Magnetorheological fluid automobile steer-by-wire road feel simulator and control method

Abstract

The application discloses a kind of magnetorheological fluid's automobile steer-by-wire road feel simulator and control method, automobile steer-by-wire road feel simulator includes feedback module, transmission module and control module;Feedback module includes cylinder body, stressed plate, piston and first to third induction coil;Transmission module includes inner ring gear, first to second rack, outer ring gear, first to third planetary gear and planet carrier;Control module is used to control the current size of first induction coil, second induction coil, third induction coil according to external instruction, and then adjust the size of feedback force generated by feedback module.The application improves the road feel simulation of steer-by-wire, improves steering safety.

Description

TECHNICAL FIELD

[0001] The application relates to a road feeling simulator for a steer-by-wire system of an automobile. BACKGROUND

[0002] With the rapid development of automobile electrification, intelligence and networking, the steer-by-wire technology has been applied, which is an important link in the development of automobiles. Road feeling is an important part of feedback information in the driving process and has an important influence on driving safety. Compared with traditional steering, the steer-by-wire system cannot directly receive information from the road, so a device is needed to simulate road feeling.

[0003] Li Jing et al. designed a steer-by-wire hydraulic steering system (patent number 201710291027.4). In order to cancel the road feeling motor for simulating road feeling, a linear pressure regulating valve is used to realize road feeling simulation during steering. When the steering system is working, the electronic control unit (ECU) controls the pressure and flow of the linear pressure regulating valve, so that the linear pressure regulating valve presents different damping characteristics, thereby being able to produce various road feeling simulation. In addition, by using two pull pressure sensors, feedback control of road feeling simulation can be realized. However, due to the use of hydraulic mode, the real-time performance of road feeling feedback has certain defects, and sometimes there is a certain lag in response.

[0004] Wang Daoming et al. designed an automobile steer-by-wire road feeling simulation device and a control method thereof (patent number 202010069514.8). The device includes a mechanical transmission mechanism and an information acquisition and control mechanism. A magneto-rheological damper, an output coupling, an electromagnetic clutch, a pinion, a second coupling, a torque sensor, a first coupling and a steering wheel common center shaft are sequentially connected. The pinion is connected to the output shaft of the electromagnetic clutch to form a road feeling simulation mechanism. The simulation of road feeling mainly comes from the magneto-rheological damper. The damping that can be generated by the magneto-rheological damper has a certain upper limit, and may cause danger in special situations.

[0005] He Denguan et al. designed a road feeling simulation device for a steer-by-wire system and a control method thereof (patent number 202210777016.8). The device includes a steering column, a torque and angle sensor, a speed reducer, and a motor and a controller connected in sequence. The controller controls the road feeling motor to output a target torque to realize real-time road feeling simulation of the vehicle during driving. However, the device has a complex structure, and the control of the road feeling motor required for steering road feeling simulation is complex, and the performance requirements for the motor are high.

[0006] Yang Xiaofeng et al. designed a kind of steer-by-wire system based on hydraulic inertial damper (patent number 201710484112.2), which integrates magneto-rheological fluid in hydraulic inertial damper. By changing the magnetic induction intensity around the hydraulic inertial damper, the viscosity of the magneto-rheological fluid is changed, so as to adjust the damping force of the hydraulic inertial damper. The road feel simulation of steering inertia is realized by using the dynamic inertia effect of the hydraulic inertial damper. The device uses the extrusion mode in the magneto-rheological fluid, which can provide damping, but the damping force is large and the adjustment is difficult. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a kind of automobile steer-by-wire road feel simulator and control method of magneto-rheological fluid for the defects involved in the background art.

[0008] The present application adopts the following technical solutions to solve the above technical problems:

[0009] A kind of automobile steer-by-wire road feel simulator of magneto-rheological fluid, including feedback module, transmission module and control module;

[0010] The feedback module includes cylinder body, stress plate, piston and first to third induction coils;

[0011] The first cavity, the second cavity and the third cavity are arranged in the cylinder body, wherein the first cavity is a horizontally arranged cylinder, the second cavity is a cuboid with the lower end surface parallel to the axis of the first cavity, and the third cavity is a cylinder coaxial with the first cavity and surrounding the first cavity;And the cylinder body is provided with a first channel and a second channel corresponding to the two ends of the lower end surface of the second cavity at both ends of the first cavity;The first cavity, the second cavity, the first channel and the second channel are filled with magneto-rheological fluid;

[0012] The cylinder body is symmetrically provided with a first sliding hole and a second sliding hole matched with the stress plate at both ends of the second cavity;The two ends of the stress plate pass out of the first sliding hole and the second sliding hole respectively, and are in sealed sliding connection with the cylinder body, which can freely slide along the first sliding hole and the second sliding hole;The stress plate is located on the axis of the second cavity and parallel to the lower end surface of the second cavity;

[0013] The cylinder body is provided with a third sliding hole matched with the piston rod of the piston at the center of one end of the first cavity;The piston is arranged in the first cavity, and the piston head and the first cavity are matched with each other, and the piston rod passes out of the third sliding hole to the outside of the cylinder body and is in sealed sliding connection with the cylinder body;

[0014] The first induction coil and the second induction coil are symmetrically arranged on the upper end surface and the lower end surface of the second cavity with respect to the stress plate, forming an induction coil group for generating a magnetic field force perpendicular to the stress plate;

[0015] The third induction coil is arranged in the third cavity and wound outside the second cavity, and is used for generating a magnetic field force parallel to the piston rod.

[0016] The transmission module comprises an inner gear ring, first and second gear racks, an outer gear ring, first and third planetary gears, and a planet carrier.

[0017] The inner gear ring is arranged on the steering column of the automobile and coaxially fixed to the steering column of the automobile.

[0018] The planet carrier is fixed to the automobile frame and used for mounting the first and third planetary gears.

[0019] The first and third planetary gears are uniformly arranged between the inner gear ring and the outer gear ring in the circumferential direction and respectively mesh with the outer teeth of the inner gear ring and the inner teeth of the outer gear ring.

[0020] The first and second gear racks are arranged on the same side of the cylinder body, wherein the first gear rack is rigidly connected to one end of the force receiving plate, the second gear rack is rigidly connected to the piston rod of the piston, and the first and second gear racks are parallel to the axis of the first cavity; the teeth on the first and second gear racks are opposite to each other, and the first and second gear racks are meshed with the outer teeth of the outer gear ring.

[0021] The control module is used for controlling the current size of the first, second and third induction coils according to external instructions.

[0022] The application further discloses a control method of the automobile steer-by-wire road feel simulator.

[0023] Step 1) calculating the current size i of the first and second induction coils when the automobile steer-by-wire road feel simulator generates a preset steering wheel feedback torque threshold value.

[0024] Step 2) adjusting the current of the first and second induction coils when the control module receives a return torque M generated by the automobile. Wherein, L e is the effective magnetic circuit length, η is the transmission efficiency of the steering system, D is the diameter of the steering wheel, i w is the transmission ratio, K is the dynamic yield stress coefficient, N is the number of turns of the induction coil, and A is the upper and lower surface area of the force receiving plate.

[0025] Step 3) controlling the current of the third induction coil to be maximum when the control module receives an alarm signal.

[0026] Compared with the prior art, the application has the following technical effects:

[0027] 1. Simple structure: the planetary gear mechanism is installed on the steering column, and the cylinder is connected with the planetary gear mechanism through special design, so that the connection is simple, and the overall structure is compact.

[0028] 2. Simple control: the ECU only needs to convert the collected return torque to obtain the resistance required by the simulated road feeling, and then control the current size of the inductor to obtain different resistances.

[0029] 3. Good real-time performance: the magneto-rheological fluid can achieve millisecond response time under the action of the magnetic field, and the ECU can generate resistance as long as the coil is powered on. For the change of road feeling, the ECU can obtain different resistances by constantly changing the size of the current.

[0030] 4. High safety: by providing adjustable steering torque feedback, the driver's driving experience is provided, thereby reducing the probability of driver error. When there is a driving risk in the state of the driver, the vehicle steer-by-wire road feeling simulator sends an alarm signal to provide a large resistance to the steering column to avoid the danger of hitting the steering wheel hard. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structure diagram of a magneto-rheological fluid vehicle steer-by-wire road feeling simulator of the application.

[0032] In the figure, 1-cylinder, 2-stress plate, 3-piston head of piston, 4-piston rod of piston, 5-first inductor, 6-second inductor, 7-third inductor, 8-inner ring gear, 9-outer ring gear, 10-first planetary gear, 11-carrier, 12-first rack, 13-second rack, 14-control module. DETAILED DESCRIPTION

[0033] The technical solutions of the application will be further described in detail below in combination with the drawings:

[0034] The application can be implemented in many different forms, and should not be considered limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete, and to fully convey the scope of the application to those skilled in the art. In the drawings, the components are enlarged for clarity.

[0035] It should be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components and / or parts, these elements, components and / or parts are not limited by these terms. These terms are only used to distinguish one element, component and / or part from another. Therefore, the first element, component and / or part discussed below can become the second element, component or part without departing from the teaching of the application.

[0036] As Figure 1The application discloses a kind of automobile steer-by-wire road feel simulators of magnetorheological fluid, including feedback module, transmission module and control module.

[0037] The feedback module includes a cylinder, a force plate, a piston, and first to third induction coils.

[0038] The cylinder is provided with airtight first, second and third cavities, wherein the first cavity is a horizontally arranged cylinder, the second cavity is a cuboid with its lower end surface parallel to the axis of the first cavity, and the third cavity is a cylinder coaxial with the first cavity and surrounding the first cavity; the cylinder is provided with a first channel and a second channel at both ends of the first cavity, respectively, which are in communication with both ends of the lower end surface of the second cavity; the first cavity, the second cavity, the first channel and the second channel are filled with magnetorheological fluid.

[0039] The cylinder is symmetrically provided with a first sliding hole and a second sliding hole at both ends of the second cavity, which cooperate with the force plate; the two ends of the force plate pass through the first sliding hole and the second sliding hole, respectively, and are in airtight sliding connection with the cylinder, allowing free sliding along the first sliding hole and the second sliding hole; the force plate is located on the axis of the second cavity and parallel to the lower end surface of the second cavity.

[0040] The cylinder is provided with a third sliding hole at the center of one end of the first cavity, which cooperates with the piston rod of the piston; the piston is arranged in the first cavity, and the piston head and the first cavity cooperate with each other, and the piston rod passes out of the third sliding hole to the outside of the cylinder and is in airtight sliding connection with the cylinder.

[0041] The first and second induction coils are symmetrically arranged on the upper and lower end surfaces of the second cavity with respect to the force plate, forming an induction coil group for generating a magnetic field perpendicular to the force plate.

[0042] The third induction coil is arranged in the third cavity and wound around the second cavity to generate a magnetic field parallel to the piston rod.

[0043] The transmission module includes an inner ring gear, first and second racks, an outer ring gear, first to third planetary gears, and a planet carrier.

[0044] The inner ring gear is arranged on the steering column of the automobile and is coaxially fixed to the steering column.

[0045] The planet carrier is fixed to the automobile frame for mounting the first to third planetary gears.

[0046] The first to third planetary gears are uniformly arranged between the inner ring gear and the outer ring gear in a circumferential direction and are respectively engaged with the outer teeth of the inner ring gear and the inner teeth of the outer ring gear.

[0047] The first rack and the second rack are arranged on the same side of the cylinder body, wherein one end of the first rack is rigidly connected with the force receiving plate, the second rack is rigidly connected with the piston rod of the piston, and the first rack and the second rack are parallel to the axis of the first cavity; the teeth on the first rack and the second rack are opposite, and the first rack and the second rack are in mesh with the external teeth of the external gear ring.

[0048] The control module is used for controlling the current size of the first induction coil, the second induction coil and the third induction coil according to external instructions.

[0049] The application further discloses a control method of the automobile steer-by-wire road feel simulator.

[0050] Step 1) calculating the current size i of the first induction coil and the second induction coil when the automobile steer-by-wire road feel simulator generates a preset steering wheel feedback torque threshold value;

[0051] Step 2) adjusting the current of the first induction coil and the second induction coil when the control module receives a return torque M generated by the automobile Wherein, L e is the effective magnetic circuit length, η is the transmission efficiency of the steering system, D is the diameter of the steering wheel, i w is the transmission ratio, K is the dynamic yield stress coefficient, N is the number of turns of the induction coil, and A is the upper and lower surface area of the force receiving plate.

[0052] Step 3) controlling the current of the third induction coil to be maximum when the control module receives an alarm signal.

[0053] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined.

[0054] The above specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A magneto-rheological fluid based steer-by-wire road feel simulator for a vehicle, characterized in that, The feedback module, the transmission module and the control module are included. The feedback module includes a cylinder, a force receiving plate, a piston, and first to third induction coils. The cylinder is provided with airtight first, second and third cavities, wherein the first cavity is a horizontally arranged cylinder, the second cavity is a cuboid with its lower end surface parallel to the axis of the first cavity, and the third cavity is a cylinder coaxial with the first cavity and surrounding the first cavity; the cylinder is provided with first and second passages at both ends of the first cavity, respectively, which are in communication with both ends of the lower end surface of the second cavity; the first cavity, the second cavity, the first passage and the second passage are filled with magnetorheological fluid; The cylinder is symmetrically provided with first and second sliding holes at both ends of the second cavity, which are matched with the force receiving plate; the force receiving plate is provided with two ends which pass through the first and second sliding holes, respectively, and is in airtight sliding connection with the cylinder, so as to be freely slidable along the first and second sliding holes; the force receiving plate is located on the axis of the second cavity and parallel to the lower end surface of the second cavity; The cylinder is provided with a third sliding hole at the center of one end of the first cavity, which is matched with the piston rod of the piston; the piston is arranged in the first cavity, and the piston head and the first cavity are matched with each other, and the piston rod passes out of the third sliding hole to the outside of the cylinder and is in airtight sliding connection with the cylinder; The first and second induction coils are symmetrically arranged on the upper and lower end surfaces of the second cavity with respect to the force receiving plate, forming an induction coil group, for generating a magnetic field force perpendicular to the force receiving plate; The third induction coil is arranged in the third cavity and wound around the second cavity, for generating a magnetic field force parallel to the piston rod; The transmission module includes an inner gear ring, first and second racks, an outer gear ring, first to third planetary gears, and a planet carrier; The inner gear ring is arranged on the steering column of the automobile and is coaxially fixed to the steering column of the automobile; The planet carrier is fixed to the automobile frame and is used for mounting the first to third planetary gears; The first to third planetary gears are uniformly arranged between the inner gear ring and the outer gear ring in a circumferential direction, and are respectively engaged with the outer teeth of the inner gear ring and the inner teeth of the outer gear ring; The first and second racks are arranged on the same side of the cylinder, wherein one end of the first rack is rigidly connected to the force receiving plate, and the piston rod of the piston is rigidly connected to the second rack; the first and second racks are parallel to the axis of the first cavity; the teeth on the first and second racks are opposite to each other, and the first and second racks are engaged with the outer teeth of the outer gear ring; The control module is used for controlling the current size of the first, second and third induction coils according to external instructions.

2. The control method of the MR fluid-based steer-by-wire road-feel simulator for a vehicle according to claim 1, characterized by The steps include: Step 1), calculating the current size i of the first and second induction coils when the steer-by-wire road feel simulator generates a preset steering wheel feedback torque threshold value; Step 2), when the control module receives the positive torque M generated by the car, the current of the first and second induction coils is adjusted wherein L e is the effective magnetic circuit length, η is the transmission efficiency of the steering system, D is the steering wheel diameter, i w is the transmission ratio, K is the dynamic yield stress coefficient, N is the number of turns of the induction coil, and A is the upper and lower surface area of the force plate; Step 3), when the control module receives an alarm signal, the current of the third induction coil is controlled to be maximum.

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