Vehicle U-turn control method and related device

Abstract

This application discloses a vehicle U-turn control method and related equipment, relating to the field of vehicle control technology. The method includes: when a target vehicle meets preset U-turn conditions, determining a locking wheel and a drive wheel from among the target vehicle's multiple wheels; acquiring the target vehicle's wheelbase, yaw rate, and a first distance from the vehicle's center of gravity to the locking wheel; determining the target vehicle's actual rotation angle based on the yaw rate, wheelbase, and first distance; performing zero-speed closed-loop control on the locking wheel; and adjusting the drive wheel's speed based on the angle deviation between the actual rotation angle and the target rotation angle to drive the target vehicle to rotate around the locking wheel. This application, by constructing a simplified dynamic model with the locking wheel as the fulcrum and the drive wheel as the driving source, and combining rotation angle derivation based on vehicle parameters with angle error closed-loop control, can achieve high-precision, adaptive vehicle U-turn control without additional sensors.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and more specifically, to a vehicle U-turn control method and related equipment. Background Technology

[0002] With the continuous development of intelligent driving technology and vehicle chassis control technology, the demand for vehicle maneuverability in confined spaces is increasing, especially in scenarios such as underground parking lots, narrow urban roads, and complex work sites. How to achieve efficient and precise on-the-spot U-turn control has become an important direction for improving vehicle handling performance. Vehicle U-turn control is not only related to driving convenience, but also directly affects driving safety and spatial adaptability. Therefore, research on precise control methods for the vehicle U-turn process is of great significance.

[0003] In related technologies, vehicle U-turns on the spot typically rely on driver experience to control steering and drive, or simplify control through fixed steering angles and drive force distribution. Some solutions employ preset speeds or steering strategies for U-turns. However, these methods are usually based on open-loop control or simple linear control models, which struggle to accurately reflect the vehicle's true motion characteristics during the U-turn process and fail to establish an effective rotation angle calculation mechanism, resulting in insufficient angle control precision during the U-turn. In other words, related technologies suffer from low control precision and insufficient stability during vehicle U-turns on the spot. Summary of the Invention

[0004] In the summary section of this application, the relevant technical solutions are described in general terms, and a series of simplified concepts are introduced. These concepts will be further elaborated in the detailed embodiments section. This summary section should not be construed as limiting the key or essential technical features of the claimed solutions, nor is it intended to limit the scope of protection of the claimed solutions.

[0005] The vehicle turning control method and related equipment provided in this application can achieve high-precision, feedback-enabled, and adaptive vehicle turning control without additional sensors by constructing a simplified dynamic model with the locking wheel as the fixed fulcrum and the drive wheel as the driving source, and by combining the rotation angle derivation and angle error closed-loop control based on vehicle parameters.

[0006] In a first aspect, this application provides a vehicle U-turn control method applied to a target vehicle, comprising: when the target vehicle meets preset U-turn conditions, determining a locking wheel and a drive wheel from a plurality of wheels of the target vehicle; acquiring the vehicle wheelbase, yaw rate, and a first distance from the vehicle's center of gravity to the locking wheel; determining the actual rotation angle of the target vehicle based on the yaw rate, the vehicle wheelbase, and the first distance; performing zero-speed closed-loop control on the locking wheel, and adjusting the speed of the drive wheel based on the angle deviation between the actual rotation angle and the target rotation angle to drive the target vehicle to rotate around the locking wheel, wherein the target rotation angle is a preset rotation parameter obtained through a human-machine interface.

[0007] In some implementations, determining the actual rotation angle of the target vehicle based on the yaw rate, the vehicle wheelbase, and the first distance includes: determining a first intermediate parameter based on the product of the yaw rate and the vehicle wheelbase; determining the rotational angular velocity of the locking wheel based on the ratio of the first intermediate parameter to the first distance; and performing time integration on the rotational angular velocity to obtain the actual rotation angle.

[0008] In some embodiments, the zero-speed closed-loop control of the locking wheel includes: adjusting the output torque of the locking wheel in a closed loop based on the speed deviation between the real-time speed of the locking wheel and the zero-speed target value, so that the real-time speed approaches the zero-speed target value; determining a first torque limit value based on the road surface adhesion coefficient of the current driving road of the target vehicle, determining a second torque limit value based on the rated torque of the first drive motor of the locking wheel, and determining a third torque limit value based on the torque balance condition of the entire vehicle system of the target vehicle; during the closed-loop adjustment of the output torque of the locking wheel, the output torque is limited by the first torque limit threshold, the second torque limit threshold, and the third torque limit threshold.

[0009] In some embodiments, the step of adjusting the rotational speed of the drive wheel based on the angular deviation between the actual rotational angle and the target rotational angle includes: determining a reference rotational speed of the drive wheel by querying a preset mapping relationship based on the angular deviation and the target rotational angle, wherein the preset mapping relationship is a pre-calibrated two-dimensional lookup table relationship, which takes the angular deviation and the target rotational angle as input and the reference rotational speed of the drive wheel as output; generating a rotational speed attenuation factor based on the absolute value of the angular deviation and a preset attenuation coefficient, wherein the rotational speed attenuation factor decreases non-linearly as the absolute value of the deviation decreases, and the absolute value of the deviation is the absolute value of the angular deviation; determining the target rotational speed of the drive wheel based on the product of the reference rotational speed and the rotational speed attenuation factor; and adjusting the rotational speed of the drive wheel to the target rotational speed through rotational speed closed-loop control.

[0010] In some implementations, the speed attenuation factor is generated by an exponential function with the natural constant e as the base and the negative of the product of the preset attenuation coefficient and the absolute value of the deviation as the exponent.

[0011] In some embodiments, the plurality of wheels further includes an auxiliary wheel set, the auxiliary wheel set including a first side auxiliary wheel and a second side auxiliary wheel. The vehicle turning control method further includes: determining a first target torque direction and a first target torque absolute value for the first side auxiliary wheel, and a second target torque direction and a second target torque absolute value for the second side auxiliary wheel, based on the angle deviation value and the current rotation direction of the target vehicle, wherein the first target torque direction is opposite to the second target torque direction, the first target torque absolute value and the second target torque absolute value are both proportional to the angle deviation value, and in response to the angle deviation value being zero, both the first target torque absolute value and the second target torque absolute value are determined to be zero; issuing a first torque control command to the first side auxiliary wheel according to the first target torque direction and the first target torque absolute value, and issuing a second torque control command to the second side auxiliary wheel according to the second target torque direction and the second target torque absolute value, to form an additional yaw moment matching the current rotation direction.

[0012] In some embodiments, during the process of driving the target vehicle to rotate around the locking wheel, the vehicle turning control method further includes: acquiring the cumulative slip distance of the locking wheel, the stall duration of the first drive motor of the locking wheel, and the winding temperature of the first drive motor; terminating the vehicle turning control when the cumulative slip distance is greater than a preset distance threshold or the winding temperature is greater than a first preset temperature threshold; reducing the target speed of the drive wheel based on a preset torque reduction ratio when the stall duration is greater than a preset duration threshold; and cooling the first drive motor when the winding temperature is greater than a second preset temperature threshold and less than or equal to the first preset temperature threshold, wherein the first preset temperature is greater than the second preset temperature.

[0013] In some embodiments, the method further includes: acquiring the target vehicle's current driving speed, current gear status, sensor signal status, and fault status information of each drive motor, wherein the sensor signals include inertial measurement unit signal status, wheel speed signal status, and temperature signal status; if the current driving speed is less than a preset vehicle speed threshold, the current gear status belongs to a preset gear set, and the sensor signal status indication and the fault status information all indicate no abnormality, then the target vehicle is determined to meet the preset U-turn conditions.

[0014] Secondly, this application also provides a vehicle U-turn control device applied to a target vehicle, comprising: a wheel determination unit, configured to determine a locking wheel and a drive wheel from a plurality of wheels of the target vehicle when the target vehicle meets preset U-turn conditions; a data acquisition unit, configured to acquire the vehicle wheelbase, yaw rate, and a first distance from the vehicle center of gravity to the locking wheel of the target vehicle; a rotation determination unit, configured to determine the actual rotation angle of the target vehicle based on the yaw rate, the vehicle wheelbase, and the first distance; and a vehicle U-turn unit, configured to perform zero-speed closed-loop control on the locking wheel and, based on the angle deviation between the actual rotation angle and the target rotation angle, perform speed regulation processing on the drive wheel to drive the target vehicle to rotate around the locking wheel, wherein the target rotation angle is a preset rotation parameter obtained through a human-machine interface.

[0015] Thirdly, this application also provides a vehicle, including: a memory and a processor, the processor being configured to execute a computer program stored in the memory to implement the steps of the vehicle turning control method described in the first aspect.

[0016] Fourthly, this application also provides a computer-readable storage medium storing computer-executable instructions or a computer program, which, when executed by a processor, implement the steps of the vehicle U-turn control method described in the first aspect.

[0017] Fifthly, this application also provides a computer program product, including a computer program or computer-executable instructions, which, when executed by a processor, implement the steps of the vehicle U-turn control method provided in the embodiments of this application.

[0018] In summary, this application, when meeting preset U-turn conditions, determines the combination of the locking wheel and the drive wheel from multiple wheels. This is equivalent to artificially constructing a simplified dynamic model of a fixed fulcrum and drive source in the vehicle's motion system. This transforms the complex motion problem of multi-wheel coupling into a rotation problem around a single fulcrum, effectively constraining the vehicle's degrees of freedom within a controllable range. This dimensionality reduction from a multivariable system to a problem with a single rotation center reduces the uncertainty caused by control coupling, thereby improving the controllability and stability of the U-turn process. By obtaining the vehicle's wheelbase, yaw rate, and the distance from the vehicle's center of gravity to the locking wheel, and deriving the actual rotation angle, a geometric mapping relationship between the center of gravity motion and the fulcrum motion can be established. The yaw rate originally describes the rotational state of the vehicle's center of gravity; however, by introducing the wheelbase and the distance from the center of gravity to the locking wheel, this rotational state can be equivalently converted into the rotation angle around the locking wheel, thus achieving indirect measurement of the actual U-turn angle. This allows the vehicle to obtain the rotation angle without additional angle detection devices. This system utilizes angle information to reduce system complexity while ensuring measurement continuity. By implementing zero-speed closed-loop control on the locking wheel, it remains stationary throughout the entire turning process, thus stably acting as the rotation center. Simultaneously, the deviation between the actual rotation angle and the target rotation angle is used as feedback to regulate the speed of the drive wheel, forming a closed-loop adjustment mechanism centered on angle error. This means that the power output is no longer a fixed value but dynamically adjusted according to the turning process. When the angle deviation is large, the drive wheel provides a higher speed to improve rotation efficiency. As the angle gradually approaches the target value, the speed decreases accordingly, thereby suppressing overshoot and achieving smooth convergence. The target rotation angle is preset by the human-machine interface and serves as the target input of the control system. It forms a closed-loop comparison with the actual rotation angle calculated in real time, transforming the turning process from a traditional open-loop operation into a quantifiable and feedback-enabled closed-loop control process. This allows for precise angle alignment at the end of the turning, reducing reliance on human experience and improving the consistency and repeatability of the turning operation. In summary, the vehicle turning control method provided in this application can achieve high-precision, feedback-enabled, and adaptive vehicle turning control without additional sensors by constructing a simplified dynamic model with the locking wheel as the fixed fulcrum and the drive wheel as the driving source, and by combining the rotation angle derivation and angle error closed-loop control based on vehicle parameters. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit this specification. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a vehicle U-turn control method provided in an embodiment of this application; Figure 2 This is a schematic diagram of the composition structure of a vehicle U-turn control device provided in an embodiment of this application; Figure 3 This is a schematic diagram of the composition structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0020] The terms used in the specification, claims, and drawings of this application, such as "first," "second," "third," "fourth," etc. (if any), are used to distinguish similar objects and not to describe a specific order or sequence. Therefore, it is to be understood that these terms can be used interchangeably where appropriate, allowing the described embodiments to be used in different orders, unless specifically required by the illustrations or description. Furthermore, the terms "is" and "has," and any variations thereof, are intended to cover, non-exclusively, all possible constituent elements. For example, a process, method, system, product, or apparatus comprising several steps or units is not necessarily limited to the steps or units explicitly listed, but may also include other steps or units not explicitly listed, or steps or units inherent to the process, method, product, or apparatus.

[0021] In this application, a "module" or "unit" refers to a computer program or part of a computer program that has a specific function and works in conjunction with other related parts to achieve a predetermined goal. These modules or units can be implemented by software, hardware (e.g., processing circuitry or memory), or a combination of both. One or more processors or memories can implement one or more modules or units. Furthermore, each module or unit can also be part of a larger module or unit.

[0022] The technical solutions of this application will be described in detail below with reference to the accompanying drawings of the embodiments. It should be noted that the described embodiments are only a part of this application, and not all embodiments. In the following description, the "some embodiments" mentioned are only a subset of all possible embodiments, which may be the same or different subsets, and different embodiments can be combined with each other without conflict.

[0023] Figure 1 This is a schematic flowchart illustrating a vehicle U-turn control method provided in an embodiment of this application. For example, see [link to example]. Figure 1The vehicle turning control method provided in this application targets a vehicle undergoing a U-turn operation. The target vehicle can be a four-motor distributed drive new energy vehicle, which has multiple independently controllable wheels. Each wheel can achieve independent speed and torque regulation, meeting the requirements for precise wheel-end control during a U-turn and adapting to the application scenario of this control method. The vehicle turning control method may include the following steps 101 to 104: Step 101: If the target vehicle meets the preset U-turn conditions, determine one locking wheel and one drive wheel from the multiple wheels of the target vehicle.

[0024] In some examples, preset U-turn conditions are the basic state conditions that the target vehicle must meet to initiate a U-turn operation. The relevant state parameters of the vehicle can be collected by the vehicle's on-board control unit, and the collected parameters can be verified to determine whether each parameter meets the preset standards. For example, preset U-turn conditions include the target vehicle's current speed being within a preset low speed range, the current gear being in a preset appropriate gear, the on-board sensor signals being normal, and each drive motor being fault-free. Only when all preset conditions are met is the subsequent locking wheel and drive wheel determination step allowed to be initiated, ensuring the safety and feasibility of the U-turn operation.

[0025] The locking wheel is the wheel whose rotational speed is controlled to zero and serves as the center of rotation for the vehicle during a U-turn. After confirming that the vehicle meets the preset U-turn conditions, a wheel can be selected from among the vehicle's multiple wheels as the locking wheel based on the vehicle's current posture information, wheel distribution, and the operational requirements of the U-turn. For example, the locking wheel could be the left front wheel of the target vehicle. Once its rotational speed is controlled to zero, this wheel can stably serve as the rotational fulcrum for the U-turn, providing a stable central reference for the vehicle's rotation around it. The drive wheel is the wheel around which a driving torque is applied to drive the vehicle's rotation around the locking wheel during the U-turn. After selecting the locking wheel, a wheel can be selected from the remaining wheels as the drive wheel, taking into account the vehicle's power distribution characteristics, rotational direction requirements, and the power output capacity of each wheel. For example, when the locking wheel is selected as the left front wheel, the drive wheel could be selected as the right front wheel of the target vehicle. This wheel outputs corresponding driving force through subsequent speed control, driving the vehicle to smoothly complete the U-turn around the left front wheel.

[0026] For example, the vehicle control unit of the target vehicle first initiates the verification process of the preset U-turn conditions. It collects relevant parameters such as the current driving speed and gear status of the target vehicle in real time through the vehicle sensors and verifies each parameter one by one. When it is confirmed that the various states of the target vehicle meet the preset U-turn conditions, the vehicle control unit combines the current attitude information of the vehicle and the preset U-turn operation requirements, and reasonably selects one locking wheel and one drive wheel from the multiple wheels of the vehicle.

[0027] By implementing step 101, when the preset turning conditions are met, the combination of locking wheel and driving wheel is determined from multiple wheels. This is equivalent to artificially dividing the functional roles of fixed fulcrum and driving source in the multi-wheel coupling system of the whole vehicle, so that the vehicle motion is transformed from a complex multi-wheel coordination problem into a rotation problem around a single fulcrum. This effectively constrains the system's degrees of freedom, reduces coupling interference between wheels, and improves the controllability and execution stability of the turning process.

[0028] Step 102: Obtain the target vehicle's wheelbase, yaw rate, and the first distance from the vehicle's center of gravity to the locking wheel.

[0029] In some examples, the vehicle wheelbase is the straight-line distance between the center lines of the front and rear axles of the target vehicle. This parameter is an inherent structural parameter of the target vehicle. For example, if the target vehicle is a four-motor distributed drive new energy vehicle, its factory-calibrated wheelbase is 2800 mm. The onboard control unit directly calls this 2800 mm wheelbase parameter in this step to provide a basis for subsequent related calculations. Yaw velocity is the angular velocity of the target vehicle when rotating around its vertical axis perpendicular to the ground. It reflects the speed of the vehicle's rotation and can be collected by an inertial measurement unit (IMU) mounted on the target vehicle. The IMU is fixedly installed near the center of mass of the target vehicle and can detect the vehicle's attitude parameters in real time. For example, when the target vehicle is about to initiate a U-turn, the initial value of the yaw velocity collected by the IMU is 0 radians per second. As the U-turn is initiated, this value will change in real time according to the vehicle's rotation speed and be continuously transmitted. The vehicle's center of gravity is the center of the overall mass of the target vehicle and serves as the reference point for vehicle dynamics analysis and control. For example, the center of gravity of the aforementioned four-motor distributed drive new energy vehicle is located 50 millimeters forward of the center position between the front and rear axles. The first distance is the straight-line distance from the target vehicle's center of gravity to the center of the locking wheel. For example, when the locking wheel is selected as the left front wheel of the target vehicle, the onboard control unit calls the preset vehicle center of gravity position parameters and the left front wheel center position parameters, and calculates the first distance as 1200 millimeters using the distance formula between the two points.

[0030] By implementing step 102, the vehicle wheelbase, yaw rate, and distance from the vehicle's center of mass to the locking wheel are obtained, providing the necessary geometric and motion parameters for subsequent rotational state calculations. This enables the motion information at the vehicle's center of mass to establish a correlation with the rotational state at the locking wheel, providing data support for constructing the mapping relationship between the center of mass motion and the fulcrum motion, and improving the accuracy and consistency of subsequent angle calculations.

[0031] Step 103: Determine the actual rotation angle of the target vehicle based on the yaw rate, vehicle wheelbase, and first distance.

[0032] In some examples, the actual rotation angle is the angle that the target vehicle actually turns around the locking wheel during a U-turn, reflecting the vehicle's current rotational attitude and serving as the basis for determining whether the vehicle has reached the target rotation angle. Step 102 first obtains three basic parameters: yaw rate, vehicle wheelbase, and first distance. Then, the vehicle control unit combines these three parameters according to preset calculation rules to obtain the actual rotation angle. For example, if the vehicle wheelbase obtained in step 102 is 2800 mm, the first distance is 1200 mm, and the yaw rate collected by the inertial measurement unit is 0.5 radians per second, the vehicle control unit can calculate the actual rotation angle at the corresponding moment by combining these three parameters using preset calculation logic, providing a precise basis for subsequent control of the drive wheel speed.

[0033] By implementing step 103, the yaw rate is converted and calculated by combining the vehicle wheelbase and the distance from the center of gravity to the locking wheel, so as to realize the equivalent mapping from the rotation state of the center of gravity to the rotation angle around the locking wheel. This allows the actual rotation angle of the target vehicle to be obtained, enabling the vehicle to continuously measure the turning angle without the need for an additional angle detection device. This ensures the real-time acquisition of the angle and reduces the complexity of the vehicle hardware.

[0034] Step 104: Perform zero-speed closed-loop control on the locking wheel, and adjust the speed of the drive wheel based on the angular deviation between the actual rotation angle and the target rotation angle to drive the target vehicle to rotate around the locking wheel.

[0035] The target rotation angle is a preset rotation parameter obtained through the human-computer interaction interface.

[0036] In some examples, zero-speed closed-loop control involves real-time acquisition of the locking wheel's rotational speed and comparison with the zero-speed target. Based on the resulting speed deviation, the output power of the locking wheel is dynamically adjusted to continuously approach and stabilize the locking wheel's real-time rotational speed at zero. For instance, when the locking wheel is selected as the target vehicle's left front wheel, the onboard control unit initiates zero-speed closed-loop control, acquiring the real-time rotational speed of the left front wheel. If the real-time speed is higher than zero, the output power of the left front wheel is adjusted to reduce its speed; if the real-time speed is lower than zero, the output power is adjusted to increase its speed, ultimately keeping the left front wheel stably at zero speed, thus acting as a fixed fulcrum for the vehicle's rotation.

[0037] The target rotation angle is the preset rotation angle required for the vehicle to perform a U-turn. It is a preset rotation parameter used to define the target state of the U-turn and can be received by the driver through a human-machine interface (HMI). The HMI is a device on the vehicle used to facilitate information exchange between the driver and the vehicle control unit. It receives preset parameters input by the driver and provides feedback on relevant vehicle status information. For example, the HMI can be a central touchscreen or a dedicated physical button. The driver inputs the target rotation angle through the touchscreen interface or selects a preset, commonly used rotation angle through the physical button. The vehicle control unit obtains the corresponding target rotation angle parameter through this interface.

[0038] The angle deviation value is the difference between the actual rotation angle of the target vehicle and the target rotation angle. It is used to reflect the degree of deviation between the current rotation progress of the vehicle and the preset rotation target, and serves as the basis for adjusting the speed of the drive wheel. For example, if the target rotation angle is set to 180 degrees, and the actual rotation angle determined in step 103 at a certain moment is 90 degrees, then the angle deviation value at that moment is calculated to be 90 degrees. As the actual rotation angle gradually approaches 180 degrees, the angle deviation value gradually decreases until the actual rotation angle matches the target rotation angle, at which point the angle deviation value is 0 degrees.

[0039] The process of adjusting the rotational speed of the drive wheel based on the angular deviation between the actual and target rotational angles involves dynamically adjusting the drive wheel's speed according to the magnitude of the deviation. This allows the drive wheel to output corresponding driving force, causing the target vehicle to rotate around the locking wheel, gradually reducing the angular deviation until the actual and target rotational angles match. For example, when the angular deviation is large, the vehicle control unit adjusts the drive wheel to output driving force at a higher speed, accelerating the vehicle's rotation and quickly reducing the deviation. When the angular deviation is small, the drive wheel is adjusted to output driving force at a lower speed, slowly propelling the vehicle to rotate, avoiding angular overshoot and ensuring the vehicle accurately reaches the target rotational angle.

[0040] For example, firstly, the driver's preset target rotation angle can be read through the human-machine interface. Combined with the actual rotation angle calculated in step 103, the angle deviation value is calculated and stored. Then, zero-speed closed-loop control is initiated on the locking wheel. The locking wheel speed is collected in real time and its output power is dynamically adjusted to ensure that the locking wheel maintains a stable zero speed. At the same time, according to the calculated angle deviation value, the speed of the drive wheel is dynamically controlled according to the preset speed control logic. When the angle deviation value is large, the drive wheel is controlled to run at high speed. When the deviation value is small, the drive wheel is controlled to run at low speed. The driving force of the drive wheel drives the target vehicle to rotate smoothly around the locking wheel, gradually reducing the angle deviation until the vehicle reaches the target rotation angle, completing the control process of turning around on the spot.

[0041] By implementing step 104, zero-speed closed-loop control is implemented on the locking wheel to stably form the rotation fulcrum. Based on the deviation between the actual rotation angle and the target rotation angle, the speed of the power wheel is regulated, and a closed-loop control mechanism with angle error as the core is constructed. This enables the power output to be dynamically adjusted during the turning process, which can suppress angle overshoot while ensuring rotation efficiency, achieve smooth convergence of the turning process, and ultimately improve the accuracy and consistency of the turning angle control.

[0042] In summary, this embodiment of the application, when meeting preset U-turn conditions, determines the combination of the locking wheel and the drive wheel from multiple wheels. This is equivalent to artificially constructing a simplified dynamic model of a fixed fulcrum and drive source in the vehicle motion system. This transforms the complex motion problem of multi-wheel coupling into a rotation problem around a single fulcrum, effectively constraining the vehicle's degrees of freedom within a controllable range. This dimensionality reduction from a multivariable system to a problem with a single rotation center reduces the uncertainty caused by control coupling, thereby improving the controllability and stability of the U-turn process. By obtaining the vehicle's wheelbase, yaw rate, and the distance from the vehicle's center of mass to the locking wheel, and deriving the actual rotation angle, a geometric mapping relationship between the center of mass motion and the fulcrum motion can be established. The yaw rate originally describes the rotational state of the vehicle's center of mass; however, by introducing the wheelbase and the distance from the center of mass to the locking wheel, this rotational state can be equivalently converted into the rotation angle around the locking wheel, thus achieving indirect measurement of the actual U-turn angle. This allows the vehicle to obtain rotational information without the need for an additional angle detection device. Angle information is used to reduce system complexity while ensuring measurement continuity. By implementing zero-speed closed-loop control on the locking wheel, it remains stationary throughout the entire turning process, thus stably acting as the rotation center. Simultaneously, the deviation between the actual rotation angle and the target rotation angle is used as feedback to regulate the speed of the drive wheel, forming a closed-loop adjustment mechanism centered on angle error. This means that the power output is no longer a fixed value but dynamically adjusted according to the turning process. When the angle deviation is large, the drive wheel provides a higher speed to improve rotation efficiency. As the angle gradually approaches the target value, the speed decreases accordingly, thereby suppressing overshoot and achieving smooth convergence. The target rotation angle is preset by the human-machine interface and serves as the target input of the control system. It forms a closed-loop comparison with the actual rotation angle calculated in real time, transforming the turning process from a traditional open-loop operation into a quantifiable and feedback-enabled closed-loop control process. This allows for precise angle alignment at the end of the turning, reducing reliance on human experience and improving the consistency and repeatability of the turning operation. In summary, the vehicle turning control method provided in this application constructs a simplified dynamic model with the locking wheel as a fixed fulcrum and the drive wheel as the driving source, and combines the rotation angle derivation and angle error closed-loop control based on vehicle parameters, which can achieve high-precision, feedback-enabled, and adaptive vehicle turning control without additional sensors.

[0043] In some embodiments, the aforementioned step 103 may include: determining a first intermediate parameter based on the product of the yaw rate and the vehicle wheelbase; determining the rotational angular velocity of the locking wheel based on the ratio of the first intermediate parameter to a first distance; and performing time integration on the rotational angular velocity to obtain the actual rotation angle.

[0044] In some examples, the first intermediate parameter is a transitional parameter connecting the yaw rate and the locking wheel rotational angular velocity. It is used to convert the yaw motion parameters at the vehicle's center of gravity into motion parameters related to the locking wheel, providing a basis for subsequent calculations of the locking wheel's rotational angular velocity. It can call the yaw rate and vehicle wheelbase obtained in step 102, and obtain the product of the yaw rate and vehicle wheelbase through multiplication. This product is the first intermediate parameter. For example, if the yaw rate obtained in step 102 is 0.5 radians per second and the vehicle wheelbase is 2800 millimeters, the vehicle control unit can obtain the first intermediate parameter as 1400 millimeters per second by multiplying the two. This value serves as the basic transitional data for subsequent calculations.

[0045] The angular velocity of the locking wheel is the angular velocity of the locking wheel rotating around its own center. It is used to reflect the rotational characteristics of the locking wheel as the rotation fulcrum of the vehicle, and it is also an intermediate parameter for deriving the actual rotation angle of the vehicle. The first intermediate parameter and the first distance obtained in step 102 can be called up, and the ratio of the first intermediate parameter to the first distance can be obtained by division. This ratio is the angular velocity of the locking wheel. For example, if the first intermediate parameter is 1400 mm·radians per second and the first distance is 1200 mm, the vehicle control unit can obtain the angular velocity of the locking wheel as approximately 1.17 radians per second by dividing the two. This value can accurately reflect the rotation speed of the locking wheel and provide a key parameter for subsequent time integration processing.

[0046] The process of integrating the rotational angular velocity over time to obtain the actual rotation angle involves accumulating the change in the rotational angular velocity of the locking wheel over time, converting the angular velocity parameter into an angle parameter, and thus obtaining the actual angle turned by the target vehicle. For example, if the rotational angular velocity of the locking wheel is stable at 1.17 radians per second, the vehicle control unit integrates this angular velocity over time. When the integration time is 1 second, the actual rotation angle obtained is approximately 1.17 radians, which is equivalent to approximately 67 degrees. This value accurately reflects the actual rotation progress of the vehicle within that time period.

[0047] For example, firstly, the stored yaw rate and vehicle wheelbase can be retrieved, and a first intermediate parameter can be obtained through multiplication to ensure the accuracy of the calculation process. Subsequently, the vehicle control unit retrieves the stored first distance and performs a division operation between the first intermediate parameter and the first distance to obtain the rotational angular velocity of the locking wheel. This angular velocity is updated in real time as the vehicle's rotational state changes. Next, the time integration operation logic is started to continuously integrate the real-time updated rotational angular velocity of the locking wheel. An integration operation is completed every preset time interval to update the actual rotation angle. Finally, the actual rotation angle obtained from each integration is synchronously stored in the relevant control module, providing accurate and real-time parameter support for adjusting the speed of the drive wheel based on the angle deviation between the actual rotation angle and the target rotation angle in step 104, ensuring the accuracy of angle control during the vehicle's U-turn.

[0048] By implementing the above embodiments, the product of the yaw rate and the vehicle wheelbase is used as an intermediate parameter, and the distance from the center of mass to the locking wheel is combined for conversion. The actual rotation angle is then obtained through integration. This establishes a continuous mapping relationship between the motion of the center of mass and the rotation of the locking wheel, making the angle acquisition process clearer and more controllable. This not only improves the accuracy and real-time performance of the rotation angle calculation, but also enhances the method's adaptability to changes in different vehicle structural parameters, thereby further improving the accuracy and consistency of U-turn control.

[0049] In some embodiments, the aforementioned zero-speed closed-loop control of the locking wheel may include: performing closed-loop adjustment of the output torque of the locking wheel based on the speed deviation between the real-time speed of the locking wheel and the zero-speed target value, so that the real-time speed approaches the zero-speed target value; determining a first torque limit value based on the road surface adhesion coefficient of the current driving road of the target vehicle, determining a second torque limit value based on the rated torque of the first drive motor of the locking wheel, and determining a third torque limit value based on the torque balance condition of the entire vehicle system of the target vehicle; and limiting the output torque through the first torque limit threshold, the second torque limit threshold, and the third torque limit threshold during the closed-loop adjustment of the output torque of the locking wheel.

[0050] In some examples, the real-time rotational speed is the actual rotational speed of the locking wheel at the current moment, reflecting its real-time motion state and serving as the basis for determining whether the locking wheel has reached the control target in zero-speed closed-loop control. For instance, when the locking wheel first initiates zero-speed closed-loop control, the wheel speed sensor collects a real-time rotational speed of 5 revolutions per minute. As the closed-loop adjustment progresses, the real-time rotational speed gradually decreases until it approaches the zero-speed target value. The zero-speed target value is the preset target rotational speed of the locking wheel in zero-speed closed-loop control. Its purpose is to keep the locking wheel stationary, acting as the rotation fulcrum for the target vehicle to turn around in place. For example, the zero-speed target value is preset to 0 revolutions per minute, requiring the locking wheel to remain stationary throughout the entire turn-around process, providing a stable center reference for vehicle rotation.

[0051] Speed ​​deviation is the difference between the real-time speed of the locking wheel and the zero-speed target value. It reflects the degree of deviation between the current speed of the locking wheel and the control target, and serves as the basis for closed-loop adjustment of the locking wheel's output torque. For example, if the real-time speed of the locking wheel is 3 revolutions per minute and the zero-speed target value is 0 revolutions per minute, then the speed deviation at that moment is calculated to be 3 revolutions per minute. As the real-time speed gradually approaches 0 revolutions per minute, the speed deviation also gradually decreases.

[0052] By monitoring the speed deviation in real time, the output torque of the locking wheel can be dynamically adjusted to form a closed-loop feedback control, ensuring that the speed of the locking wheel continuously approaches the zero-speed target value and eventually stabilizes at zero speed. The closed-loop adjustment logic can be preset, and after calculating the speed deviation, the output torque of the locking wheel can be automatically adjusted according to the logic. For example, when the speed deviation is positive, that is, the real-time speed is higher than the zero-speed target value, the vehicle control unit adjusts the output torque of the locking wheel to increase, thereby increasing the braking force and reducing the real-time speed. When the speed deviation is negative, that is, the real-time speed is lower than the zero-speed target value, the vehicle control unit adjusts the output torque of the locking wheel to decrease, avoiding excessive braking that could cause the locking wheel to rotate in the opposite direction, and ultimately allowing the real-time speed to smoothly approach the zero-speed target value.

[0053] The road surface adhesion coefficient is a parameter that describes the adhesion between the road surface and the tires of the target vehicle. It reflects the grip performance of the road surface on the tires. It can be collected in real time by the road surface adhesion coefficient detection sensor installed on the target vehicle, or estimated by the vehicle control unit based on parameters such as wheel speed and torque. For example, when the target vehicle is driving on a dry cement road, the road surface adhesion coefficient is collected as 0.6; when driving on a wet asphalt road, the road surface adhesion coefficient is collected as 0.3. This parameter directly affects the upper limit setting of the output torque of the locking wheel. The first torque limit value is the upper limit of the locking wheel output torque determined based on the road surface adhesion coefficient of the target vehicle's current driving road. It is used to prevent the locking wheel output torque from being too high, which could cause the wheel to lock up and slip, thus ensuring stable control of the locking wheel. It can be calculated based on the collected road surface adhesion coefficient and multiplied by a preset calculation coefficient. This value will be dynamically adjusted as the road surface adhesion coefficient changes. For example, when the road surface adhesion coefficient is 0.6, the vehicle control unit calculates the first torque limit value to be 80 Nm through the preset calculation coefficient, that is, the output torque of the locking wheel must not exceed 80 Nm to avoid wheel lockup due to excessive torque.

[0054] The first drive motor is a dedicated drive motor that provides power output and braking control for the locking wheel. Its rated torque is the maximum torque value that the first drive motor can output under long-term safe and stable operation, as specified at the factory. It is an inherent performance parameter of the motor and is used to determine the second torque limit value to ensure the safe operation of the first drive motor. For example, if the rated torque of the first drive motor is specified as 100 N·m, this value is the upper limit of the torque for long-term safe operation and must not be exceeded for extended periods. The second torque limit value is the upper limit of the locking wheel's output torque, determined based on the rated torque of the first drive motor. It is used to prevent the locking wheel's output torque from exceeding the rated torque of the first drive motor, avoiding motor overload damage. It can be calculated by calling the rated torque parameter of the first drive motor and combining it with a preset ratio. For example, if the preset ratio is 70%, and the rated torque of the first drive motor is 100 N·m, then the calculated second torque limit value is 70 N·m, meaning the output torque of the locking wheel must not exceed 70 N·m, protecting the first drive motor from overload damage.

[0055] The vehicle system torque balance condition is a balance requirement that the sum of the output torques at all wheels of the target vehicle must meet. It is used to ensure the overall torque balance of the vehicle during a turn in place, and to avoid vehicle instability due to excessive local torque. The vehicle torque balance logic and related parameters can be pre-stored. This condition takes into account factors such as the vehicle's structural characteristics and power distribution, and provides a basis for determining the third torque limit value. For example, the vehicle system torque balance condition is set to ensure that the sum of the output torques at all wheels does not exceed the maximum torque that the vehicle system can withstand, so as to ensure that the torque is stable during vehicle rotation without deviation or swaying. The third torque limit value is the upper limit of the locking wheel output torque determined based on the torque balance conditions of the target vehicle's overall system. It is used to prevent excessive output torque of the locking wheel from disrupting the torque balance of the overall vehicle system and ensuring the stability of the vehicle during a U-turn. It can be calculated based on preset torque balance conditions of the overall vehicle system and the current power state of the vehicle. This value will be dynamically adjusted according to the power state of the vehicle. For example, based on the torque balance conditions of the overall vehicle system, the calculated third torque limit value is 65 Nm, meaning that the output torque of the locking wheel must not exceed 65 Nm to ensure the torque balance of the overall vehicle and avoid vehicle instability.

[0056] During the closed-loop adjustment of the locking wheel's output torque, the process of limiting the output torque using the first, second, and third torque limiting thresholds involves comparing the output torque with the three torque limiting values ​​in real time while simultaneously adjusting the locking wheel's output torque in the closed loop. The output torque is limited to the minimum of the three limiting values, preventing wheel lock-up and slippage, protecting the primary drive motor, and ensuring overall vehicle torque balance. For example, if the first torque limiting value is 80 Nm, the second is 70 Nm, and the third is 65 Nm, and the locked wheel's output torque calculated by the closed-loop adjustment is 75 Nm, this torque exceeds the second and third torque limiting values. The vehicle control unit will automatically limit the output torque to 65 Nm to ensure that all limiting requirements are met.

[0057] Through the implementation of the above embodiments, zero-speed closed-loop control based on speed deviation is implemented on the locking wheel, and a multi-torque limiting mechanism based on road surface adhesion, motor capability and vehicle torque balance is introduced. This enables the locking wheel to avoid overload or slippage while maintaining the stable fulcrum function. It can ensure the stability of the rotation center and reduce the risk of control instability caused by extreme working conditions, thereby improving the safety and stability of the vehicle during the U-turn process.

[0058] In some embodiments, the aforementioned speed control processing of the drive wheel based on the angle deviation between the actual rotation angle and the target rotation angle may include: determining the reference speed value of the drive wheel by querying a preset mapping relationship based on the angle deviation value and the target rotation angle, wherein the preset mapping relationship is a pre-calibrated two-dimensional lookup table relationship, which takes the angle deviation value and the target rotation angle as input and the reference speed value of the drive wheel as output; generating a speed attenuation factor based on the absolute value of the angle deviation value and a preset attenuation coefficient, wherein the speed attenuation factor decreases non-linearly as the absolute value of the deviation decreases, and the absolute value of the deviation is the absolute value of the angle deviation value; determining the target speed of the drive wheel based on the product of the reference speed value and the speed attenuation factor; and adjusting the speed of the drive wheel to the target speed through speed closed-loop control.

[0059] In some examples, the preset mapping relationship is a pre-calibrated and stored relationship in the vehicle control unit, used to associate the angle deviation value, the target rotation angle, and the reference speed value of the drive wheel. Its function is to provide a basic reference for the drive wheel speed under different U-turn conditions. The optimal reference speed of the drive wheel corresponding to different angle deviation values ​​and different target rotation angles can be collected through bench tests, real vehicle calibration, etc., and organized into a two-dimensional lookup table relationship, which is pre-stored in the storage module of the vehicle control unit. When the reference speed value needs to be determined, it can be directly called. For example, the preset mapping relationship is a two-dimensional lookup table. When the angle deviation value is 180 degrees and the target rotation angle is 180 degrees, the corresponding reference speed value is calibrated as 500 revolutions per minute; when the angle deviation value is 90 degrees and the target rotation angle is 180 degrees, the corresponding reference speed value is calibrated as 300 revolutions per minute, ensuring the rationality of the reference speed value under different operating conditions.

[0060] The reference speed value is a basic reference value of the drive wheel obtained by querying a preset mapping relationship based on the angle deviation value and the target rotation angle. It is used to reflect the speed corresponding to the basic driving force required by the drive wheel under different U-turn conditions and is the basic parameter for determining the target speed of the drive wheel. The angle deviation value calculated in step 104 and the target rotation angle obtained through the human-machine interface can be called to find the speed value corresponding to the two sets of parameters in the preset mapping relationship in a two-dimensional lookup table. This is the reference speed value. For example, if the current angle deviation value is 120 degrees and the target rotation angle is 180 degrees, the vehicle control unit finds the corresponding reference speed value of 400 revolutions per minute by querying the preset two-dimensional lookup table relationship. The absolute value of the deviation is the absolute value of the angle deviation. It is used to eliminate the positive and negative effects of the angle deviation and only reflects the degree of deviation between the actual rotation angle and the target rotation angle. It is an input parameter for generating the speed decay factor. For example, if the angle deviation is -50 degrees, that is, the actual rotation angle is less than the target rotation angle, the absolute value of the deviation is 50 degrees. If the angle deviation is 30 degrees, the absolute value of the deviation is 30 degrees. The larger the absolute value of the deviation, the greater the deviation between the vehicle's rotation progress and the target.

[0061] The speed attenuation factor is a coefficient used to adjust the reference speed value. Its function is to make the speed of the drive wheel decrease non-linearly as the angle deviation decreases, avoiding angle overshoot due to excessive speed at the end of the turn and ensuring the accuracy of the turn. A preset attenuation coefficient can be stored in advance. The calculated absolute value of the deviation is called up and combined with the preset attenuation coefficient to generate the speed attenuation factor through preset calculation logic. This attenuation factor decreases non-linearly as the absolute value of the deviation decreases. For example, if the preset attenuation coefficient is 0.01, when the absolute value of the deviation is 180 degrees, the speed attenuation factor approaches 1, and the attenuation effect on the reference speed value is minimal. When the absolute value of the deviation is 5 degrees, the speed attenuation factor approaches 0.2, and the attenuation effect on the reference speed value is significant, causing the speed of the drive wheel to decrease significantly.

[0062] The target speed is the final speed value that the drive wheel needs to reach and maintain stably. It is the ultimate control target for drive wheel speed regulation, used to drive the target vehicle to rotate smoothly around the locking wheel and gradually reduce the angular deviation value. A reference speed value determined through a preset mapping relationship and a generated speed attenuation factor can be used. The product of these two values ​​is the target speed of the drive wheel. For example, if the reference speed is 400 rpm and the speed attenuation factor is 0.8, the target speed is 320 rpm; if the reference speed is 300 rpm and the speed attenuation factor is 0.3, the target speed is 90 rpm. The target speed decreases as the absolute value of the deviation decreases.

[0063] The process of adjusting the speed of the drive wheel to the target speed through closed-loop speed control involves real-time monitoring of the actual speed of the drive wheel, comparing the actual speed with the target speed, and dynamically adjusting the output torque of the drive wheel based on the speed deviation. This ensures that the actual speed of the drive wheel continuously approaches and stabilizes at the target speed. The closed-loop speed control logic can be pre-set. After determining the target speed, this logic is activated, and the actual speed of the drive wheel is collected in real time by the wheel speed sensor, dynamically adjusting the output torque. For example, if the target speed of the drive wheel is 320 rpm, and the wheel speed sensor collects an actual speed of 300 rpm, the onboard control unit increases the output torque of the drive wheel, raising the actual speed; if the actual speed is 340 rpm, the output torque is decreased, lowering the actual speed, ultimately stabilizing the actual speed at 320 rpm.

[0064] By implementing the above embodiments, the reference speed is obtained based on the two-dimensional lookup table of the angle deviation and the target angle, and the target speed is generated by combining the speed attenuation factor that changes with the deviation. This enables the dynamic adjustment of the drive wheel speed as the U-turn progresses, allowing the vehicle to have higher driving force in the early stage of the U-turn to improve efficiency, and automatically reducing the speed when approaching the target angle, thereby effectively suppressing the angle overshoot phenomenon and achieving smooth convergence. This can improve the accuracy of U-turn angle control and process stability.

[0065] In some embodiments, the speed attenuation factor is generated by an exponential function with the natural constant e as the base and the negative of the product of a preset attenuation coefficient and the absolute value of the deviation as the exponent.

[0066] In some examples, the speed decay factor is generated by an exponential function with the natural constant e as the base and the negative of the product of the preset decay coefficient and the absolute value of the deviation as the exponential function is the exponential function. The logic is to use the non-linear change characteristics of the exponential function to make the speed decay factor show a smooth and gradual non-linear decay trend as the absolute value of the deviation decreases. This ensures that the adjustment process of the drive wheel speed is smooth and without abrupt changes, avoids angle overshoot caused by sudden changes in speed at the end of the turn, and further improves the accuracy of drive wheel speed control, adapting to the speed requirements of different rotation progress during the turn on the spot.

[0067] For example, the preset attenuation coefficient is calibrated to 0.01. When the absolute value of the deviation is 180 degrees, the product of the preset attenuation coefficient and the absolute value of the deviation is 0.01 × 180 = 1.8. The negative value of this product is -1.8. Using the natural constant e as the base, the exponential operation is performed, that is, e raised to the power of -1.8, resulting in a speed attenuation factor of approximately 0.165, which is close to 0.2, indicating a significant attenuation effect on the reference speed value. When the absolute value of the deviation is 90 degrees, the product of the preset attenuation coefficient and the absolute value of the deviation is 0.01 × 90 = 0. 9. The negative value of the product is -0.9. Calculating e to the power of -0.9 yields a speed attenuation factor of approximately 0.407, indicating a slight reduction in attenuation effect. When the absolute value of the deviation is 5 degrees, the product of the preset attenuation coefficient and the absolute value of the deviation is 0.01 × 5 = 0.05. The negative value of the product is -0.05. Calculating e to the power of -0.05 yields a speed attenuation factor of approximately 0.951, which is close to 1. The attenuation effect on the reference speed value is minimal, fully demonstrating the characteristic that the speed attenuation factor decreases nonlinearly as the absolute value of the deviation decreases.

[0068] Through the implementation of the above embodiments, the speed decay factor is generated in the form of an exponential function, so that the speed adjustment process has nonlinear progressive characteristics. That is, it maintains a high output when the angle deviation is large, and decays rapidly when the deviation decreases. The nonlinear adjustment mechanism of the device is more in line with the actual control requirements than the linear method, which can improve the sensitivity and convergence speed of the end control, thereby further enhancing the fine control capability and stability of the turning process.

[0069] In some embodiments, the aforementioned plurality of wheels further includes an auxiliary wheel set, which may include a first side auxiliary wheel and a second side auxiliary wheel. The aforementioned vehicle turning control method may further include: determining a first target torque direction and a first target torque absolute value for the first side auxiliary wheel, and a second target torque direction and a second target torque absolute value for the second side auxiliary wheel, based on an angle deviation value and the current rotation direction of the target vehicle, wherein the first target torque direction is opposite to the second target torque direction, the first target torque absolute value and the second target torque absolute value are both proportional to the angle deviation value, and in response to an angle deviation value of zero, both the first target torque absolute value and the second target torque absolute value are determined to be zero; issuing a first torque control command to the first side auxiliary wheel according to the first target torque direction and the first target torque absolute value, and issuing a second torque control command to the second side auxiliary wheel according to the second target torque direction and the second target torque absolute value, so as to form an additional yaw moment matching the current rotation direction.

[0070] In some examples, the auxiliary wheel set is a wheel set consisting of the wheels of the target vehicle other than the locking wheel and the drive wheel determined in step 101. Its function is to generate additional yaw torque by outputting differential torque, assisting the locking wheel and the drive wheel in driving the target vehicle to rotate smoothly, thereby improving the stability and accuracy of the vehicle's U-turn process. After determining the locking wheel and the drive wheel in step 101, the remaining wheels can be integrated into the auxiliary wheel set. For example, if the target vehicle is a four-wheeled vehicle, and step 101 determines that the left front wheel is the locking wheel and the right front wheel is the drive wheel, then the remaining left rear wheel and right rear wheel form the auxiliary wheel set to provide auxiliary driving torque for the vehicle to turn in place.

[0071] The first auxiliary wheel is the wheel located on one side of the target vehicle in the auxiliary wheel set. It is the component in the auxiliary wheel set that bears the torque output on one side. It works with the second auxiliary wheel to output a reverse torque, forming an additional yaw moment. The second auxiliary wheel is the wheel located on the other side of the target vehicle in the auxiliary wheel set. It corresponds to the first auxiliary wheel and its function is to output a reverse torque with the first auxiliary wheel, working together to form an additional yaw moment to assist the vehicle in rotating smoothly. For example, when the auxiliary wheel set consists of the left and right rear wheels, if the target vehicle is currently rotating clockwise, the vehicle control unit selects the left rear wheel as the first auxiliary wheel, bearing the output of reverse braking or driving torque. The remaining right rear wheel in the auxiliary wheel set is the second auxiliary wheel, which outputs torque in the opposite direction to the left rear wheel, together forming an additional yaw moment.

[0072] The current rotation direction is the direction in which the target vehicle rotates around the locking wheel when performing a U-turn. It is used to determine the torque direction of the auxiliary wheel set, ensuring that the additional yaw torque matches the rotation direction and assisting the vehicle to rotate smoothly. The current rotation direction can be determined by comprehensively judging the speed control logic of the drive wheel in step 104, the positive and negative changes of the angle deviation value, and the setting of the target rotation angle. For example, if the target rotation angle is 180 degrees and the angle deviation value is positive and gradually decreasing, it means that the vehicle is rotating clockwise around the locking wheel, and the current rotation direction is determined to be clockwise. If the angle deviation value is negative and gradually decreasing, it means that the vehicle is rotating counterclockwise around the locking wheel, and the current rotation direction is determined to be counterclockwise.

[0073] The first target torque direction is the torque output direction set by the vehicle control unit for the first side auxiliary wheel. It is used to determine whether the first side auxiliary wheel outputs driving torque or braking torque. It is opposite to the second target torque direction and works together to form an additional yaw moment. For example, when the current rotation direction is clockwise, the vehicle control unit determines that the first target torque direction of the first side auxiliary wheel (left rear wheel) is the braking direction, that is, outputs negative torque to assist the vehicle to rotate clockwise. The first target torque absolute value is the absolute value of the torque output set by the vehicle control unit for the first auxiliary wheel. It is used to determine the intensity of the torque output by the first auxiliary wheel. It is directly proportional to the angle deviation value. The larger the angle deviation value, the larger the torque absolute value. When the angle deviation value is zero, the torque absolute value is zero. The angle deviation value calculated in step 104 can be called up, and the first target torque absolute value of the first auxiliary wheel can be calculated according to the preset proportional calculation logic. For example, the preset proportional coefficient is 0.3. When the angle deviation value is 180 degrees, the first target torque absolute value is 180 × 0.3 = 54 N·m; when the angle deviation value is 90 degrees, the first target torque absolute value is 90 × 0.3 = 27 N·m; when the angle deviation value is 0 degrees, the first target torque absolute value is 0 N·m.

[0074] The second target torque direction is the torque output direction set by the vehicle control unit for the second auxiliary wheel. It is opposite to the first target torque direction and is crucial for generating additional yaw moment, ensuring that the torque output of the auxiliary wheel assembly can assist the vehicle in rotating smoothly in the current direction of rotation. For example, if the first target torque direction is the braking direction (negative), then the second target torque direction is the driving direction (positive); if the first target torque direction is the driving direction (positive), then the second target torque direction is the braking direction (negative). The absolute value of the second target torque is the absolute value of the torque output set by the vehicle control unit for the second auxiliary wheel. It follows the same setting logic as the absolute value of the first target torque, i.e., it is proportional to the angle deviation value. When the angle deviation value is zero, the absolute torque value is zero, ensuring balanced torque output of the auxiliary wheel assembly and avoiding additional lateral interference forces. For example, with a preset proportionality coefficient of 0.3, when the angle deviation value is 180 degrees, the absolute value of the second target torque is 54 N·m; when the angle deviation value is 90 degrees, the absolute value of the second target torque is 27 N·m; and when the angle deviation value is 0 degrees, the absolute value of the second target torque is 0 N·m.

[0075] The first torque control command is a control command issued by the vehicle control unit to the first auxiliary wheel. It is used to specify the torque output parameters of the first auxiliary wheel and ensure that the first auxiliary wheel outputs torque according to the set first target torque direction and the first target torque absolute value. After determining the first target torque direction and the first target torque absolute value, a first torque control command containing these two parameters can be generated according to a preset command generation logic and transmitted to the drive motor corresponding to the first auxiliary wheel through the vehicle communication bus. For example, if the first torque control command contains the parameters "braking direction, 54 Nm", the drive motor corresponding to the first auxiliary wheel will output braking torque according to these parameters after receiving the command, thus assisting the vehicle to rotate. The second torque control command is a control command issued by the vehicle control unit to the second auxiliary wheel. Corresponding to the first torque control command, it is used to clarify the torque output parameters of the second auxiliary wheel, ensuring that the second auxiliary wheel outputs torque according to the set second target torque direction and the absolute value of the second target torque, thus cooperating with the first auxiliary wheel to form an additional yaw moment. After determining the second target torque direction and the absolute value of the second target torque, a second torque control command containing these two parameters can be generated according to a preset command generation logic and transmitted to the drive motor corresponding to the second auxiliary wheel via the vehicle communication bus. For example, if the second torque control command contains the parameters "drive direction, 54 Nm", the drive motor corresponding to the second auxiliary wheel will receive the command and output drive torque according to these parameters, cooperating with the braking torque of the first auxiliary wheel to form an additional yaw moment.

[0076] By implementing the above embodiments, differential torque control based on angle deviation and rotation direction is introduced into the auxiliary wheel set, so that the output directions of the left and right auxiliary wheels are opposite and their magnitudes change with the deviation. This can generate an additional yaw torque to assist the vehicle's rotation, enhance the overall rotational power without interfering with the main drive, and automatically reduce the auxiliary effect in the later stage of the turn to avoid excessive intervention, thereby improving the vehicle's attitude control effect and enhancing the stability and trajectory accuracy of the vehicle's turn process.

[0077] In some embodiments, during the process of driving the aforementioned target vehicle to rotate around the locking wheel, the vehicle turning control method may further include: acquiring the cumulative slip distance of the locking wheel, the stall duration of the first drive motor of the locking wheel, and the winding temperature of the first drive motor; terminating the vehicle turning control when the cumulative slip distance is greater than a preset distance threshold or the winding temperature is greater than a first preset temperature threshold; reducing the target speed of the drive wheel based on a preset torque reduction ratio when the stall duration is greater than a preset duration threshold; and cooling the first drive motor when the winding temperature is greater than a second preset temperature threshold and less than or equal to the first preset temperature threshold, wherein the first preset temperature is greater than the second preset temperature.

[0078] In some examples, the cumulative slip distance is the total distance traveled by the locking wheel during the rotation of the target vehicle around the locking wheel, after the locking wheel slips relative to the road surface due to insufficient road adhesion or torque control deviation. This reflects the degree of slippage of the locking wheel. The real-time rotational speed of the locking wheel can be collected in real time by a wheel speed sensor. Combined with the target rotational speed (zero speed) of the locking wheel, the slip speed of the locking wheel can be calculated. Then, the slip speed is integrated over time to obtain the cumulative slip distance of the locking wheel, which is updated and stored in real time. For example, when the target vehicle performs a U-turn on a wet and slippery road surface (road adhesion coefficient less than 0.3), the locking wheel slips slightly. The wheel speed sensor collects a slip speed of 0.1 meters per second. After 10 seconds, the cumulative slip distance is calculated to be 1.0 meter through integration.

[0079] The stall duration is the duration during which the first drive motor of the locking wheel is in a stalled state. The stalled state is a state where the first drive motor outputs torque but the locking wheel does not maintain zero speed as expected, resulting in abnormal speed stagnation. This parameter is used to reflect the degree of abnormal operation of the first drive motor and to prevent damage to the motor due to prolonged stalling. The torque output signal of the first drive motor and the real-time speed of the locking wheel can be monitored in real time. When the output torque of the first drive motor is detected to be greater than the preset stall torque threshold and the real-time speed of the locking wheel deviates from the zero speed target value by more than a preset range, timing begins until the abnormal state is resolved. The timing duration is the stall duration. For example, when the output torque of the first drive motor exceeds the road surface adhesion limit torque and the real-time speed of the locking wheel continues to deviate from zero speed, the vehicle control unit starts timing. If this abnormal state lasts for 250 milliseconds, the stall duration is 250 milliseconds.

[0080] The winding temperature is the real-time temperature of the winding inside the first drive motor of the locking wheel. The winding is an important component of the first drive motor, and its temperature directly affects the motor's operational safety and service life. It is a core parameter for monitoring whether the first drive motor is overheating. The winding temperature data can be collected in real time by a temperature sensor mounted on the first drive motor. The temperature sensor transmits the collected temperature signal to the vehicle control unit in real time, where it is received and stored. For example, during the operation of the first drive motor, the temperature sensor collects the winding temperature in real time. After the motor continuously outputs torque for 30 seconds, the collected winding temperature is 125 degrees Celsius. This value is used to determine whether cooling treatment needs to be initiated or the turn-around control needs to be terminated.

[0081] The preset distance threshold is a critical distance value pre-set by the vehicle control unit to determine whether the locking wheel slippage exceeds the limit. Its function is to define whether the locking wheel has lost a stable rotation fulcrum. When the cumulative slippage distance exceeds this threshold, it indicates that the locking wheel slippage is severe and can no longer serve as a rotation fulcrum, requiring a safety response to be triggered. The critical slippage distance at which the locking wheel loses its stable fulcrum can be determined through bench testing, vehicle calibration, etc., and this distance is used as the preset distance threshold and pre-stored in the storage module of the vehicle control unit for direct retrieval during monitoring. For example, if the preset distance threshold is determined to be 0.3 meters after calibration, when the cumulative slippage distance of the locking wheel is greater than 0.3 meters, a safety response to terminate the U-turn control is triggered. The first preset temperature threshold is a critical temperature value pre-set by the vehicle control unit to determine whether the winding of the first drive motor is severely overheated. Its function is to determine whether there is a risk of burnout of the first drive motor. When the winding temperature exceeds this threshold, the turn-around control must be terminated immediately to protect the first drive motor. The safe limit temperature of the motor winding can be determined by calibration based on the factory performance parameters of the first drive motor, and this temperature can be used as the first preset temperature threshold and stored in the vehicle control unit in advance for direct recall during monitoring. For example, if the safe limit temperature of the first drive motor winding is calibrated to 130 degrees Celsius, then the first preset temperature threshold is 130 degrees Celsius. When the winding temperature is greater than 130 degrees Celsius, the turn-around control will be terminated immediately. When the cumulative slip distance exceeds the preset distance threshold or the winding temperature exceeds the first preset temperature threshold, the vehicle turning control process is terminated. When the locking wheel slips beyond the limit or the first drive motor is severely overheated, the vehicle can no longer achieve a stable and accurate turn in place. Continuing to perform the turn operation will cause risks such as loss of vehicle control and motor damage. Therefore, it is necessary to immediately terminate the turn control, restore the vehicle to normal driving status, and ensure the safety of the vehicle and equipment.

[0082] The preset duration threshold is a critical duration value pre-set by the vehicle control unit to determine whether the stall of the first drive motor exceeds the limit. Its function is to define whether the stall state will damage the first drive motor. When the stall duration exceeds this threshold, a torque reduction and stabilization response needs to be triggered to avoid long-term stall overload of the motor. The safe stall duration that the motor can withstand can be determined through calibration based on the rated performance parameters of the first drive motor, and this duration can be used as the preset duration threshold, pre-stored in the vehicle control unit, and directly called during monitoring. For example, if the preset duration threshold is determined to be 200 milliseconds after calibration, when the stall duration of the first drive motor is longer than 200 milliseconds, a response to reduce the target speed of the drive wheel is triggered. When the stall duration exceeds the preset duration threshold, the process of reducing the target speed of the drive wheel based on the preset torque reduction ratio is designed to prevent long-term stall of the first drive motor from causing overload damage. By reducing the target speed of the drive wheel, the force on the locking wheel during vehicle rotation can be reduced, alleviating the stall state of the first drive motor, avoiding motor damage, and maintaining the basic rotational state of the vehicle without directly terminating the turn-around control.

[0083] The second preset temperature threshold is a critical temperature value pre-set by the vehicle control unit to determine whether the winding of the first drive motor is slightly overheated. Its value is lower than the first preset temperature threshold. Its function is to determine whether the first drive motor needs cooling to prevent the temperature from continuously rising to the first preset temperature threshold. Based on the operating characteristics of the first drive motor, the critical temperature for slight overheating of the motor winding can be determined through calibration and used as the second preset temperature threshold, pre-stored in the vehicle control unit, and directly retrieved during monitoring. For example, if the second preset temperature threshold is determined to be 120 degrees Celsius and the first preset temperature threshold is 130 degrees Celsius, cooling is initiated when the winding temperature is between 120 and 130 degrees Celsius. When the winding temperature is greater than the second preset temperature threshold but less than or equal to the first preset temperature threshold, the process of cooling the first drive motor ensures that when the first drive motor winding is slightly overheated, there is no need to terminate the turnaround control. Initiating cooling can reduce the winding temperature, preventing a continuous rise in temperature that could lead to severe overheating, thus balancing the continuity of turnaround control and the operational safety of the motor.

[0084] For example, during the entire process of driving the target vehicle to rotate around the locking wheel, the vehicle control unit continuously initiates a safety monitoring process to acquire three core parameters in real time: the cumulative slip distance of the locking wheel, the duration of stall in the first drive motor, and the winding temperature. The vehicle control unit compares the real-time collected cumulative slip distance with a preset distance threshold, compares the winding temperature with a first preset temperature threshold and a second preset temperature threshold, and compares the duration of stall in the first drive motor with a preset duration threshold. When the cumulative slip distance is detected to be greater than 0.3 meters or the winding temperature is detected to be greater than 130 degrees Celsius, the vehicle control unit immediately issues a termination command to terminate the vehicle turning control and restore the vehicle to normal driving status. When the duration of stall in the first drive motor is detected to be greater than 200 milliseconds, the vehicle control unit reduces the target speed of the drive wheel based on a preset torque reduction ratio of 20% to alleviate the stall pressure on the first drive motor. When the winding temperature is detected to be between 120 degrees Celsius and 130 degrees Celsius, the vehicle control unit activates the cooling system of the first drive motor to cool the winding until the temperature drops to a safe range.

[0085] Through the implementation of the above embodiments, the locking wheel slip distance, motor stall duration and winding temperature are monitored in real time, and termination, torque reduction or cooling measures are triggered according to different thresholds. The safety monitoring mechanism directly participates in the control process, and can adjust or interrupt the control in time when abnormal trends occur, effectively avoiding problems such as wheel slippage, motor overload or overheating. This improves the reliability of the method while ensuring the stable operation of the vehicle turning process.

[0086] In some embodiments, the aforementioned method may further include: acquiring the target vehicle's current driving speed, current gear status, sensor signal status, and fault status information of each drive motor, wherein the sensor signals may include the inertial measurement unit signal status, wheel speed signal status, and temperature signal status; if the current driving speed is less than a preset vehicle speed threshold, the current gear status belongs to a preset gear set, and the sensor signal status indication and fault status information all indicate no abnormality, then the target vehicle is determined to meet the preset U-turn conditions.

[0087] In some examples, the current driving speed is the actual driving speed of the target vehicle at the moment it is preparing to perform a U-turn. This is used to determine whether the vehicle is in a low-speed state suitable for initiating a U-turn, thus avoiding safety risks caused by initiating a U-turn at high speed. For example, if the target vehicle is preparing to perform a U-turn in an underground parking lot and the current driving speed collected by the vehicle speed sensor is 3 kilometers per hour, this speed is within the low-speed range suitable for initiating a U-turn, providing a basis for subsequent condition judgments.

[0088] The current gear status refers to the gear mode of the target vehicle. It is used to determine whether the vehicle is in a suitable gear to initiate a U-turn, avoiding initiating a U-turn in a driving gear or an incorrect gear, and ensuring the feasibility and safety of the U-turn operation. For example, if the target vehicle is currently in park or neutral, this gear is suitable for initiating a U-turn and can ensure the basic stability of the vehicle during the U-turn.

[0089] Sensor signal status refers to the operational status of various sensors on the target vehicle used to assist in on-the-spot U-turn control. It determines whether the sensors can collect data normally, providing accurate and reliable parameter support for U-turn control and preventing control failure due to sensor malfunction. Sensor signals include inertial measurement unit (IMU) signal status, wheel speed signal status, and temperature signal status. The IMU signal status indicates the operational status of the IMU, which collects attitude parameters such as vehicle yaw rate. The onboard control unit can receive the IMU signal in real time to determine if the signal is normal. The wheel speed signal status indicates the operational status of the wheel speed sensors, which collect the real-time rotational speed of each wheel. The onboard control unit can receive the rotational speed signals from the wheel speed sensors in real time to determine if the signal is complete and stable. The temperature signal status indicates the operational status of the temperature sensors, which collect parameters such as the temperature of the first drive motor windings. The onboard control unit can receive the temperature signals from the temperature sensors in real time to determine if the signal is normal. For example, if the IMU can stably transmit yaw rate signals, the wheel speed sensors can accurately collect wheel rotational speed signals, and the temperature sensors can normally transmit winding temperature signals, then all three signal statuses indicate normal operation.

[0090] The fault status information of each drive motor refers to the abnormal operation information of all drive motors in the target vehicle (including the first drive motor corresponding to the locking wheel, the drive motor corresponding to the drive wheel, and the drive motor corresponding to the auxiliary wheel set). It is used to determine whether the drive motor can output torque and speed normally, and to avoid the failure of turn-around control due to motor failure. The motor's operating parameters can be collected in real time through the motor controller corresponding to each drive motor. The motor can be judged whether there is a fault based on the parameters and generate fault status information. For example, if the on-board control unit collects the current, voltage, speed and other parameters of each drive motor and they are all within the normal range, and no fault codes are generated, then the fault status information of each drive motor indicates no abnormality.

[0091] The preset speed threshold is a critical speed value pre-set by the vehicle control unit to determine whether the target vehicle is at a suitable speed for initiating a U-turn. Its function is to define the speed range for initiating a U-turn, ensuring that the U-turn operation is performed at a low speed to guarantee safety. The maximum speed suitable for initiating a U-turn can be determined through bench testing, real vehicle calibration, etc., and this speed is used as the preset speed threshold and stored in the storage module of the vehicle control unit in advance, and directly called when making a condition judgment. For example, if the preset speed threshold is determined to be 5 kilometers per hour after calibration, this condition is only met when the current driving speed is less than 5 kilometers per hour.

[0092] The preset gear set is a set of gears pre-set by the vehicle control unit that are suitable for initiating a U-turn operation. Its function is to define the range of gears that can be used to initiate a U-turn operation, avoid initiating a U-turn in the wrong gear, and ensure the feasibility of the U-turn operation. For example, the preset gear set includes parking gear and neutral gear, meaning that this condition is only met when the current gear is parking gear or neutral gear.

[0093] The sensor signal status indication and fault status information both indicate no abnormalities, meaning that the vehicle control unit detects that the signals from all relevant sensors (inertial measurement unit, wheel speed sensor, temperature sensor) are complete, stable, without loss or abnormal fluctuations, and that all drive motors are fault-free and can work normally, providing reliable equipment and data support for on-the-spot U-turn control.

[0094] For example, upon receiving a request to initiate a U-turn, the vehicle control unit immediately initiates a verification process for preset U-turn conditions. First, the vehicle control unit acquires the target vehicle's current speed, current gear status, sensor signal status (including inertial measurement unit signal status, wheel speed signal status, and temperature signal status), and fault status information of each drive motor via the vehicle speed sensor, gear position sensor, various related sensors, and motor controller. Then, the vehicle control unit compares the current speed with a pre-stored preset speed threshold to determine if the current speed is less than the preset speed threshold. Simultaneously, it determines if the current gear status is... Belonging to a preset gear set, the system detects the status of sensor signals to determine if there are any abnormalities, and also detects the fault status information of each drive motor to determine if there are any abnormalities. When all verification conditions are met, namely, the current driving speed is less than 5 kilometers per hour, the current gear is parking, the sensor signals are all normal, and each drive motor is fault-free, the vehicle control unit determines that the target vehicle meets the preset U-turn conditions, providing a basis for subsequent steps such as initiating the stationary U-turn mode and determining the locking and drive wheels. If any condition is not met, the vehicle control unit determines that the vehicle does not meet the preset U-turn conditions and does not initiate the stationary U-turn mode, ensuring the safety and feasibility of the U-turn operation.

[0095] By implementing the above embodiments, the vehicle speed, gear status, sensor signals, and motor fault status are comprehensively verified before the U-turn control is initiated. This ensures that the vehicle enters the U-turn mode only under safe and controllable conditions, thereby avoiding control execution risks under abnormal operating conditions from the source and ensuring that subsequent control strategies can operate on a stable basis. This provides a prerequisite guarantee for achieving high-precision and high-stability U-turn control.

[0096] In some embodiments, the driver can press the "U-turn" soft switch via a physical button on the central control panel. The human-machine interface module sends a U-turn function trigger command to the vehicle control unit (VCU). The VCU simultaneously receives the center of gravity yaw rate collected by the inertial measurement unit module, the wheel speed signals collected by the wheel speed sensors, the motor winding temperature signals collected by the temperature sensors, and real-time data from the vehicle speed sensor and gear position sensor. It then automatically verifies the access conditions corresponding to the trigger command, specifically including: vehicle speed ≤ 3 kph (vehicle speed 0 kph in this condition, meeting access requirements); vehicle gear in P or N (N gear in this condition, meeting access requirements); no abnormalities in IMU signal, wheel speed signal, and temperature signal (signals valid, meeting access requirements); and no fault codes in any motor (no faults in this condition, meeting access requirements). If all access conditions are met, the VCU, based on the vehicle's current attitude and the road adhesion coefficient (μ=0.6 in this condition), selects the left front wheel as the locking wheel and moves the right front wheel (main wheel) and rear wheel assembly (auxiliary wheel) downwards. The system issues a preparatory command for coordinated control and simultaneously initializes the rotation angle parameters, setting the target rotation angle θ_req=180° and initializing monitoring parameters such as angle deviation Δθ and cumulative slip distance of the locking wheel to 0. The human-machine interface module synchronously updates the interface status, illuminates the locking wheel status indicator (initially green, indicating successful locking wheel selection), displays the target rotation angle of 180° and the initial actual rotation angle of 0° in real time, and provides feedback to the driver that the function activation preparation is complete. Finally, the vehicle controller first requests the release of the electronic handbrake or automatic parking (ensuring that the wheels are not mechanically locked), then issues a preparatory command for closed-loop speed control to the left front wheel locking wheel control unit (such as the left front motor), starts locking wheel speed monitoring and torque limiting preparation, and simultaneously issues speed / torque adjustment parameter initialization commands to the main wheel (such as the right front motor) and auxiliary wheel control units (such as the left rear motor and right rear motor), completing all parameter preparation work before the U-turn control.

[0097] At time t0, the vehicle controller sends a locking wheel control command to the left front wheel drive actuator. This command includes the target locking wheel speed of 0 rpm, three-level torque limiting parameters (road adhesion limit torque 100 Nm × 80% = 80 Nm, motor rated torque 70%, and vehicle total torque balance threshold), and a stall torque monitoring threshold (road adhesion limit torque 100 Nm). At t0 + 100 ms, the left front wheel drive actuator initiates closed-loop speed control according to the command, real-time acquisition of wheel speed signals, and adjustment of motor output torque to gradually bring the left front wheel speed closer to 0 rpm. Simultaneously, the safety monitoring module begins to calculate the cumulative locking wheel slip distance through wheel speed signal integration. At t0 + 300 ms, the vehicle controller acquires the actual left front wheel speed = 0 rpm and the stall torque = 85 Nm (this value is less than the road adhesion limit torque 100 Nm). With the torque exceeding the first-level limiting threshold of 80 Nm and greater than 80 Nm, the locking wheel has stably acted as the rotation fulcrum, and the turn-around control officially enters the execution phase. If the stall torque exceeds the first-level limiting threshold during this process, the vehicle controller will immediately activate the first-level load reduction protection to reduce the torque output of the locking wheel. Subsequently, the initial power distribution and rotation start-up phase (t0+300ms-t0+500ms) begins. The vehicle controller first converts the yaw rate of the center of gravity collected by the IMU into the actual rotational angular velocity at the locking wheel through a preset coordinate system transformation logic. Then, through time integration, the initial actual rotation angle is obtained as 0°, and the initial angle deviation Δθ = 180° - 0° = 180° is calculated. Subsequently, the reference speed of the main wheel is obtained through a two-dimensional lookup table, combined with the preset deviation attenuation logic (in this operating condition, Δθ = 180°, attenuation factor e^(-k)). (180°)≈1), calculating the target speed of the main drive wheel to be 500 rpm, a speed control command is sent to the right front wheel drive actuator. Simultaneously, based on the vehicle's rotation direction (clockwise) and angle deviation Δθ=180°, the differential torque of the auxiliary wheels is calculated, and torque control commands are sent to the left and right rear wheels respectively. The left rear wheel torque is -50 Nm (in braking mode), and the right rear wheel torque is +50 Nm (in driving mode). Each drive actuator receives the commands synchronously and starts power output. The vehicle, using the left front wheel as a fulcrum, begins to rotate clockwise, completing the initial turn. Start-up begins; entering the mid-term dynamic control and torque balance phase (t0+500ms-t0+2s), the vehicle controller collects IMU data every 10ms, repeatedly performs coordinate system transformation and integration calculations, and updates the actual rotation angle in real time. Under this condition, at t0+2s, the actual rotation angle is 90°, and the calculated angle deviation Δθ = 180° - 90° = 90° is obtained. Based on this angle deviation, the vehicle controller re-queries the two-dimensional table to obtain the reference speed of the main drive wheel, and calculates the attenuated target speed of 300 rpm using the deviation attenuation logic, moving to the right. The front wheels issue a speed adjustment command, reducing the main drive wheel speed from 500 rpm to 300 rpm. Simultaneously, based on Δθ=90°, the absolute value of the auxiliary wheel differential torque is reduced, and torque update commands are issued to the left and right rear wheels, with the left rear wheel set to -25 Nm and the right rear wheel to +25 Nm. This reduces the additional yaw moment, preventing the vehicle from rotating too quickly and deviating from its trajectory. The safety monitoring module monitors the cumulative slip distance of the locking wheel in real time (0.12 m at t0+2s in this condition, less than the preset threshold of 0.3 m) and the stall torque (85 Nm in this condition, less than...). At monitoring thresholds of 100 Nm and motor temperature (100℃ under this condition, less than the preset threshold of 120℃), all parameters are within safe ranges, and no warning is triggered. Entering the final precise deceleration and trajectory correction phase (t0+2s-t0+4s), the vehicle controller continuously collects IMU and wheel speed data. At t0+4s, the actual rotation angle is 175°, and the calculated angle deviation Δθ = 180° - 175° = 5°. Based on this angle deviation, the vehicle controller queries a two-dimensional table to obtain the reference speed of the main drive wheel, combined with the deviation attenuation logic (e^(-k...). (5°)≈0.2), calculating the target speed = 50rpm, a deceleration command is issued to the right front wheel to reduce the speed of the main wheel to below 50rpm, avoiding angle overshoot. Simultaneously, based on Δθ=5°, the differential torque of the auxiliary wheel is further reduced, and torque commands are issued to the left and right rear wheels, with the left rear wheel = -5Nm and the right rear wheel = +5Nm. This small differential torque corrects the vehicle's rotation trajectory, ensuring the actual rotation angle accurately approaches the target rotation angle of 180°. The safety monitoring module continues to monitor various parameters in real time. Under this condition, the cumulative slip distance of the locking wheel is 0.23m and the motor temperature is 105℃, both posing no safety risk; therefore, the current control strategy remains unchanged. Then, the vehicle enters the turn-around completion and power termination phase (t0+4s-t0+4.5s). The vehicle controller collects the actual rotation angle = 180° and calculates the angle deviation Δθ = 180° - 180° = 0°. It is determined that the actual rotation angle is consistent with the target rotation angle, and the turn-around control is completed. Subsequently, the power termination command is sent to the drive actuators of the left front wheel, main wheel, and auxiliary wheel at the same time, requiring the speed and torque of each wheel end to return to zero immediately. After receiving the command, each drive actuator quickly cuts off the motor power output. The speed of the left front wheel, right front wheel, and rear wheel set all drop to 0 rpm, the stall torque returns to zero, and the vehicle stays stably at the 180° turn-around position without slippage or overshoot.

[0098] The vehicle controller sends a U-turn completion signal to the human-machine interface (HMI) module, and the HMI simultaneously displays a "U-turn Complete" message. The locking wheel status indicator remains green, informing the driver that the compass U-turn operation is complete. Subsequently, the vehicle controller resets control parameters such as rotation angle, angle deviation, locking wheel slip distance, and wheel end speed / torque to their initial state, preparing for the next activation of the compass U-turn function. The safety monitoring module performs a final check on parameters such as motor temperature, torque, and wheel speed. After confirming no abnormalities, it stops the special safety monitoring and resumes the normal monitoring mode. Each drive actuator receives a reset command from the vehicle controller, releases the closed-loop control of locking wheel speed and the coordinated control of the main and auxiliary wheels, and restores the power distribution mode for normal driving. Finally, the HMI module clears the target angle, actual angle, and other U-turn-related display parameters, the locking wheel status indicator turns off, and the interface returns to the normal driving control interface, completing the entire compass U-turn function exit process.

[0099] Furthermore, as an implementation of the aforementioned method embodiments, this application also provides a vehicle U-turn control device for implementing the aforementioned method embodiments. This device embodiment corresponds to the aforementioned method embodiments. For ease of reading, this vehicle U-turn control device embodiment will not repeat the details of the aforementioned method embodiments one by one, but it should be understood that the device in this application embodiment can correspondingly implement all the contents of the aforementioned method embodiments. For example... Figure 2As shown, the vehicle turning control device 20 includes: a wheel determination unit 201, a data acquisition unit 202, a rotation determination unit 203, and a vehicle turning unit 204. The wheel determination unit 201 is used to determine one locking wheel and one driving wheel from multiple wheels of the target vehicle when the target vehicle meets preset turning conditions. The data acquisition unit 202 is used to acquire the target vehicle's wheelbase, yaw rate, and a first distance from the vehicle's center of gravity to the locking wheel. The rotation determination unit 203 is used to determine the actual rotation angle of the target vehicle based on the yaw rate, wheelbase, and the first distance. The vehicle turning unit 204 is used to perform zero-speed closed-loop control on the locking wheel and to adjust the speed of the driving wheel based on the angle deviation between the actual rotation angle and the target rotation angle, thereby driving the target vehicle to rotate around the locking wheel. The target rotation angle is a preset rotation parameter obtained through a human-machine interface.

[0100] In some embodiments, the rotation determination unit 203 is further configured to determine a first intermediate parameter based on the product of the yaw rate and the vehicle wheelbase; determine the rotational angular velocity of the locking wheel based on the ratio of the first intermediate parameter to the first distance; and perform time integration on the rotational angular velocity to obtain the actual rotation angle.

[0101] In some embodiments, the vehicle turning unit 204 is further configured to perform closed-loop adjustment of the output torque of the locking wheel based on the speed deviation between the real-time speed of the locking wheel and the zero-speed target value, so that the real-time speed approaches the zero-speed target value; determine a first torque limit value based on the road surface adhesion coefficient of the current driving road of the target vehicle, determine a second torque limit value based on the rated torque of the first drive motor of the locking wheel, and determine a third torque limit value based on the torque balance condition of the whole vehicle system of the target vehicle; during the closed-loop adjustment of the output torque of the locking wheel, the output torque is limited by the first torque limit threshold, the second torque limit threshold, and the third torque limit threshold.

[0102] In some embodiments, the vehicle turning unit 204 is further configured to: determine the reference speed value of the drive wheel based on the angle deviation value and the target rotation angle by querying a preset mapping relationship, wherein the preset mapping relationship is a pre-calibrated two-dimensional lookup table relationship, which takes the angle deviation value and the target rotation angle as input and the reference speed value of the drive wheel as output; generate a speed attenuation factor based on the absolute value of the angle deviation value and a preset attenuation coefficient, wherein the speed attenuation factor decreases non-linearly as the absolute value of the deviation decreases, and the absolute value of the deviation is the absolute value of the angle deviation value; determine the target speed of the drive wheel based on the product of the reference speed value and the speed attenuation factor; and adjust the speed of the drive wheel to the target speed through speed closed-loop control.

[0103] In some embodiments, the speed attenuation factor is generated by an exponential function with the natural constant e as the base and the negative of the product of a preset attenuation coefficient and the absolute value of the deviation as the exponent.

[0104] In some embodiments, the plurality of wheels further include an auxiliary wheel set, the auxiliary wheel set including a first side auxiliary wheel and a second side auxiliary wheel; the vehicle turning unit 204 is further configured to determine a first target torque direction and a first target torque absolute value of the first side auxiliary wheel, and a second target torque direction and a second target torque absolute value of the second side auxiliary wheel based on the angle deviation value and the current rotation direction of the target vehicle, wherein the first target torque direction is opposite to the second target torque direction, the first target torque absolute value and the second target torque absolute value are both proportional to the angle deviation value, and in response to the angle deviation value being zero, both the first target torque absolute value and the second target torque absolute value are determined to be zero; according to the first target torque direction and the first target torque absolute value, a first torque control command is issued to the first side auxiliary wheel, and according to the second target torque direction and the second target torque absolute value, a second torque control command is issued to the second side auxiliary wheel to form an additional yaw torque matching the current rotation direction.

[0105] In some embodiments, the vehicle turning unit 204 is further configured to acquire the cumulative slip distance of the locking wheel, the stall duration of the first drive motor of the locking wheel, and the winding temperature of the first drive motor; when the cumulative slip distance is greater than a preset distance threshold or the winding temperature is greater than a first preset temperature threshold, the vehicle turning control is terminated; when the stall duration is greater than a preset duration threshold, the target speed of the drive wheel is reduced based on a preset torque reduction ratio; when the winding temperature is greater than a second preset temperature threshold and less than or equal to the first preset temperature threshold, the first drive motor is cooled, wherein the first preset temperature is greater than the second preset temperature.

[0106] In some embodiments, the vehicle turning control device 20 further includes a condition judgment unit, used to acquire the target vehicle's current driving speed, current gear status, sensor signal status, and fault status information of each drive motor, wherein the sensor signals include the inertial measurement unit signal status, wheel speed signal status, and temperature signal status; if the current driving speed is less than a preset vehicle speed threshold, the current gear status belongs to a preset gear set, and the sensor signal status indication and fault status information all indicate no abnormality, then it is determined that the target vehicle meets the preset turning conditions.

[0107] This application also provides a computer-readable storage medium storing computer-executable instructions or computer programs, which, when executed by a processor, will cause the processor to perform any step of the vehicle U-turn control method provided in this application.

[0108] In some embodiments, the computer-readable storage medium may be a random access memory (RAM), a read-only memory (ROM), flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM); or it may be a variety of devices that include one or any combination of the above-mentioned memories.

[0109] In some embodiments, computer-executable instructions may take the form of programs, software, software modules, scripts, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as stand-alone programs or as modules, components, subroutines, or other units suitable for use in a computing environment.

[0110] In some embodiments, computer-executable instructions may, but do not necessarily, correspond to files in a file system, and may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple co-located files (e.g., files that store one or more modules, subroutines, or code sections).

[0111] like Figure 3 As shown, this application also provides a vehicle 30, including a memory 310, a processor 320, and a computer program 311 stored in the memory 310 and executable on the processor. When the processor 320 executes the computer program 311, it implements any step of the above-described vehicle turning control method.

[0112] This application also provides a computer program product comprising a computer program or computer-executable instructions stored in a computer-readable storage medium. A vehicle's processor reads the computer program or computer-executable instructions from the computer-readable storage medium and executes the computer program or computer-executable instructions, causing the vehicle to perform any step of the vehicle U-turn control method described above.

[0113] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A vehicle U-turn control method, characterized in that, Applied to the target vehicle, the vehicle U-turn control method includes: If the target vehicle meets the preset U-turn conditions, a locking wheel and a drive wheel are determined from the multiple wheels of the target vehicle. Obtain the target vehicle's wheelbase, yaw rate, and the first distance from the vehicle's center of gravity to the locking wheel; The actual rotation angle of the target vehicle is determined based on the yaw rate, the vehicle wheelbase, and the first distance. The locking wheel is subjected to zero-speed closed-loop control, and the speed of the drive wheel is adjusted based on the angular deviation between the actual rotation angle and the target rotation angle to drive the target vehicle to rotate around the locking wheel. The target rotation angle is a preset rotation parameter obtained through a human-machine interface.

2. The vehicle U-turn control method according to claim 1, characterized in that, Determining the actual rotation angle of the target vehicle based on the yaw rate, the vehicle wheelbase, and the first distance includes: The first intermediate parameter is determined based on the product of the yaw rate and the vehicle wheelbase. The rotational angular velocity of the locking wheel is determined based on the ratio of the first intermediate parameter to the first distance. The actual rotation angle is obtained by integrating the rotational angular velocity over time.

3. The vehicle U-turn control method according to claim 1, characterized in that, The zero-speed closed-loop control of the locking wheel includes: Based on the speed deviation between the real-time speed of the locking wheel and the zero-speed target value, the output torque of the locking wheel is adjusted in a closed loop so that the real-time speed approaches the zero-speed target value. A first torque limit value is determined based on the road surface adhesion coefficient of the current driving road of the target vehicle, a second torque limit value is determined based on the rated torque of the first drive motor of the locking wheel, and a third torque limit value is determined based on the torque balance condition of the whole vehicle system of the target vehicle. During the closed-loop adjustment of the output torque of the locking wheel, the output torque is limited by the first torque limiting threshold, the second torque limiting threshold, and the third torque limiting threshold.

4. The vehicle U-turn control method according to claim 1, characterized in that, The step of adjusting the rotational speed of the drive wheel based on the angular deviation between the actual rotational angle and the target rotational angle includes: Based on the angle deviation value and the target rotation angle, the reference speed value of the drive wheel is determined by querying a preset mapping relationship. The preset mapping relationship is a pre-calibrated two-dimensional lookup table relationship, which takes the angle deviation value and the target rotation angle as input and the reference speed value of the drive wheel as output. Based on the absolute value of the angle deviation and a preset attenuation coefficient, a speed attenuation factor is generated, wherein the speed attenuation factor decreases non-linearly as the absolute value of the deviation decreases, and the absolute value of the deviation is the absolute value of the angle deviation. The target speed of the drive wheel is determined based on the product of the reference speed value and the speed decay factor. The rotational speed of the drive wheel is adjusted to the target rotational speed through closed-loop speed control.

5. The vehicle U-turn control method according to claim 4, characterized in that, The speed attenuation factor is generated by an exponential function with the natural constant e as the base and the negative value of the product of the preset attenuation coefficient and the absolute value of the deviation as the exponent.

6. The vehicle U-turn control method according to claim 1, characterized in that, The plurality of wheels also includes an auxiliary wheel assembly, the auxiliary wheel assembly including a first side auxiliary wheel and a second side auxiliary wheel; the vehicle turning control method further includes: Based on the angle deviation value and the current rotation direction of the target vehicle, the first target torque direction and the first target torque absolute value of the first side auxiliary wheel, and the second target torque direction and the second target torque absolute value of the second side auxiliary wheel are determined, wherein the first target torque direction is opposite to the second target torque direction, the first target torque absolute value and the second target torque absolute value are both proportional to the angle deviation value, and in response to the angle deviation value being zero, the first target torque absolute value and the second target torque absolute value are both determined to be zero; Based on the first target torque direction and the absolute value of the first target torque, a first torque control command is issued to the first side auxiliary wheel, and based on the second target torque direction and the absolute value of the second target torque, a second torque control command is issued to the second side auxiliary wheel to form an additional yaw torque that matches the current rotation direction.

7. The vehicle U-turn control method according to claim 1, characterized in that, During the process of driving the target vehicle to rotate around the locking wheel, the vehicle turning control method further includes: The cumulative slip distance of the locking wheel, the stall duration of the first drive motor of the locking wheel, and the winding temperature of the first drive motor are obtained. When the cumulative slip distance is greater than a preset distance threshold or the winding temperature is greater than a first preset temperature threshold, the vehicle turning control is terminated. When the stall duration exceeds a preset duration threshold, the target rotational speed of the drive wheel is reduced based on a preset torque reduction ratio. When the winding temperature is greater than the second preset temperature threshold and less than or equal to the first preset temperature threshold, the first drive motor is cooled, wherein the first preset temperature is greater than the second preset temperature.

8. The vehicle U-turn control method according to claim 1, characterized in that, The vehicle U-turn control method also includes: The current driving speed, current gear status, sensor signal status, and fault status information of each drive motor of the target vehicle are obtained. The sensor signals include the status of the inertial measurement unit signal, the wheel speed signal, and the temperature signal. If the current driving speed is less than a preset speed threshold, the current gear position belongs to a preset gear set, and the sensor signal status indication and the fault status information all indicate no abnormality, then the target vehicle is determined to meet the preset U-turn conditions.

9. A vehicle U-turn control device, characterized in that, Applied to the target vehicle, the vehicle turning control device includes: A wheel determination unit is used to determine a locking wheel and a drive wheel from a plurality of wheels of the target vehicle when the target vehicle meets preset turning conditions. The data acquisition unit is used to acquire the vehicle wheelbase, yaw rate, and first distance from the vehicle's center of gravity to the locking wheel of the target vehicle. A rotation determination unit is used to determine the actual rotation angle of the target vehicle based on the yaw rate, the vehicle wheelbase, and the first distance. The vehicle turning unit is used to perform zero-speed closed-loop control on the locking wheel, and to adjust the speed of the drive wheel based on the angle deviation between the actual rotation angle and the target rotation angle, so as to drive the target vehicle to rotate around the locking wheel. The target rotation angle is a preset rotation parameter obtained through a human-machine interface.

10. A vehicle comprising: The memory and processor are characterized in that the processor, when executing a computer program stored in the memory, implements the steps of the vehicle U-turn control method as described in any one of claims 1 to 7.

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