Redundant steering system by wire

Abstract

This invention discloses a steer-by-wire redundant steering device. A first motor drives a pulley reduction assembly to rotate, and a second motor drives a worm gear reduction assembly to rotate. The pulley reduction assembly and the worm gear reduction assembly are respectively engaged with a steering screw. A steering controller is connected to both the first and second motors. When the assist limiting current I of the first motor... lim ≥ Target current I g When the steering controller is engaged, the second motor maintains zero current output; when the first motor's assist limit current I... lim < Target current I g At that time, according to the differential current ΔI=I g -I lim The system controls the output compensation current of the second motor; when a fault is detected in the first motor, which is currently the main drive source, the system switches the second motor, which is currently the backup motor, to become the main drive source. Furthermore, the pulley reduction assembly and the worm gear reduction assembly employ differentiated transmissions to avoid common fault risks, such as slippage of the double pulleys or jamming of the double worm gears.

Description

Technical Field

[0001] This invention relates to the field of automotive steering technology, and more specifically to a steer-by-wire redundant steering device. Background Technology

[0002] Automotive steering performance is one of the core performance indicators of a vehicle, directly determining its handling stability and driving safety. With the increasing speed of automobiles, the non-professionalization of drivers, and the intensification of road traffic, the demand for ease of handling and reliability of steering systems is becoming increasingly prominent. While traditional mechanical steering systems and electric power steering (EPS) systems can achieve basic steering functions, their mechanical connection structures limit the flexible adjustment of the steering ratio. Furthermore, in extreme conditions (such as high-speed lane changes or emergency obstacle avoidance), they struggle to balance steering ease and road feel feedback, resulting in insufficient driving adaptability. In addition, mechanical transmission components are susceptible to wear and impact loads, and long-term use may lead to steering play or sluggish response, increasing safety hazards.

[0003] In recent years, steer-by-wire (SBW) systems, as a new generation of steering technology, have eliminated the mechanical connection between the steering wheel and the steering wheels, enabling pure electric signal transmission of steering commands. This not only significantly improves steering freedom (such as variable steering ratio and personalized driving mode adaptation) but also enhances vehicle dynamic stability by optimizing wheel steering angle and torque distribution through active control algorithms. However, SBW systems are highly dependent on the reliability of the electronic control unit (ECU) and the actuator motor. If problems such as signal transmission interruption, steering controller failure, or power failure occur, steering function will be lost directly, leading to serious driving risks. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a steer-by-wire redundant steering device. When the first motor fails, the controller can quickly switch to the second motor for drive, meeting the safety requirements of the steering device. Furthermore, the pulley reduction assembly and the worm gear reduction assembly employ differentiated transmissions to avoid common failure risks, such as slippage of both pulleys or jamming of both worm gears.

[0005] The technical solution adopted by this invention is as follows: A steer-by-wire redundant steering device includes a steering controller, a first motor, a pulley reduction assembly, a second motor, a worm gear reduction assembly, and a steering screw. The first motor drives the pulley reduction assembly to rotate, and the second motor drives the worm gear reduction assembly to rotate. The pulley reduction assembly and the worm gear reduction assembly are respectively engaged with the steering screw. The steering controller is connected to the first motor and the second motor respectively. When the assist limiting current I of the first motor... lim ≥ Target current I g When the steering controller is engaged, the second motor maintains zero current output; when the first motor's assist limit current I...lim < Target current I g At that time, according to the differential current ΔI=I g -I lim Control the output compensation current of the second motor; when a fault is detected in the first motor, which is in the state of being the main drive source, control the second motor, which is in the state of being the standby motor, to switch to being the main drive source.

[0006] Optionally, the pulley reduction assembly includes a driving pulley, a driven pulley, a timing belt, and a steering nut. The driving pulley is coaxially and fastened to the output shaft of the first motor. The outer peripheral wall of the steering screw is provided with a first threaded raceway, and the inner peripheral wall of the steering nut is provided with a second threaded raceway. The first threaded raceway and the second threaded raceway form a spiral raceway for the movement of steel balls. The driven pulley is coaxially and fastened to the outer peripheral wall of the steering nut, and the timing belt is wound around the outer peripheral walls of the driving pulley and the driven pulley.

[0007] Optionally, the worm gear reducer assembly includes a worm, a worm wheel, and a wheel shaft. The worm is coaxially and fastened to the output shaft of the second motor. One end of the steering screw is provided with the first threaded raceway, and the other end of the steering screw is provided with an axially extending rack. One end of the wheel shaft meshes with the rack, and the other end of the wheel shaft is coaxially and fastened with the worm wheel, which meshes with the worm.

[0008] Optionally, it also includes a housing disposed on the outer peripheral wall of the steering screw, wherein a clearance adjustment assembly is provided on the side of the steering screw away from the rack, the clearance adjustment assembly includes a pressure block, a pressure plug and a spring, the pressure plug is fastened to the housing, one end of the spring abuts against the pressure block, the other end of the spring abuts against the pressure plug, and one end of the pressure block abuts against one side of the steering screw radially.

[0009] Optionally, the pressure block is provided with a first groove, and the pressure plug is provided with a second groove. The first groove and the second groove are respectively arranged to form a cavity for accommodating the spring, and the spring is in a compressed state in the cavity.

[0010] Optionally, the pressure block has an arc-shaped groove at one end facing the steering screw, the surface of the arc-shaped groove is provided with a pad, and the side of the pad facing the steering screw has a matrix of grooves.

[0011] Optionally, it also includes a road feel simulation system, which includes a road feel controller, a road feel motor, a torque sensor, a steering angle sensor, and an angular velocity sensor.

[0012] The angular velocity sensor is used to collect the angular velocity signal of the steering wheel and send it to the road feel controller;

[0013] The torque sensor is used to collect the torque signal from the steering wheel and send it to the road feel controller;

[0014] The steering angle sensor is used to collect the steering wheel angle signal and send it to the road feel controller;

[0015] The road feel controller is connected to the torque sensor, steering angle sensor, angular velocity sensor, road feel motor, and steering controller. The road feel controller calculates the road feel torque based on the received steering wheel angle signal, steering wheel torque signal, and steering wheel angular velocity signal, and converts the calculated road feel torque value into a control signal and transmits it to the road feel motor. The road feel motor transmits the simulated road feel torque to the driver through the steering wheel. At the same time, the road feel controller sends commands to the first motor and the second motor through the steering controller.

[0016] Optionally, a steering wheel torque balance equation is established based on the steering wheel torque signal, steering angle signal, and steering wheel angular velocity signal. The steering wheel torque balance equation is as follows:

[0017]

[0018] Among them, T sw For the steering wheel torque, θ sw J is the steering wheel angle. sw B is the moment of inertia of the steering wheel. sw T is the steering wheel damping coefficient. s K is the steering column torque. s For the steering column torque stiffness, θ m1 Road sensor motor rotation angle, G m T is the reduction ratio of the reducer. f The friction torque of the steering wheel, The angular velocity of the steering wheel. This refers to the angular acceleration of the steering wheel.

[0019] The road sensor controller calculates the electromagnetic torque of the road sensor motor:

[0020]

[0021] Among them, T m1 J is the electromagnetic torque of the road induction motor. m1 B is the moment of inertia of the road induction motor. m1 T is the damping coefficient of the induction motor. f1 The frictional torque of the road induction motor, The angular velocity of the road sensor motor. The angular acceleration of the road sensor motor;

[0022] Establish the potential balance equation in the armature winding of the induction motor:

[0023]

[0024] Among them, ua i is the voltage of the armature of the induction motor. a R is the armature current of the induction motor. a K is the resistance of the armature winding of the induction motor. a L is the proportional coefficient of the back electromotive force of the induction motor. a C is the inductance of the armature winding of the induction motor. m The electromagnetic torque coefficient of the induction motor is... The angular velocity of the armature of the road sensor motor;

[0025] Establish the torque balance equation for the first motor:

[0026]

[0027] Among them, T m2 T represents the electromagnetic torque of the first motor. a The assist torque provided by the first motor, J m2 B is the moment of inertia of the first motor. m2 Let θ be the damping coefficient of the first motor. m2 K is the output angle of the first motor. m Let θ be the torque coefficient of the first motor. c i1 is the wheel axle rotation angle, i2 is the reduction ratio of the drive wheel to the driven wheel, and i3 is the reduction ratio of the steering nut to the steering screw. The angular velocity of the first motor is... The angular acceleration of the first motor;

[0028] Establish the torque balance equation for the second motor:

[0029]

[0030] Among them, T m3 T represents the electromagnetic torque of the second motor. a 'The assist torque provided to the second motor, J m3 B is the moment of inertia of the second motor. m3 Let θ be the damping coefficient of the second motor. m3 K is the output angle of the second motor. m ' is the torque coefficient of the second motor, θ c i3 is the wheel-axle rotation angle, i4 is the reduction ratio of the worm gear and worm drive, and i5 is the reduction ratio of the wheel-axle and steering screw drive. The angular velocity of the second motor. This refers to the angular acceleration of the second motor.

[0031] When the assist limiting current I of the first motor lim ≥ Target current I g At that time, the electromagnetic torque T of the second motor m3and the assist torque T provided by the auxiliary motor a 'All are 0, the electromagnetic torque T of the road induction motor m1 =T m2 When the assist limiting current I of the first motor lim < Target current I g At that time, the steering controller distributes a differential current Δi to the second motor, and the second motor outputs an electromagnetic torque T. m3 T m1 =T m2 + T m3 .

[0032] The beneficial effects of the present invention are: (1) By real-time monitoring of the first motor limiting current I lim With target current I g The difference ΔI is used to dynamically adjust the output of the second motor, achieving seamless power connection between the two motors, in normal steering I. lim ≥I g When only the first motor is working, power consumption may be reduced by 20% to 30%; under high load, the two motors work together to achieve a peak torque of up to 2500 N•m, avoiding overheating from a single motor due to overload; when the first motor fails, the controller can quickly switch to the second motor drive to meet the safety requirements of the steering device. Furthermore, the pulley reduction assembly and the worm gear reduction assembly use differentiated transmissions to avoid common fault risks, such as slippage of the two pulleys or jamming of the two worm gears.

[0033] (2) The first motor and the second motor cooperate through redundant control to generate and distribute appropriate steering torque. This torque is transmitted to the pulley reduction assembly-steering screw and the worm gear reduction assembly-steering screw, respectively, thereby driving the steering wheel to rotate and completing the vehicle's steering action. The road feel controller calculates the road feel torque at this time based on the received steering wheel angle signal, steering wheel torque signal and steering wheel angular velocity signal, and converts the calculated road feel torque value into a control signal and transmits it to the road feel motor. The road feel motor transmits the simulated road feel torque to the driver through the steering wheel. At the same time, the road feel controller sends commands to the first motor and the second motor through the steering controller. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the steer-by-wire redundant steering device proposed in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the pulley reduction assembly of the steer-by-wire redundant steering device proposed in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the worm gear reduction assembly of the steer-by-wire redundant steering device proposed in an embodiment of the present invention;

[0037] Figure 4This is a schematic diagram of the gap adjustment component of the steer-by-wire redundant steering device proposed in an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram illustrating the control strategy of the steer-by-wire redundant steering device proposed in an embodiment of the present invention.

[0039] Figure 6 This is a block diagram of the current distribution of the wire-controlled redundant steering device proposed in an embodiment of the present invention.

[0040] The labels in the attached figures are as follows: 1. First motor; 2. Pulley reduction assembly; 21. Driving pulley; 22. Driven pulley; 23. Synchronous belt; 24. Steering nut; 3. Second motor; 4. Worm gear reduction assembly; 41. Worm; 42. Worm gear; 43. Wheel axle; 5. Steering screw; 51. First threaded raceway; 52. Rack; 6. Housing; 7. Clearance adjustment assembly; 71. Pressure block; 72. Pressure plug; 721. Second groove; 73. Spring; 74. Gasket; 75. Slot. Detailed Implementation

[0041] The present application will now be described in further detail with reference to the accompanying drawings and embodiments.

[0042] like Figures 1 to 3 As shown, this embodiment discloses a steer-by-wire redundant steering device, including a steering controller, a first motor 1, a pulley reduction assembly 2, a second motor 3, a worm gear reduction assembly 4, and a steering screw 5. The first motor 1 drives the pulley reduction assembly 2 to rotate, and the second motor 3 drives the worm gear reduction assembly 4 to rotate. The pulley reduction assembly 2 and the worm gear reduction assembly 4 are respectively engaged with the steering screw 5. The steering controller is connected to the first motor 1 and the second motor 3 respectively. When the assist limiting current I of the first motor 1... lim ≥ Target current I g When the steering controller controls the second motor 3 to maintain zero current output; when the first motor's assist limit current I... lim < Target current I g At that time, according to the differential current ΔI=I g -I lim The second motor outputs a compensation current; when the first motor 1 fails, the steering controller switches the second motor 3 as the main drive source. The current I of the first motor 1 is limited by real-time monitoring. lim With target current I g The difference ΔI is used to dynamically adjust the output of the second motor 3, achieving seamless power connection between the two motors, in normal steering I. lim ≥I gWhen only the first motor 1 is working, energy consumption may be reduced by 20% to 30%; under high load, the two motors work together to output peak torque of up to 2500 N•m, avoiding overheating of a single motor due to overload; when the first motor 1 fails, the controller can quickly switch to the second motor 3 for drive, meeting the safety requirements of the steering device. Furthermore, the pulley reduction assembly 2 and the worm gear reduction assembly 4 adopt differentiated transmission to avoid common failure risks, such as slippage of the two pulleys or jamming of the two worm gears 41.

[0043] In this embodiment, as Figure 2 As shown, the pulley reduction assembly 2 includes a driving pulley 21, a driven pulley 22, a timing belt 23, and a steering nut 24. The driving pulley 21 is coaxially and fastened to the output shaft of the first motor 1. The outer peripheral wall of the steering screw 5 has a first threaded raceway 51, and the inner peripheral wall of the steering nut 24 has a second threaded raceway. The first threaded raceway 51 and the second threaded raceway form a helical raceway for the movement of steel balls. The driven pulley 22 is coaxially and fastened to the outer peripheral wall of the steering nut 24. The timing belt 23 is wound around the outer peripheral walls of the driving pulley 21 and the driven pulley 22. The steering nut and the steering screw cooperate through the rolling of steel balls, converting the rotational motion of the steering nut into the linear motion of the steering screw.

[0044] In this embodiment, as Figure 3 As shown, the worm gear reducer assembly 4 includes a worm 41, a worm wheel 42, and a wheel shaft 43. The worm 41 is coaxially and fastened to the output shaft of the second motor 3. One end of the steering screw 5 is provided with the first threaded raceway 51, and the other end of the steering screw 5 is provided with an axially extending rack 52. One end of the wheel shaft 43 meshes with the rack 52, and the other end of the wheel shaft 43 is coaxially and fastened with the worm wheel 42, which meshes with the worm 41. Traditional double-pulley reducer assemblies 2 have the common risks of synchronous belt 23 breakage and slippage; the double worm gear reducer assembly 4 may also experience simultaneous jamming due to lubrication failure. The pulley reduction assembly 2 is suitable for medium and low speed, high precision transmission, with a transmission efficiency of over 95% and low noise; while the worm gear reduction assembly 4 has a high reduction ratio (15:1~25:1) and self-locking characteristics, and can bear greater torque. The pulley reduction assembly 2 is responsible for regular steering assistance, while the worm gear reduction assembly 4 intervenes in emergency high torque demand, providing redundant power and avoiding overload of a single mechanism.

[0045] In this embodiment, as Figure 4As shown, the system also includes a housing 6 disposed on the outer peripheral wall of the steering screw 5. A clearance adjustment assembly 7 is provided on the side of the steering screw 5 opposite to the rack 52. The clearance adjustment assembly 7 includes a pressure block 71, a pressure plug 72, and a spring 73. One end of the pressure block 71 abuts against one side of the steering screw radially, and the other end of the pressure block 71 has a first groove. The pressure plug 72 has a second groove 721. The first groove and the second groove 721 are correspondingly arranged to form a cavity to accommodate the spring 73. The pressure plug 72 is fastened to the housing 6. By adjusting the spring 73 to press the pressure block 71, the pressure block 71 presses against the steering screw 5, thereby adjusting the meshing clearance between the steering screw 5 and the wheel axle 43.

[0046] In this embodiment, as Figure 4 As shown, the pressure block 71 has an arc-shaped groove at one end facing the steering screw 5, and a liner 74 is provided on the surface of the arc-shaped groove. The liner 74 has a matrix of recesses 75 on the side facing the steering screw 5. The liner 74 is made of microporous polyurethane foam. The recesses 75 can distribute stress more evenly, reduce local stress concentration, and thus improve the overall contact performance, effectively compensating for the gap changes between the steering screw 5 and the wheel axle 43.

[0047] In this embodiment, as Figure 5 and 6 As shown, it also includes a road feel simulation system, which comprises a road feel controller, a road feel motor, a torque sensor, a steering angle sensor, and an angular velocity sensor. The angular velocity sensor collects the angular velocity signal of the steering wheel and sends it to the road feel controller; the torque sensor collects the torque signal of the steering wheel and sends it to the road feel controller; the steering angle sensor collects the steering angle signal of the steering wheel and sends it to the road feel controller. The road feel controller is connected to the torque sensor, steering angle sensor, angular velocity sensor, road feel motor, and steering controller. The road feel controller calculates the road feel torque based on the received steering wheel steering angle signal, steering wheel torque signal, and steering wheel angular velocity signal, and converts the calculated road feel torque value into a control signal and transmits it to the road feel motor. The road feel motor transmits the simulated road feel torque to the driver through the steering wheel. Simultaneously, the road feel controller sends commands to the first motor and the second motor through the steering controller, calculates the road feel torque, converts the calculated road feel torque value into a control signal and transmits it to the road feel motor, and the road feel motor transmits the simulated road feel torque to the driver through the steering wheel. The first motor 1 and the second motor 3 cooperate through redundant control to generate and distribute appropriate steering torque. This torque is transmitted to the pulley reduction assembly-steering screw and the worm gear reduction assembly-steering screw, respectively, thereby driving the steering wheels to rotate and completing the vehicle's steering action.

[0048] A steering wheel torque balance equation is established based on the steering wheel torque signal, steering angle signal, and steering wheel angular velocity signal. The steering wheel torque balance equation is as follows:

[0049]

[0050] Among them, T sw For the steering wheel torque, θ sw J is the steering wheel angle. sw B is the moment of inertia of the steering wheel. sw T is the steering wheel damping coefficient. s K is the steering column torque. s For the steering column torque stiffness, θ m1 Road sensor motor rotation angle, G m T is the reduction ratio of the reducer. f The friction torque of the steering wheel, The angular velocity of the steering wheel. This refers to the angular acceleration of the steering wheel.

[0051] The road sensor controller calculates the electromagnetic torque of the road sensor motor:

[0052]

[0053] Among them, T m1 J is the electromagnetic torque of the road induction motor. m1 B is the moment of inertia of the road induction motor. m1 T is the damping coefficient of the induction motor. f1 The frictional torque of the road induction motor, The angular velocity of the road sensor motor. The angular acceleration of the road sensor motor;

[0054] Establish the potential balance equation in the armature winding of the induction motor:

[0055]

[0056] Among them, u a i is the voltage of the armature of the induction motor. a R is the armature current of the induction motor. a K is the resistance of the armature winding of the induction motor. a L is the proportional coefficient of the back electromotive force of the induction motor. a C is the inductance of the armature winding of the induction motor. m The electromagnetic torque coefficient of the induction motor is... The angular velocity of the armature of the road sensor motor;

[0057] Establish the torque balance equation for the first motor:

[0058]

[0059] Among them, T m2 T represents the electromagnetic torque of the first motor. a The assist torque provided by the first motor, J m2 B is the moment of inertia of the first motor. m2 Let θ be the damping coefficient of the first motor. m2 K is the output angle of the first motor. m Let θ be the torque coefficient of the first motor. c i1 is the wheel axle rotation angle, i2 is the reduction ratio of the drive wheel to the driven wheel, and i3 is the reduction ratio of the steering nut to the steering screw. The angular velocity of the first motor is... The angular acceleration of the first motor;

[0060] Establish the torque balance equation for the second motor:

[0061]

[0062] Among them, T m3 T represents the electromagnetic torque of the second motor. a 'The assist torque provided to the second motor, J m3 B is the moment of inertia of the second motor. m3 Let θ be the damping coefficient of the second motor. m3 K is the output angle of the second motor. m ' is the torque coefficient of the second motor, θ c i3 is the wheel-axle rotation angle, i4 is the reduction ratio of the worm gear and worm drive, and i5 is the reduction ratio of the wheel-axle and steering screw drive. The angular velocity of the second motor. This refers to the angular acceleration of the second motor.

[0063] When the assist limiting current I of the first motor lim ≥ Target current I g At that time, the first motor assists the target current I. g1 =I g The second motor assists the target current I g2 =0, the electromagnetic torque T of the second motor m3 and the assist torque T provided by the auxiliary motor a 'All are 0, the electromagnetic torque T of the road induction motor m1 =T m2 When the assist limiting current I of the first motor lim < Target current I g At that time, the first motor assists the target current I. g1 =I limThe steering controller distributes a differential current Δi to the second motor, and the second motor assists the target current I. g2 =ΔI=I g -I lim The second motor outputs electromagnetic torque T m3 T m1 =T m2 + T m3 .

[0064] The steering column is connected to the steering wheel. The torque of the steering column is distributed to the road feel motor, and then distributed to the first motor and the second motor via the steering controller. Specifically, the assist current I of the first motor is used to limit the torque. lim ≥ Target current I g At that time, T s =T m1 =T m2 When the assist limiting current I of the first motor lim < Target current I g At that time, T s =T m1 =T m2 +T m3 .

[0065] It is understood that the specific embodiments described above are merely for explaining the relevant invention and not for limiting the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict with each other. Any equivalent structural transformations made based on the content of this specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of this invention.

Claims

1. A steer-by-wire redundant steering device, characterized in that, The system includes a steering controller, a first motor, a pulley reduction assembly, a second motor, a worm gear reduction assembly, and a steering screw. The first motor drives the pulley reduction assembly to rotate, and the second motor drives the worm gear reduction assembly to rotate. The pulley reduction assembly and the worm gear reduction assembly are respectively engaged with the steering screw. The steering controller is connected to both the first motor and the second motor. When the assist limiting current I of the first motor... lim ≥ Target current I g When the steering controller is engaged, the second motor maintains zero current output; when the first motor's assist limit current I... lim < Target current I g At that time, according to the differential current ΔI=I g -I lim Control the output compensation current of the second motor; when a fault is detected in the first motor, which is in the state of being the main drive source, control the second motor, which is in the state of being the standby motor, to switch to the main drive source. A steering wheel torque balance equation is established based on the steering wheel torque signal, steering angle signal, and steering wheel angular velocity signal. The steering wheel torque balance equation is as follows: Among them, T sw For the steering wheel torque, θ sw J is the steering wheel angle. sw B is the moment of inertia of the steering wheel. sw T is the steering wheel damping coefficient. s K is the steering column torque. s For the steering column torque stiffness, θ m1 Road sensor motor rotation angle, G m T is the reduction ratio of the reducer. f The friction torque of the steering wheel, The angular velocity of the steering wheel. This refers to the angular acceleration of the steering wheel. The road sensor controller calculates the electromagnetic torque of the road sensor motor: Among them, T m1 J is the electromagnetic torque of the road induction motor. m1 B is the moment of inertia of the road induction motor. m1 T is the damping coefficient of the induction motor. f1 The frictional torque of the road induction motor, The angular velocity of the road sensor motor. The angular acceleration of the road sensor motor; Establish the potential balance equation in the armature winding of the induction motor: Among them, u a i is the voltage of the armature of the induction motor. a R is the armature current of the induction motor. a K is the resistance of the armature winding of the induction motor. a L is the proportional coefficient of the back electromotive force of the induction motor. a C is the inductance of the armature winding of the induction motor. m The electromagnetic torque coefficient of the induction motor is... The angular velocity of the armature of the road induction motor; Establish the torque balance equation for the first motor: Among them, T m2 T represents the electromagnetic torque of the first motor. a The assist torque provided by J to the first motor m2 B is the moment of inertia of the first motor. m2 Let θ be the damping coefficient of the first motor. m2 K is the output angle of the first motor. m Let θ be the torque coefficient of the first motor. c i1 is the wheel axle rotation angle, i2 is the reduction ratio of the drive wheel to the driven wheel, and i3 is the reduction ratio of the steering nut to the steering screw. The angular velocity of the first motor is... The angular acceleration of the first motor; Establish the torque balance equation for the second motor: Among them, T m3 T represents the electromagnetic torque of the second motor. a 'The assist torque provided to the second motor, J m3 B is the moment of inertia of the second motor. m3 Let θ be the damping coefficient of the second motor. m3 K is the output angle of the second motor. m ' is the torque coefficient of the second motor, θ c i3 is the wheel-axle rotation angle, i4 is the reduction ratio of the worm gear and worm drive, and i5 is the reduction ratio of the wheel-axle and steering screw drive. The angular velocity of the second motor. This refers to the angular acceleration of the second motor. When the assist limiting current I of the first motor lim ≥ Target current I g At that time, the electromagnetic torque T of the second motor m3 and the assist torque T provided by the auxiliary motor a 'All are 0, the electromagnetic torque T of the road induction motor m1 =T m2 When the assist limiting current I of the first motor lim < Target current I g At that time, the steering controller distributes a differential current Δi to the second motor, and the second motor outputs an electromagnetic torque T. m3 T m1 =T m2 + T m3。 2. The steer-by-wire redundant steering device according to claim 1, characterized in that, The pulley reduction assembly includes a driving pulley, a driven pulley, a timing belt, and a steering nut. The driving pulley is coaxially and fastened to the output shaft of the first motor. The outer peripheral wall of the steering screw is provided with a first threaded raceway, and the inner peripheral wall of the steering nut is provided with a second threaded raceway. The first threaded raceway and the second threaded raceway form a spiral raceway for the movement of steel balls. The driven pulley is coaxially and fastened to the outer peripheral wall of the steering nut, and the timing belt is wound around the outer peripheral walls of the driving pulley and the driven pulley.

3. The steer-by-wire redundant steering device according to claim 2, characterized in that, The worm gear reducer assembly includes a worm, a worm wheel, and a wheel shaft. The worm is coaxially and fastened to the output shaft of the second motor. One end of the steering screw is provided with the first threaded raceway, and the other end of the steering screw is provided with an axially extending rack. One end of the wheel shaft meshes with the rack, and the other end of the wheel shaft is coaxially and fastened with the worm wheel, which meshes with the worm.

4. The steer-by-wire redundant steering device according to claim 3, characterized in that, It also includes a housing disposed on the outer peripheral wall of the steering screw, and a clearance adjustment assembly is provided on the side of the steering screw away from the rack. The clearance adjustment assembly includes a pressure block, a pressure plug and a spring. The pressure plug is fastened to the housing. One end of the spring abuts against the pressure block and the other end of the spring abuts against the pressure plug. One end of the pressure block abuts against one side of the steering screw radially.

5. The steer-by-wire redundant steering device according to claim 4, characterized in that, The pressure block has a first groove, and the pressure plug has a second groove. The first groove and the second groove are respectively arranged to form a cavity to accommodate the spring, and the spring is in a compressed state in the cavity.

6. The steer-by-wire redundant steering device according to claim 4, characterized in that, The pressure block has an arc-shaped groove at one end facing the steering screw, the surface of the arc-shaped groove is provided with a pad, and the side of the pad facing the steering screw has a matrix of grooves.

7. The steer-by-wire redundant steering device according to claim 1, characterized in that, It also includes a road feel simulation system, which comprises a road feel controller, a road feel motor, a torque sensor, a steering angle sensor, and an angular velocity sensor. The angular velocity sensor is used to collect the angular velocity signal of the steering wheel and send it to the road feel controller; The torque sensor is used to collect the torque signal from the steering wheel and send it to the road feel controller; The steering angle sensor is used to collect the steering wheel angle signal and send it to the road feel controller; The road feel controller is connected to the torque sensor, steering angle sensor, angular velocity sensor, road feel motor, and steering controller. The road feel controller calculates the road feel torque based on the received steering wheel angle signal, steering wheel torque signal, and steering wheel angular velocity signal, and converts the calculated road feel torque value into a control signal and transmits it to the road feel motor. The road feel motor transmits the simulated road feel torque to the driver through the steering wheel. At the same time, the road feel controller sends commands to the first motor and the second motor through the steering controller.

Images