A worm-type wire-controlled steering system and its control system

Abstract

The present invention discloses a worm-type wire-controlled steering system and its control system, which belongs to the technical field of steering mechanisms. The worm-type wire-controlled steering system includes a torque feedback device, a steering column including a spline shaft, one end of which is connected to the steering wheel; a torque feedback component including a first gear shaft, an angle torque sensor, a motor, a worm, and a worm wheel; the first gear shaft is connected to the spline shaft, and the angle torque sensor is installed on one side of the first gear shaft; the worm wheel is installed on the first gear shaft; and a worm that matches the worm wheel is provided at the output end of the motor. The torque and angle of the steering wheel are detected by the angle torque sensor; based on the detected torque and angle, the feedback torque is simulated by the motor, the worm, and the worm wheel, and the steering damping can be simulated and adjusted by the motor to achieve linear steering control; mechanical decoupling between the steering wheel and the steering actuator is achieved, the steering feel is improved, and personalized driving needs can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of steering mechanisms, and in particular to a worm-type wire-controlled steering system and a control system thereof. Background Art

[0002] Traditional steering systems consist of a steering column, an intermediate steering shaft, and a steering actuator. The steering wheel and the steering rods connected to the wheels are mechanically connected, and steering generally operates at a fixed angle ratio. During vehicle movement, feedback from the road and tires is transmitted to the steering wheel via the steering gear, intermediate shaft, and steering column.

[0003] With the development of intelligent and autonomous driving functions in automobiles, new requirements have been put forward for steering systems, such as variable steering angle transmission ratio, adjustable steering feel, folding steering wheel, and telescopic column. Traditional steering systems can no longer meet the requirements of intelligent driving for steering systems.

[0004] It is necessary to design a steering system that can achieve linear or nonlinear angle transmission ratios to meet personalized driving needs. Steer-by-wire systems have broad market application prospects in intelligent and autonomous vehicles. Summary of the Invention

[0005] In response to the above technical problems existing in the prior art, the present invention provides a worm-type wire-controlled steering system and a control system thereof, which realizes mechanical decoupling of the steering actuator and simulates the steering road feel through a torque road feel feedback component.

[0006] The present invention discloses a worm-type wire-controlled steering system, including a torque feedback device, which includes a steering column and a torque feedback assembly, the steering column includes a spline shaft, one end of which is connected to a steering wheel; the torque feedback assembly includes a first gear shaft, an angular torque sensor, a motor, a worm and a worm wheel; the first gear shaft is connected to the spline shaft, the angular torque sensor is installed on one side of the first gear shaft; the worm wheel is installed on the first gear shaft; and the output end of the motor is provided with a worm that cooperates with the worm wheel.

[0007] Preferably, a concave cavity is provided at one end of the housing of the torque feedback assembly, and the outer end of the first gear shaft is rotatably mounted in the concave cavity;

[0008] A limiting ring is rotatably mounted in the concave cavity, and the inner teeth of the limiting ring are engaged with the outer teeth of the first gear shaft;

[0009] A second limiting boss is provided on one side of the limiting ring;

[0010] A first limiting boss that matches the second limiting boss is arranged in the concave cavity.

[0011] Preferably, an end cap is provided at the outer end of the cavity;

[0012] The spline shaft is connected to the steering wheel via an external spline at the outer end;

[0013] An upper bracket is provided on the shell, and the upper bracket is mounted on the vehicle pipe beam through a mounting hole.

[0014] Preferably, the system further comprises a controller assembly, the controller assembly being connected to the motor and the angle torque sensor respectively; an input shaft is provided at the other end of the spline shaft, the inner hole of the input shaft is rigidly connected to one end of the torsion bar, and the other end of the torsion bar is rigidly connected to the inner hole of the first gear shaft;

[0015] The angular torque sensor includes a target plate and a body that are spaced apart.

[0016] The body is connected to the controller assembly via a wiring harness.

[0017] Preferably, it also includes a steering actuator,

[0018] The steering actuator includes an electric drive controller, a drive motor, a ball screw nut pair and a steering rod.

[0019] The electric drive controller is connected to the controller component and the drive motor respectively;

[0020] The output end of the driving motor is connected to the ball screw nut pair, and the screw of the ball screw nut pair is connected to the steering rod.

[0021] Preferably, a rack is provided on the lead screw;

[0022] The outer teeth on one side of the second gear shaft are engaged with the rack. An angle sensor is provided on the outer side of the second gear shaft, and the angle sensor is connected to the electric drive controller.

[0023] Preferably, the output end of the driving motor is connected to the ball screw nut pair through a belt transmission mechanism;

[0024] The angle sensor is connected to the electric drive controller via a sensor harness;

[0025] The controller component is connected to the electric drive controller via a CAN bus.

[0026] The present invention also provides a control system for the worm-type steer-by-wire system, comprising a road feel feedback module and a rack force merging module.

[0027] The road feel feedback module is used to calculate the feedback torque of the steering wheel;

[0028] The rack force merging module is used to measure the position of the rack according to the angle feedback from the angle sensor and calculate the rack force of the steering actuator;

[0029] The method for calculating the rack force includes: if the current vehicle speed is less than a first threshold, the rack force adopts an estimated rack force;

[0030] If the current vehicle speed exceeds a first threshold, the rack force is calculated using a vehicle model.

[0031] Preferably, the control system further includes an end limit module,

[0032] The end limit module is used to calculate the target angle of the steering actuator and the rack end protection position based on the steering reference position, vehicle speed, steering wheel angle, steering wheel speed and steering line angle ratio; when the current rack position reaches the rack end protection position, the steering wheel feedback torque is increased and the power assist is reduced.

[0033] Preferably, the control system further comprises any one of the following modules or a combination thereof: a damping torque module, an active return module, a hysteresis torque module, a rack force estimation module, a rack force estimation monitoring module, a position control monitoring module, a steering position control module, a torque control module and an operation mode management module.

[0034] The road feel feedback module is used to obtain the rack force, steering wheel torque and current vehicle speed; based on the torque and current vehicle speed, the feedback torque is obtained;

[0035] Specifically, the road feel feedback module extracts the specific frequency of the rack force and adds it to the final drive torque. The feedback torque is adjusted based on the frequency according to vehicle speed and driver torque. The feedback torque is determined by two-dimensional calibration data with rack force dependency and vehicle speed dependency.

[0036] The damping torque module is used to provide damping torque through a damping torque function. The damping torque function includes linear and quadratic damping control, which are calculated based on steering wheel speed and vehicle speed respectively. The oversteer or understeer condition is then factored based on the vehicle driving state.

[0037] The active return module is used to calculate an active return torque based on vehicle speed and steering position, and to generate an active rotational torque through speed closed-loop control to assist in the active return of the steering wheel.

[0038] The hysteresis torque module is used to simulate hysteresis torque. The friction coefficient of hysteresis torque is adjusted according to the vehicle speed.

[0039] The rack force estimation module is used to calculate the estimated rack force of the steering actuator based on the rack position, steering wheel hand force and drive motor torque;

[0040] The rack force estimation and monitoring module is used to calculate a second rack force based on the estimated rack force, the state of the rack force estimation module, the rack movement speed, the steering wheel hand force, and the filtered drive motor torque, and calculate the error between the estimated rack force and the second rack force;

[0041] A position control monitoring module is configured to monitor the position error between the target rack position and the actual rack position; if the position error exceeds a third threshold and persists for a period exceeding a fourth threshold, an error is reported, wherein the third threshold is adjustable and the fourth threshold is adjustable based on vehicle speed and the position error threshold;

[0042] The steering position control module uses the PID algorithm to convert the position control requirements into torque control, and drives the rack position by monitoring the actual position of the rack. It can track the target rack position to achieve the position control target;

[0043] The torque control module is used to calculate the motor torque demand value and torque control state based on the driver's reference torque, steering wheel hand force, steering wheel feedback torque, damping torque, active rotation torque, hysteresis torque, reference torque and limit torque. By calculating the motor torque demand, the steering actuator steering torque can track the reference torque for torque drive, and at the same time monitor the error between the reference torque and the steering torque;

[0044] The operation mode management module is used for switching between different control modes, for checking switching conditions, and for managing the control modes required by ADAS, which include steering alignment, handwheel hold, and manual steering.

[0045] Compared with the existing technology, the beneficial effects of the present invention are: the torque and angle of the steering wheel are detected by an angle torque sensor; based on the detected torque and angle, the feedback torque is simulated by the motor, worm and worm gear, and the steering damping can be simulated and adjusted by the motor to achieve linear steering control; mechanical decoupling between the steering wheel and the steering actuator is achieved, the steering feel is improved, and personalized driving needs can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic structural diagram of a worm-type steer-by-wire system of the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of the torque road feedback device

[0048] Figure 3 is a cross-sectional view of the torque feedback assembly;

[0049] Figure 4 This is a schematic diagram of the installation of the worm gear and screw;

[0050] Figure 5This is a schematic diagram of the transmission structure of the torque road sense feedback device;

[0051] Figure 6 It is a structural diagram of the cavity;

[0052] Figure 7 Schematic diagram of the structure of the limit ring;

[0053] Figure 8 It is the logic block diagram of the worm-type steer-by-wire system;

[0054] Figure 9 It is a logic block diagram of the control system of the present invention.

[0055] Mark in the figure: 1 torque road sense feedback device,

[0056] 11 steering column, 111 spline shaft, 112 external spline, 115 upper bracket, 116 mounting hole,

[0057] 12 torque feedback assembly, 121 housing, 122 end cover, 123 cavity, 125 first limiting boss,

[0058] 13 input shaft, 14 torsion bar, 15 first gear shaft, 16 angle torque sensor, 161 wiring harness, 162 body, 163 target plate, 17 limiting ring, 171 second limiting boss, 172 internal gear, 18 controller assembly; 181 motor, 182 worm, 183 worm wheel;

[0059] 2 steering wheels;

[0060] 3 Steering actuator, 31 Electric drive controller, 32 Drive motor, 33 Belt drive mechanism, 35 Steering rod, 37 Ball screw nut pair, 371 Lead screw, 372 Rack, 38 Angle sensor, 381 Sensor harness, 39 Second gear shaft;

[0061] 51 rack force merging module, 52 road sense feedback module, 53 damping torque module, 54 active return module, 55 hysteresis torque module, 56 reference torque calculation module, 57 end limit module, 58 torque control module,

[0062] 61 rack force estimation module, 62 rack force estimation monitoring module, 63 position control monitoring module, 64 steering position control module. DETAILED DESCRIPTION

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0064] The present invention is described in further detail below with reference to the accompanying drawings:

[0065] The present invention provides a worm-type wire-controlled steering system, such as Figures 1-8 , including a torque feel feedback device (TFU) 1, the torque feel feedback device 1 includes a steering column 11 and a torque feedback assembly 12, the steering column 11 includes a spline shaft 111, one end of the spline shaft 111 is connected to the steering wheel 2; the torque feedback assembly 12 includes a first gear shaft 15, an angular torque sensor 16, a motor 181, a worm 182 and a worm wheel 183; the first gear shaft 15 is connected to the spline shaft 111, and the angular torque sensor 16 is installed on one side of the first gear shaft 15; the worm wheel 183 is installed on the first gear shaft 15; the output end of the motor 181 is provided with a worm 182 that cooperates with the worm wheel 183.

[0066] An angle-torque sensor 16 detects the torque and angle of the steering wheel 2. Based on the detected torque and angle, the motor, worm, and worm gear simulate feedback torque. The motor can also simulate and adjust steering damping to achieve linear steering control. This mechanical decoupling between the steering wheel and steering actuator 3 improves steering feel and meets personalized driving needs. Impact and vibration from the road and tires are not transmitted to the steering wheel.

[0067] like Figure 3-Figure 7The housing 121 of the torque feedback assembly 12 has a recessed cavity 123 at one end, within which the outer end of the first gear shaft 15 is rotatably mounted. A limiting ring 17 is rotatably mounted within the recessed cavity 123, with the inner teeth 172 of the limiting ring 17 meshing with the outer teeth of the first gear shaft 15. A second limiting boss 171 is provided on one side of the limiting ring 17. A first limiting boss 125 is provided within the recessed cavity 123, cooperating with the second limiting boss 171 to limit the maximum rotation angle of the gear shaft 15 and the steering wheel. Angle limiting is achieved by the outer teeth of the first gear shaft, the inner teeth of the angle limiting ring, and a set of limiting bosses provided on the limiting ring and the housing, respectively. The first gear shaft 15 and the inner gear of the limiting ring 17 are eccentrically arranged. By adjusting the transmission ratio between the first gear shaft 15 and the inner gear of the angle limiting ring 17, different rotational numbers of the steering wheel 2 can be achieved. When the two limiting bosses contact and limit each other, the first gear shaft 15 is restricted from rotating. The same is true when rotating in the opposite direction, thereby achieving the steering wheel 2 angle restriction.

[0068] like Figure 2 The outer end of the concave cavity 123 is provided with an end cover 122; the spline shaft 111 is connected to the steering wheel 2 through the external spline 112 at the outer end; an upper bracket 115 is provided on the shell 121, and the upper bracket 115 is installed on the vehicle pipe beam through the mounting hole 116.

[0069] Figure 2 A controller assembly 18 is also shown, which is connected to the motor 181 and the angular torque sensor 16 respectively; an input shaft 13 is provided at the other end of the spline shaft 111, the inner hole of the input shaft 13 is rigidly connected to one end of the torsion bar 14, and the other end of the torsion bar 14 is rigidly connected to the inner hole of the first gear shaft 15; the angular torque sensor 16 includes a target plate 163 and a body 162 arranged at intervals, and the body 162 is connected to the controller assembly 18 via a wiring harness 161.

[0070] The controller component controls the rotation of the motor to generate resistance torque through a control algorithm. The torque output by the motor is transmitted to the first gear shaft through the worm and worm wheel. The first gear shaft transmits the resistance torque to the steering wheel 2 through the torsion bar, input shaft and spline shaft to achieve torque road feel feedback. The torque felt on the steering wheel 2 depends entirely on the torque control of the torque feedback device.

[0071] Figure 1The steering actuator (FAA) 3 is shown. It includes an electric drive controller 31, a drive motor 32, a ball screw nut assembly 37, and a steering rod 35. The electric drive controller 31 is connected to the controller assembly 18 and the drive motor 32, respectively. The output end of the drive motor 32 is connected to the ball screw nut assembly 37, and the screw 371 of the ball screw nut assembly 37 is connected to the steering rod 35. The steering actuator 3 is connected to the controller assembly 18 via the CAN bus, achieving mechanical decoupling of the steering actuator 3 from the torque feedback device 1 and the steering wheel. Steering commands are issued to the steering actuator 3 via the controller assembly 18.

[0072] A rack 372 is mounted on the lead screw 371. External teeth on one side of a second gear shaft 39 mesh with the rack 372. An angle sensor 38 is mounted on the outer side of the second gear shaft 39 and is connected to the electric drive controller 31. The angle sensor 38 detects the position and displacement of the rack and is used to monitor steering control results.

[0073] More specifically, the output end of the drive motor 32 is connected to the ball screw nut pair 37 via a belt drive mechanism 33; the angle sensor 38 is connected to the electric drive controller 31 via a sensor harness 381; and the controller assembly 18 is connected to the electric drive controller 31 via a CAN bus. The CAN bus can be a proprietary CAN bus.

[0074] The present invention also provides a control system for the above-mentioned worm-type wire-controlled steering system, such as Figure 9 The control system includes a road feel feedback module 52 and a rack force merging module 51.

[0075] The rack force combining module 51 is used to measure the rack position based on the angle feedback from the angle sensor 38 and calculate the rack force of the steering actuator 3 (referred to as the combined rack force). The rack force calculation method includes: if the current vehicle speed is less than a first threshold, the rack force is estimated; if the current vehicle speed exceeds the first threshold, the rack force is calculated using the vehicle model (Vehicle Model Rack Force).

[0076] The road feel feedback module 52 calculates steering wheel feedback torque and transmits this feedback torque to the controller assembly, which simulates this feedback torque via the motor. More specifically, the feedback torque is calculated and controlled using an interpolation function based on rack force, vehicle speed, and steering wheel force (steering wheel torque). The road feel feedback module extracts the specific frequency of the rack force and adds it to the final drive torque. The feedback torque is then adjusted based on the frequency and vehicle speed and driver torque.

[0077] The damping torque module 53 is used to provide a damping torque through a damping torque function, which includes linear and quadratic damping control. The linear and quadratic damping controls are calculated by the steering wheel speed and the vehicle speed respectively; and then the oversteer or understeer condition is factored and outputted according to the vehicle driving state.

[0078] The active return module 54 calculates an active return torque based on vehicle speed and steering position. This active rotational torque, generated through closed-loop speed control, assists in steering wheel self-centering. The active return module calculates the active rotational torque based on the following factors: vehicle speed, driving state, steering wheel speed, steering wheel hand force, and steering wheel angle.

[0079] The hysteresis torque module 55 is used to simulate the hysteresis torque. The friction coefficient of the hysteresis torque is adjusted according to the vehicle speed. The hysteresis torque is calculated based on the following factors: rack force, steering wheel hand force, steering wheel angle and steering wheel speed.

[0080] The reference torque calculation module 56 is used to calculate a reference torque based on the combined rack force, vehicle speed, and driving state. The driving state is calculated using a vehicle dynamics function that considers vehicle speed, target angle, yaw rate, and lateral acceleration. The goal is to provide a basic steering reference torque based on the estimated rack force. This basic steering reference torque is determined using two-dimensional calibration data that is rack force-dependent and vehicle speed-dependent.

[0081] The end limit module 57 is used to calculate the target angle of the steering actuator and the rack end protection position based on the steering reference position (TFU RES position), vehicle speed, steering wheel angle, steering wheel speed and steering line angle ratio; when the current rack position reaches the rack end protection position, increase the steering wheel feedback torque (referred to as the limit torque) and reduce the power assist.

[0082] This module uses vehicle speed, steering wheel angle, and steering line angle ratio to calculate the target angle of the steering actuator and the rack end protection position of the torque road feel simulator. The target angle and the rack end protection position of the torque road feel simulator are affected by steering position and vehicle speed. At different vehicle speeds, the steering line angle ratio is set differently, resulting in different steering wheel angles when the rack reaches the end protection. When the rack reaches the rack end protection stroke, the torque road feel simulator increases the steering resistance torque to make the driver feel the increased steering damping, preventing oversteering of the steering wheel and achieving rack end protection. In other words, the rack end protection angle of the torque road feel simulator varies at different vehicle speeds.

[0083] The target angle and the end protection position are affected by the vehicle speed and the steering line angle ratio. The steering reference position is generated by the steering reference position generation module based on the vehicle speed, steering angle position and steering gear ratio to calculate the axle target position (Axle Target Position), the target angle and the steering reference position (TFU RES position).

[0084] An additional reference torque is generated by the vehicle speed, steering position and speed, which reduces the power assist when the steering actuator approaches the end, thereby achieving the mechanical protection function of the rack.

[0085] The torque control module 58 calculates the motor torque demand and torque control status based on the driver's reference torque, steering wheel hand force, steering wheel feedback torque, damping torque, active slewing torque, hysteresis torque, reference torque, and limit torque. By calculating the motor torque demand, the steering actuator's steering torque tracks the reference torque for torque drive, while also monitoring the error between the reference torque and the steering torque.

[0086] The rack force estimation module 61 is used to calculate the estimated rack force of the steering actuator according to the rack position, the steering wheel hand force and the driving motor torque.

[0087] The rack force estimation and monitoring module 62 is used to calculate the second rack force based on the estimated rack force, the state of the rack force estimation module 61, the rack movement speed, the steering wheel hand force, and the filtered drive motor torque (torque), and calculate the error between the estimated rack force and the second rack force.

[0088] The position control monitoring module 63 is used to monitor the position error between the target rack position and the actual rack position; if the position error exceeds a third threshold and the duration exceeds a fourth threshold, an error is reported, wherein the third threshold is adjustable and the fourth threshold is adjustable according to the vehicle speed and the position error threshold.

[0089] The steering position control module 64 uses a PID algorithm to convert the position control demand into torque control, and drives the rack position by monitoring the actual position of the rack, and can track the target rack position to achieve the position control target.

[0090] The operating mode management module is responsible for switching between different control modes, checking transition conditions, and managing the control modes required by the ADAS, including steering alignment, wheel grip, and manual steering. This module provides the driver with different steering feel depending on the vehicle mode. Driver mode switching first checks steering wheel torque and vehicle speed, then uses an interpolation function to determine the current steering feel.

[0091] This invention eliminates the steering intermediate shaft, mechanically decoupling the upper steering column and steering actuator. A torque feedback mechanism is added to the steering column to create a steer-by-wire system that simulates steering feel. Because there's no mechanical connection between the steering wheel and the steering actuator, the control program can achieve varying, even nonlinear, angular transmission ratios to meet personalized driving needs. The torque feedback mechanism, connected to the steering wheel, allows for flexible adjustment of steering damping, enabling personalized steering feel and other advanced features.

[0092] Therefore, the steer-by-wire system of the present invention has broad market application prospects in intelligent and autonomous vehicles. It features a compact and reliable structure, high safety redundancy, adjustable angle transmission ratio, and adjustable steering feel, and can support telescopic / folding steering wheels and silent steering wheels.

[0093] The torque angle sensor detects the steering wheel force, angle, and speed signals, and receives vehicle control signals, external torque or angle requests, and steering mode or status and measurement values ​​through the vehicle CAN bus. The control unit calculates the feedback torque, performs steering feel control, and outputs the angle request value to the steering actuator.

[0094] The torque feedback device converts the driver's angular input into the steering wheel position required by the steering actuator. Based on the rack force and rack position feedback from the steering actuator, the torque feedback device generates simulated feedback torque to the driver's hand.

[0095] The steering angle sensor detects rack position signals, receives angle request signals via the control-by-wire system's private CAN bus, and receives external vehicle angle request signals and vehicle speed signals via the vehicle's CAN bus. The control unit calculates torque and controls the steering actuator's position. Simultaneously, the steering actuator provides feedback on its current status, including measured rack position and calculated rack force, to the torque feedback device. The steering actuator pushes the steering wheel to the target position according to defined performance requirements. The steering actuator calculates the current rack force and detects rack position in real time, feeding this data and status back to the torque feedback device.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A worm-type wire-controlled steering system, characterized in that: The invention comprises a torque road sense feedback device (1), wherein the torque road sense feedback device (1) comprises a steering column (11) and a torque feedback component (12). The steering column (11) comprises a spline shaft (111), one end of which is connected to the steering wheel (2); The torque feedback assembly (12) includes a first gear shaft (15), an angular torque sensor (16), a motor (181), a worm (182) and a worm wheel (183); A concave cavity (123) is provided at one end of the housing (121) of the torque feedback assembly (12), and the outer end of the first gear shaft (15) is rotatably mounted in the concave cavity (123); A limiting ring (17) is rotatably mounted in the concave cavity (123), and a second limiting boss (171) is provided on one side of the limiting ring (17); a first limiting boss (125) is provided in the concave cavity (123) and matches the second limiting boss (171); the inner teeth (172) of the limiting ring (17) are meshed with the outer teeth of the first gear shaft (15), and the first gear shaft (15) and the inner gear of the limiting ring (17) are eccentrically arranged; The first gear shaft (15) is connected to the spline shaft (111), and the angle torque sensor (16) is installed on one side of the first gear shaft (15); The worm gear (183) is mounted on the first gear shaft (15); There are two motors (181), and the output end of each motor (181) is provided with a worm (182), the threads on the surface of the worm (182) mesh with the external teeth of the worm wheel (183), and under the action of the two motors (181), the two worms (182) jointly drive the worm wheel (183) to rotate; The worm-type wire-controlled steering system further includes a control system, wherein the control system includes a road sense feedback module (52) and a rack force merging module (51). The road feeling feedback module (52) is used to calculate the feedback torque of the steering wheel; The rack force merging module (51) is used to measure the position of the rack according to the angle fed back by the angle sensor, and calculate the rack force of the steering actuator; Among them, the method of calculating the rack force includes: If the current vehicle speed is less than the first threshold, the rack force adopts the estimated rack force; If the current vehicle speed exceeds a first threshold, the rack force is calculated using a vehicle model.

2. The worm-type steer-by-wire system according to claim 1, characterized in that: An end cover (122) is provided at the outer end of the cavity (123); The spline shaft (111) is connected to the steering wheel (2) via an external spline (112) at an outer end; An upper bracket (115) is provided on the housing (121), and the upper bracket (115) is mounted on the vehicle pipe beam through a mounting hole (116).

3. The worm-type steer-by-wire system according to claim 1, characterized in that: The invention also includes a controller component (18), wherein the controller component (18) is connected to the motor (181) and the angular torque sensor (16) respectively; an input shaft (13) is provided at the other end of the spline shaft (111); an inner hole of the input shaft (13) is rigidly connected to one end of a torsion bar (14); and the other end of the torsion bar (14) is rigidly connected to the inner hole of the first gear shaft (15); The angular torque sensor (16) comprises a target plate (163) and a body (162) which are spaced apart. The body (162) is connected to the controller assembly (18) via a wiring harness (161).

4. The worm-type steer-by-wire system according to claim 3, characterized in that: Also includes a steering actuator (3), The steering actuator comprises an electric drive controller (31), a drive motor (32), a ball screw nut pair (37) and a steering rod (35). The electric drive controller (31) is connected to the controller component (18) and the drive motor (32) respectively; The output end of the driving motor (32) is connected to a ball screw nut pair (37), and the lead screw (371) of the ball screw nut pair (37) is connected to a steering rod (35).

5. The worm-type steer-by-wire system according to claim 4, characterized in that: The lead screw (371) is provided with a rack (372); The outer teeth on one side of the second gear shaft (39) are meshed with the rack (372), and an angle sensor (38) is provided on the outer side of the second gear shaft (39), and the angle sensor (38) is connected to the electric drive controller (31).

6. The worm-type steer-by-wire system according to claim 5, characterized in that: The output end of the driving motor (32) is connected to the ball screw nut pair (37) through a belt transmission mechanism (33); The angle sensor (38) is connected to the electric drive controller (31) via a sensor harness (381); The controller component (18) is connected to the electric drive controller (31) via a CAN bus.

7. A control system, characterized in that: Used to control the worm-type steer-by-wire system as described in any one of claims 1-6.

8. The control system according to claim 7, characterized in that: Also includes an end limit module (57), The end limit module (57) is used to calculate the target angle of the steering actuator and the rack end protection position according to the steering reference position, vehicle speed, steering wheel angle, steering wheel speed and steering line angle ratio; when the current rack position reaches the rack end protection position, the steering wheel feedback torque is increased and the power assist is reduced.

9. The control system according to claim 8, characterized in that: The system further comprises any one of the following modules or a combination thereof: a damping torque module (53), an active return module (54), a hysteresis torque module (55), a rack force estimation module (61), a rack force estimation monitoring module (62), a position control monitoring module (63), a steering position control module (64), a torque control module (58) and an operation mode management module. The road sense feedback module (52) is used to obtain the rack force, steering wheel torque and current vehicle speed; and obtain feedback torque according to the torque and current vehicle speed; The damping torque module (53) is used to provide a damping torque through a damping torque function, wherein the damping torque function includes linear and quadratic damping control, wherein the linear and quadratic damping control are calculated by the steering wheel speed and the vehicle speed respectively; Then, the oversteering or understeering condition is factored out based on the vehicle driving state; The active return module (54) is used to calculate the active return torque according to the reference vehicle speed and the steering position, and to assist the steering wheel in actively returning to the center by generating the active rotation torque through the speed closed loop control; The hysteresis torque module (55) is used to simulate the hysteresis torque, and the friction coefficient of the hysteresis torque is adjusted according to the vehicle speed; The rack force estimation module (61) is used to calculate the estimated rack force of the steering actuator based on the rack position, the steering wheel hand force and the driving motor torque; The rack force estimation and monitoring module (62) is used to calculate the second rack force based on the estimated rack force, the state of the rack force estimation module, the rack movement speed, the steering wheel hand force, and the filtered drive motor torque, and calculate the error between the estimated rack force and the second rack force; The position control monitoring module (63) is used to monitor the position error between the target rack position and the actual rack position; if the position error exceeds a third threshold and the duration exceeds a fourth threshold, an error is reported, wherein the third threshold is adjustable and the fourth threshold is adjustable according to the vehicle speed and the position error threshold; The steering position control module (64) uses a PID algorithm to convert the position control demand into torque control, and drives the rack position by monitoring the actual position of the rack, and can track the target rack position to achieve the position control target; The torque control module (58) is used to calculate the motor torque demand value and the torque control state according to the driver's reference torque, the steering wheel hand force, the steering wheel feedback torque, the damping torque, the active rotation torque, the hysteresis torque, the reference torque and the limit torque, and to enable the steering actuator steering torque to track the reference torque for torque driving by calculating the motor torque demand, while monitoring the error between the reference torque and the steering torque; The operation mode management module is used for switching between different control modes, for checking switching conditions, and for managing the control modes required by the ADAS, which control modes include steering alignment, handwheel holding, and manual steering.

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