CN113232722B - Control method and control system of wire-controlled steering system and motor vehicle - Google Patents

Control method and control system of wire-controlled steering system and motor vehicle Download PDF

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Publication number
CN113232722B
CN113232722B CN202110600875.5A CN202110600875A CN113232722B CN 113232722 B CN113232722 B CN 113232722B CN 202110600875 A CN202110600875 A CN 202110600875A CN 113232722 B CN113232722 B CN 113232722B
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steering
steering wheel
torque
feedback
angle
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CN113232722A (en
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王希珂
郭振杰
孙启明
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Beijing Ruiyada Technology Co ltd
Zibo Vocational Institute
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Beijing Ruiyada Technology Co ltd
Zibo Vocational Institute
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/008—Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention discloses a control method and a control system of a wire-controlled steering system and a motor vehicle, and relates to the technical field of automobile steering systems, wherein the control method comprises the steps of acquiring steering data and driving data in an artificial road feel feedback driving mode; the steering data includes a steering torque of the steering shaft and a steering wheel angle of the steering wheel; the travel data includes a travel speed of the vehicle; driving the steering wheel to steer according to the steering wheel angle; calculating a feedback torque according to the vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to the road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; the vehicle dynamic model is a virtual simulation model of the vehicle; and driving the steering wheel to be aligned according to the aligning torque. The invention can achieve the aim of simulating the aligning moment.

Description

Control method and control system of wire-controlled steering system and motor vehicle
Technical Field
The invention relates to the technical field of automobile steering systems, in particular to a control method and a control system of a wire-controlled steering system and a motor vehicle.
Background
The steering-by-wire System (SBW) comprises three main parts, namely a steering wheel assembly, a steering execution assembly and a main controller (ECU), and an automatic failure prevention system, a power supply and other auxiliary systems.
The steer-by-wire system aims to cancel a mechanical transmission structure between a steering wheel and a steering wheel, and drive the steering wheel to steer by controlling a steering motor, thereby realizing the steering of a vehicle. Because a mechanical transmission structure between the steering wheel and the steering wheel is cancelled, a driver cannot obtain the aligning moment fed back to the steering wheel from the road surface. However, in some driving scenarios, the driver still needs to determine the road condition according to the aligning torque, and then perform corresponding operations. Therefore, how to simulate the aligning moment is one direction of current research.
Disclosure of Invention
The invention aims to provide a control method and a control system of a wire-controlled steering system and a motor vehicle, so as to achieve the aim of simulating a aligning moment.
In order to achieve the purpose, the invention provides the following scheme:
a control method of a steer-by-wire system, comprising:
acquiring steering data and driving data under an artificial road feel feedback driving mode; the steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the travel data includes a travel speed of the vehicle; the steering torque is measured by a torque sensor, the steering wheel angle is measured by a first steering angle sensor, and the running speed is measured by a speed sensor;
driving a steering wheel to steer according to the steering wheel angle;
calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to a road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle;
and driving the steering wheel to be aligned according to the aligning moment.
Optionally, the calculating a feedback torque according to the vehicle dynamics model, the steering data, and the driving data specifically includes:
calculating a feedback moment estimated value according to the vehicle dynamic model and the steering wheel angle;
and calculating the feedback torque according to the feedback torque estimated value, the steering torque and the running speed.
Optionally, the calculating the feedback torque according to the estimated feedback torque value, the steering torque, and the driving speed specifically includes:
calculating a feedback torque target value according to the feedback torque estimated value and the running speed;
and calculating the feedback torque according to the feedback torque target value and the steering torque.
Optionally, the calculating a feedback torque estimated value according to the vehicle dynamics model and the steering wheel angle specifically includes:
calculating the steering angle of the steering wheel according to the steering wheel angle; the steering angle comprises a steering angle of a left front steering wheel and a steering angle of a right front steering wheel;
according to the formula
Figure BDA0003092880990000021
Calculating the feedback moment estimated value;
wherein, the
Figure BDA0003092880990000022
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr The lateral force of the right front steering wheel is determined according to the steering angle of the left front steering wheel, and the lateral force of the right front steering wheel is determined according to the steering angle of the right front steering wheel; n is K Is a virtual kingpin front finger; n is R Is the virtual lateral force back offset.
Optionally, the calculating a feedback torque target value according to the feedback torque estimated value and the driving speed specifically includes:
according to the formula
Figure BDA0003092880990000023
Calculating a feedback moment target value by reverse deduction;
wherein, the
Figure BDA0003092880990000024
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the M is i The feedback torque target value is obtained;
acquiring a torque value of the steering support arm; the torque value is acquired through a strain gauge type torque sensor, the strain gauge type torque sensor comprises two strain gauges, and the two strain gauges are installed on the steering support arm in a crossed mode;
and correcting the feedback torque target value according to the torque value.
Optionally, the calculating the feedback torque according to the feedback torque target value and the steering torque specifically includes:
calculating an absolute value of a difference between the corrected target value of the feedback torque and the steering torque;
if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage;
if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback moment determined in the previous stage and the set step length as the feedback moment corresponding to the current stage;
and if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
Optionally, the method further includes:
in an automatic driving mode, transmitting the steering wheel angle information sent by the vehicle control unit to a steering motor control module in the steer-by-wire system; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
the steering motor control module is used for controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the corner feedback signal of the last stage; the rotation angle feedback signal is acquired by a sensor arranged on an output shaft of the second planetary gear speed reducing mechanism; the second planetary gear speed reducing mechanism is arranged on the steering wheel assembly.
Optionally, the controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the last-stage corner feedback signal specifically includes:
determining a steering wheel steering instruction of the current stage according to the steering wheel angle information and the steering angle feedback signal corresponding to the previous stage, and sending the steering wheel steering instruction to a steering motor in a steer-by-wire system;
the steering motor is used for driving the planetary gear speed reducing mechanism to work according to the steering wheel steering instruction, and the work comprises that an output shaft of the planetary gear speed reducing mechanism drives the steering support arm to move so as to drive the steering wheel to steer and/or return to the right.
Optionally, the method further includes:
acquiring the steering wheel angle information of a steering wheel in an artificial non-road feel feedback driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
and driving the steering wheel to steer and/or return to the right according to the steering wheel angle information.
A control system of a steer-by-wire system, comprising:
the acquisition module is used for acquiring steering data and driving data in an artificial road feel feedback driving mode; the steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the travel data includes a travel speed of the vehicle; the acquisition module comprises a torque sensor, a first rotation angle sensor and a speed sensor; the steering torque is measured by the torque sensor, the steering wheel angle is measured by the first steering angle sensor, and the running speed is measured by the speed sensor;
the steering wheel control module is used for driving the steering wheel to steer according to the steering wheel angle;
the steering wheel control module is used for calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data and sending the feedback torque to a road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle;
and the steering wheel control module is used for driving the steering wheel to be aligned according to the aligning torque.
Optionally, in the aspect of calculating the feedback torque according to the vehicle dynamics model, the steering data, and the driving data, the steering wheel control module is specifically configured to:
calculating a feedback moment estimated value according to the vehicle dynamic model and the steering wheel angle;
and calculating the feedback torque according to the feedback torque estimated value, the steering torque and the running speed.
Optionally, in the aspect of calculating the feedback torque according to the estimated feedback torque value, the steering torque, and the driving speed, the steering wheel control module is specifically configured to:
calculating a feedback torque target value according to the feedback torque estimated value and the running speed;
and calculating the feedback torque according to the feedback torque target value and the steering torque.
Optionally, in the aspect of calculating the feedback torque estimated value according to the vehicle dynamics model and the steering wheel angle, the steering wheel control module is specifically configured to:
calculating the steering angle of the steering wheel according to the steering wheel angle; the steering angle comprises a steering angle of a left front steering wheel and a steering angle of a right front steering wheel;
according to the formula
Figure BDA0003092880990000051
Calculating the feedback moment estimated value;
wherein, the
Figure BDA0003092880990000052
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr For turning right forwardsA lateral force to the front wheels, and the lateral force of the front left steering wheel is determined according to the steering angle of the front left steering wheel, and the lateral force of the front right steering wheel is determined according to the steering angle of the front right steering wheel; n is K Is a virtual kingpin front finger; n is R Is the virtual lateral force back offset.
Optionally, in terms of calculating a feedback torque target value according to the feedback torque estimated value and the driving speed, the steering wheel control module is specifically configured to:
according to the formula
Figure BDA0003092880990000053
Calculating a feedback moment target value by reverse deduction;
wherein, the
Figure BDA0003092880990000054
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the M is i The feedback torque target value is obtained;
acquiring a torque value of the steering support arm; the torque value is acquired through a strain gauge type torque sensor, the strain gauge type torque sensor comprises two strain gauges, and the two strain gauges are installed on the steering support arm in a crossed mode;
and correcting the feedback torque target value according to the torque value.
Optionally, the feedback torque includes a feedback torque corresponding to the current stage; in the aspect of calculating the feedback torque according to the feedback torque target value and the steering torque, the steering wheel control module is specifically configured to:
calculating an absolute value of a difference between the corrected target value of the feedback torque and the steering torque;
if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage;
if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback moment determined in the previous stage and the set step length as the feedback moment corresponding to the current stage;
and if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
Optionally, the control system is provided with a first torque transmission path;
the devices involved in the first torque transmission path include a steering shaft, a gear transmission mechanism, the torque sensor mounted on the steering shaft, the first angle sensor mounted near the gear transmission mechanism, the speed sensor provided on the vehicle, a first planetary gear reduction mechanism, a worm gear transmission mechanism, the steering wheel control module, a road feel motor, and a steering motor control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm mounted on each steering wheel assembly;
the steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor, the torque sensor and the speed sensor are all connected with the steering wheel control module;
the steering wheel is connected with the first planetary gear speed reducing mechanism through the steering shaft;
the first planetary gear speed reducing mechanism is also connected with the worm gear and worm transmission mechanism;
the steering wheel control module is connected with the worm and gear transmission mechanism through the road sensing motor; the steering wheel control module is connected with the steering support arm sequentially through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism; the steering support arm is used for driving the steering wheel to rotate;
the steering shaft is used for keeping torque balance and generating steering torque under the action of steering torque input by the steering wheel and resisting torque input by the worm gear and worm transmission mechanism;
the road sensing motor is used for driving the worm gear and worm transmission mechanism to rotate so as to feed the aligning torque determined by the road sensing motor according to the feedback torque back to the steering wheel through the worm gear and worm transmission mechanism.
Optionally, the steering wheel control module is configured to send steering wheel angle information issued by the vehicle control unit to a steering motor control module in the steer-by-wire system in the automatic driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
the steering motor control module is used for controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the corner feedback signal of the last stage; the rotation angle feedback signal is acquired by a sensor arranged on an output shaft of the planetary gear speed reducing mechanism; the planetary gear speed reducing mechanism is arranged on the steering wheel assembly.
Optionally, the control system is provided with a second torque transmission path; the devices involved in the second torque transmission path include the steering wheel control module, and the steering motor control module, steering motor, second planetary gear reduction mechanism, steering support arm, and second rotation angle sensor mounted on each steering wheel;
the steering wheel control module is connected with the steering motor control module;
the steering motor control module is also connected with the steering motor; an output shaft of the steering motor is connected with the second planetary gear speed reducing mechanism; an output shaft of the second planetary gear speed reducing mechanism is connected with the steering support arm; the steering support arm is arranged on the steering wheel; the second rotational angle sensor is provided on an output shaft of the second planetary gear reduction mechanism.
Optionally, the obtaining module is configured to obtain the steering wheel angle information of the steering wheel in an artificial road-feel-free feedback driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
and the steering wheel control module is used for driving the steering wheel to steer and/or return to the right according to the steering wheel angle information.
Optionally, the control system is provided with a third torque transmission path;
the devices involved in the third torque transmission path include a steering shaft, a gear transmission, the first rotation angle sensor mounted in the vicinity of the gear transmission, the steering wheel control module, and a steering motor control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm mounted on each steering wheel assembly;
the steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor is connected with the steering wheel control module;
the steering wheel control module is connected with the steering support arm sequentially through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism; the steering support arm is used for driving the steering wheel to rotate.
A motor vehicle includes a control system for a steer-by-wire system.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a control method and a control system of a wire-controlled steering system and a motor vehicle, wherein in a manual road feel feedback driving mode, a vehicle dynamic model and a sensing signal detected by a sensor can be combined to calculate a feedback torque, and a road feel motor provides a corresponding aligning torque for a steering wheel according to the feedback torque so as to simulate the aligning torque generated by the vehicle in the driving process; thus, even if the steer-by-wire system is used and the mechanical transmission structure between the steering wheel and the steered wheels is eliminated, the driver can obtain the aligning moment which is fed back to the steering wheel from the road surface.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a block diagram of a control system of a steer-by-wire system of the present invention;
FIG. 2 is a flow chart illustrating a control method of the steer-by-wire system of the present invention;
FIG. 3 is a schematic view of the overall construction of the steer-by-wire system and control system of the present invention;
FIG. 4 is a schematic flow chart of a feedback torque calculation method according to the present invention;
FIG. 5 is a schematic view of a strain gage assembly according to the present invention;
FIG. 6 is a schematic diagram of a strain gage bridge circuit of the present invention;
FIG. 7 is an interactive view of the control system of the present invention with a steer-by-wire system;
FIG. 8 is a flowchart illustrating a method of controlling a steer-by-wire system according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a control method and a control system of a wire-controlled steering system and a motor vehicle, so as to achieve the aim of simulating aligning torque.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The control method and the control system can be exemplarily applied to a motor vehicle and used for controlling the operation of a steer-by-wire system in the motor vehicle. Besides, the control method and the control system can be used for controlling the steer-by-wire system for other application scenes using the steer-by-wire system besides the motor vehicle.
It should be noted that the steer-by-wire system itself also has a control function, and the control system can be a component of the control function of the steer-by-wire system itself, or can be independent of the steer-by-wire system.
Unless otherwise stated, the control method and the control system will be described hereinafter with reference to a motor vehicle as an example.
The control method and the control system can work in at least one working mode, for example, the control system can work in a manual road feel feedback driving mode, in which a driver drives manually, and the control system is cooperated with other devices of the motor vehicle to simulate a aligning moment.
The application scenarios of the artificial road feel feedback driving mode exemplarily include:
when the road condition is complex and the driving speed is high, in order to ensure the maneuverability, a proper aligning moment needs to be provided for the steering wheel, and at the moment, the manual road feel feedback driving mode can be selected. The basis for selecting the artificial road feel feedback driving mode can comprise the following steps:
firstly, prompting an artificial road feel feedback driving mode by a driver according to a driving road condition or navigation software;
and secondly, automatically selecting an artificial road feel feedback driving mode according to the feedback information of the navigation software.
Referring to fig. 1, the control system may exemplarily include: an acquisition module 100 and a steering wheel control module 110.
The obtaining module 100 may be configured to obtain steering data and driving data required for simulating a aligning torque. In one example, the acquisition module 100 includes sensors that collect steering data and sensors that collect travel data; in another example, the acquisition module 100 may include a communication device in communication with the sensors to receive steering data and driving data collected by the sensors.
The steering wheel control module 110 may be mainly used to calculate a feedback torque according to the steering data and the driving data in the artificial road feel feedback driving mode. The feedback torque can be sent to a road sensing motor in the steer-by-wire system, and the road sensing motor provides corresponding aligning torque for the steering wheel, so that the aim of simulating the aligning torque is fulfilled.
The steering wheel control module 110 may specifically include an ECU in a steer-by-wire system, which may be a separate device, and may also be a main ECU of the vehicle or another ECU performing its function. Those skilled in the art can design flexibly according to the needs, and detailed description is omitted here.
The use of the above-described module will be described in detail later herein in connection with a control method.
Example one
The present embodiment provides a control method of a steer-by-wire system, as shown in fig. 2, which exemplarily includes:
step 201: and acquiring steering data and driving data under the artificial road feel feedback driving mode.
The steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the running data includes a running speed of the vehicle.
Step 201 may be performed by the aforementioned obtaining module 100.
Wherein the steering torque is measured by a torque sensor, the steering wheel angle is measured by a first angle sensor, and the running speed is measured by a speed sensor.
In one example, the acquisition module 100 may include the various sensors described above.
In another example, the acquisition module 100 includes a communication device that can interact with the sensors described above to acquire data collected by each sensor.
Step 202: and driving the steering wheel to steer according to the steering wheel angle.
The specific implementation process comprises the following steps:
the steering wheel control module 110 issues the steering wheel angle to a steering motor control module in the steer-by-wire system, and the steering motor control module drives the steering wheel to rotate according to the steering wheel angle.
Step 203: and calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to a road sensing motor.
The road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle.
Step 203 may be performed by the steering wheel control module 110 as previously described.
Step 204: and driving the steering wheel to be aligned according to the aligning moment.
The specific implementation process comprises the following steps:
in step 203, the aligning torque is acted on the steering wheel so as to rotate the steering wheel; then the first rotating angle sensor acquires the rotating angle of the steering wheel, namely the rotating angle of the return rotating wheel; the steering wheel control module 110 sends the acquired angle of the return turning wheel to a steering motor control module in the steer-by-wire system, and the steering motor control module drives the steering wheel to return according to the angle of the return turning wheel.
Therefore, in the embodiment, in the manual road feel feedback driving mode, a vehicle dynamic model and a sensing signal detected by a sensor can be combined to calculate a feedback moment, and a road feel motor provides a corresponding aligning moment for a steering wheel according to the feedback moment so as to simulate the aligning moment generated by a vehicle in the driving process; thus, even if the steer-by-wire system is used and the mechanical transmission structure between the steering wheel and the steered wheels is eliminated, the driver can obtain the aligning moment which is fed back to the steering wheel from the road surface.
Example two
FIG. 3 illustrates an exemplary architecture of a steer-by-wire system and control system:
wherein, steer-by-wire system includes: the steering wheel 1, the steering shaft 2, the gear transmission mechanism 3, the vehicle control unit 6, the first spline hub 701, the planet carrier 702, the gear ring 703, the second spline hub 704, the sun gear 705, the planet gear 706, the movable turbine 801, the driving worm 802, the road sensing motor 9, the CAN communication bus 10, the steering motor control module 11, the steering motor 12, the second planet gear speed reducing mechanism 13, the steering support arm 14 and the strain gauge type torque sensor 15.
The control system may then include: a first angle of rotation sensor 305, a torque sensor 4, a steering wheel control module 5 and a speed sensor.
Of course, it has been mentioned above that the control system may be a component of the control function of the steer-by-wire system itself, and therefore, fig. 3 may also be considered to show an exemplary architecture of the steer-by-wire system.
Based on the above framework, in the process of steering operation controlled and executed by the driver, the devices cooperate with each other to realize the following processes of 'steering the steering wheel according to the steering wheel angle' and 'steering the steering wheel according to the aligning torque':
turning:
when a driver rotates a steering wheel 1, the steering wheel 1 drives a steering shaft 2 to move, the steering shaft 2 drives a first spline hub 701 through a spline shaft, the first spline hub 701 drives a planet carrier 702 (the first planetary gear speed reducing mechanism comprises the planet carrier 702, a sun wheel 705, a planet wheel 706 and a gear ring 703) in a first planetary gear speed reducing mechanism to rotate, at the moment, the sun wheel 705 and the planet wheel 706 brake, and torque is transmitted to the gear ring 703 through the planet wheel 706.
The gear ring 703 drives the second spline hub 704 to move, and the second spline hub 704 drives the moving worm wheel 801 in the worm and gear mechanism through the spline shaft (the worm and gear mechanism includes the moving worm wheel 801 and the driving worm 802); because the worm gear and worm mechanism has unidirectional force transmission, namely reverse self-locking characteristic, the worm 802 cannot be driven by the movable worm gear 801, namely the worm 802 generates resistance torque on the movable worm gear 801. In this way, the steering shaft 2 maintains torque balance under the action of the steering torque and the resisting torque input by the steering wheel 1, and is torsionally deformed, so that the torque sensor 4 provided on the steering shaft 2 collects the steering torque of the steering shaft 2, which is also the steering torque input by the steering wheel 1, and transmits the steering torque to the steering wheel control module 5.
Meanwhile, when the driver turns the steering wheel 1, the steering wheel 1 turns a certain angle therewith, and the first steering angle sensor 305 may detect the steering wheel angle of the steering wheel 1 and transmit the steering wheel angle to the steering wheel control module 5. The steering wheel control module 5 CAN calculate the corresponding corner messages of the 4 steering wheels (i.e. the wheels) at the time based on the steering wheel angle, and send the corner messages to the CAN communication bus 10.
The corner message comprises a wheel steering angle; in one example, the transmission time interval of the corner message is 20ms, the data length of the corner message is 108 bits, and the data content of the corner message is 64 bits, which is 8 bytes in total; the wheel steering angle value of each steered wheel occupies 2 bytes.
The steering motor control module 11 of each steering wheel receives the corner message on the CAN communication bus 10, and based on the corner message, controls the corresponding steering motor 12 to drive the second planetary gear reduction mechanism 13 to reduce the speed and increase the torque, the second planetary gear reduction mechanism 13 drives the steering support arm 14 through the spline shaft after reducing the speed and increasing the torque, and the steering support arm 14 drives the steering wheel to steer.
The steering motor control module 11 to the steering support arm 14 may constitute a steering wheel drive control system.
And (3) a correction process:
the aligning includes steering wheel aligning and steering wheel aligning. Which respectively comprise the following cooperation processes:
1, steering wheel aligning:
because the worm gear and worm mechanism has unidirectional force transmission, namely reverse self-locking characteristic, the steering wheel control module 5 can control the road feel motor 9 to drive the worm 802 to rotate, the worm 802 drives the movable worm wheel 801 to rotate, the movable worm wheel 801 sequentially drives the first planetary gear speed reducing mechanism and the steering shaft 2 to rotate, namely, the steering wheel control module 5 can transmit the feedback torque to the road feel motor 9, the road feel motor 9 can determine the aligning torque acting on the steering wheel 1 according to the feedback torque, and the aligning torque acts on the steering wheel 1 through the worm gear and worm mechanism, the first planetary gear speed reducing mechanism and the steering shaft 2.
2, steering wheel alignment:
similar to steering wheel return, when the steering wheel 1 rotates by a certain angle under the action of the return torque, the first rotation angle sensor 305 may detect a return rotation wheel angle of the steering wheel 1 (the direction of the return rotation wheel angle is different from the aforementioned steering wheel angle), and transmit the return rotation wheel angle to the steering wheel control module 5. The steering wheel control module 5 CAN calculate the corresponding corner message of the 4 steering wheels (i.e. the wheels) at the moment based on the angle of the return rotating wheel, and send the corner message to the CAN communication bus 10.
The steering motor control module 11 of each steering wheel receives the corner message on the CAN communication bus 10, controls the corresponding steering motor 12 to drive the second planetary gear speed reducing mechanism 13 to reduce the speed and increase the torque based on the corner message, and drives the steering support arm 14 through the spline shaft, and the steering support arm 14 drives the steering wheel to return to the right.
It should be noted that fig. 3 only shows one steering wheel drive control system, and for the application of independent steering drive wheels, one steering wheel drive control system can be designed for each steering wheel.
EXAMPLE III
In the first embodiment, reference is made to calculating the feedback torque, and the present embodiment focuses on a calculation process of the feedback torque.
As shown in fig. 4, the feedback torque calculation process specifically includes:
step 401: and calculating a feedback moment estimated value according to the vehicle dynamic model and the steering wheel angle.
Because the steer-by-wire system cancels the mechanical connection between the steering wheel and the steering wheel, the aligning moment can not be transmitted to the steering wheel through the mechanical structure, and in order to obtain the estimation of the feedback moment, a vehicle dynamic model is firstly established according to a real vehicle with the mechanical structure to be used as a virtual simulation model of the current vehicle. Therefore, before step 401 is performed for the first time, a vehicle dynamics model is first established.
In one example, step 401 may further comprise:
step A: calculating the steering angle of the steering wheel according to the steering wheel angle;
the steering angle includes a steering angle of the front left steering wheel and a steering angle of the front right steering wheel. The person skilled in the art can calculate the steering angle of the left front steering wheel and the steering angle of the right front steering wheel according to the existing manner or a new calculation manner in the future as long as the steering angle of the left front steering wheel and the steering angle of the right front steering wheel can be calculated.
And B, step B: according to the formula
Figure BDA0003092880990000141
Calculating the feedback moment estimated value;
wherein, the
Figure BDA0003092880990000142
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr A lateral force of a right front steering wheel, and the lateral force of the left front steering wheel is determined according to the steering angle of the left front steering wheel, and the lateral force of the right front steering wheel is determined according to the steering angle of the right front steering wheel; n is K Is a virtual kingpin front finger; n is R Is the virtual lateral force back offset.
The virtual kingpin comprises a kingpin in the vehicle dynamic model, and the front finger comprises a steering wheel positioning parameter.
Step 402: and calculating the feedback torque according to the feedback torque estimated value, the steering torque and the running speed.
Further, step 402 may specifically include:
step a: and calculating a feedback torque target value according to the feedback torque estimated value and the running speed.
Step b: and calculating the feedback torque according to the feedback torque target value and the steering torque.
In one example, step a specifically includes:
step a 1: according to the formula
Figure BDA0003092880990000143
Calculating a feedback moment target value by reverse deduction;
wherein, the
Figure BDA0003092880990000144
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the M is i And the feedback torque target value is obtained.
The drive ratio of the steer-by-wire system is adjustable, so i * Taking values within an adjustable range and changing i according to the vehicle speed * Value of (A)。
In this embodiment, i * Is the gear ratio of the first planetary gear reduction mechanism, and n1+ α n2 (1+ α) n3 is 0; where n1 is the rotational speed of the sun gear 705, n2 is the rotational speed of the ring gear 703, n3 is the rotational speed of the carrier 702, and α is the ratio of the number of teeth of the ring gear 703 to the number of teeth of the sun gear 705; when the sun gear 705 is braked, n1 is equal to 0, so that the transmission ratio i of the first planetary gear reduction mechanism from the movable gear 801 to the steering shaft 2 can be obtained * 。
The target value of the feedback torque obtained in step a1 can be regarded as the original value, and is corrected in the following steps.
Step a 2: and acquiring a torque value of the steering support arm.
In one example, the torque value may be collected by a strain gauge torque sensor 15 shown in FIG. 3.
Specifically, referring to fig. 5, the strain gauge type torque sensor 15 includes two strain gauges, and the two strain gauges are mounted on the steering support arm 14 in a crossing manner. This is because:
the strain gauges are mounted in a crossed manner, and the torsional deformation sensitivity of the steering support arm 14 caused by the aligning moment generated under the action of the lateral force of the steering wheel is highest.
Meanwhile, the installation position of each strain gauge is the position with the maximum torsional deformation under the action of the torsional moment through finite element analysis.
The calculation formula of the resistance value of the strain gauge is that R is rho l/s, wherein R, rho, l and s are the resistance value, the resistivity, the length and the cross-sectional area in sequence, the design of a bridge circuit is shown in FIG. 6, and R1 and R4 are strain gauges; and determining the torque value of the steering supporting arm based on the strain gauge resistance value calculation formula.
Step a 3: and correcting the feedback torque target value according to the torque value.
And (3) correction process: and carrying out normalization processing calculation on the torque value and the feedback torque target value to obtain a corrected feedback torque target value.
Correspondingly, the step b specifically includes:
step b 1: and calculating the absolute value of the difference between the corrected target value of the feedback torque and the steering torque.
Step b 2: if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage;
those skilled in the art can flexibly design the range of the set interval according to the specific vehicle type, even considering the vehicle speed, etc., and will not be described herein.
Step b 3: if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback moment determined in the previous stage and the set step length as the feedback moment corresponding to the current stage;
step b 4: and if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
The initial value of the feedback torque is the steering torque acquired by the torque sensor 4, and the set step length is determined according to the actual requirement.
In other embodiments of the present invention, in addition to the above-mentioned modes, the control method and the control system in all the above-mentioned embodiments can also work in other modes, for example, an automatic driving mode, a manual road-feel-free feedback driving mode, and the like. The following description will be made one by one.
Example four
Referring to fig. 7, in the automatic driving mode, the control method executed by the control system further includes the following interactive steps:
step 701: in the automatic driving mode, the steering wheel control module 5 sends the steering wheel angle information issued by the vehicle control unit 6 to the steering motor control module 11 in the steer-by-wire system.
The turning wheel angle information includes a turning wheel angle and a return turning wheel angle.
Step 702: and the steering motor control module 11 is used for controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the steering angle feedback signal of the last stage.
The rotation angle feedback signal is acquired by a sensor arranged on an output shaft of the second planetary gear speed reducing mechanism 13; the second planetary gear reduction mechanism 13 is mounted on the steering wheel assembly.
In one example, step 702 may specifically include:
and determining a steering wheel steering instruction of the current stage according to the steering wheel angle information and the steering angle feedback signal corresponding to the previous stage, and sending the steering wheel steering instruction to a steering motor in the steer-by-wire system.
The steering motor is used for driving the planetary gear speed reducing mechanism to work according to the steering wheel steering instruction, and the work comprises that an output shaft of the planetary gear speed reducing mechanism drives the steering support arm to move so as to drive the steering wheel to steer and/or return to the right.
The following describes an example of a specific steering process in the automatic driving mode as follows:
as shown in fig. 2, the vehicle control unit 6 sends out the steering wheel angle information, and the steering wheel angle information is transmitted to the steering wheel control module 5 through the CAN communication bus 10 and then transmitted to the four steering motor control modules 11, or the vehicle control unit 6 directly sends the steering wheel angle information to the steering motor control module 11 corresponding to each steering wheel through the CAN communication bus 10 (fig. 2 only shows one steering wheel assembly, and the other three steering wheel assemblies are identical), and the steering angle data of the four steering wheels is transmitted through a frame of corner message, so that the four steering wheels CAN respond at the same time as much as possible. For the corner turning message, please refer to the above record, and it is not described herein again.
Then, each steering motor control module 11 controls the corresponding steering motor 12 to operate according to the corner message. Specifically, the method comprises the following steps: the steering motor 12 drives the second planetary gear speed reducing mechanism 13 to reduce speed and increase torque, an output shaft of the second planetary gear speed reducing mechanism 13 drives the corresponding steering support arm 14 to rotate, and the steering support arm 14 further drives the steering wheel to steer;
and a second rotation angle sensor arranged on an output shaft of the second planetary gear speed reducing mechanism 13 feeds back a feedback signal (bearing rotation angle information of the steering wheel) to the steering motor control module 11 of each steering wheel, so that closed-loop control is realized.
EXAMPLE five
When the speed is low and the road surface condition is good, the artificial road-feel-free feedback driving mode can be selected. The basis for selecting the artificial road feel feedback driving mode can comprise the following steps:
secondly, prompting an artificial road-feel-free feedback driving mode by a driver according to the driving road condition or navigation software;
and secondly, automatically selecting an artificial road feel-free feedback driving mode according to the feedback information of the navigation software.
Referring to fig. 8, in the manual road-feel-free feedback driving mode, the control method executed by the control system further includes the following steps:
step 800: and acquiring the steering wheel angle information of the steering wheel in an artificial road-feel-free feedback driving mode.
The turning wheel angle information includes a turning wheel angle and a return turning wheel angle.
Step 810: and driving the steering wheel to steer and/or return to the right according to the steering wheel angle information.
In the manual road feel feedback-free driving mode, the specific steering process is as follows:
in this mode, a driver operates the steering wheel 1 to rotate through a certain rotation angle, the steering wheel 1 and the steering shaft 2 are rigidly connected through a bolt, the steering shaft 2 drives the large gear 301 of the gear transmission mechanism 3 mounted on the steering shaft 2 to rotate (the gear transmission mechanism 3 comprises the large gear 301, the small gear 302, the gear shaft 303 and the measuring gear 304), the large gear 301 drives the small gear 302 to rotate, the small gear 302 is rigidly connected with one end of the gear shaft 303 and drives the gear shaft 303, the other end of the gear shaft 303 is connected with the measuring gear 304 with teeth missing, and further, the steering wheel angle information of the steering wheel 1 can be detected through the first steering angle sensor 305 mounted near the measuring gear 304.
One end of the steering shaft 2 is connected with a first spline hub 701 through a spline shaft, the first spline hub 701 is connected with a planet carrier 702 of a first planetary gear speed reducing mechanism through a bolt, a gear ring 703 is connected with a second spline hub 704 through a nut, the second spline hub 704 is connected with a worm gear mechanism through a spline shaft, and a road sensing motor 9 is fixed below the worm gear mechanism. At this time, the road sensing motor 9 does not operate, and the feedback torque cannot be transmitted back to the steering wheel 1 through the worm gear mechanism and the first planetary gear reduction mechanism.
The first steering angle sensor 305 transmits the collected steering angle information to the steering wheel control module 5. The steering wheel control module 5 is provided with a CAN interface, and the steering angles required to be completed by 4 steering wheels are sent to the steering motor control module 11 corresponding to each steering wheel through the CAN interface in the form of the same frame of corner message.
The steering motor 12 drives the second planetary gear speed reducing mechanism 13 to reduce speed and increase torque, so as to drive the steering support arm 14, and the steering support arm 14 drives the steering wheel to steer.
The turn angle message is referred to the above record, and is not described herein.
EXAMPLE six
To achieve the above object, the present embodiment provides a control system of a steer-by-wire system, as shown in fig. 1, including:
the obtaining module 100 is configured to obtain steering data and driving data in an artificial road feel feedback driving mode.
The steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the running data includes a running speed of the vehicle.
A steering wheel control module 110 for:
driving a steering wheel to steer according to the steering wheel angle;
calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to a road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle;
and driving the steering wheel to be aligned according to the aligning moment.
Further, in said calculating a feedback torque based on a vehicle dynamics model, said steering data and said driving data, said steering wheel control module 110 is specifically configured to:
and calculating a feedback moment estimated value according to the vehicle dynamic model and the steering wheel angle.
And calculating the feedback torque according to the feedback torque estimated value, the steering torque and the running speed.
Further, in the aspect of calculating the feedback torque according to the estimated feedback torque value, the steering torque, and the driving speed, the steering wheel control module 110 is specifically configured to:
and calculating a feedback torque target value according to the feedback torque estimated value and the running speed.
And calculating the feedback torque according to the feedback torque target value and the steering torque.
Further, in the aspect of calculating the feedback torque estimation value according to the vehicle dynamic model and the steering wheel angle, the steering wheel control module 110 is specifically configured to:
calculating the steering angle of the steering wheel according to the steering wheel angle; the steering angle includes a steering angle of the front left steering wheel and a steering angle of the front right steering wheel.
According to the formula
Figure BDA0003092880990000191
And calculating the feedback torque estimated value.
Wherein, the
Figure BDA0003092880990000192
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr The lateral force of the right front steering wheel is determined according to the steering angle of the left front steering wheel, and the lateral force of the right front steering wheel is determined according to the steering angle of the right front steering wheel; n is K Is a virtual kingpin front finger; n is R Is the virtual lateral force back offset.
Further, in terms of calculating a feedback torque target value according to the feedback torque estimated value and the driving speed, the steering wheel control module 110 is specifically configured to:
according to the formula
Figure BDA0003092880990000193
And calculating a feedback torque target value by reverse deduction.
Wherein, the
Figure BDA0003092880990000194
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the M is i And the feedback torque target value is obtained.
Acquiring a torque value of the steering support arm; the torque value is acquired through a strain gauge type torque sensor, the strain gauge type torque sensor comprises two strain gauges, and the two strain gauges are installed on the steering support arm in a crossed mode.
And correcting the feedback torque target value according to the torque value.
Further, the feedback torque comprises a feedback torque corresponding to the current stage; in the aspect of calculating the feedback torque according to the feedback torque target value and the steering torque, the steering wheel control module 110 is specifically configured to:
and calculating the absolute value of the difference between the corrected target value of the feedback torque and the steering torque.
And if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage.
And if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback moment determined in the previous stage and the set step length as the feedback moment corresponding to the current stage.
And if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
In other embodiments of the present invention, the steering wheel control module 110 in all the embodiments is further configured to:
in an automatic driving mode, transmitting the steering wheel angle information sent by the vehicle control unit to a steering motor control module in the steer-by-wire system; the turning wheel angle information includes a turning wheel angle and a return turning wheel angle.
The steering motor control module is used for controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the turning angle feedback signal of the last stage; the rotation angle feedback signal is acquired by a sensor arranged on an output shaft of the planetary gear speed reducing mechanism; the planetary gear speed reducing mechanism is arranged on the steering wheel assembly.
In other embodiments of the present invention, the obtaining module 100 in all the embodiments is further configured to obtain the steering wheel angle information of the steering wheel in the artificial road-feel-free feedback driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle; the steering wheel control module 110 is further configured to drive the steering wheel to steer and/or return to the right according to the steering wheel angle information.
Further, the control system is provided with a first torque transmission path, a second torque transmission path and a third torque transmission path; the acquisition module 100 includes a torque sensor, a first rotation angle sensor, and a speed sensor.
The devices involved in the first torque transmission path include a steering shaft, a gear transmission mechanism, the torque sensor mounted on the steering shaft, the first angle sensor mounted on the gear transmission mechanism, the speed sensor provided on the vehicle, a first planetary gear reduction mechanism, a worm gear transmission mechanism, the steering wheel control module, a road feel motor, and a steering motor control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm mounted on each steering wheel assembly.
The steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor, the torque sensor and the speed sensor are all connected with the steering wheel control module; the steering wheel is connected with the first planetary gear speed reducing mechanism through the steering shaft; the first planetary gear speed reducing mechanism is also connected with the worm gear and worm transmission mechanism; the steering wheel control module is connected with the worm and gear transmission mechanism through the road sensing motor; the steering wheel control module is connected with the steering support arm sequentially through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism; the steering support arm is used for driving the steering wheel to rotate; the steering shaft is used for keeping torque balance and generating steering torque under the action of steering torque input by the steering wheel and resisting torque input by the worm gear and worm transmission mechanism; the road sensing motor is used for driving the worm gear and worm transmission mechanism to rotate so as to feed the aligning torque determined by the road sensing motor according to the feedback torque back to the steering wheel through the worm gear and worm transmission mechanism.
The devices involved in the second torque transmission path include the steering wheel control module, and the steering motor control module, steering motor, second planetary gear reduction mechanism, steering support arm, and second rotation angle sensor mounted on each of the steered wheels.
The steering wheel control module is connected with the steering motor control module; the steering motor control module is also connected with the steering motor; an output shaft of the steering motor is connected with the second planetary gear speed reducing mechanism; an output shaft of the second planetary gear speed reducing mechanism is connected with the steering support arm; the steering supporting arm is arranged on the steering wheel; the second rotation angle sensor is arranged on the output shaft of the second planetary gear speed reducing mechanism.
The devices involved in the third torque transmission path include a steering shaft, a gear transmission, the first rotation angle sensor mounted on the gear transmission, the steering wheel control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm.
The steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor is connected with the steering wheel control module; the steering wheel control module is connected with the steering support arm through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism in sequence; the steering support arm is used for driving the steering wheel to rotate.
EXAMPLE seven
The embodiment also provides a motor vehicle comprising the control system of the steer-by-wire system according to any one of the above embodiments.
The invention provides a control system of a steer-by-wire system, which can be switched between an automatic driving mode and a manual driving mode; under the automatic driving mode, the power torque transmission between the steering wheel and the road feel motor is cut off, and the road feel motor can provide feedback torque under the manual driving mode, so that more accurate driving operation is realized.
It should be noted that, currently, for estimating the feedback torque, there are three methods:
firstly, a dynamic model corresponding to a steer-by-wire system is established for a specific vehicle type, then a feedback moment is calculated according to the dynamic model and is applied to a steering wheel, but the high-precision dynamic model is difficult to obtain.
Secondly, a transfer function of the steer-by-wire system is constructed in a segmented mode to estimate the feedback torque by taking vehicle state parameters such as vehicle speed, vehicle body acceleration, roll angle and the like as input, and the steer-by-wire system has the advantages that the transfer function is adjustable, various feedback torque requirements can be provided according to driving habits of different drivers, and the steer-by-wire system has the defects of insufficient authenticity and certain delay.
Thirdly, the rack force is measured through a corresponding sensor, and a curve graph reflecting the feedback torque is fitted through a large number of experiments and used as the basis of the feedback torque. However, this method cannot be applied to a four-wheel steering vehicle without a rack.
In addition, the future development trend is to drive a steering driving wheel with a large-angle steering function by a hub motor; however, for a considerable period of time, vehicles often require both manual driving and automated driving, and for manual driving, road feel feedback is required. At present, research and products for generating aligning torque by independently steering driving wheels are lacked.
Compared with the prior art, the invention has the following specific beneficial effects:
1. the invention provides a solution for the feedback moment in the manual control mode of the independent steering wheel linear control chassis; compared with a traditional four-wheel independent driving steering platform, the four-wheel independent driving steering platform can better provide road surface feedback moment and improve the vehicle handling performance.
2. When the feedback torque is calculated, a technical scheme of combining a vehicle dynamic model and a sensor detection signal is adopted, and the aligning torque generated in the driving process of the estimated vehicle is calculated; in addition, because the strain gauge type torque sensor monitors and corrects in real time, the complexity of a vehicle dynamic model can be properly reduced, and the response time of feedback torque calculation and transmission is shortened.
3. In the process of transmitting the feedback torque to the steering wheel, the feedback torque is transmitted by a worm gear mechanism, and the feedback torque is increased through secondary speed reduction, so that the feedback torque is larger, a smaller and more compact motor structure can be adopted, and the weight of the steer-by-wire system is reduced.
4. The planetary gear speed reducing mechanism is arranged in the transmission path of the steering torque, so that the switching between the automatic driving mode and the manual driving mode and between the powerful torque feedback mode and the non-torque feedback mode is easier to realize.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principle and the embodiment of the present invention are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (8)

1. A control method of a steer-by-wire system, comprising:
acquiring steering data and driving data under an artificial road feel feedback driving mode; the steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the travel data includes a travel speed of the vehicle; the steering torque is measured by a torque sensor, the steering wheel angle is measured by a first steering angle sensor, and the running speed is measured by a speed sensor;
driving a steering wheel to steer according to the steering wheel angle;
calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to a road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle;
driving the steering wheel to be aligned according to the aligning torque;
the calculating a feedback torque according to the vehicle dynamics model, the steering data and the driving data specifically comprises:
calculating the steering angle of the steering wheel according to the steering wheel angle; the steering angle comprises a steering angle of a left front steering wheel and a steering angle of a right front steering wheel;
according to the formula
Figure FDA0003720765810000011
Calculating the feedback moment estimated value;
wherein, the
Figure FDA0003720765810000012
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr Is the lateral force of the right front steering wheel, and the lateral force of the left front steering wheel is determined according to the steering angle of the left front steering wheel, and the lateral force of the right front steering wheel is determined according to the right front steering wheelThe steering angle of the wheel is determined; n is K Is a virtual kingpin front finger; n is R Is a virtual lateral force back offset distance;
according to the formula
Figure FDA0003720765810000021
Calculating a feedback torque target value by reverse deduction;
wherein, the
Figure FDA0003720765810000022
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the above-mentionedM i The feedback torque target value is obtained;
acquiring a torque value of the steering support arm; the torque value is acquired through a strain gauge torque sensor, the strain gauge torque sensor comprises two strain gauges, and the two strain gauges are installed on the steering support arm in a crossed mode;
correcting the feedback torque target value according to the torque value;
calculating an absolute value of a difference between the corrected target value of the feedback torque and the steering torque;
if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage;
if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback moment determined in the previous stage and the set step length as the feedback moment corresponding to the current stage;
and if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
2. A control system of a steer-by-wire system, comprising:
the acquisition module is used for acquiring steering data and driving data in an artificial road feel feedback driving mode; the steering data includes a steering torque of a steering shaft and a steering wheel angle of a steering wheel; the travel data includes a travel speed of the vehicle; the acquisition module comprises a torque sensor, a first rotation angle sensor and a speed sensor; the steering torque is measured by the torque sensor, the steering wheel angle is measured by the first steering angle sensor, and the running speed is measured by the speed sensor;
a steering wheel control module to:
driving a steering wheel to steer according to the steering wheel angle;
calculating a feedback torque according to a vehicle dynamic model, the steering data and the driving data, and sending the feedback torque to a road sensing motor; the road sensing motor is used for providing corresponding aligning torque for the steering wheel according to the feedback torque; wherein the vehicle dynamics model is a virtual simulation model of the vehicle;
driving the steering wheel to be aligned according to the aligning torque;
in the aspect of calculating the feedback torque based on the vehicle dynamics model, the steering data, and the driving data, the steering wheel control module is specifically configured to:
calculating the steering angle of the steering wheel according to the steering wheel angle; the steering angle comprises a steering angle of a left front steering wheel and a steering angle of a right front steering wheel;
according to the formula
Figure FDA0003720765810000031
Calculating the feedback moment estimated value;
wherein, the
Figure FDA0003720765810000032
Estimating a value for the feedback torque; said F Vl Is a lateral force of the front left steering wheel, said F Vr Is the lateral force of the right front steering wheel, and the lateral force of the left front steering wheel is determined according to the steering angle of the left front steering wheel, and the lateral force of the right front steering wheel is determined according to the lateral force of the left front steering wheelThe steering angle of the front right steering wheel is determined; n is a radical of an alkyl radical K Is a virtual kingpin front finger; n is R Is a virtual lateral force back offset distance;
according to the formula
Figure FDA0003720765810000033
Calculating a feedback moment target value by reverse deduction;
wherein, the
Figure FDA0003720765810000034
A predicted value is feedback torque; i is described * Is a gear ratio of the steer-by-wire system; the V is L Is the driving speed; the above-mentionedM i The feedback torque target value is obtained;
acquiring a torque value of the steering support arm; the torque value is acquired through a strain gauge torque sensor, the strain gauge torque sensor comprises two strain gauges, and the two strain gauges are arranged on the steering support arm in a crossed mode;
correcting the feedback torque target value according to the torque value;
calculating an absolute value of a difference between the corrected target value of the feedback torque and the steering torque;
if the absolute value is within a set interval, determining the feedback torque target value as the feedback torque corresponding to the current stage;
if the absolute value is larger than the maximum value of the set interval, determining the sum of the feedback torque determined in the previous stage and the set step length as the feedback torque corresponding to the current stage;
and if the absolute value is smaller than the minimum value of the set interval, determining the difference between the feedback torque corresponding to the previous stage and the set step length as the feedback torque corresponding to the current stage.
3. The control system of a steer-by-wire system according to claim 2, wherein the control system is provided with a first torque transmission path;
the devices involved in the first torque transmission path include a steering shaft, a gear transmission mechanism, the torque sensor mounted on the steering shaft, the first angle sensor mounted near the gear transmission mechanism, the speed sensor provided on the vehicle, a first planetary gear reduction mechanism, a worm gear transmission mechanism, the steering wheel control module, a road feel motor, and a steering motor control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm mounted on each steering wheel assembly;
the steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor, the torque sensor and the speed sensor are all connected with the steering wheel control module;
the steering wheel is connected with the first planetary gear speed reducing mechanism through the steering shaft;
the first planetary gear speed reducing mechanism is also connected with the worm gear and worm transmission mechanism;
the steering wheel control module is connected with the worm and gear transmission mechanism through the road sensing motor; the steering wheel control module is connected with the steering support arm through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism in sequence; the steering support arm is used for driving the steering wheel to rotate;
the steering shaft is used for keeping torque balance and generating steering torque under the action of steering torque input by the steering wheel and resisting torque input by the worm gear and worm transmission mechanism;
the road sensing motor is used for driving the worm gear and worm transmission mechanism to rotate so as to feed the aligning torque determined by the road sensing motor according to the feedback torque back to the steering wheel through the worm gear and worm transmission mechanism.
4. The control system of a steer-by-wire system according to claim 2,
the steering wheel control module is used for sending the steering wheel angle information issued by the vehicle control unit to a steering motor control module in the steer-by-wire system in an automatic driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
the steering motor control module is used for controlling the steering wheel to steer and/or return to the right according to the steering wheel angle information and the corner feedback signal of the last stage; the rotation angle feedback signal is acquired by a sensor arranged on an output shaft of the planetary gear speed reducing mechanism; the planetary gear speed reducing mechanism is arranged on the steering wheel assembly.
5. The control system of a steer-by-wire system according to claim 4, wherein said control system is provided with a second torque transmission path; the devices involved in the second torque transmission path include the steering wheel control module, and the steering motor control module, steering motor, second planetary gear reduction mechanism, steering support arm, and second rotation angle sensor mounted on each steering wheel;
the steering wheel control module is connected with the steering motor control module;
the steering motor control module is also connected with the steering motor; an output shaft of the steering motor is connected with the second planetary gear speed reducing mechanism; an output shaft of the second planetary gear speed reducing mechanism is connected with the steering support arm; the steering supporting arm is arranged on the steering wheel; the second rotational angle sensor is provided on an output shaft of the second planetary gear reduction mechanism.
6. The control system of a steer-by-wire system according to claim 2,
the acquisition module is used for acquiring the steering wheel angle information of the steering wheel in an artificial road-feel-free feedback driving mode; the turning wheel angle information comprises a turning wheel angle and a returning turning wheel angle;
and the steering wheel control module is used for driving the steering wheel to steer and/or return to the right according to the steering wheel angle information.
7. The control system of a steer-by-wire system according to claim 2, wherein the control system is provided with a third torque transmission path;
the devices involved in the third torque transmission path include a steering shaft, a gear transmission, the first angle sensor mounted near the gear transmission, the steering wheel control module, and a steering motor control module, a steering motor, a second planetary gear reduction mechanism, and a steering support arm mounted on each steering wheel assembly;
the steering wheel is connected with the gear transmission mechanism through the steering shaft; the first rotating angle sensor is connected with the steering wheel control module;
the steering wheel control module is connected with the steering support arm sequentially through the steering motor control module, the steering motor and the second planetary gear speed reducing mechanism; the steering support arm is used for driving the steering wheel to rotate.
8. A motor vehicle, characterized by comprising the control system of a steer-by-wire system according to any one of claims 2 to 7.
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