Vehicle turning control device, vehicle and vehicle turning control method

Abstract

The invention provides a vehicle turning control device, a vehicle and a vehicle turning control method, and relates to the technical field of auxiliary driving. The vehicle turning control device can determine the target rotating speed ratio of wheels on the inner side and the outer side of the vehicle according to the steering angle of the vehicle and output a corresponding PWM control signal so that a differential can control the rotating speed ratio of the wheels on the inner side and the outer side according to the PWM control signal, and the larger the rotating speed ratio of the wheels on the inner side and the outer side is, the smaller the turning radius of the vehicle is. When the steering angle of the vehicle changes, the rotating speed ratio of the inner side wheel and the outer side wheel of the vehicle changes accordingly, so that the purpose that the turning radius is automatically adjusted by dynamically adjusting the rotating speed ratio of the inner side wheel and the outer side wheel, the vehicle with the original insufficient turning radius can smoothly turn on a narrow road is achieved, and a driver can easily control the vehicle to turn.

Description

Technical Field

[0001] The present application relates to the field of assisted driving technology, and in particular to a vehicle turning control device, a vehicle, and a vehicle turning control method. Background Art

[0002] As more and more vehicles are on the road, the road becomes more and more congested. In actual driving, it is often necessary to turn or make a U-turn on narrow and winding roads.

[0003] When a vehicle turns, if the turning radius of the vehicle is large, it will be difficult for the vehicle to turn smoothly and pass through narrow roads. For example, the vehicle may need to adjust by repeatedly moving forward and backward to complete the turning process, or even be unable to complete the turn on some narrow roads. Summary of the invention

[0004] In order to solve the above-mentioned problems in the prior art, the present application example provides a vehicle turning control device, a vehicle and a vehicle turning control method, which can allow the vehicle to turn smoothly on a narrow road by automatically adjusting the turning radius.

[0005] In a first aspect, an embodiment of the present application provides a vehicle turning control device installed in a vehicle; the vehicle turning control device includes a processor and a differential;

[0006] The processor is configured to, during the driving of the vehicle, obtain a steering angle of the vehicle; determine a target speed ratio between an inner wheel and an outer wheel of the vehicle according to the steering angle of the vehicle; and output a pulse width modulation (PWM) control signal according to the target speed ratio;

[0007] The differential is configured to control the outer wheels or the inner wheels of the vehicle to rotate according to the PWM control signal output by the processor so that the speed ratio between the inner wheels and the outer wheels reaches the target speed ratio.

[0008] In a possible implementation manner, the processor is specifically configured to: use the product of a setting coefficient and a steering angle of the vehicle as the target speed ratio; wherein the setting coefficient is determined according to the wheelbase of the vehicle.

[0009] In a possible implementation, the processor is specifically configured to:

[0010] During the driving process of the vehicle, the speed of the vehicle is obtained; if the speed of the vehicle is less than or equal to a set speed threshold, the steering angle of the vehicle is obtained; if the steering angle of the vehicle is greater than or equal to a set steering angle threshold, the target speed ratio is determined according to the steering angle of the vehicle.

[0011] In a possible implementation manner, the processor is specifically configured to: determine a duty cycle of the PWM control signal according to the target speed ratio; and output the PWM control signal according to the determined duty cycle.

[0012] determining a target rotational speed for an inner wheel of the vehicle;

[0013] Inputting the speed difference between the target speed of the inner wheel of the vehicle and the measured speed of the inner wheel of the vehicle into a speed proportional integral PI controller to obtain a specified torque output by the speed PI controller;

[0014] The torque difference between the designated torque and the actually measured torque of the vehicle is input into a torque PI controller to obtain a duty cycle of the PWM control signal output by the torque PI controller.

[0015] The product of the actually measured rotation speed of the outer wheels of the vehicle and the target rotation speed ratio is used as the target rotation speed of the inner wheels of the vehicle.

[0016] In a possible implementation manner, the differential is specifically configured as follows:

[0017] When the PWM control signal is at a high level, the inner wheel is controlled to rotate; when the PWM control signal is at a low level, the inner wheel is controlled to stop rotating.

[0018] In a possible implementation manner, the differential is specifically configured as follows:

[0019] If the speed ratio of the inner wheel to the outer wheel is greater than the target speed ratio, the outer wheel of the vehicle is controlled to rotate according to the PWM control signal; if the speed ratio of the inner wheel to the outer wheel is less than the target speed ratio, the inner wheel of the vehicle is controlled to rotate according to the PWM control signal.

[0020] In a second aspect, an embodiment of the present application provides a vehicle, comprising the vehicle turning control device and wheels according to the first aspect.

[0021] In a third aspect, an embodiment of the present application provides a vehicle turning control method, the method comprising: obtaining a steering angle of the vehicle during driving of the vehicle; determining a target speed ratio between an inner wheel and an outer wheel of the vehicle according to the steering angle of the vehicle; outputting a pulse width modulation (PWM) control signal according to the target speed ratio; the PWM control signal is used to control the rotation of the outer wheel or the inner wheel of the vehicle so that the speed ratio between the inner wheel and the outer wheel reaches the target speed ratio.

[0022] In a fourth aspect, an embodiment of the present application provides a vehicle turning control device, the vehicle turning control device comprising:

[0023] A speed ratio determination unit, used to obtain a steering angle of the vehicle during the driving of the vehicle; and determine a target speed ratio between an inner wheel and an outer wheel of the vehicle according to the steering angle of the vehicle;

[0024] A control unit is used to output a pulse width modulation (PWM) control signal according to the target speed ratio; the PWM control signal is used to control the rotation of the outer wheel or the inner wheel of the vehicle so that the speed ratio of the inner wheel and the outer wheel reaches the target speed ratio.

[0025] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the method described in the third aspect is implemented.

[0026] The present application provides a vehicle turning control device, which can determine the target speed ratio of the inner and outer wheels of the vehicle according to the steering angle of the vehicle, and output a corresponding PWM control signal, so that the differential controls the speed ratio of the inner and outer wheels according to the PWM control signal. The larger the speed ratio of the inner and outer wheels, the smaller the turning radius of the vehicle. When the steering angle of the vehicle changes, the speed ratio of the inner and outer wheels of the vehicle will change accordingly, thereby achieving the purpose of automatically adjusting the turning radius by dynamically adjusting the speed ratio of the inner and outer wheels, so that vehicles with insufficient turning radius can turn smoothly on narrow roads, and it also helps the driver to control the vehicle to turn more easily. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 A schematic diagram of the internal structure of a vehicle provided in an embodiment of the present application;

[0029] Figure 2 A schematic diagram of the structure of a vehicle turning control device provided in an embodiment of the present application;

[0030] Figure 3 A schematic diagram of a differential structure of a vehicle provided in an embodiment of the present application;

[0031] Figure 4A flow chart of a vehicle turning control method provided in an embodiment of the present application;

[0032] Figure 5 A flow chart of determining a target speed ratio between an inner wheel and an outer wheel of a vehicle according to a steering angle of the vehicle provided in an embodiment of the present application;

[0033] Figure 6 A flow chart for determining a target speed ratio between an inner wheel and an outer wheel of a vehicle according to a vehicle speed and a steering angle of the vehicle provided in an embodiment of the present application;

[0034] Figure 7 A flow chart for determining a final target speed ratio according to a relationship between a target speed ratio and a maximum speed ratio provided in an embodiment of the present application;

[0035] Figure 8 A flow chart of outputting a PWM control signal provided in an embodiment of the present application;

[0036] Fig. 9 A schematic diagram of a PI controller control logic provided in an embodiment of the present application;

[0037] Fig.10 A schematic diagram of a PWM control signal provided in an embodiment of the present application;

[0038] Fig.11 Another schematic diagram of a PWM control signal provided in an embodiment of the present application;

[0039] Fig.12 Another schematic diagram of a PWM control signal provided in an embodiment of the present application;

[0040] Fig.13 A flowchart for determining whether to control an inner wheel or an outer wheel according to a PWM control signal provided in an embodiment of the present application;

[0041] Fig.14 Another schematic diagram of a PWM control signal provided in an embodiment of the present application;

[0042] Fig.15 A flowchart of a vehicle turning control method executed by a vehicle processor provided in an embodiment of the present application;

[0043] Fig.16 A structural block diagram of a vehicle turning control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] It should be noted that the application scenarios described in the following embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. A person of ordinary skill in the art can know that with the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0046] As more and more vehicles are on the road, the road becomes more and more crowded. In actual driving, it is often necessary to turn or make a U-turn on narrow and winding roads. When turning, if the turning radius of the vehicle is large, it will cause the vehicle to turn inflexibly and it will be difficult for the vehicle to pass through the narrow road smoothly. For example, the vehicle may need to adjust by repeatedly moving forward and backward to complete the turning process, or even be unable to complete the turn on some narrow roads.

[0047] Based on this, the present application provides a vehicle turning control device, which can determine the target speed ratio of the inner and outer wheels of the vehicle according to the steering angle of the vehicle, and output the corresponding PWM control signal, so that the differential controls the speed ratio of the inner and outer wheels according to the PWM control signal. The larger the speed ratio of the inner and outer wheels, the smaller the turning radius of the vehicle. When the steering angle of the vehicle changes, the speed ratio of the inner and outer wheels of the vehicle will change accordingly, thereby achieving the purpose of automatically adjusting the turning radius by dynamically adjusting the speed ratio of the inner and outer wheels, so that vehicles with insufficient turning radius can turn smoothly on narrow roads, and it also helps the driver to control the vehicle to turn more easily.

[0048] The vehicle turning control device provided in the embodiment of the present application is installed in a vehicle. Figure 1 FIG. 1 shows a schematic diagram of the internal structure of a vehicle. The vehicle may be a sedan, an off-road vehicle, a small van or a truck. Figure 1 As shown, the vehicle may include a data acquisition module 200 and a vehicle turning control device 100. The data acquisition module 200 may be connected to the vehicle turning control device 100 via a CAN bus. The data acquisition module 200 includes a vehicle speed acquisition module 210, a steering angle acquisition module 220, a wheel speed acquisition module 230, and a torque acquisition module 240.

[0049] The vehicle speed collection module 210 can use a speed detection sensor to collect the speed of the vehicle at every moment during the driving process. In some embodiments, the speed detection sensor can be installed in the axle housing of the drive axle or in the gearbox housing, and can accurately measure the driving speed of the vehicle. For example, when the vehicle turns, the speed usually does not exceed 30 kilometers per hour.

[0050] The steering angle acquisition module 220 can use a steering angle sensor to collect the steering angle of the vehicle during turning. In some embodiments, the steering angle sensor can be installed in the steering wheel to collect the steering angle of the steering wheel. Exemplarily, the steering angle range of the steering wheel can be between 0° and 540°. In other embodiments, the steering angle sensor can be installed in the wheel to collect the steering angle of the wheel. For example, the steering angle sensor can be installed on the left front wheel or the right front wheel of the vehicle. Exemplarily, the steering angle range of the wheel can be between 0° and 60°.

[0051] The wheel speed acquisition module 230 can use a wheel speed sensor to collect the wheel speed of the vehicle during driving. For example, the wheel speed sensor can be installed on the left front wheel or the right front wheel of the vehicle. The wheel speed sensor installed on the left front wheel of the vehicle can collect the speed of the left front wheel during driving, and the wheel speed sensor installed on the right front wheel of the vehicle can collect the speed of the right front wheel during driving.

[0052] The torque acquisition module 240 can use a torque sensor to measure the torque. For example, the torque sensor is usually installed on the engine or drive shaft of the vehicle to measure and monitor the torque output or torque input of the vehicle. In the engine part, the torque sensor is usually installed on the output shaft of the engine to measure the torque output of the engine. In the transmission system, the torque sensor can be installed on the drive shaft, transmission device or clutch. The torque sensor can measure the torque of the drive shaft to monitor the efficiency and load condition of power transmission in real time, which is very important to ensure the normal operation of the transmission system and prevent overload.

[0053] The real-time data collected by the above-mentioned various collection modules during the driving process of the vehicle can be transmitted to the vehicle turning control device 100 via the CAN bus.

[0054] Figure 1The vehicle shown may also include a left wheel 310 and a right wheel 320. The vehicle turning control device 100 may control the rotation of the left wheel 310 and the right wheel 320 according to four real-time data, namely, the speed of the vehicle acquired by the speed acquisition module 210, the steering angle of the vehicle acquired by the steering angle acquisition module 220, the wheel speed acquired by the wheel speed acquisition module 230, and the vehicle torque acquired by the torque acquisition module 240 during the driving process of the vehicle. The left wheel 310 may be the left front wheel of the vehicle, and the right wheel 320 may be the right front wheel of the vehicle. The left front wheel and the right front wheel serve as the active wheels of the vehicle. During the turning process of the vehicle, the left front wheel and the right front wheel are mainly responsible for the steering work. The vehicle turning control device 100 may automatically adjust the turning radius of the vehicle by controlling the rotation of the left wheel 310 and the right wheel 320.

[0055] Figure 2 FIG. 1 shows a schematic diagram of the structure of the processor 110 and the differential 120 in the vehicle turning control device 100. Figure 2 As shown, the vehicle turning control device includes a processor 110 and a differential 120. The processor 110 may include a calculation unit 111 and a PWM generator 112. The above-mentioned acquisition modules transmit the collected real-time data to the calculation unit 111 in the processor 110 through the CAN bus. The calculation unit 111 can calculate the target speed ratio according to the steering angle of the vehicle collected by the steering angle acquisition module 220, generate a corresponding duty cycle according to the target speed ratio, and transmit the determined duty cycle to the PWM generator 112. The PWM generator 112 outputs a PWM control signal according to the determined duty cycle, and transmits the PWM control signal to the differential 120. The differential 120 can control the outer wheel or the inner wheel to rotate or stop rotating according to the PWM control signal.

[0056] Figure 3 A differential structure is shown, such as Figure 3 As shown, the differential may include a planetary gear 340, a left gear 331, a right gear 332, a pinion bearing 350, a ring gear 360, a left gear actuator 311, and a right gear actuator 321. The left gear 331 is a gear corresponding to the left wheel 310, and the right gear 332 is a gear corresponding to the right wheel 320. The left gear 331 is connected to the left wheel 310 through the left gear actuator 311, and the right gear 332 is connected to the right wheel 320 through the right gear actuator 321.

[0057] During the driving process of the vehicle, the power of the engine is transmitted to the ring gear 360 through the pinion bearing 350. A planetary gear 340 is connected to the ring gear 360, and the planetary gear 340 can rotate along the ring gear 360 in both forward and reverse directions. When the planetary gear 340 is meshed with the two side gears, the power of the engine is transmitted by the pinion bearing 350 through contact with the ring gear 360, and the ring gear 360 is then contacted and transmitted with the left gear 331 and the right gear 332, driving the left gear 331 and the right gear 332 to rotate. The left gear 331 then transmits the power to the left wheel 310 through the left gear actuator 311, driving the left wheel 310 to rotate; the right gear 332 then transmits the power to the right wheel 320 through the left gear actuator 311, driving the right wheel 320 to rotate.

[0058] When turning, the planetary gear 340 will also rotate. During the rotation process, it will again transmit a positive force and a reverse force to the two side gears respectively, which will increase the speed of one of the two side wheels and reduce the speed of the other side wheel, thereby meeting the requirement that the speeds of the wheels on both sides are different when the vehicle turns. For example, when the vehicle turns left, the planetary gear 340 can transmit a positive force to the right gear 332 to increase the speed of the right gear 332, and the right gear 332 can drive the right wheel 320 to increase the speed through the right gear actuator 321; at the same time, it can transmit a reverse force to the left gear 331 to slow down the speed of the left gear 331, and the left gear 331 can drive the left wheel 310 to slow down the speed through the left gear actuator 311, so that the speeds of the wheels on both sides of the vehicle are different when turning, making it easier to turn.

[0059] Furthermore, when the vehicle is in a normal straight-line driving state, the planetary gear 340 drives the left gear 331 and the right gear 332 to rotate synchronously. The left gear 331 drives the left wheel to rotate via the left gear actuator 311, and the right gear 332 drives the right wheel to rotate via the right gear actuator 321. The speed ratio of the left and right wheels is 1.

[0060] In the embodiment of the present application, when the vehicle turns, in addition to relying on the rotation of the planetary gear 340 to change the speed ratio of the inner and outer wheels, the steering angle acquisition module can also collect the steering angle of the vehicle. The processor outputs a PWM control signal according to the steering angle of the vehicle, and the differential can control the outer wheel or the inner wheel to rotate or stop rotating according to the PWM control signal.

[0061] Exemplarily, the steering angle collected by the steering angle collection module 220 carries a positive and negative mark, and the inner and outer wheels can be determined according to the positive and negative of the steering angle of the vehicle. For example, in some embodiments, when the vehicle turns left, the steering angle of the vehicle is negative, at this time, the left wheel is the inner wheel, and the right wheel is the outer wheel; when the vehicle turns right, the steering angle of the vehicle is positive, the right wheel is the inner wheel, and the left wheel is the outer wheel.

[0062] Since the speed ratio between the inner wheel and the outer wheel is usually greater than the target speed ratio during the vehicle turning process, the differential can control the rotation of the inner wheel of the vehicle according to the PWM control signal. Taking the vehicle turning left as an example, after the differential receives the PWM control signal output by the processor, it can control the side gear corresponding to the inner wheel to rotate or stop according to the PWM control signal, that is, the left gear 331 corresponding to the left wheel is controlled to rotate or stop according to the PWM control signal, and the left gear 331 then drives the left wheel to rotate or stop through the left gear actuator 311, while the right wheel keeps rotating, so that the speed of the left wheel is lower than that of the right wheel, and the target speed ratio between the left wheel and the right wheel is achieved to reduce the turning radius.

[0063] Figure 4 A flow chart of a vehicle turning control method provided by an embodiment of the present application is shown. Figure 4 As shown, the method may include the following steps:

[0064] Step S401, obtaining the steering angle of the vehicle while the vehicle is traveling.

[0065] Step S402, determining a target speed ratio between the inner wheels and the outer wheels of the vehicle according to the steering angle of the vehicle.

[0066] In some embodiments, the vehicle processor can receive the steering angle collected by the steering angle collection module in real time. When the steering angle is small, it can be considered that the vehicle is in a straight-moving state, and at this time, there is no need to adjust the speed ratio of the inner wheel to the outer wheel. When the steering angle is large, it can be considered that the vehicle is in a turning state. At this time, the speed ratio of the inner wheel to the outer wheel can be adjusted according to the method of the embodiment of the present application, that is, the step of determining the target speed ratio of the inner wheel to the outer wheel of the vehicle according to the steering angle of the vehicle can be performed.

[0067] For example, the process can be performed by Figure 5 The process can include the following steps:

[0068] Step S501, receiving the steering angle of the vehicle collected by the steering angle collection module.

[0069] Step S502, determining whether the steering angle of the vehicle is greater than a set steering angle threshold; if so, executing step S503; if not, returning to executing step S501.

[0070] Exemplarily, whether the vehicle is turning can be determined based on the above-mentioned steering angle threshold. The steering angle of the wheel can be taken as 30° as the threshold. When the steering angle of the vehicle is less than or equal to 30°, it can be determined that the vehicle is not turning; when the steering angle of the vehicle is greater than 30°, it can be determined that the vehicle is in the process of turning.

[0071] Step S503, determining a target speed ratio between the inner wheels and the outer wheels of the vehicle according to the steering angle of the vehicle.

[0072] In an optional embodiment, when the steering angle of the vehicle is greater than the set steering angle threshold, the product of the set coefficient and the steering angle of the vehicle can be used as the target speed ratio between the inner wheel and the outer wheel. For example, the processor can determine the target speed ratio according to the following formula; ω=k*θ. Among them, θ is the steering angle of the vehicle, ω is the target speed ratio between the inner wheel and the outer wheel, and k is the set coefficient. After many experiments, it can be concluded that the k value of different types of vehicles can be different. Exemplarily, k can be determined based on the wheelbase of the vehicle. For example, for a vehicle with a longer wheelbase, the distance between the front and rear wheels is larger, and the difference between the inner and outer wheels when turning is smaller, so the k value is smaller; for a vehicle with a shorter wheelbase, the distance between the front and rear wheels is smaller, and the difference between the inner and outer wheels when turning is larger, so the k value is larger.

[0073] In the above embodiment, the formula for determining the target speed ratio of the inner wheel to the outer wheel of the vehicle according to the steering angle of the vehicle is a linear relationship function. The specific relationship between the steering angle and the target speed ratio of the inner and outer wheels depends on the design of the vehicle and the working principle of the steering mechanism.

[0074] In another optional embodiment, the target speed ratio between the inner wheel and the outer wheel of the vehicle determined according to the steering angle of the vehicle may not be a linear function. For example, the function may be a curve function, a quadratic equation function, etc. For example, the formula for determining the target speed ratio between the inner wheel and the outer wheel of the vehicle according to the steering angle of the vehicle may be ω=k*θ 2 .

[0075] In other embodiments, the vehicle processor may also utilize the vehicle speed acquisition module to acquire the vehicle's driving speed in real time. When the vehicle speed is slow, the rotation speeds of the inner and outer wheels are adjusted according to the vehicle's steering angle, thereby affecting the ratio of the inner and outer wheel speeds. When the vehicle speed is fast, the rotation speeds of the inner and outer wheels are not controlled, and the ratio of the inner and outer wheel speeds is kept stable to prevent the vehicle from rolling over due to a large speed difference.

[0076] For example, the process can be performed by Figure 6 The process can include the following steps:

[0077] Step S601, receiving the vehicle speed collected by the vehicle speed collection module.

[0078] Step S602, determine whether the vehicle speed is less than a set speed threshold; if so, execute step S603; if not, return to execute step S601.

[0079] Exemplarily, whether the vehicle is turning can be determined based on the above-mentioned speed threshold. The speed of the vehicle when turning can be set at 30 kilometers per hour as the threshold. When the speed is less than or equal to 30 kilometers per hour, it can be determined that the vehicle is in a turning state; when the speed is greater than 30 kilometers per hour, it can be determined that the vehicle is not in the process of turning.

[0080] Step S603, determining whether the steering angle of the vehicle is greater than a set steering angle threshold; if so, executing step S604; if not, returning to executing step S601.

[0081] Step S604, determining a target speed ratio between the inner wheels and the outer wheels of the vehicle according to the steering angle of the vehicle.

[0082] Specifically, assuming that the vehicle speed does not exceed the specified threshold, the differential adjustment function is activated and the maximum inner and outer wheel speed ratio is given according to the current vehicle speed. When the steering wheel angle is greater than a certain threshold and the vehicle speed is higher than a certain threshold, the differential control also needs to be released to prevent the vehicle from rolling over due to excessive speed difference.

[0083] In some embodiments, a maximum speed ratio may be set. When the calculated target speed ratio is greater than the maximum speed ratio, the maximum speed ratio may be used as the target speed ratio to ensure vehicle stability, normal operation of the transmission system, and tire life. Figure 7 As shown, the process may include the following steps:

[0084] Step S701, determining an initial target speed ratio between the inner wheels and the outer wheels of the vehicle according to the steering angle of the vehicle;

[0085] Step S702, determining whether the determined initial target speed ratio is less than the maximum speed ratio; if not, executing step S703; if yes, executing step S704.

[0086] Step S703: taking the maximum speed ratio as the final target speed ratio.

[0087] Step S704: taking the initial target speed ratio as the final target speed ratio.

[0088] The maximum speed ratio is a preset value.

[0089] Specifically, when the speed difference between the inner and outer wheels is too large, the vehicle may not be able to turn smoothly when turning, and may even cause the vehicle to lose control. This is because the speed difference between the inner and outer wheels will cause the vehicle to generate asymmetric torque when turning, making it difficult for the vehicle to maintain a stable driving state. In addition, the excessive speed difference between the inner and outer wheels will also cause excessive load on the vehicle's transmission system and uneven wear of the tires, reducing the service life of the tires. Therefore, the maximum speed ratio is set. When the target speed ratio of the vehicle is greater than the maximum speed ratio, in order to ensure the stability of the vehicle, the normal operation of the transmission system and the life of the tires, the speed difference between the inner and outer wheels should be kept within a reasonable range, and excessive speed differences should be avoided, so the maximum speed ratio is used as the final target speed ratio. On the contrary, when the target speed ratio is less than the maximum speed ratio, it proves that the target speed ratio is more reasonable, and the target speed ratio can be directly used for the next step.

[0090] After the target speed ratio is determined in step S402 , the process proceeds to step S403 .

[0091] Step S403: determining the duty cycle of the PWM control signal according to the target speed ratio.

[0092] Step S404: output a PWM control signal according to the determined duty cycle.

[0093] Specifically, due to the delay of the mechanical structure, the required inner and outer wheel speed ratio of the corresponding vehicle steering angle cannot be reached instantly, or even if it is reached, due to the influence of external friction or other factors, the inner and outer wheels cannot maintain the optimal target speed ratio for a long time when controlled by the PWM control signal with a fixed duty cycle, resulting in easy slippage of the wheels during the vehicle turning process. Therefore, closed-loop control is required to collect the speed of the inner and outer wheels and correct the control amount in time.

[0094] For example, cascade proportional-integral (PI) control can be used, where P is proportional control, which makes the system more responsive and allows the system to quickly reach a given speed ratio. I is integral control, which makes the system more stable and maintains a smaller static error with the given speed ratio.

[0095] Figure 8 A flow chart of outputting a PWM control signal provided in an embodiment of the present application is shown; Fig. 9 FIG. 1 shows a control logic diagram of a PI controller provided in an embodiment of the present application. Figure 8 and Fig. 9 As shown, the process may include the following steps:

[0096] Step S801, collecting the actual measured rotation speed of the wheel and the actual measured torque of the vehicle in real time.

[0097] When the vehicle is turning, the speed of the left and right wheels is collected in real time through the wheel speed collection module, and the vehicle torque is collected in real time through the torque collection module. The measured wheel speed and the measured torque of the vehicle are transmitted to the PI controller through the CAN bus.

[0098] Step S802: The product of the actual speed of the outer wheels of the vehicle and the target speed ratio is used as the target speed of the inner wheels of the vehicle.

[0099] When using PWM control signals to control wheel rotation, since controlling the wheels on both sides will cause the planetary gear to idle and cause energy waste, the start and stop of the inner wheel can be controlled by only controlling the start and stop of the inner gear, thereby controlling the speed ratio of the inner and outer wheels.

[0100] Taking the vehicle turning left as an example, the left wheel is the inner wheel and the right wheel is the outer wheel. The product of the measured speed of the right wheel of the vehicle and the target speed ratio can be used as the target speed of the left wheel of the vehicle.

[0101] For example, when the vehicle is turning left, the speed of the right wheel is 100 revolutions per minute, and the target speed ratio is measured to be 0.6. According to the target speed of the left wheel of the vehicle being equal to the product of the measured speed of the right wheel of the vehicle and the target speed ratio, 100*0.6=60, it can be obtained that the target speed of the left wheel is 60 revolutions per minute.

[0102] Step S803, determining the speed difference between the target speed of the inner wheel of the vehicle and the actual speed of the inner wheel of the vehicle.

[0103] Step S804, inputting the speed difference into the speed PI controller to obtain a specified torque output by the speed PI controller.

[0104] like Fig. 9 As shown, the speed difference is input into the speed PI controller 901, and the required specified torque can be calculated according to the PI parameters inside the speed PI controller 901. The PI parameters include a proportional parameter and an integral time constant. Exemplarily, the speed PI controller 901 can determine the required specified torque by the following formula:

[0105] u(t1)=K p *e(t1)+K i *∫e(t1)dt1

[0106] Where, u(t1) is the specified torque, K pis the proportional gain, e(t1) is the internal speed difference, K i is the integral gain, and the inner speed difference e(t1) is the difference between the target speed e(t0) of the inner wheel and the measured speed r(t1) of the inner wheel, that is, e(t1) = e(t0) - n(t1). The functions of the PI controller are as follows:

[0107] Proportional term: The proportional term is adjusted directly according to the current error, making the output proportional to the error. p The larger the value, the stronger the proportional control effect. However, if K p Too large may cause overshoot or instability problems.

[0108] Integral term: The historical value of the integral term accumulates the error and makes adjustments to eliminate the static error of the system and improve the system's error-free performance. i The larger the value, the stronger the effect of integral control. However, if K i If it is too large, the system may respond too slowly or become unstable.

[0109] Exemplarily, the above PI parameters refer to the PI parameters in the cascade PI control algorithm, which is a control strategy commonly used in complex control systems. It consists of two cascaded PI controllers, one of which is called the outer loop controller and the other is called the inner loop controller. The goal of the outer loop controller is to adjust the main control variable, and the task of the inner loop controller is to adjust the auxiliary control variable according to the output of the outer loop controller. One of the advantages of the cascade PI control algorithm is that it can effectively solve multiple control requirements of the system. The outer loop controller can make overall adjustments to the main control variables of the system, while the inner loop controller can perform more detailed control of the auxiliary variables to improve the response speed and stability of the system.

[0110] Step S805, determining the torque difference between the specified torque and the actual torque of the vehicle.

[0111] Step S806: input the torque difference into the torque PI controller to obtain the duty cycle of the PWM control signal output by the torque PI controller.

[0112] Exemplarily, the torque PI controller 902 may determine the duty cycle of the PWM control signal by the following formula:

[0113] u(t2)=K p *e(t2)+K i *∫e(t2)dt2

[0114] Among them, u(t2) is the duty cycle of the PWM control signal, e(t2) is the torque difference between the specified torque and the measured torque of the vehicle, and the torque difference e(t2) is the difference between the given torque e(t1) and the measured torque r(t2), that is, e(t2)=e(t1)-r(t2).

[0115] The calculation unit can determine the duty cycle in real time through the above PI control process, and transmit the determined duty cycle to the PWM generator, and the PWM generator outputs a PWM control signal according to the determined duty cycle. It can be seen that the PWM generator does not always output a PWM control signal with the same duty cycle. At different times, the duty cycle of the PWM control signal output by the PWM generator is different.

[0116] The duty cycle of the PWM control signal indicates the ratio of the time occupied by the high level to the low level. For example, the larger the duty cycle, the longer the time occupied by the high level; the smaller the duty cycle, the shorter the time occupied by the high level. Figure 10 to Figure 12 Several PWM control signals with different duty cycles are shown. Fig.10 In the PWM control signal shown, the duty ratio of high and low levels is 1:1; Fig.11 In the PWM control signal shown, the duty ratio of the high and low levels is greater than 1:1, that is, the proportion of the high level is greater than the proportion of the low level. Fig.12 In the PWM control signal shown, the duty ratio of the high and low levels is less than 1:1, that is, the proportion of the high level is less than the proportion of the low level.

[0117] In some embodiments, after the PWM generator outputs a PWM control signal, the differential can control the inner wheel to rotate or stop according to the high and low levels in the PWM control signal. Specifically, when the PWM control signal outputs a high level, the differential controls the inner wheel to rotate through the side gear actuator; when the output is a low level, the differential controls the inner wheel to stop rotating through the side gear actuator. The PWM control period is set to be above 1Khz, that is, the duration of rotation + stop rotation = 1ms, so that there will be no obvious sense of frustration of wheel rotation and stop during execution.

[0118] In other embodiments, it can be determined whether to control the inner wheel according to the PWM control signal or the outer wheel according to the PWM control signal according to the real-time speed ratio of the inner wheel and the outer wheel. Fig.13 As shown, the process includes the following steps:

[0119] Step S1301, determining the current speed ratio between the inner wheel and the outer wheel.

[0120] For example, when the vehicle is turning, the measured speed of the inner wheel is 60 revolutions per minute, and the measured speed of the outer wheel is 100 revolutions per minute. According to the current speed ratio of the inner wheel to the outer wheel is equal to the ratio of the measured speed of the inner wheel to the measured speed of the outer wheel, 60 / 100=0.6, it can be obtained that the current speed ratio of the inner wheel to the outer wheel is 0.6.

[0121] Step S1302, determine whether the current speed ratio is greater than the target speed ratio; if not, execute step S1303; if so, execute step S1304.

[0122] Step S1303: output a negative PWM control signal.

[0123] The negative PWM control signal is used to control the outer wheels of the vehicle, that is, the differential can control the outer wheels of the vehicle to rotate or stop according to the negative PWM control signal.

[0124] For example, during a vehicle turning process, if the speed ratio between the inner wheel and the outer wheel is less than the target speed ratio, it means that the actual speed of the inner wheel is less than the required target speed. In this case, there is no need to reduce the speed of the inner wheel, but the speed of the outer wheel can be appropriately reduced. Therefore, the PWM control signal output by the processor can be a negative value, that is, the high level and the low level of the PWM control signal are both negative values, such as Fig.14 The differential can control the outer wheels of the vehicle to rotate or stop according to the negative PWM control signal.

[0125] Taking the vehicle turning left as an example, the speed ratio between the left wheel and the right wheel is less than the target speed ratio. After the differential receives the PWM control signal output by the processor, it can control the right wheel to rotate or stop according to the PWM control signal, that is, control the right gear corresponding to the right wheel to rotate or stop according to the PWM control signal, and the right gear then drives the right wheel to rotate or stop through the right gear actuator, while the left wheel keeps rotating, so that the target speed ratio between the left wheel and the right wheel is reached.

[0126] Step S1304, outputting a positive PWM control signal.

[0127] The positive PWM control signal is used to control the inner wheels of the vehicle, that is, the differential can control the inner wheels of the vehicle to rotate or stop according to the positive PWM control signal.

[0128] For example, during a vehicle turning process, if the speed ratio between the inner wheel and the outer wheel is greater than the target speed ratio, it means that the actual speed of the inner wheel is greater than the required target speed, and the speed of the inner wheel needs to be reduced. Therefore, the PWM control signal output by the processor can be a positive value, that is, the high level and the low level of the PWM control signal are both positive values, such as Figure 10 to Figure 12 The differential can control the inner wheels of the vehicle to rotate or stop according to the positive PWM control signal.

[0129] Taking the vehicle turning left as an example, the speed ratio between the left wheel and the right wheel is greater than the target speed ratio. After the differential receives the PWM control signal output by the processor, it can control the left wheel to rotate or stop according to the PWM control signal, that is, the left gear corresponding to the left wheel is controlled to rotate or stop according to the PWM control signal, and the left gear then drives the left wheel to rotate or stop through the left gear actuator, while the right wheel keeps rotating, so that the target speed ratio between the left wheel and the right wheel is reached.

[0130] In other embodiments, when the current speed ratio between the inner wheel and the outer wheel is less than the target speed ratio, the system may be set not to perform any operation, that is, the inner wheel or the outer wheel is no longer controlled.

[0131] Specifically, as mentioned above, in principle, only the inner wheel is controlled. When the actual speed ratio is smaller than the target speed ratio, the PWM control signal output by the processor is positive, that is, the inner wheel is controlled to output more power to the outer wheel. When the actual speed ratio is larger than the target speed ratio, the PWM control signal output by the processor is negative, indicating that the speed of the outer wheel has exceeded the predetermined value, or the inner wheel is lower than the given value. At this time, the system can be set not to perform any operation, that is, the inner wheel is no longer controlled. Or select the stable control mode, at this time the outer wheel control works, so that the power is distributed to the inner wheel, so that the outer wheel speed is reduced and the inner wheel speed is increased to reach the predetermined speed ratio.

[0132] In some embodiments, the vehicle can turn on the extreme mode. When the extreme mode is turned on, it can determine whether the steering wheel has reached the limit to the left or right at the current moment. If the steering wheel has reached the limit to the left or right, the inner wheel will be locked and all the power will be distributed to the outer wheel, so that the vehicle can make extreme turns in a small space.

[0133] In a specific embodiment, a process of a vehicle turning control method executed by a vehicle processor may be as follows: Fig.15 As shown, the following steps are included:

[0134] Step S1501, during the driving process of the vehicle, receiving the vehicle speed collected by the vehicle speed collection module and the vehicle steering angle collected by the steering angle collection module.

[0135] Step S1502, determine whether the vehicle speed is less than a set speed threshold; if so, execute step S1503; if not, return to execute step S1501.

[0136] Step S1503, determine whether the steering angle of the vehicle is greater than a set steering angle threshold; if so, execute step S1504; if not, return to execute step S1501.

[0137] Step S1504, determining an initial target speed ratio between the inner wheels and the outer wheels of the vehicle according to the steering angle of the vehicle.

[0138] Step S1505, determining whether the determined initial target speed ratio is less than the maximum speed ratio; if not, executing step S1506; if so, executing step S1507.

[0139] Step S1506, taking the maximum speed ratio as the final target speed ratio.

[0140] Step S1507: taking the initial target speed ratio as the final target speed ratio.

[0141] Step S1508, collecting the actual measured rotation speed of the wheel and the actual measured torque of the vehicle in real time.

[0142] Step S1509, determining the target speed of the inner wheel according to the measured speed of the outer wheel and the target speed ratio, and determining the speed difference between the target speed of the inner wheel and the measured speed of the inner wheel.

[0143] Step S1510, input the speed difference into the speed PI controller to obtain the specified torque output by the speed PI controller.

[0144] Step S1511, determining the torque difference between the specified torque and the measured torque of the vehicle, inputting the torque difference into the torque PI controller, and obtaining the duty cycle output by the torque PI controller.

[0145] Step S1512: output a PWM control signal according to the determined duty cycle.

[0146] After the processor outputs the PWM control signal, the differential can control the inner wheel to rotate or stop according to the high and low levels in the PWM control signal; or, the differential can control the outer wheel to rotate or stop according to the high and low levels in the PWM control signal.

[0147] Based on the same inventive concept, the present application also provides a vehicle turning control device, such as Fig.16As shown, the vehicle turning control device comprises:

[0148] The speed ratio determination unit 1601 is used to obtain the steering angle of the vehicle during the vehicle driving process; and determine the target speed ratio between the inner wheel and the outer wheel of the vehicle according to the steering angle of the vehicle;

[0149] The control unit 1602 is used to output a pulse width modulation (PWM) control signal according to the target speed ratio; the PWM control signal is used to control the rotation of the outer wheel or the inner wheel of the vehicle so that the speed ratio of the inner wheel and the outer wheel reaches the target speed ratio.

[0150] In an optional implementation manner, the speed ratio determining unit 1601 is specifically configured to:

[0151] The product of a setting coefficient and a steering angle of the vehicle is used as the target speed ratio; wherein the setting coefficient is determined according to the wheelbase of the vehicle.

[0152] In an optional implementation manner, the speed ratio determining unit 1601 is specifically configured to:

[0153] During the driving of the vehicle, obtaining the speed of the vehicle;

[0154] If the speed of the vehicle is less than or equal to a set speed threshold, obtaining a steering angle of the vehicle;

[0155] If the steering angle of the vehicle is greater than or equal to a set steering angle threshold, the target speed ratio is determined according to the steering angle of the vehicle.

[0156] In an optional implementation manner, the speed ratio determining unit 1601 is specifically configured to:

[0157] Determining a duty cycle of the PWM control signal according to the target speed ratio;

[0158] The PWM control signal is output according to the determined duty cycle.

[0159] In an optional implementation manner, the speed ratio determining unit 1601 is specifically configured to:

[0160] determining a target rotational speed for an inner wheel of the vehicle;

[0161] Inputting the speed difference between the target speed of the inner wheel of the vehicle and the measured speed of the inner wheel of the vehicle into a speed proportional integral PI controller to obtain a specified torque output by the speed PI controller;

[0162] The torque difference between the designated torque and the actually measured torque of the vehicle is input into a torque PI controller to obtain a duty cycle of the PWM control signal output by the torque PI controller.

[0163] In an optional implementation manner, the speed ratio determining unit 1601 is specifically configured to:

[0164] The product of the actually measured rotation speed of the outer wheels of the vehicle and the target rotation speed ratio is used as the target rotation speed of the inner wheels of the vehicle.

[0165] An embodiment of the present application also provides a computer-readable storage medium, which stores computer-executable instructions. When the computer program is executed by a processor, it can be used to implement the vehicle turning control method recorded in any embodiment of the present application.

[0166] In some possible implementations, various aspects of the vehicle turning control method provided by the present application may also be implemented in the form of a program product, which includes program code. When the program product is run on a computer device, the program code is used to enable the computer device to execute the steps of the vehicle turning control method according to various exemplary embodiments of the present application described above in this specification. For example, the computer device may execute the following steps: Figure 4 The process of the vehicle turning control method is shown.

[0167] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0168] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0169] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0170] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0171] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A vehicle turning control device, characterized in that: Installed in a vehicle; the vehicle turning control device includes a processor and a differential; The processor is configured to, during the driving of the vehicle, obtain a steering angle of the vehicle; determine a target speed ratio between an inner wheel and an outer wheel of the vehicle according to the steering angle of the vehicle; and output a pulse width modulation (PWM) control signal according to the target speed ratio; The differential is configured to control the outer wheels or the inner wheels of the vehicle to rotate according to the PWM control signal output by the processor so that the speed ratio between the inner wheels and the outer wheels reaches the target speed ratio.

2. The turning control device according to claim 1, characterized in that: The processor is specifically configured to: The product of a setting coefficient and a steering angle of the vehicle is used as the target speed ratio; wherein the setting coefficient is determined according to the wheelbase of the vehicle.

3. The turning control device according to claim 1, characterized in that: The processor is specifically configured to: During the driving of the vehicle, obtaining the speed of the vehicle; If the speed of the vehicle is less than or equal to a set speed threshold, obtaining a steering angle of the vehicle; If the steering angle of the vehicle is greater than or equal to a set steering angle threshold, the target speed ratio is determined according to the steering angle of the vehicle.

4. The turning control device according to claim 1, characterized in that: The processor is specifically configured to: Determining a duty cycle of the PWM control signal according to the target speed ratio; The PWM control signal is output according to the determined duty cycle.

5. The turning control device according to claim 4, characterized in that: The processor is specifically configured to: determining a target rotational speed for an inner wheel of the vehicle; Inputting the speed difference between the target speed of the inner wheel of the vehicle and the measured speed of the inner wheel of the vehicle into a speed proportional integral PI controller to obtain a specified torque output by the speed PI controller; The torque difference between the designated torque and the actually measured torque of the vehicle is input into a torque PI controller to obtain a duty cycle of the PWM control signal output by the torque PI controller.

6. The turning control device according to claim 5, characterized in that: The processor is specifically configured to: The product of the actually measured rotation speed of the outer wheels of the vehicle and the target rotation speed ratio is used as the target rotation speed of the inner wheels of the vehicle.

7. The turning control device according to claim 4, characterized in that: The PWM control signal includes a high level and a low level output according to the duty cycle; the differential is specifically configured as follows: When the PWM control signal is at a high level, the inner wheel is controlled to rotate; When the PWM control signal is at a low level, the inner wheel is controlled to stop rotating.

8. The turning control device according to claim 1, characterized in that: The differential is specifically configured as follows: If the speed ratio of the inner wheel to the outer wheel is less than the target speed ratio, the outer wheel of the vehicle is controlled to rotate according to the PWM control signal; If the speed ratio between the inner wheel and the outer wheel is greater than the target speed ratio, the inner wheel of the vehicle is controlled to rotate according to the PWM control signal.

9. A vehicle, characterized in that: The invention comprises the vehicle turning control device and the wheel as described in claims 1 to 8.

10. A vehicle turning control method, characterized in that: The method comprises: During the driving of the vehicle, obtaining a steering angle of the vehicle; Determining a target speed ratio between an inner wheel and an outer wheel of the vehicle according to a steering angle of the vehicle; According to the target speed ratio, a pulse width modulation (PWM) control signal is output; the PWM control signal is used to control the rotation of the outer wheel or the inner wheel of the vehicle so that the speed ratio of the inner wheel and the outer wheel reaches the target speed ratio.

Images