Vehicle differential steering control method based on motor modulation, terminal equipment and storage medium

Abstract

The invention provides a vehicle differential steering control method based on motor modulation, terminal equipment and a storage medium. The problems that in the prior art, the response speed is low, the control precision is low, and complex road condition changes are difficult to adapt are solved. Comprising the following steps: periodically acquiring real-time rotating speed signals of left and right wheel motors, and averaging the real-time rotating speed signals through a moving average filtering algorithm; and comparing the average rotating speed data of the left and right wheels, and judging whether the vehicle tends to turn leftwards or rightwards or not. Calculating the expected steering radius and the current linear speed according to a differential control algorithm, determining the due rotating speed difference of left and right wheels, and adjusting the rotating speed of the motor. Factors such as an Ackerman steering geometric model, a road adhesion coefficient and a side slip angle are introduced, and calculation of the steering radius is optimized. A three-phase driving signal is generated through space vector modulation, the on-off state of a three-phase inverter is controlled, and accurate speed control is achieved.

Description

Technical Field

[0001] This application relates to the field of intelligent vehicle control technology, and particularly to a vehicle differential steering control method, terminal device, and storage medium based on motor modulation. Background Art

[0002] With the development of autonomous driving and intelligent transportation systems, higher requirements are put forward for the control accuracy and response speed of vehicles. Traditional vehicle steering control methods mainly rely on mechanical differentials to achieve speed differences between the left and right wheels, thereby changing the driving direction of the vehicle. However, this method has some limitations, such as slow response speed, low control accuracy, and difficulty in adapting to complex road condition changes, etc.

[0003] Chinese Patent CN114987610B discloses an articulated tracked vehicle differential steering device and control method, belonging to the field of mechanical engineering technology. The steering gear angle sensor and the actual angle sensor are electrically connected to the differential controller, and the differential controller is electrically connected to the differential steering switching valve. The differential controller receives the signals of the steering gear angle sensor at the steering gear position and the actual angle sensor at the articulated mechanism. The steering gear angle sensor detects the steering angle α of the steering gear, and the actual steering angle sensor detects the actual steering angles β of the front and rear vehicles. The advantages are: it can reduce the ground friction resistance during steering, reduce the engine torque requirement, and improve the steering flexibility; it provides a hydraulic system with differential steering function, increasing the emergency steering function. The limit protection control is carried out on the passive telescopic limit position of the oil cylinder, improving the steering accuracy and response speed, and ensuring the safety of the articulated mechanism.

[0004] In the above solution, although an electro-hydraulic control system is introduced, the execution end still relies on the mechanical structure of the oil cylinder expansion and contraction, and the response speed of the mechanical structure of the oil cylinder expansion and contraction is limited by the flow rate and pressure of the hydraulic system. Although the electro-hydraulic control system can improve the response speed to a certain extent, the expansion and contraction action of the oil cylinder still takes a certain amount of time to complete. Especially in the case of rapid steering or frequent direction adjustment, the response speed may not meet the requirements of high precision and high dynamics.

[0005] Therefore, we hereby propose a vehicle differential steering control method, terminal device, and storage medium based on motor modulation. Summary of the Invention

[0006] The main purpose of this application is to provide a vehicle differential steering control method, terminal device, and storage medium based on motor modulation, aiming to solve the problems of slow response speed, low control accuracy, and difficulty in adapting to complex road condition changes in the prior art. By real-time monitoring the rotational speed signals of the left and right wheel motors and using advanced control algorithms to adjust the motor output, more precise and rapid steering control is achieved, thereby improving the control accuracy and response speed of the vehicle.

[0007] To achieve the above object, the present application provides a vehicle differential steering control method based on motor modulation, including the following steps:

[0008] S1. Periodically obtain the real-time rotational speed signals n i (t) of the left and right wheel motors, and perform averaging processing on the real-time rotational speed signals of the left and right wheel motors through a moving average filtering algorithm to obtain the average rotational speed data of the left wheel motor A and the average rotational speed data of the right wheel motor B

[0009] S2. Compare the average rotational speed data of the left wheel motor A obtained in step S1 with the average rotational speed data of the right wheel motor B to determine whether the vehicle has a tendency to turn left or right;

[0010] S3. When it is determined in step S2 that the vehicle has a tendency to turn left or right, then proceed to the next step; when it is determined in step S2 that the vehicle continues to travel straight, then return to step S1;

[0011] S4. Calculate the expected turning radius R and the current linear speed V of the vehicle according to the differential control algorithm, determine the rotational speed difference Δω that the left and right wheels should have, and adjust the rotational speeds of the left wheel motor A and / or the right wheel motor B.

[0012] Preferably, step S4 specifically includes the following steps:

[0013] S4-1. Establish the relationship between the effective rolling radius r of the wheel and the wheel speed difference Δn based on the Ackermann steering geometry model, and the relationship between the wheelbase L of the vehicle and the center distance W between the left and right wheels and the expected turning radius R, and calculate the absolute value of the expected turning radius R;

[0014] S4-2. Calculate the current linear speed V of the vehicle through formula (2) ; S4-3. Determine the target rotational speed difference Δω according to the absolute value of the expected turning radius R and the current linear speed V of the vehicle obtained in step S4-1 and step S4-2;

[0015] S4-4. Establish the mapping relationship between the output voltage of the three-phase inverter and the target rotational speed difference Δω, and generate three-phase drive signals through space vector modulation;

[0016] S4-5. Adjust the actual rotational speeds of the left wheel motor A and the right wheel motor B according to the three-phase drive signals generated in step S4-4.

[0017] Preferably, the relationship between the effective rolling radius r of the wheel and the wheel speed difference Δn in step S4, and the relationship between the wheelbase L of the vehicle, the center distance W between the left and right wheels, and the expected turning radius R are specifically as follows: the larger the effective rolling radius r of the wheel, the greater the required speed difference; and the wheelbase L of the vehicle and the center distance W between the left and right wheels are inversely proportional to the expected turning radius R, that is, the larger the wheelbase or the smaller the wheel distance, the smaller the expected turning radius.

[0018] Preferably, the calculation of the expected turning radius of the vehicle further includes:

[0019] introducing the road surface adhesion coefficient μ and the centroid side slip angle β, and through formula (3) correcting the expected turning radius R to obtain the corrected expected turning radius R W ;

[0020] where K μ is the slip compensation coefficient, μ max is the maximum adhesion coefficient of the current road surface, and the μ max can be obtained through the in-vehicle IMU.

[0021] Preferably, step S4-4 specifically includes the following steps:

[0022] S44-1. Calculate the target speed of the left wheel and the target speed of the right wheel according to the obtained target speed difference Δω and the preset reference speed of the vehicle.

[0023] S44-2. Calculate the first target output voltage and the second target output voltage of the three-phase inverter according to the obtained target speed of the left wheel and the target speed of the right wheel.

[0024] S44-3. Convert the obtained first target output voltage and second target output voltage into a three-phase reference voltage vector U ref ;

[0025] S44-4. Judge the sector where it is located according to the angle of the obtained three-phase reference voltage vector U ref and select the two basic voltage vectors closest to the three-phase reference voltage vector U ref ; S44-5. Calculate the duty ratios of the two basic voltage vectors closest to the obtained three-phase reference voltage vector U ref ;

[0026] S44-6. Calculate the zero vector duty ratio according to the duty ratios of the two basic voltage vectors obtained above, and generate a three-phase PWM drive signal according to the duty ratios of the two basic voltage vectors closest to the three-phase reference voltage vector U ref and the zero vector duty ratio to control the switching state of the three-phase inverter

[0027] Preferably, the zero vector duty ratio is calculated by subtracting the duty ratios of the two basic voltage vectors closest to the three-phase reference voltage vector U ref from the PWM period.

[0028] Preferably, the sliding average filtering algorithm presets the length of the sliding window to N, and the sliding window N is a positive integer. In each sampling period, the real-time rotational speed signal n i (t) of the left-wheel motor A and the rotational speed data in the previous N - 1 sampling periods together form a data sequence, and then according to Equation (1) the arithmetic mean of this data sequence is calculated as the average rotational speed data of the left-wheel motor A in the current sampling period

[0029] wherein, the n A (t - j) represents the real-time rotational speed of the left-wheel motor A at the previous j-th sampling period (time t - j).

[0030] Preferably, the specific step S2 is as follows: when the average rotational speed data of the left-wheel motor A is greater than the average rotational speed data of the right-wheel motor B , the vehicle has a tendency to turn left; when the average rotational speed data of the left-wheel motor A is less than the average rotational speed data of the right-wheel motor B , the vehicle has a tendency to turn right; when the average rotational speed data of the left-wheel motor A is equal to the average rotational speed data of the right-wheel motor B , the vehicle keeps moving straight.

[0031] To achieve the above object, the present application further provides a terminal device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, the steps of the vehicle differential steering control method based on motor modulation are implemented.

[0032] To achieve the above object, the present application further provides a readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the vehicle differential steering control method based on motor modulation are implemented.

[0033] The beneficial effects of the technical solution of the present invention are as follows:

[0034] On the one hand, by adopting the method of periodically acquiring the real-time rotational speed signals of the left and right wheel motors, the current driving state and steering demand of the vehicle can be quickly reflected. At the same time, the real-time rotational speed signals of the left and right wheel motors are processed by a moving average filtering algorithm to obtain smoother average rotational speed data, reducing the influence of rotational speed fluctuations on the control accuracy. Further, by comparing the average rotational speed data of the left wheel motor A obtained above with the average rotational speed data of the right wheel motor B it can better reflect the overall driving state of the vehicle over a period of time, rather than just the state at a certain moment.

[0035] The Ackermann steering geometry model establishes that when the vehicle is steering, the motion trajectories of the four wheels should intersect at the instantaneous steering center on the extension line of the rear axle. By establishing the relationship between the effective rolling radius of the wheels and the wheel speed difference through this model, the rotational speed that each wheel should have can be accurately calculated according to the actual driving state and steering demand of the vehicle, avoiding the situation where the rotational speed of the wheels cannot accurately match the steering angle during the vehicle steering process, thereby generating a lateral sliding force and causing the vehicle to deviate from the expected driving trajectory, ensuring that the vehicle can drive more smoothly and safely along the curve during turning and preventing the occurrence of lateral sliding. By establishing the mapping relationship between the output voltage of the three-phase inverter and the rotational speed difference, and using the space vector modulation (SVPWM) technology to generate three-phase drive signals, the rotational speeds of the left wheel motor A and the right wheel motor B can be accurately adjusted. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the vehicle differential steering model in an embodiment of the present application;

[0037] Figure 2 It is the internal structure diagram of the terminal device in an embodiment of the present application.

[0038] The realization, functional characteristics and advantages of the purpose of the present application will be further described in combination with the embodiments with reference to the drawings. Detailed Embodiment

[0039] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and should not be construed as a limitation to the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0040] In addition, if descriptions such as "first", "second", etc. are involved in this application, they are only for descriptive purposes (such as for distinguishing the same or similar components), and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0041] See Figure 1 , a vehicle differential steering control method based on motor modulation, comprising the following steps:

[0042] S1. Periodically obtain the real-time speed signals n i (t) of the left and right wheel motors, and perform averaging processing on the real-time speed signals of the left and right wheel motors through a moving average filtering algorithm to obtain the average speed data of the left wheel motor A and the average speed data of the right wheel motor B

[0043] Specifically, the moving average filtering algorithm presets the length of the moving window as N, and the moving window N is a positive integer. And within each sampling period, the real-time speed signal n i (t) of the left wheel motor A and the speed data in the previous N - 1 sampling periods are together formed into a data sequence, and then according to Equation (1)

[0044]

[0045] calculate the arithmetic mean of this data sequence as the average speed data of the left wheel motor A in the current sampling period

[0046] wherein, the n A (t - j) represents the real-time speed of the left wheel motor A before the jth sampling period (at time t - j).

[0047] S2. Compare the average speed data of the left wheel motor A obtained in step S1 with the average speed data of the right wheel motor B to judge whether the vehicle has a tendency to turn left or right;

[0048] Specifically, when the average speed data of the left wheel motor A is greater than the average speed data of the right wheel motor B , then the vehicle has a tendency to turn left; when the average speed data of the left wheel motor A Less than the average rotational speed data of the right wheel motor B then the vehicle has a tendency to turn to the right; when the average rotational speed data of the left wheel motor A is equal to the average rotational speed data of the right wheel motor B then the vehicle maintains a straight line;

[0049] S3. When it is determined in step S2 that the vehicle has a tendency to turn left or right, then proceed to the next step; when it is determined in step S2 that the vehicle continues to move straight, then return to step S1;

[0050] S4. Calculate the expected turning radius R and the current linear speed V of the vehicle according to the differential control algorithm, determine the rotational speed difference Δω that should exist between the left and right wheels, and adjust the rotational speeds of the left wheel motor A and / or the right wheel motor B; the specific steps of step S4 are as follows:

[0051] S4-1. Based on the Ackermann steering geometry model, establish the relationship between the effective rolling radius r of the wheel and the rotational speed difference Δn, as well as the relationship between the wheelbase L of the vehicle and the center distance W between the left and right wheels and the expected turning radius R, and calculate the absolute value of the expected turning radius R;

[0052] S4-2. Calculate the current linear speed V of the vehicle through Equation (2) ;

[0053] S4-3. Determine the target rotational speed difference Δω based on the absolute value of the expected turning radius R obtained in step S4-1 and the current linear speed V of the vehicle obtained in step S4-2;

[0054] S4-4. Establish the mapping relationship between the output voltage of the three-phase inverter and the target rotational speed difference Δω, and generate three-phase drive signals through space vector modulation;

[0055] S4-5. Adjust the actual rotational speeds of the left wheel motor A and the right wheel motor B according to the three-phase drive signals generated in step S4-4.

[0056] In this embodiment, on the one hand, by adopting the method of periodically acquiring the real-time rotational speed signals of the left and right wheel motors, the current driving state and steering requirements of the vehicle can be quickly reflected. At the same time, the real-time rotational speed signals of the left and right wheel motors are processed by the sliding average filtering algorithm to obtain smoother average rotational speed data, reducing the influence of rotational speed fluctuations on the control accuracy. Further, by comparing the average rotational speed data of the left wheel motor A obtained above with the average rotational speed data of the right wheel motor B It can better reflect the overall driving state of the vehicle over a period of time, rather than just the state at a certain moment. Compared with directly judging by the current driving speed of the vehicle in the prior art, it can effectively avoid the interference of factors such as instantaneous noise, sensor errors, or road surface unevenness, resulting in misjudgment of the vehicle's steering trend. Thus, it can avoid the situation where due to the large instantaneous change in the current rotational speed, the control system frequently adjusts the motor speed, generating unnecessary adjustment actions, causing oscillation or instability in the vehicle's steering control.

[0057] On the other hand, the Ackermann steering geometry model establishes that when the vehicle is steering, the movement trajectories of the four wheels should intersect at the instantaneous steering center on the extension line of the rear axle. By establishing the relationship between the effective rolling radius of the wheels and the wheel speed difference through this model, it can accurately calculate the rotational speed that each wheel should have according to the actual driving state and steering requirements of the vehicle, avoiding the situation where during the vehicle's steering process, the rotational speed of the wheels cannot accurately match the steering angle, thereby generating a lateral sliding force and causing the vehicle to deviate from the expected driving trajectory, ensuring that the vehicle can drive more smoothly and safely along the curve during turning and preventing the occurrence of lateral sliding. By establishing the mapping relationship between the output voltage of the three-phase inverter and the speed difference, and using the space vector modulation (SVPWM) technology to generate three-phase drive signals, it can accurately adjust the rotational speeds of the left wheel motor A and the right wheel motor B. This modulation technology can not only quickly respond to the rotational speed adjustment requirements but also ensure the smooth change of the motor speed, thereby avoiding vehicle jitter or unstable steering caused by sudden changes in speed.

[0058] In one of the embodiments, the relationship between the effective rolling radius r of the wheels and the wheel speed difference Δn in step S4, as well as the relationship between the wheelbase L of the vehicle, the center distance W between the left and right wheels, and the expected steering radius R, can be expressed by Equation (5) as shown.

[0059] From the above Equation (5), it can be obtained that the wheel speed difference Δn is directly proportional to the effective rolling radius r of the wheels, that is, the larger the effective rolling radius r of the wheels, the larger the required speed difference; while the wheelbase L of the vehicle and the center distance W between the left and right wheels are inversely proportional to the expected steering radius R, that is, the larger the wheelbase or the smaller the wheel spacing, the smaller the expected steering radius.

[0060] Based on the Ackermann steering geometry model and the vehicle kinematics relationship, by eliminating the front wheel steering angle parameter through simultaneous equations, the simplified relationship between the steering radius R and the left and right wheel speed difference Δn is finally obtained. The specific steps are as follows:

[0061] According to the Ackermann steering principle, the rotational speeds of the inner and outer wheels during vehicle steering need to satisfy the following proportional relationship Equation (6):

[0062]

[0063] Then, define the left and right wheel speed difference Δn as: Δn = n A - n B ; The average rotational speed of the left wheel motor A and the right wheel motor B is defined as:

[0064] Since n A > n B , and Δn = n A - n B ; then express n A as: n B is expressed as:

[0065] Substitute the expressions of n A and n B into the relational expression (6), and the following relational expression (7) can be obtained:

[0066]

[0067] Perform cross - multiplication on the relational expression (7):

[0068]

[0069] After expansion:

[0070]

[0071] Subtract the right - hand side formula from the left - hand side formula:

[0072]

[0073] After simplification, the formula (8) can be obtained:

[0074]

[0075] Furthermore, organize the formula (8) into:

[0076]

[0077] At the same time, since both Δn and are positive numbers, and the positive and negative values of the turning radius R represent the wheel turning direction, that is, when R > 0, the wheel turns left, and when R < 0, the wheel turns right.

[0078] Therefore, the absolute - value expression (4) of the turning radius R can be obtained as:

[0079]

[0080] And the absolute value of the expected turning radius R in step S4-3 is expected to be inversely proportional to the left and right wheel speed difference Δn to satisfy the geometric constraint conditions of Ackermann steering.

[0081] In one of the embodiments, the calculation of the expected turning radius of the vehicle further includes:

[0082] Introduce the road surface adhesion coefficient μ and the centroid side slip angle β, and through Equation (3) Correct the expected turning radius R to obtain the corrected expected turning radius R W ;

[0083] Where K μ is the slip compensation coefficient, μ max is the maximum adhesion coefficient of the current road surface, and the μ max can be obtained through the on-vehicle IMU;

[0084] In this embodiment, not only the adhesion conditions of the road surface are considered, but also the side slip characteristics during the dynamic driving of the vehicle are incorporated, making the calculation of the expected turning radius closer to the actual driving situation. Specifically, the slip compensation coefficient K in Equation (3) μ and the maximum adhesion coefficient μ of the current road surface max act together to adjust the initially estimated expected turning radius. This adjustment is based on the actual friction condition between the road surface and the tire, ensuring that the steering behavior of the vehicle can still be accurately predicted under wet, muddy or other low-adhesion road surface conditions. At the same time, the introduction of the centroid side slip angle β further considers the influence of the lateral force generated by the centroid offset during vehicle steering. Avoiding the centroid from shifting towards the inside of the turn during the steering process, which may lead to the occurrence of side slip and affect the actual steering trajectory of the vehicle.

[0085] In one of the embodiments, step S4-4 specifically includes the following steps:

[0086] S44-1. According to the obtained target speed difference Δω and the preset vehicle reference speed, calculate the target speed of the left wheel and the target speed of the right wheel through Equation (9) where W is the center distance between the left and right wheels; r is the effective rolling radius of the wheel.

[0087] S44-2. According to the obtained target speed of the left wheel and the target speed of the right wheel, calculate the first target output voltage and the second target output voltage of the three-phase inverter; specifically, there is a linear relationship between the target speed of the left wheel and the target speed of the right wheel and the first target output voltage and the second target output voltage of the three-phase inverter, that is, the first target output voltage is equal to the target speed of the left wheel * motor constant, and the second target output voltage is equal to the target speed of the right wheel * motor constant;

[0088] S44 - 3. Through - type (10) Convert the above - obtained first target output voltage and second target output voltage into a three - phase reference voltage vector U ref ; where U A is the first target output voltage, U B is the second target output voltage, U C is the third - phase voltage, and are unit vectors, representing the rotation angles of each phase voltage in the complex plane;

[0089] S44 - 4. According to the above - obtained three - phase reference voltage vector U ref 's angle, determine the sector it is in, and select the two basic voltage vectors closest to the three - phase reference voltage vector U ref ;

[0090] S44 - 5. Through formula (11) and formula (12) Calculate the duty cycles of the two basic voltage vectors closest to the above - obtained three - phase reference voltage vector U ref ; where T S is the PWM period; U dc is the DC - bus voltage; θ sector is the relative angle of the reference voltage vector in the current sector;

[0091] S44 - 6. Calculate the zero - vector duty cycle according to the duty cycles of the two basic voltage vectors obtained above, and generate three - phase PWM drive signals according to the duty cycles of the two basic voltage vectors closest to the three - phase reference voltage vector U ref and the zero - vector duty cycle, to control the switching states of the three - phase inverter. The zero - vector duty cycle is calculated by subtracting the duty cycles of the two basic voltage vectors closest to the three - phase reference voltage vector U ref from the PWM period.

[0092] In this embodiment, by calculating the target speed difference and the left and right wheel target speeds derived therefrom, it can be ensured that when the vehicle is turning or accelerating in a straight line, the speed difference between the left and right wheels can be effectively managed, thereby reducing tire wear and improving driving safety. Then, by converting the wheel target speeds into the output voltage of the three - phase inverter and further into a three - phase reference voltage vector, a smooth transition from speed control to voltage control is achieved.

[0093] Meanwhile, by determining the sector where the three-phase reference voltage vector is located, selecting the two closest basic voltage vectors, and calculating the duty cycles of these two basic voltage vectors, a more accurate PWM signal is generated to drive the three-phase inverter, enabling the inverter to operate with higher efficiency as it reduces harmonic distortion and switching losses.

[0094] Finally, by calculating the zero vector duty cycle and combining it with the duty cycles of the two basic voltage vectors to generate a three-phase PWM drive signal, not only is it ensured that the voltage and frequency output by the inverter meet the expectations, but also the effective control of the inverter switching state is achieved, further improving the overall performance and reliability of the system.

[0095] In addition, an embodiment of the present application also provides a terminal device, and the internal structure of the terminal device can be as Figure 2 shown. The terminal device includes a processor, a memory, a communication interface, and a database connected through a system bus. Among them, the processor is used to provide computing and control capabilities. The memory of the terminal device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the terminal device is used to store data called by the computer program. The communication interface of the terminal device is used for data communication with an external terminal. The input device of the terminal device is used to receive signals input by an external device. When the computer program is executed by the processor, it implements a vehicle differential steering control method based on motor modulation as described in the above embodiments.

[0096] Those skilled in the art can understand that Figure 2 the structure shown in

[0097] is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the terminal device to which the solution of the present application is applied.

[0098] In summary, the vehicle differential steering control method, device, terminal device, and readable storage medium provided in the embodiments of the present application based on motor modulation can quickly respond to current fluctuations to maintain a stable output voltage, improve the safety and reliability of downstream devices; adapt to different working conditions and power supply requirements, reduce manual intervention and maintenance costs; improve the overall efficiency and reliability of the power management system, enhance device performance and user experience; and have a wide range of applications, being applicable to various circuits and application scenarios.

[0099] Those of ordinary skill in the art can understand that all or part of the processes in implementing the above-described vehicle differential steering control method based on motor modulation in the embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-described embodiments of the vehicle differential steering control method based on motor modulation. Among them, any reference to a memory, storage, database, or other medium provided in the present application and used in the embodiments can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0100] It should be noted that in this article, the terms "include", "comprise", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, device, article, or vehicle differential steering control method based on motor modulation including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such a process, device, article, or vehicle differential steering control method. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, device, article, or vehicle differential steering control method including that element.

[0101] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall similarly be included in the patent protection scope of the present application.

Claims

1. A vehicle differential steering control method based on motor modulation, characterized in that, It includes the following steps: S1. Periodically obtain the real-time rotational speed signals n i (t) of the left and right wheel motors, and perform averaging processing on the real-time rotational speed signals of the left and right wheel motors through a moving average filtering algorithm to obtain the average rotational speed data of the left wheel motor A and the average rotational speed data of the right wheel motor B S2. Compare the average rotational speed data of the left wheel motor A obtained in step S1 with the average rotational speed data of the right wheel motor B to determine whether the vehicle has a tendency to turn left or right; S3. When it is determined in step S2 that the vehicle has a tendency to turn left or right, proceed to the next step; when it is determined in step S2 that the vehicle is driving straight continuously, return to step S1; S4. Calculate the expected turning radius R of the vehicle and the current linear speed V according to the differential control algorithm, determine the required rotational speed difference Δω between the left and right wheels, and adjust the rotational speeds of the left wheel motor A and / or the right wheel motor B.

2. The vehicle differential steering control method based on motor modulation according to claim 1, wherein The specific steps of step S4 include the following steps: S4-1. Based on the Ackermann steering geometry model, establish the relationship between the effective rolling radius r of the wheels and the rotational speed difference Δn, and the relationship between the wheelbase L of the vehicle, the center distance W between the left and right wheels, and the expected turning radius R, and calculate the absolute value of the expected turning radius R; S4-2, Pass-through type Calculate the linear velocity V of the current vehicle; S4-3. Determine the target rotational speed difference Δω according to the absolute value of the expected turning radius R obtained in step S4-1 and the current linear speed V of the vehicle; S4-4. Establish the mapping relationship between the output voltage of the three-phase inverter and the target rotational speed difference Δω, and generate a three-phase drive signal through space vector modulation; S4-5. Adjust the actual rotational speeds of the left wheel motor A and the right wheel motor B according to the three-phase drive signal generated in step S4-4.

3. A vehicle differential steering control method based on motor modulation according to claim 1, characterized in that, The relationship between the effective rolling radius r of the wheels and the rotational speed difference Δn in step S4, and the relationship between the wheelbase L of the vehicle, the center distance W between the left and right wheels, and the expected turning radius R are specifically as follows: The larger the effective rolling radius r of the wheels, the larger the required rotational speed difference; the wheelbase L of the vehicle and the center distance W between the left and right wheels are inversely proportional to the expected turning radius R, that is, the larger the wheelbase or the smaller the wheel spacing, the smaller the expected turning radius.

4. A vehicle differential steering control method based on motor modulation according to claim 1, characterized in that, The calculation of the expected turning radius of the vehicle further includes: Introduce the road surface adhesion coefficient μ and the centroid side slip angle β, and through Equation (3) Correct the expected turning radius R to obtain the corrected expected turning radius R W ; Among them, K μ is the slip compensation coefficient, and μ max is the maximum adhesion coefficient of the current road surface, and the μ max can be obtained through the in-vehicle IMU.

5. A vehicle differential steering control method based on motor modulation according to claim 1, characterized in that, The specific steps of step S4-4 include the following steps: S44-1. Calculate the target rotational speed of the left wheel and the target rotational speed of the right wheel according to the obtained target rotational speed difference Δω and the preset reference rotational speed of the vehicle; S44-2. Calculate the first target output voltage and the second target output voltage of the three-phase inverter according to the obtained target rotational speed of the left wheel and the target rotational speed of the right wheel; S44-3. Convert the obtained first target output voltage and second target output voltage into a three-phase reference voltage vector U ref ; S44-4. Determine the angle of the three-phase reference voltage vector U ref obtained above, judge the sector where it is located, and select the two basic voltage vectors that are closest to the three-phase reference voltage vector U ref ; S44-5. By calculating the duty ratios of the two basic voltage vectors that are closest to the above-obtained three-phase reference voltage vector U ref nearest thereto; S44-6. Calculate the duty ratio of the zero vector based on the duty ratios of the two basic voltage vectors obtained above, and generate three-phase PWM drive signals according to the duty ratios of the two basic voltage vectors closest to the three-phase reference voltage vector U ref and the duty ratio of the zero vector to control the switching states of the three-phase inverter.

6. The vehicle differential steering control method based on motor modulation according to claim 1, characterized in that The duty ratio of the zero vector is calculated by subtracting the duty ratios of the two basic voltage vectors closest to the three-phase reference voltage vector U ref from the PWM period.

7. A vehicle differential steering control method based on motor modulation according to claim 1, characterized in that The sliding average filtering algorithm presets the length of the sliding window to be N, and the sliding window N is a positive integer, and within each sampling period, the real-time rotational speed information of the left wheel motor A Number n i (t) together with the rotational speed data in the previous N - 1 sampling periods constitutes a data sequence, and then according to Equation (1) calculate the arithmetic mean of this data sequence as the average rotational speed data of the left wheel motor A in the current sampling period Among them, the said n A (t - j) represents the real-time rotational speed of the left wheel motor A before the j-th sampling period (at time t - j).

8. A vehicle differential steering control method based on motor modulation according to claim 1, characterized in that, The specific content of step S2 is as follows: When the average rotational speed data of the left wheel motor A is greater than the average rotational speed data of the right wheel motor B , the vehicle has a tendency to turn left; when the average rotational speed data of the left wheel motor A is less than the average rotational speed data of the right wheel motor B , the vehicle has a tendency to turn right; when the average rotational speed data of the left wheel motor A is equal to the average rotational speed data of the right wheel motor B , the vehicle keeps moving straight.

9. A terminal device, characterized in that The terminal device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the vehicle differential steering control method based on motor modulation according to any one of claims 1 to 7.

10. A readable storage medium, characterized in that, A computer program is stored on the readable storage medium. When the computer program is executed by the processor, it implements the steps of the vehicle differential steering control method based on motor modulation according to any one of claims 1 to 7.

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