm that performs a proportional-integral-derivative (PID) operation based on the difference between the target speed and the actual speed to obtain a target torque that matches the difference between the target speed and the actual speed.

[0121] For example, Figure 7 As shown, the chassis domain controller can determine the feedforward coefficient corresponding to the current steering wheel speed parameter from the preset fourth mapping relationship by looking up the table. The product of the target rack movement speed and the feedforward coefficient is used as the feedforward rack movement speed. The rack speed difference between the feedforward rack movement speed and the actual rack speed parameter is calculated. The rack speed difference is input into the preset speed loop (a data processing structure that stores the steering torque calculation logic, and the steering torque calculation logic includes the proportional coefficient, differential coefficient and integral coefficient obtained by simulation calculation based on the rack speed difference and the steering torque) for proportional differential integral operation processing to generate the corresponding target steering torque and realize closed-loop control of the speed.

[0122] In this embodiment, a feedforward coefficient corresponding to the steering wheel speed is obtained by looking up a table, and the target rack movement speed is adjusted using the feedforward coefficient. The rack speed difference between the feedforward rack movement speed obtained after adjustment and the actual rack speed parameter is then input into the speed loop to calculate the target steering torque, which can improve the reliability of the target steering torque.

[0123] In an exemplary embodiment, Figure 9As shown, step S104 may further include the following steps S902 to S908. Among them:

[0124] Step S902: Calculate the actual left and right wheel speed difference using the actual wheel speed.

[0125] Step S904: Compare the target left and right wheel speed difference with the actual left and right wheel speed difference.

[0126] For example, the chassis domain controller may calculate the actual left-right wheel speed difference between the left and right front wheels using the actual wheel speeds of the left and right front wheels, and compare the target left-right wheel speed difference between the left and right front wheels with the actual left-right wheel speed difference. Furthermore, the chassis domain controller may calculate the actual left-right wheel speed difference between the left and right rear wheels using the actual wheel speeds of the left and right rear wheels, and compare the target left-right wheel speed difference between the left and right rear wheels with the actual left-right wheel speed difference. If the target left-right wheel speed difference is greater than the actual left-right wheel speed difference, step S906 is executed. If the target left-right wheel speed difference is not greater than (less than or equal to) the actual left-right wheel speed difference, step S908 is executed.

[0127] Step S906: The actual wheel speed of the first wheel is used as the target wheel speed of the first wheel, and the difference between the actual wheel speed of the first wheel and the target left and right wheel speed difference is used as the target wheel speed of the second wheel.

[0128] Step S908: The sum of the actual wheel speed of the second wheel and the difference between the target left and right wheel speeds is used as the target wheel speed of the first wheel, and the actual wheel speed of the second wheel is used as the target wheel speed of the second wheel.

[0129] Among them, the first wheel and the second wheel are both left and right front wheels. For example, when the first wheel is the left front wheel, the second wheel can be used to refer to the right front wheel; when the first wheel is the right front wheel, the second wheel can be used to refer to the left front wheel.

[0130] Alternatively, the first wheel and the second wheel are both left and right rear wheels. For example, when the first wheel is the left rear wheel, the second wheel can be used to refer to the right rear wheel; when the first wheel is the right rear wheel, the second wheel can be used to refer to the left rear wheel.

[0131] Optionally, in some embodiments, when both the first wheel and the second wheel are left and right front wheels, the chassis domain controller may calculate the actual left and right front wheel speed difference according to the following formula:

[0132] The actual left and right front wheel speed difference = the actual wheel speed of the left front wheel - the actual wheel speed of the right front wheel.

[0133] When the target left and right front wheel speed difference is greater than the actual left and right front wheel speed difference, the target wheel speed of the corresponding wheel can be calculated according to the following formula:

[0134] The target wheel speed of the left front wheel = the actual wheel speed of the left front wheel (i.e. the speed of the left front wheel remains unchanged);

[0135] The target wheel speed of the right front wheel = the actual wheel speed of the left front wheel - the target difference between the left and right front wheel speeds.

[0136] When the target left and right front wheel speed difference is less than or equal to the actual left and right front wheel speed difference, the target wheel speed of the corresponding wheel can be calculated using the following formula:

[0137] The target wheel speed of the right front wheel = the actual wheel speed of the right front wheel (i.e. the speed of the right front wheel remains unchanged);

[0138] The target wheel speed of the left front wheel = the actual wheel speed of the right front wheel + the target difference between the left and right front wheel speeds.

[0139] Optionally, in some embodiments, when both the first wheel and the second wheel are left and right rear wheels, the chassis domain controller may calculate the actual left and right rear wheel speed difference according to the following formula:

[0140] The actual left and right rear wheel speed difference = the actual wheel speed of the left rear wheel - the actual wheel speed of the right rear wheel.

[0141] When the target left and right rear wheel speed difference is greater than the actual left and right rear wheel speed difference, the target wheel speed of the corresponding wheel can be calculated according to the following formula:

[0142] The target wheel speed of the left rear wheel = the actual wheel speed of the left rear wheel (i.e. the speed of the left rear wheel remains unchanged);

[0143] The target wheel speed of the right rear wheel = the actual wheel speed of the left rear wheel - the target difference between the left and right rear wheel speeds.

[0144] When the target left and right rear wheel speed difference is less than or equal to the actual left and right rear wheel speed difference, the target wheel speed of the corresponding wheel can be calculated using the following formula:

[0145] The target wheel speed of the right rear wheel = the actual wheel speed of the right rear wheel (i.e. the speed of the right rear wheel remains unchanged);

[0146] The target wheel speed of the left rear wheel = the actual wheel speed of the right rear wheel + the target difference between the left and right rear wheel speeds.

[0147] In this embodiment, the target wheel speed is calculated in different ways based on the comparison result between the target left and right wheel speed difference and the actual left and right wheel speed difference, so that the accuracy of the target wheel speed can be improved.

[0148] In an exemplary embodiment, Figure 10As shown, a differential braking judgment logic is also provided, including the following steps S1002 to S1006.

[0149] Step S1002: Obtain steering fault information.

[0150] For example, the chassis domain controller can obtain steering fault information from a steer-by-wire vehicle. Based on the steering fault information, it is determined whether torque degradation has occurred in the steering motor of the steer-by-wire system. If torque degradation has not occurred, steps S102 through S108 are not required for differential braking compensation. Otherwise, the following step S1004 is executed.

[0151] Step S1004 : When the steering fault information includes torque degradation of the steering motor, detecting the working state of the electronic mechanical brake mechanism, which is used to provide braking steering torque.

[0152] Among them, the Electro Mechanical Braking (EMB) mechanism can be used to brake the corresponding wheels to provide braking steering torque.

[0153] Step S1006: Determine that the working status is normal working.

[0154] For example, chassis domain control can detect the operating status of the electromechanical brake mechanism when the steering motor of the steer-by-wire system experiences torque degradation. If the electromechanical brake mechanism fails, it cannot provide braking steering torque to the steering wheel, and steps S102 through S108 are not required for differential braking compensation. Otherwise, step S1006 is executed to determine that the electromechanical brake mechanism is operating normally, has no faults, and can support differential braking. Then, steps S102 through S108 are executed for differential braking compensation.

[0155] Optionally, in some embodiments, when the actual steering torque output by the steering motor matches the steering command parameters of the vehicle steering command, the steering motor torque actually output by the steering motor of the wire-controlled steer system can be used to control the wheel to perform a steering operation that matches the vehicle steering command.

[0156] In this embodiment, by judging whether the steering motor of the steer-by-wire system has torque degradation based on the steering fault information, and then judging whether the electronic mechanical braking mechanism is working normally when torque degradation occurs, and then introducing the electronic mechanical braking mechanism to perform differential braking compensation when the electronic mechanical braking mechanism is working normally, the flexibility and success rate of the steering control can be improved.

[0157] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0158] Based on the same inventive concept, embodiments of the present application also provide a chassis domain controller for implementing the aforementioned differential braking and steering control method, and a drive-by-wire vehicle incorporating the chassis domain controller. The solutions provided by the chassis domain controller and drive-by-wire vehicle are similar to those described in the aforementioned method. Therefore, the specific limitations of one or more chassis domain controller and drive-by-wire vehicle embodiments provided below can be found in the aforementioned limitations of the differential braking and steering control method, and will not be further elaborated here.

[0159] Each module in the chassis domain controller and the controlled-by-wire vehicle described above can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device's memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0160] In an exemplary embodiment, Figure 11 As shown, a wire-controlled vehicle 1100 is provided, including a steering wheel 1102 , wheels 1104 , a wire-controlled steering actuator 1106 , an electromechanical braking mechanism 1108 , and a chassis domain controller 1110 .

[0161] For example, the chassis domain controller 1110 can control the steering of the wheels 1104 using the actual steering torque output by the steering motor of the steer-by-wire actuator 1106 in response to a driver-triggered vehicle steering command containing steering command parameters. Steering fault information generated after the wheels 1104 perform the steering operation is obtained. If the steering fault information includes torque degradation in the steering motor of the steer-by-wire actuator 1106, the operating status of the electro-mechanical brake mechanism 1108 is detected. If the electro-mechanical brake mechanism 1108 is determined to be operating normally, the following operations are performed: the chassis domain controller 1110 can obtain the steering angle parameters and speed parameters of the steering wheel 1102, as well as the rack position parameters and rack speed parameters of the wheel rack of the steer-by-wire actuator 1106, via sensors (e.g., a hand-feel simulation mechanism) or a data communication interface.

[0162] like Figure 12 As shown, the chassis domain controller 1110 may be equipped with a steering torque calculation module 1202 (see Figure 7 The algorithm logic is designed in ), differential braking compensation calculation module 1204 (can refer to Figure 5 The algorithm logic in the design) and the differential braking force distribution module 1206 (can refer to Figure 3 Design the algorithm logic in ).

[0163] The chassis domain controller 1110 can use the steering torque calculation module 1202 to calculate the steering torque based on the steering wheel 1102 angle parameter and speed parameter, as well as the wheel rack position parameter and rack speed parameter of the steer-by-wire actuator 1106, to obtain the target steering torque. The differential braking compensation calculation module 1204 can use the steering motor torque, the target steering torque, and the actual wheel speed of the wheel 1104 to calculate the target wheel speed of the wheel 1104. The differential braking force distribution module 1206 can use closed-loop control to calculate the braking steering torque based on the deviation between the target wheel speed and the actual wheel speed of the wheel 1104.

[0164] The chassis domain controller 1110 may use the braking steering torque and the actual steering torque output by the steering motor of the steer-by-wire actuator 1106 together to control the steering of the wheel 1104 , so that the wheel 1104 performs a steering operation that matches the steering instruction parameters.

[0165] Those skilled in the art will understand that the structures shown in the drawings in the above description are merely block diagrams of partial structures related to the scheme of the present application, and do not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device may include more or fewer components than shown in the drawings, or combine certain components, or have a different arrangement of components.

[0166] In an exemplary embodiment, a chassis domain controller is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0167] In an exemplary embodiment, a storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0168] In an exemplary embodiment, a program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0169] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), quantum computing-based data processing logic devices, artificial intelligence (AI) processors, and the like.

[0170] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0171] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A differential braking steering control method, characterized in that: For compensating steering torque, the method comprises: Get steer-by-wire parameters and actual wheel speed; determining a target left-right wheel speed difference based on the steer-by-wire parameter and the actual steering torque of the steering motor, and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed; performing closed-loop control on a wheel speed difference between the target wheel speed and the actual wheel speed to obtain a braking steering torque for the corresponding wheel; The braking steering torque is used to compensate the actual steering torque of the steering motor to perform steering compensation on the wheel.

2. The differential braking steering control method according to claim 1, characterized in that: The performing closed-loop control on the wheel speed difference between the target wheel speed and the actual wheel speed to obtain the braking steering torque of the corresponding wheel includes: calculating a wheel speed difference between a target wheel speed and an actual wheel speed of the wheel; The wheel speed difference and the proportional integral coefficient are used to perform calculation processing to obtain a proportional adjustment torque; The wheel speed difference and the integral adjustment coefficient are used to perform calculation processing to obtain the integral adjustment torque; The wheel speed difference and the differential coefficient are used to perform calculation processing to obtain a differential adjustment torque; The proportional adjustment torque, the integral adjustment torque, and the differential adjustment torque are summed to obtain the braking steering torque.

3. The differential braking steering control method according to claim 1, characterized in that: The steer-by-wire parameters include steering wheel parameters and rack motion parameters; determining a target left-right wheel speed difference based on the steer-by-wire parameters and an actual steering torque of a steering motor, and determining a target wheel speed using the target left-right wheel speed difference and the actual wheel speed, including: determining a target steering torque of the steering motor according to the steering wheel steering parameter and the rack motion parameter; determining a torque difference between an actual steering torque of the steering motor and the target steering torque; Querying and obtaining a target left-right wheel speed difference corresponding to the torque difference from a preset first mapping relationship; Obtaining a speed-dependent coefficient corresponding to the actual wheel speed from a preset second mapping relationship; The target left-right wheel speed difference is adjusted using the speed-following coefficient, and the target wheel speed is calculated based on the adjusted target left-right wheel speed difference and the actual wheel speed.

4. The differential braking steering control method according to claim 3, characterized in that: The steering wheel parameters include angle parameters and speed parameters; the rack motion parameters include rack position parameters and rack speed parameters; The determining the target steering torque of the steering motor according to the steering wheel steering parameter and the rack motion parameter includes: Querying and obtaining a target rack position corresponding to the rotation angle parameter from a preset third mapping relationship; determining a position difference between the target rack position and the rack position parameter; The position difference is processed by a preset position loop algorithm to obtain a target rack movement speed; The target rack moving speed and the rack speed parameter are processed to obtain the target steering torque.

5. The differential braking steering control method according to claim 4, characterized in that: The performing calculation processing on the target rack movement speed and the rack speed parameter to obtain the target steering torque includes: Obtaining a feedforward coefficient corresponding to the speed parameter from a preset fourth mapping relationship; Multiplying the target rack moving speed by the feedforward coefficient to obtain the feedforward rack moving speed; determining a rack speed difference between the feedforward rack speed and the rack speed parameter; The rack speed difference is processed by a preset speed loop algorithm to obtain the target steering torque.

6. The differential braking steering control method according to any one of claims 1 to 5, characterized in that: The determining the target wheel speed by using the target left and right wheel speed difference and the actual wheel speed includes: Calculating an actual left and right wheel speed difference using the actual wheel speed; When the target left-right wheel speed difference is greater than the actual left-right wheel speed difference, the actual wheel speed of the first wheel is used as the target wheel speed of the first wheel, and the difference between the actual wheel speed of the first wheel and the target left-right wheel speed difference is used as the target wheel speed of the second wheel; When the target left-right wheel speed difference is not greater than the actual left-right wheel speed difference, the sum of the actual wheel speed of the second wheel and the target left-right wheel speed difference is used as the target wheel speed of the first wheel, and the actual wheel speed of the second wheel is used as the target wheel speed of the second wheel; Wherein, the first wheel and the second wheel are both left and right front wheels, or the first wheel and the second wheel are both left and right rear wheels.

7. The differential braking steering control method according to any one of claims 1 to 5, characterized in that: Before obtaining the steer-by-wire parameters and the actual wheel speed, the method further includes: Get steering fault information; detecting a working state of an electromechanical brake mechanism, which is used to provide the braking steering torque, when the steering fault information includes torque degradation of the steering motor; Determine that the working state is normal working.

8. A controlled-by-wire vehicle comprising wheels, a steering motor, an electromechanical brake mechanism, and a chassis domain controller, wherein the chassis domain controller comprises a memory and a processor, wherein the memory stores a computer program, characterized in that: The chassis domain controller is used to obtain a braking steering torque by executing the computer program through the processor to implement the steps of the differential braking steering control method described in any one of claims 1 to 7, and to compensate the actual steering torque of the steering motor based on the braking steering torque through the electronic mechanical braking mechanism to perform steering compensation on the wheel.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the differential braking steering control method according to any one of claims 1 to 7 are implemented.

10. A program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the differential braking steering control method according to any one of claims 1 to 7 are implemented.

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