Vehicle steering control system and method based on track and differential combination

Abstract

The invention relates to the technical field of vehicle engineering, in particular to a vehicle steering control system and method based on track and differential combination. Comprising a vehicle control unit VCU, a front axle driving motor assembly, a middle axle driving motor assembly, a rear axle driving motor assembly, an engine assembly ECU, a generator assembly GCU, an electronic hydraulic power-assisted brake module EHB, a plurality of electronic power-assisted steering assemblies EPS, a power battery BMS, a front axle transmission, a middle axle transmission, a rear axle transmission and a vehicle speed sensor. The vehicle control unit VCU is in communication connection with a front axle driving motor assembly, a middle axle driving motor assembly, a rear axle driving motor assembly, an engine assembly ECU, a generator assembly GCU, an electronic hydraulic power-assisted brake module EHB and a power battery BMS through a CAN bus. In this way, the technical problems that in the prior art, an all-terrain vehicle cannot have excellent stability and comfort during high-speed steering and cannot have sufficient steering capacity and compact steering radius during low-speed steering at the same time in the aspect of steering performance are solved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle engineering technology, and in particular to a vehicle steering control system and method based on a combination of trajectory and differential speed. Background Art

[0002] Currently, all-terrain vehicles (ATVs) are primarily categorized by their powertrains: gasoline-powered and range-extended hybrid. Range-extended hybrid ATVs, with their numerous advantages, are gradually encroaching on the market share of traditional gasoline-powered ATVs.

[0003] In terms of layout, most extended-range hybrid systems adopt an H-type layout. The advantage of this layout is that it can realize the driving and steering functions of the entire vehicle by relying on only two drive motor assemblies, and can achieve flexible low-speed steering characteristics, but it also has disadvantages such as insufficient high-speed steering stability and poor steering comfort. In addition, some vehicles use a full-axis drive motor assembly layout. Although this layout can install a track steering mechanism to achieve high-speed steering stability and steering comfort, it has related problems such as insufficient steering ability and a large steering radius under low-speed steering conditions.

[0004] In summary, in terms of steering performance, all-terrain vehicles in the prior art cannot simultaneously have excellent stability and comfort during high-speed steering, as well as sufficient steering capability and a compact turning radius during low-speed steering. Summary of the Invention

[0005] The purpose of the present invention is to provide a vehicle steering control system and method based on a combination of trajectory and differential speed, aiming to solve the technical problem in the prior art that all-terrain vehicles cannot simultaneously have excellent stability and comfort during high-speed steering, as well as sufficient steering ability and a compact turning radius during low-speed steering.

[0006] To achieve the above objectives, the present invention adopts a vehicle steering control system based on a combination of trajectory and differential speed, including a vehicle controller VCU, a front axle drive motor assembly, a middle axle drive motor assembly, a rear axle drive motor assembly, an engine assembly ECU, a generator assembly GCU, an electronic hydraulic power-assisted brake module EHB, multiple electronic power steering assemblies EPS, a power battery BMS, a front axle transmission, a middle axle transmission, a rear axle transmission and a vehicle speed sensor. The vehicle controller VCU is arranged on the vehicle body and is communicatively connected to the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, the engine assembly ECU, the generator assembly GCU, the electronic hydraulic power-assisted brake module EHB and the power battery BMS via a CAN bus. The electronic hydraulic power-assisted brake module EHB is used to achieve braking, and the vehicle speed sensor is arranged on the electronic hydraulic power-assisted brake module EHB; The crankshaft output end of the engine assembly ECU is mechanically connected to the rotor shaft of the generator assembly GCU, the output shaft of the front axle drive motor assembly is mechanically connected to the input shaft of the front axle transmission, and the output shaft of the front axle transmission is connected to the front axle wheel via a half-shaft through a differential; the output shaft of the middle axle drive motor assembly is mechanically connected to the input shaft of the middle axle transmission, and the output shaft of the middle axle transmission is connected to the middle axle wheel via a half-shaft through a differential; the output shaft of the rear axle drive motor assembly is mechanically connected to the input shaft of the rear axle transmission, and the output shaft of the rear axle transmission is connected to the rear axle wheel via a half-shaft through a differential, and multiple electronic power steering assemblies EPS are respectively arranged on the steering rods of each axle wheel, and the power battery BMS is connected to the generator, the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly and the electronic power steering assembly EPS busbar through a high-voltage cable.

[0007] Among them, the electronic hydraulic power-assisted braking module EHB includes an electronic hydraulic brake assembly, two brake lines, a brake valve assembly and multiple brake discs. The multiple brake discs are respectively connected to the corresponding tires. One end of the two brake lines is connected to the electronic hydraulic brake assembly, and the other end of the two brake lines is connected to multiple corresponding floating calipers. The brake valve assembly is arranged on the two brake lines.

[0008] Wherein, the brake valve assembly includes a left brake valve and a right brake valve, and the left brake valve and the right brake valve are respectively arranged on the corresponding brake pipelines.

[0009] The vehicle controller VCU is also hard-wired to a steering wheel sensor mounted on the steering wheel, and the vehicle speed sensor is also connected to the vehicle controller VCU.

[0010] Wherein, the vehicle speed sensor is mounted on the brake disc of the rear axle wheel.

[0011] Among them, the vehicle controller VCU is used to receive the steering wheel angle signal input, the vehicle speed sensor signal input, the accelerator pedal input, and the brake pedal input signal, so as to analyze the driver's operation instructions, and execute the driver's intentions through the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, the electronic power steering assembly EPS, and the electronic hydraulic power brake module EHB to complete the vehicle's straight driving, steering, and braking control.

[0012] Among them, the front axle drive motor assembly, the middle axle drive motor assembly, and the rear axle drive motor assembly controllers are used to receive VCU control instructions issued through CAN, including instructions such as the working mode, rotation direction, torque size, speed size, etc. of the drive motor assembly, and report the relevant status and execution status of the drive motor assembly to complete the vehicle's driving and steering functions.

[0013] Among them, the vehicle controller VCU calculates the power currently required by the vehicle, decides whether power generation is needed, determines the required power generation power, and sends the target torque and target speed to the engine and the generator. Through the coordinated work of the engine and the generator, power following is completed to provide energy support for the vehicle.

[0014] Among them, the power battery BMS is used to provide energy source for the electrical equipment of the whole vehicle. At the same time, according to the driving torque and speed issued by the vehicle controller VCU, combined with the charging and discharging characteristics of the power battery BMS, it provides energy support for vehicle driving, and at the same time absorbs the surplus current generated by the range extender to balance the power system.

[0015] In non-differential steering situations, the left and right brake valves remain normally open, acting as brake lines, allowing brake fluid to flow through and cooperating with the electronic hydraulic booster brake module (EHB) to achieve normal braking. During differential steering, the opening and closing of the left and right brake valves are controlled to control the on-off connection of the brake lines, cooperating with the drive motor assembly to achieve differential steering.

[0016] The electronic power steering assembly EPS: when steering in a normal trajectory, it can control the steering angles of the front, middle and rear axle steering wheels by receiving controller instructions from the vehicle controller VCU to achieve different trajectory steering functions.

[0017] Steering wheel sensor and vehicle speed sensor: Provide steering input and current vehicle speed input to the vehicle controller VCU, so that the vehicle controller VCU can analyze the driver's driving intention.

[0018] Front, middle and rear axle transmissions: They mainly reduce speed and increase torque, and can also provide high and low gears and neutral gears to increase the vehicle's ability to pass through complex roads The present invention also provides a vehicle steering control method based on the combination of trajectory and differential speed, which adopts the vehicle steering control system based on the combination of trajectory and differential speed as described above. The steps include: First, the vehicle controller VCU receives a steering wheel angle signal, a vehicle speed sensor signal, an accelerator pedal signal, and a brake pedal signal; The vehicle controller (VCU) then analyzes the received signal to determine the driver's control instructions and intentions, including straight driving, steering, and braking requirements; When traveling straight, the output shafts of the front axle drive motor assembly, the middle axle drive motor assembly, and the rear axle drive motor assembly are mechanically connected to the front axle transmission, the middle axle transmission, and the rear axle transmission, and then transmit power to the wheel ends through the differential and the half shafts to achieve straight-line travel; When turning, the vehicle controller VCU automatically selects the track steering mode or the differential steering mode according to the driver's steering intention and the current vehicle speed; When the trajectory steering mode is selected, trajectory steering is achieved through the electronic power steering assembly EPS. When the differential steering mode is selected, differential steering of the vehicle is achieved through the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, and the electronic hydraulic power brake module EHB.

[0019] At the same time, the electronic hydraulic booster brake module EHB adjusts the opening and closing of the brake valve according to the braking demand to achieve braking control When braking is required, according to the driver's braking intention, the vehicle controller VCU adjusts the hydraulic pressure in the brake line through the electronic hydraulic booster brake module EHB to achieve precise braking control.

[0020] The present invention relates to a vehicle steering control system and method based on the combination of trajectory and differential speed. The present invention adopts the vehicle controller VCU as the core, and is connected to the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, the engine assembly ECU, the generator assembly GCU, the electronic hydraulic power-assisted brake module EHB and the like through a CAN bus to achieve real-time information transmission and rapid response to instructions; the engine assembly ECU is mechanically connected to the generator assembly GCU to provide power for the system; the front axle drive motor assembly, the middle axle drive motor assembly, and the rear axle drive motor assembly are connected to the corresponding wheels through the front axle transmission, the middle axle transmission, and the rear axle transmission to achieve independent transmission and adjustment of power; the electronic hydraulic power-assisted brake module EHB is used to achieve braking and is integrated with the vehicle speed sensor to monitor vehicle speed information in real time. Multiple electronic power steering assemblies EPS are respectively arranged on the steering rods of the wheels of each axle to achieve precise steering control; Specifically, during high-speed steering, the vehicle control unit (VCU) adjusts the output torque and speed of the front, center, and rear axle drive motor assemblies based on the vehicle speed sensor and steering input to achieve stable steering. The electronic power steering (EPS) provides the necessary steering assistance to ensure smooth and comfortable steering.

[0021] During low-speed steering, the vehicle control unit (VCU) employs a trajectory planning algorithm, combined with the steering angle and position information of each axle's wheels, to achieve sufficient steering and a tight turning radius through differential control strategies. At this time, the electronic hydraulic booster brake module (EHB) and the electronic power steering assembly (EPS) work together to provide sufficient steering force and precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a structural principle diagram of the vehicle steering control system based on the combination of trajectory and differential speed of the present invention.

[0024] Figure 2 This is a control principle diagram of the vehicle steering control method based on the combination of trajectory and differential speed of the present invention.

[0025] Figure 3 It is a schematic diagram of steering mode judgment of the vehicle steering control method based on the combination of trajectory and differential speed of the present invention.

[0026] 101-Vehicle Controller VCU, 102-Front Axle Drive Motor Assembly, 103-Mid-Axle Drive Motor Assembly, 104-Rear Axle Drive Motor Assembly, 105-Engine Assembly ECU, 106-Generator Assembly GCU, 107-Electronic Power Steering Assembly EPS, 108-Power Battery BMS, 109-Front Axle Transmission, 110-Mid-Axle Transmission, 111-Rear Axle Transmission, 112-Vehicle Speed ​​Sensor, 113-Electronic Hydraulic Brake Assembly, 114-Brake Line, 115-Brake Disc, 116-Left Brake Valve, 117-Right Brake Valve. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0028] See also Figure 1 , Figure 1 It is a structural principle diagram of the vehicle steering control system based on the combination of trajectory and differential speed of the present invention.

[0029] The present invention provides a vehicle steering control system based on trajectory and differential combination, including a vehicle controller VCU101, a front axle drive motor assembly 102, a middle axle drive motor assembly 103, a rear axle drive motor assembly 104, an engine assembly ECU105, a generator assembly GCU106, an electronic hydraulic power-assisted brake module EHB, multiple electronic power-assisted steering assemblies EPS107, a power battery BMS108, a front axle transmission 109, a middle axle transmission 110, a rear axle transmission 111 and a vehicle speed sensor 112. The vehicle controller VC U101 is arranged on the vehicle body, and the vehicle controller VCU101 is connected to the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104, the engine assembly ECU105, the generator assembly GCU106, the electronic hydraulic power-assisted brake module EHB and the power battery BMS108 through the CAN bus. The electronic hydraulic power-assisted brake module EHB is used to achieve braking, and the vehicle speed sensor 112 is provided on the electronic hydraulic power-assisted brake module EHB; The crankshaft output end of the engine assembly ECU 105 is mechanically connected to the rotor shaft of the generator assembly GCU 106, the output shaft of the front axle drive motor assembly 102 is mechanically connected to the input shaft of the front axle transmission 109, and the output shaft of the front axle transmission 109 is connected to the front axle wheel through the differential via the half-shaft; the output shaft of the middle axle drive motor assembly 103 is mechanically connected to the input shaft of the middle axle transmission 110, and the output shaft of the middle axle transmission 110 is connected to the middle axle wheel through the differential via the half-shaft; the rear axle drive motor assembly 103 is mechanically connected to the input shaft of the middle axle transmission 110, and the output shaft of the middle axle transmission 110 is connected to the middle axle wheel through the differential via the half-shaft; The output shaft of the motor assembly 104 is mechanically connected to the input shaft of the rear axle transmission 111, and the output shaft of the rear axle transmission 111 is connected to the rear axle wheel via a differential via a half-shaft. Multiple electronic power steering assemblies EPS107 are respectively arranged on the steering rods of each axle wheel, and the power battery BMS108 is connected to the generator, the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104 and the electronic power steering assembly EPS107 bus through a high-voltage cable.

[0030] The electronic hydraulic booster brake module EHB includes an electronic hydraulic brake assembly 113, two brake lines 114, a brake valve assembly, and a plurality of brake discs 115. The plurality of brake discs 115 are respectively connected to corresponding tires. One end of each of the two brake lines 114 is connected to the electronic hydraulic brake assembly 113, and the other ends of the two brake lines 114 are connected to a plurality of corresponding floating calipers. The brake valve assembly is provided on the two brake lines 114. The brake valve assembly includes a left brake valve 116 and a right brake valve 117 , and the left brake valve 116 and the right brake valve 117 are respectively arranged on the corresponding brake pipe 114 ; The vehicle controller VCU 101 is also hard-wired to a steering wheel sensor mounted on the steering wheel, and the vehicle speed sensor 112 is also connected to the vehicle controller VCU 101 .

[0031] For this specific embodiment, the present invention adopts the vehicle controller VCU101 as the core, and communicates with the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104, the engine assembly ECU105, the generator assembly GCU106, the electronic hydraulic booster brake module EHB, etc. through the CAN bus to achieve real-time information transmission and rapid response to instructions; the engine assembly ECU105 is mechanically connected to the generator assembly GCU106 to provide power for the system. force; the front axle drive motor assembly 102, the middle axle drive motor assembly 103, and the rear axle drive motor assembly 104 are connected to the corresponding wheels through the front axle transmission 109, the middle axle transmission 110, and the rear axle transmission 111 to achieve independent transmission and adjustment of power; the electronic hydraulic power-assisted brake module EHB is used to achieve braking and is integrated with the vehicle speed sensor 112 to monitor vehicle speed information in real time. Multiple electronic power steering assemblies EPS107 are respectively arranged on the steering rods of the wheels of each axle to achieve precise steering control; Specifically, during high-speed steering, the vehicle controller VCU 101 adjusts the output torque and speed of the front axle drive motor assembly 102, the center axle drive motor assembly 103, and the rear axle drive motor assembly 104 based on the vehicle speed sensor 112 and steering input information to achieve stable steering. At this time, the electronic power steering assembly EPS 107 provides the necessary steering assistance to ensure smooth and comfortable steering.

[0032] The vehicle speed sensor 112 is mounted on the brake disc 115 of the rear axle wheel.

[0033] According to this specific embodiment, the vehicle speed sensor 112 rotates synchronously with the wheels.

[0034] Secondly, the vehicle controller VCU101 is used to receive the steering wheel angle signal input, the vehicle speed sensor 112 signal input, the accelerator pedal input, and the brake pedal input signal, so as to analyze the driver's operation instructions, and execute the driver's intentions through the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104, the electronic power steering assembly EPS107, and the electronic hydraulic power brake module EHB to complete the vehicle's straight driving, steering, and braking control.

[0035] At the same time, the controllers of the front axle drive motor assembly 102, the middle axle drive motor assembly 103, and the rear axle drive motor assembly 104 are used to receive VCU control instructions issued through CAN, including instructions such as the working mode, rotation direction, torque size, speed size, etc. of the drive motor assembly, and report the relevant status and execution status of the drive motor assembly to complete the vehicle's driving and steering functions.

[0036] In addition, the vehicle controller VCU101 calculates the power currently required by the vehicle, decides whether power generation is needed, determines the required power generation power, and sends the target torque and target speed to the engine and the generator. Through the coordinated work of the engine and the generator, power following is completed to provide energy support for the vehicle.

[0037] Again, the power battery BMS108 is used to provide energy source for the electrical equipment of the entire vehicle. At the same time, according to the driving torque and speed issued by the vehicle controller VCU101, combined with the charging and discharging characteristics of the power battery BMS108, it provides energy support for vehicle driving, and at the same time absorbs the surplus current generated by the range extender to balance the power system.

[0038] The vehicle steering control system based on the combination of trajectory and differential speed of this embodiment is used. The present invention adopts the vehicle controller VCU101 as the core, and is connected to the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104, the engine assembly ECU105, the generator assembly GCU106, the electronic hydraulic booster brake module EHB and the like through the CAN bus to achieve real-time information transmission and rapid response to instructions; the engine assembly ECU105 and the generator assembly GCU106 are mechanically connected. The front axle drive motor assembly 102, the middle axle drive motor assembly 103, and the rear axle drive motor assembly 104 are connected to the corresponding wheels through the front axle transmission 109, the middle axle transmission 110, and the rear axle transmission 111 to achieve independent transmission and adjustment of power; the electronic hydraulic power-assisted brake module EHB is used to achieve braking and is integrated with the vehicle speed sensor 112 to monitor vehicle speed information in real time. Multiple electronic power-assisted steering assemblies EPS107 are respectively arranged on the steering rods of the wheels of each axle to achieve precise steering control; Specifically, during high-speed steering, the vehicle controller VCU 101 adjusts the output torque and speed of the front axle drive motor assembly 102, the center axle drive motor assembly 103, and the rear axle drive motor assembly 104 based on the vehicle speed sensor 112 and steering input information to achieve stable steering. At this time, the electronic power steering assembly EPS 107 provides the necessary steering assistance to ensure smooth and comfortable steering.

[0039] During low-speed steering, the vehicle controller VCU 101 employs a trajectory planning algorithm, combined with the steering angle and position information of each axle's wheels, to achieve full steering control and a tight turning radius through differential control strategies. At this time, the electronic hydraulic booster brake module (EHB) and the electronic power steering assembly (EPS) 107 work together to provide sufficient steering force and precision. See also Figure 2 and Figure 3 , Figure 2 This is a control principle diagram of the vehicle steering control method based on the combination of trajectory and differential speed of the present invention. Figure 3 It is a schematic diagram of steering mode judgment of the vehicle steering control method based on the combination of trajectory and differential speed of the present invention.

[0040] The present invention also provides a vehicle steering control method based on the combination of trajectory and differential speed, which adopts the vehicle steering control system based on the combination of trajectory and differential speed as described above. The steps include: First, the vehicle controller VCU 101 receives a steering wheel angle signal, a vehicle speed sensor 112 signal, an accelerator pedal signal, and a brake pedal signal; The vehicle controller VCU 101 then analyzes the received signal to determine the driver's control instructions and intentions, including straight driving, steering and braking requirements; When traveling straight, the output shafts of the front axle drive motor assembly 102, the middle axle drive motor assembly 103, and the rear axle drive motor assembly 104 are mechanically connected to the front axle transmission 109, the middle axle transmission 110, and the rear axle transmission 111, respectively, and then the power is transmitted to the wheel ends through the differential and the half shafts to achieve straight-line travel; When turning, the vehicle controller VCU101 automatically selects the track steering mode or the differential steering mode according to the driver's steering intention and the current vehicle speed; When the trajectory steering mode is selected, trajectory steering is achieved through the electronic power steering assembly EPS107. When the differential steering mode is selected, the vehicle's differential steering is achieved through the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104, and the electronic hydraulic power brake module EHB.

[0041] The specific control methods of several steering modes are as follows: 1. Normal travel trajectory steering mode: In normal driving steering mode, the front axle steering wheel and the middle axle steering wheel rotate with the steering wheel, and the rear axle steering wheel remains in the "0" position and does not move with the steering wheel.

[0042] Trigger condition: When the target turning curvature C is less than the C1 value (C1 is the target curvature threshold for entering trajectory steering), the vehicle enters the normal trajectory steering mode.

[0043] Steering Principle: The vehicle controller VCU101 receives steering wheel input and interprets it as a steering curvature signal between -C1 and C1. Taking into account the current vehicle speed, lateral stability, and steering smoothness, it calculates the steering angle of the front axle wheels. The steering angle of the center axle wheels is multiplied by the center axle steering gain factor k1 to meet the equivalent Ackerman steering principle. In normal trajectory steering mode, the rear axle steering mechanism adopts a fixed control mode, always maintaining a steering angle of "0".

[0044] 2. Low-speed and small-radius trajectory steering mode: In the low-speed, small-radius steering mode, both the front and rear axle steering mechanisms participate in the steering process. When the driver turns the steering wheel, the front axle steering wheel moves in the same direction as the steering wheel, while the rear axle steering wheel moves in the opposite direction, which greatly reduces the turning radius and improves steering flexibility.

[0045] Trigger condition: When the steering curvature is greater than C2 and less than C3 (C2 < C3, C2 is the target curvature threshold for entering the small-radius trajectory steering mode, and C3 is the threshold for exiting the small-radius steering), and at the same time, when the vehicle speed is lower than V1 and greater than V2 (V1 > V2, V1 is the speed threshold for entering the small-radius trajectory steering mode, and V2 is the threshold for exiting the small-radius steering), the vehicle enters the low-speed small-radius trajectory steering mode.

[0046] Steering principle: The above-mentioned vehicle controller VCU101 receives the steering signal input of the steering wheel and the current vehicle speed signal, and judges whether the vehicle has entered the low-speed small-radius trajectory steering mode. If the trigger condition is met, the front axle steering wheels rotate in the same direction as the steering wheel, and the rear axle steering wheels rotate in the opposite direction to the steering wheel. The angle of the rear axle steering wheels is k2 times the angle of the front axle steering wheels (the value of the coefficient k2 can be set according to specific steering requirements).

[0047] 3. Differential steering mode during normal driving: In the differential steering mode, the locking or opening of the left brake valve 116 and the right brake valve 117 can be controlled, and at the same time, in cooperation with the front axle drive motor assembly 102, the middle axle drive motor assembly 103, the rear axle drive motor assembly 104 and the electronic hydraulic power-assisted braking module EHB, the function of differential steering can be realized.

[0048] Trigger condition: When the vehicle speed V is lower than V2 and the target curvature C is greater than C3 (V2 is the vehicle speed threshold for entering differential steering, V2 is greater than or equal to 0; C3 is the curvature threshold for entering differential steering, and the absolute value of C3 is less than or equal to 1), the vehicle enters the differential steering mode.

[0049] Steering principle: When the vehicle controller VCU101 receives that the current vehicle speed V is lower than V2 and at the same time the vehicle requires a large steering condition (when the target curvature C is greater than C3), the vehicle controller VCU101 judges that the vehicle should enter the differential steering mode. Taking the left differential steering as an example, when the vehicle triggers the left differential steering mode, the brake valve in the right brake pipeline 114 is locked in advance, and then the vehicle controller VCU101 controls the electronic hydraulic power-assisted braking module EHB to brake. The magnitude of the braking force is comprehensively evaluated according to the current vehicle speed and the target curvature, and a suitable braking pressure is calculated and sent to the electronic hydraulic power-assisted control module through the CAN bus for braking. Since the vehicle controller VCU101 controls the right brake valve 117 to lock before braking, the right side does not brake, and the left side brakes normally to decelerate, so as to realize differential steering (left turn) during driving. Differential steering (right turn) is the same.

[0050] 4. 1 / 2 in-place steering mode in the parking state: The implementation method of the 1 / 2 in-situ transformation mode is similar to that of differential steering, both of which are achieved by locking and opening and closing the left brake valve 116 and the right brake valve 117. The difference is the triggering conditions; when the 1 / 2 in-situ steering is triggered, the steering center of the vehicle is located on the radial line of the steering side wheel along the road surface.

[0051] Trigger condition: There is a "1 / 2 on-the-spot steering mode" switch in the vehicle's operating area. By turning on this switch, the vehicle can enter the "1 / 2 on-the-spot steering mode".

[0052] Steering principle: When the 1 / 2 stationary steering switch is turned on, the vehicle enters the 1 / 2 stationary steering mode. Taking the left 1 / 2 stationary steering as an example, when the target curvature is greater than a threshold value C4, the right brake valve 117 can be locked in advance, and the left brake valve 116 is in an open and closed state. By controlling the accelerator pedal to control the output torque of the drive motors of the front, middle and rear axles, the vehicle's 1 / 2 stationary steering function is realized. The same applies to the right 1 / 2 stationary steering.

[0053] The beneficial effects of the present invention are as follows: By combining trajectory steering and differential steering in all-axle drive and steering special vehicles, it is ensured that the special vehicles have the advantages of good steering stability and comfort at high speeds, small turning radius and flexible steering at low speeds, thereby improving high-speed handling stability and low-speed steering sensitivity.

[0054] The precise control of the front axle drive motor assembly 102, the middle axle drive motor assembly 103, and the rear axle drive motor assembly 104 by the vehicle controller VCU 101 achieves excellent stability of the vehicle during high-speed steering, effectively avoiding safety hazards such as sideslip and loss of control. The application of the electronic power steering assembly EPS 107 makes the vehicle's steering process smoother, reducing the driver's operating burden and fatigue. When turning at low speed, trajectory planning and differential control strategies are used to achieve full vehicle steering and a compact turning radius, improving the vehicle's flexibility and passability in various complex terrain conditions.

[0055] The vehicle controller VCU101 is connected to each component via the CAN bus, achieving real-time information transmission and fault detection, and improving the reliability and safety of the system.

[0056] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A vehicle steering control system based on a combination of trajectory and differential speed, characterized in that: It includes a vehicle controller VCU, a front axle drive motor assembly, a middle axle drive motor assembly, a rear axle drive motor assembly, an engine assembly ECU, a generator assembly GCU, an electronic hydraulic power-assisted brake module EHB, multiple electronic power steering assemblies EPS, a power battery BMS, a front axle transmission, a middle axle transmission, a rear axle transmission and a vehicle speed sensor. The vehicle controller VCU is arranged on the vehicle body. The vehicle controller VCU is communicated with the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, the engine assembly ECU, the generator assembly GCU, the electronic hydraulic power-assisted brake module EHB and the power battery BMS through a CAN bus. The electronic hydraulic power-assisted brake module EHB is used to achieve braking, and the vehicle speed sensor is provided on the electronic hydraulic power-assisted brake module EHB; The crankshaft output end of the engine assembly ECU is mechanically connected to the rotor shaft of the generator assembly GCU, the output shaft of the front axle drive motor assembly is mechanically connected to the input shaft of the front axle transmission, and the output shaft of the front axle transmission is connected to the front axle wheel via a half-shaft through a differential; the output shaft of the middle axle drive motor assembly is mechanically connected to the input shaft of the middle axle transmission, and the output shaft of the middle axle transmission is connected to the middle axle wheel via a half-shaft through a differential; the output shaft of the rear axle drive motor assembly is mechanically connected to the input shaft of the rear axle transmission, and the output shaft of the rear axle transmission is connected to the rear axle wheel via a half-shaft through a differential, and multiple electronic power steering assemblies EPS are respectively arranged on the steering rods of each axle wheel, and the power battery BMS is connected to the generator, the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly and the electronic power steering assembly EPS busbar through a high-voltage cable.

2. The vehicle steering control system based on the combination of trajectory and differential speed as claimed in claim 1, characterized in that: The electronic hydraulic power-assisted braking module EHB includes an electronic hydraulic brake assembly, two brake lines, a brake valve assembly and multiple brake discs. The multiple brake discs are respectively connected to corresponding tires. One end of the two brake lines is connected to the electronic hydraulic brake assembly, and the other end of the two brake lines is connected to multiple corresponding floating calipers. The brake valve assembly is arranged on the two brake lines.

3. The vehicle steering control system and method based on trajectory and differential combination as claimed in claim 2, characterized in that: The brake valve assembly includes a left brake valve and a right brake valve, and the left brake valve and the right brake valve are respectively arranged on the corresponding brake pipelines.

4. The vehicle steering control system based on the combination of trajectory and differential speed as claimed in claim 3, characterized in that: The vehicle controller VCU is also hard-wired to a steering wheel sensor mounted on the steering wheel, and the vehicle speed sensor is also connected to the vehicle controller VCU.

5. The vehicle steering control system based on the combination of trajectory and differential speed as claimed in claim 4, characterized in that: The vehicle speed sensor is mounted on the brake disc of the rear axle wheel.

6. The vehicle steering control system based on the combination of trajectory and differential speed as claimed in claim 5, characterized in that: The vehicle controller VCU is used to receive steering wheel angle signal input, vehicle speed sensor signal input, accelerator pedal input, and brake pedal input signal, thereby analyzing the driver's operating instructions and executing the driver's intentions through the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, the electronic power steering assembly EPS, and the electronic hydraulic power brake module EHB to complete the vehicle's straight driving, steering, and braking control.

7. The vehicle steering control system and method based on the combination of trajectory and differential speed as claimed in claim 6, characterized in that: The front axle drive motor assembly, the middle axle drive motor assembly, and the rear axle drive motor assembly controllers are used to receive VCU control instructions issued via CAN to complete the vehicle's driving and steering functions.

8. The vehicle steering control system and method based on the combination of trajectory and differential speed as claimed in claim 7, characterized in that: The vehicle controller VCU calculates the power currently required by the vehicle, decides whether power generation is needed, determines the required power generation power, and sends the target torque and target speed to the engine and the generator. Through the coordinated work of the engine and the generator, power following is completed to provide energy support for the vehicle.

9. The vehicle steering control system based on the combination of trajectory and differential speed as claimed in claim 8, characterized in that: The power battery BMS is used to provide energy sources for the electrical equipment of the entire vehicle. At the same time, according to the driving torque and speed issued by the vehicle controller VCU, combined with the charging and discharging characteristics of the power battery BMS, it provides energy support for vehicle driving, and at the same time absorbs the surplus current generated by the range extender to balance the power system.

10. A vehicle steering control method based on a combination of trajectory and differential speed, using the vehicle steering control system based on a combination of trajectory and differential speed as claimed in claim 9, characterized in that: The steps include: First, the vehicle controller VCU receives a steering wheel angle signal, a vehicle speed sensor signal, an accelerator pedal signal, and a brake pedal signal; The vehicle controller (VCU) then analyzes the received signal to determine the driver's control instructions and intentions, including straight driving, steering, and braking requirements; When traveling straight, the output shafts of the front axle drive motor assembly, the middle axle drive motor assembly, and the rear axle drive motor assembly are mechanically connected to the front axle transmission, the middle axle transmission, and the rear axle transmission, and then transmit power to the wheel ends through the differential and the half shafts to achieve straight-line travel; When turning, the vehicle controller VCU automatically selects the track steering mode or the differential steering mode according to the driver's steering intention and the current vehicle speed; When the trajectory steering mode is selected, trajectory steering is achieved through the electronic power steering assembly EPS. When the differential steering mode is selected, differential steering of the vehicle is achieved through the front axle drive motor assembly, the middle axle drive motor assembly, the rear axle drive motor assembly, and the electronic hydraulic power brake module EHB.

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