CN112519793B - Intelligent drive-by-wire chassis architecture based on digital twin and active fault tolerance method thereof - Google Patents

Intelligent drive-by-wire chassis architecture based on digital twin and active fault tolerance method thereof Download PDF

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CN112519793B
CN112519793B CN202011447210.7A CN202011447210A CN112519793B CN 112519793 B CN112519793 B CN 112519793B CN 202011447210 A CN202011447210 A CN 202011447210A CN 112519793 B CN112519793 B CN 112519793B
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wire
brake
front wheel
chassis
rear wheel
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CN112519793A (en
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周长志
周小川
赵万忠
栾众楷
高犇
徐坤豪
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/02—Ensuring safety in case of control system failures, e.g. by diagnosing, circumventing or fixing failures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/32—Control or regulation of multiple-unit electrically-propelled vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/02—Ensuring safety in case of control system failures, e.g. by diagnosing, circumventing or fixing failures
    • B60W50/0205—Diagnosing or detecting failures; Failure detection models
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/08—Interaction between the driver and the control system
    • B60W50/14—Means for informing the driver, warning the driver or prompting a driver intervention
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W2050/0001—Details of the control system
    • B60W2050/0043—Signal treatments, identification of variables or parameters, parameter estimation or state estimation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/02—Ensuring safety in case of control system failures, e.g. by diagnosing, circumventing or fixing failures
    • B60W50/0205—Diagnosing or detecting failures; Failure detection models
    • B60W2050/021—Means for detecting failure or malfunction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W50/00—Details of control systems for road vehicle drive control not related to the control of a particular sub-unit, e.g. process diagnostic or vehicle driver interfaces
    • B60W50/08—Interaction between the driver and the control system
    • B60W50/14—Means for informing the driver, warning the driver or prompting a driver intervention
    • B60W2050/143—Alarm means
    • 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

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Human Computer Interaction (AREA)
  • Power Engineering (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)

Abstract

The invention discloses an intelligent drive-by-wire chassis architecture based on digital twin and an active fault-tolerant method thereof, wherein the intelligent drive-by-wire chassis architecture comprises the following steps: an intelligent line control chassis system and a digital twin diagnosis system; the intelligent drive-by-wire chassis system comprises: the system comprises a drive-by-wire system, a steer-by-wire system, a brake-by-wire system, a chassis control unit, a drive-by-wire controller, a steer-by-wire controller and a control controller; the drive-by-wire chassis system integrates a drive-by-wire system, a steer-by-wire system and a brake-by-wire system, and provides a platform for researching the coupling among a plurality of subsystems; meanwhile, the mechanical structure connection is reduced, the actuator can respond to the instruction of the driver more quickly, and the driving safety is enhanced.

Description

Intelligent drive-by-wire chassis architecture based on digital twin and active fault tolerance method thereof
Technical Field
The invention belongs to the technical field of automobile chassis systems, and particularly relates to an intelligent drive-by-wire chassis architecture based on a digital twin and an active fault-tolerant method thereof.
Background
With the higher and higher degree of automobile intelligence, the wire control technology is applied to the automobile more and more. The wire control technology utilizes a vehicle-mounted communication line to replace mechanical connection between a driver and an actuator in a traditional vehicle, reduces coupling between machines, realizes quick response of the actuator to the instruction of the driver, and improves the driving safety of the vehicle in a complex environment.
The existing research on the steer-by-wire technology mainly focuses on the steer-by-wire technology and the brake-by-wire technology. The wire control steering technology realizes the decoupling between a steering wheel and a steering wheel, the steering wheel corner signal acquired by a sensor is used for controlling a steering motor to output a steering power-assisted moment to realize the driving steering by utilizing a controller, the steering operation of a driver can be quickly responded, and the steering stability is improved; the brake-by-wire technology cancels rigid connection and a hydraulic device between a brake pedal and a brake, and utilizes a brake motor to realize quick response to brake signals, thereby improving the stability of automobile braking. However, the above-mentioned wire-controlled technology mainly focuses on the research of an independent system, and rarely performs system integration coordination control on a wire-controlled steering system, a wire-controlled brake system and a wire-controlled driving system from the perspective of the whole wire-controlled chassis integrated system, and mutual assistance and integration control of three subsystems cannot be realized, so that when a certain system fails, other normal systems cannot respond in time to perform auxiliary operation, thereby causing huge potential safety hazard.
The digital twin technology is used as an effective means for constructing virtual-real blending between a physical model and a virtual model, and is increasingly widely applied to the field of fault diagnosis. The digital twin technology can fully utilize data such as a physical model, sensor updating, operation history and the like, integrate a multidisciplinary, multi-physical quantity, multi-scale and multi-probability simulation process, and complete mapping in a virtual space so as to reflect the full life cycle process of corresponding entity equipment, thereby realizing prediction of possible problems and faults of various equipment and preventing in advance to eliminate potential safety hazards. However, the application of the digital twin technology in the field of chassis fault diagnosis of automobile drive-by-wire is very limited, but the digital twin technology has a great application prospect and is a problem worthy of research.
Disclosure of Invention
In view of the defects of the prior art, the present invention aims to provide an intelligent drive-by-wire chassis architecture based on digital twin and an active fault-tolerant method thereof, so as to realize integrated cooperative control of three subsystems, namely a drive-by-wire drive system, a steer-by-wire system and a brake-by-wire system, and diagnose possible faults of the whole drive-by-wire chassis system by using a digital twin technology, thereby performing fault-tolerant control among the subsystems.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention relates to an intelligent drive-by-wire chassis architecture based on digital twin, which comprises: an intelligent line control chassis system and a digital twin diagnosis system; the intelligent drive-by-wire chassis system comprises: the system comprises a drive-by-wire system, a steer-by-wire system, a brake-by-wire system, a chassis control unit, a drive-by-wire controller, a steer-by-wire controller and a control controller; wherein the content of the first and second substances,
the drive-by-wire system includes: the system comprises an accelerator pedal, an accelerator pedal position sensor, a left front wheel hub motor, a right front wheel hub motor, a left rear wheel hub motor, a right rear wheel hub motor, a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor, a right rear wheel speed sensor, a left front wheel, a right front wheel, a left rear wheel and a right rear wheel; the accelerator pedal position sensor is fixedly arranged on the accelerator pedal; the left front wheel hub motor and the left front wheel speed sensor are arranged in the left front wheel; the right front wheel hub motor and the right front wheel speed sensor are arranged in the right front wheel; the left rear wheel hub motor and the left rear wheel speed sensor are arranged in the left rear wheel; a right rear wheel hub motor and a right rear wheel speed sensor are arranged in the right rear wheel; the rotary motion output by the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor and the right rear wheel hub motor is respectively converted into the rotary motion of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel to drive the vehicle to run;
the steer-by-wire system includes: the steering wheel, the steering column, the road feel simulation device and the steering assembly;
the steering wheel is connected with a steering column, a corner sensor and a torque sensor are respectively and fixedly installed on the steering column, and acting force input by the steering wheel acts on the road feel simulation device through the steering column;
the steering assembly includes: the steering motor, the steering motor rotating speed sensor, the steering speed reducing mechanism, the steering ball screw, the steering tie rod and the steering trapezoid; the output end of the steering motor is connected to a nut of the steering ball screw through a steering motor rotating speed sensor and a steering speed reducing mechanism in sequence; a screw rod end of the steering ball screw breaks the tie rod, and two ends of the steering ball screw are axially and fixedly connected with two broken ports of the tie rod; the rotary motion output by the steering motor is converted into the displacement motion of a steering tie rod through a steering speed reducing mechanism and a steering ball screw, and the displacement motion of the steering tie rod completes the steering action of the vehicle through a steering trapezoid and wheels;
the brake-by-wire system includes: a brake pedal, a brake pedal position sensor, a left front wheel brake motor speed sensor, a left front wheel speed reduction mechanism, a left front wheel ball screw, a left front wheel brake cylinder, a right front wheel brake motor speed sensor, a right front wheel speed reduction mechanism, a right front wheel ball screw, a right front wheel brake cylinder, a left rear wheel brake motor speed sensor, a left rear wheel speed reduction mechanism, a left rear wheel ball screw, a left rear wheel brake cylinder, a right rear wheel brake motor speed sensor, a right rear wheel speed reduction mechanism, a right rear wheel ball screw, a right rear wheel brake cylinder; the brake pedal position sensor is fixedly arranged on the brake pedal; the output end of the left front wheel brake motor is connected to a left front wheel ball screw through a left front wheel brake motor rotating speed sensor and a left front wheel speed reducing mechanism in sequence, and one end of the left front wheel ball screw is connected to a left front wheel brake cylinder; the output end of the right front wheel brake motor is connected to a right front wheel ball screw through a right front wheel brake motor rotating speed sensor and a right front wheel speed reducing mechanism in sequence, and one end of the right front wheel ball screw is connected to a right front wheel brake cylinder; the output end of the left rear wheel brake motor is connected to a left rear wheel ball screw through a left rear wheel brake motor wheel speed sensor and a left rear wheel speed reducing mechanism in sequence, and one end of the left rear wheel ball screw is connected to a left rear wheel brake cylinder; the output end of the right rear wheel brake motor is connected to a right rear wheel ball screw through a right rear wheel brake motor rotating speed sensor and a right rear wheel speed reducing mechanism in sequence, and one end of the right rear wheel ball screw is connected to a right rear wheel brake cylinder; the rotary motion of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor respectively passes through the left front wheel speed reduction mechanism and the left front wheel ball screw, the right front wheel speed reduction mechanism and the right front wheel ball screw, the left rear wheel speed reduction mechanism and the left rear wheel ball screw, the right rear wheel speed reduction mechanism and the right rear wheel ball screw in sequence and is converted into the displacement motion of the screw rod end of the left front wheel ball screw, the screw rod end of the right front wheel ball screw, the screw rod end of the left rear wheel ball screw and the screw rod end of the right rear wheel ball screw, and the displacement motion respectively acts on the left front wheel brake cylinder, the right front wheel brake master cylinder, the left rear wheel brake master cylinder and the right rear wheel brake master cylinder to generate brake torque, so as to finish the brake operation of the vehicle;
the wire-controlled chassis control unit includes: the drive-by-wire chassis integrated controller and other state units of the vehicle; the input end of the drive-by-wire chassis integrated controller is connected with a corner sensor, a torque sensor, a drive-by-wire steering controller, a brake pedal displacement sensor, an accelerator pedal displacement sensor, a drive-by-wire controller, and other state units of the vehicle through a vehicle-mounted communication line; the other state units of the vehicle are used for acquiring the vehicle speed and the yaw rate;
the input end of the steer-by-wire controller is connected with a steering motor rotating speed sensor through a vehicle-mounted communication line, and the output end of the steer-by-wire controller is connected with the steer-by-wire chassis integrated controller;
the input end of the drive-by-wire controller is connected with a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor and a right rear wheel speed sensor through a vehicle-mounted communication line, and the output end of the drive-by-wire controller is connected with a drive-by-wire chassis integrated controller;
the input end of the line control controller is connected with a left front wheel brake motor rotating speed sensor, a right front wheel brake motor rotating speed sensor, a left rear wheel brake motor rotating speed sensor and a right rear wheel brake motor rotating speed sensor through a vehicle-mounted communication line, and the output end of the line control controller is connected with a line control chassis integrated controller;
the digital twin diagnostic system includes: the system comprises an initial model building module, a correction parameter determining module, a correction quantity determining module, a model updating module and a fault diagnosis module;
the initial model building module is used for obtaining initial state parameters and initial response parameters of the intelligent drive-by-wire chassis system so as to build an initial twin model of the intelligent drive-by-wire chassis system;
the correction parameter determining module is used for acquiring target response parameters of the intelligent line control chassis system and corresponding update parameters thereof, calculating the sensitivity of each update parameter relative to the target response parameters, and taking the update parameters with the sensitivity meeting the preset requirements as the correction parameters;
the correction quantity determining module is used for constructing a response surface model between the target response parameter and the correction parameter and determining the correction value of the correction parameter based on the response surface model;
the model updating module is used for updating the initial digital twin model by using the correction value of the correction parameter to obtain a digital twin model of the intelligent line control chassis system;
and the fault diagnosis module is used for diagnosing faults of the intelligent drive-by-wire chassis system by utilizing the digital twin model.
Further, the chassis-by-wire integrated controller includes: the system comprises a signal processing unit, a chassis decision database, a fault diagnosis unit, a fault alarm unit and a chassis driving unit;
the signal processing unit is respectively electrically connected with the corner sensor, the torque sensor, the brake pedal position sensor, the accelerator pedal position sensor, the drive-by-wire controller, the steer-by-wire controller and the wire control controller to acquire signals acquired by the sensors in real time and signals output by the drive-by-wire controller, the steer-by-wire controller and the wire control controller, and is electrically connected with other state units of the vehicle to acquire a vehicle speed signal and a yaw velocity signal of the vehicle; the input end of the fault diagnosis unit is electrically connected with the signal processing unit, the sensor information and the vehicle state information are obtained, and the state information of the wire-controlled chassis is output to the chassis decision unit through the vehicle-mounted communication line after calculation; the fault alarm unit receives a control instruction of the chassis decision unit through a vehicle-mounted communication line;
the chassis decision unit receives input signals of the signal processing unit, the chassis decision database and the fault diagnosis unit through a vehicle-mounted communication line respectively, and outputs instructions to the chassis driving unit and the fault alarm unit through the vehicle-mounted communication line after calculation; the chassis driving unit respectively outputs control signals of the road feel simulation device, the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor, the right rear wheel hub motor, the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor; the fault alarm unit reminds a driver of the fault information of the current drive-by-wire chassis according to the received control instruction; and finishing the integrated control process of the drive-by-wire chassis.
Further, the fault diagnosis unit includes: the device comprises a parameter obtaining unit, a parameter relation determining unit, a first difference function constructing unit, a second difference function constructing unit and a variation determining unit;
the parameter acquisition unit is used for acquiring a first state parameter corresponding to a target fault of the intelligent line control chassis system;
the parameter relation determining unit is used for representing the first state parameter by using the response parameter of the intelligent line control chassis system to obtain a response parameter representation function corresponding to the first state parameter;
the first difference function building unit is used for building a first difference function between an actual value of a response parameter and a simulated value obtained based on the initial digital twin model;
the second difference function construction unit is used for constructing a second difference function between the actual variation of the response parameter before and after the fault and the simulation variation determined based on the digital twin model based on the response parameter characterization function;
and the variable quantity determining unit is used for carrying out minimization processing on the second difference function to obtain the variable quantity of the first state parameter, and further determining the fault diagnosis result of the intelligent line control chassis system.
The invention discloses an active fault-tolerant method of an intelligent drive-by-wire chassis architecture based on a digital twin, which comprises the following steps based on the architecture:
1) accelerating, braking or steering according to the current running condition of the vehicle;
2) the drive-by-wire controller receives the left front wheel rotating speed signal, the right front wheel rotating speed signal, the left rear wheel rotating speed signal and the right rear wheel rotating speed signal in real time, integrates the received signals to obtain a drive-by-wire system state signal, and transmits the drive-by-wire system state signal to the drive-by-wire chassis integrated controller; the line control controller receives a rotating speed signal of a left front wheel brake motor, a rotating speed signal of a right front wheel brake motor, a rotating speed signal of a left rear wheel brake motor and a rotating speed signal of a right rear wheel brake motor in real time, integrates the received signals to obtain a state signal of a line control brake system, and transmits the state signal to the line control chassis integrated controller; the steer-by-wire controller receives a rotating speed signal of a steering motor in real time, integrates the received signal to obtain a state signal of the steer-by-wire system, and transmits the state signal to the steer-by-wire chassis integrated controller;
3) the signal processing unit receives a corner signal, a torque signal, a steer-by-wire system state signal, a brake pedal position signal, an accelerator pedal position signal, a brake-by-wire system state signal and a drive-by-wire system state signal in real time, integrates the signals to obtain a current chassis state signal, and transmits the current chassis state signal to the chassis decision unit;
4) the chassis decision unit carries out decision calculation on the chassis state signals according to the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle in each chassis state stored in the chassis decision database to obtain the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle at the next moment; meanwhile, the expected driving road feeling at the next moment is obtained, and the steering column torque corresponding to the expected driving road feeling at the next moment is calculated; and outputting instructions to the drive unit;
5) the chassis driving unit selects the working modes of a drive-by-wire system, a brake-by-wire system and a steer-by-wire system in the drive-by-wire chassis system according to an instruction output by the chassis decision unit, and respectively outputs a road feel control signal, a brake-by-wire system control signal, a drive-by-wire system control signal and a steer-by-wire system control signal to complete driving road feel feedback, brake torque output, drive torque output and steering assistance torque output, thereby realizing integrated cooperative control of the drive-by-wire chassis system.
Further, the fault detection of the intelligent drive-by-wire chassis system based on the digital twin method in the step 5) specifically includes:
51) the intelligent drive-by-wire chassis system is used as a physical model in an actual working environment, a digital twin model matched with the physical model is built on a simulation platform based on a digital twin technology, the simulation working environment of the digital twin model is configured to keep consistent with the actual working environment of the physical model, the collected physical data generated by the operation of the physical model and the collected virtual data generated by the operation of the digital twin model are received through a communication line, and a large amount of heterogeneous physical data and virtual data are subjected to data analysis and fusion processing;
52) initial state parameter c of intelligent drive-by-wire chassis system is obtained by initial model building module0Data and initial response parameter t0Obtaining an initial twin model of the intelligent drive-by-wire chassis system through data;
53) the correction parameter determining module obtains a target response parameter t of the intelligent line control chassis system and an update parameter u corresponding to the target response parameter t, and calculates each update parameter uiWith respect to the target response parameter tiSensitivity S ofiTaking an updated parameter with the sensitivity meeting a preset requirement as a correction parameter d; for n update parameters u ═ u1,u2,...,un]TThe corresponding target response parameter is t ═ t1,t2,...,tm]TThen, the sensitivity of the jth target response parameter corresponding to the ith update parameter is approximately expressed as:
Figure GDA0003295068630000051
wherein h is the assumed amount of change;
the integrated sensitivity corresponding to the ith update parameter is expressed as:
Figure GDA0003295068630000052
setting a threshold value T when S (u)i) When the value is more than or equal to T, the parameter u is considered to be updatediFor target response parameter tiIs determined as the correction parameter di；
54) A correction quantity determining module constructs a response surface model between a response parameter t and a correction parameter d of the intelligent drive-by-wire chassis system, and the construction method of the response surface model comprises a full factor method, an orthogonal method, a uniform method and the like; determining a correction value d of the correction parameter based on the response surface model; the model updating module updates the digital twin model by using the correction value d of the correction parameter to obtain a digital twin model with a real-time updated working state;
55) a first difference function construction unit in the fault diagnosis module constructs an actual value a of a response parameter of the intelligent drive-by-wire chassis systemiAnd a simulation value s obtained based on the initial digital twin modeliA first difference function therebetween, the first difference function being expressed as:
Figure GDA0003295068630000061
a correction quantity determining module for determining the first difference function E based on the response surface model1Performing minimization processing, and searching the value d of the correction parameter satisfying the above formula in the response surface space1；
56) A parameter acquisition unit in a fault diagnosis module acquires a first state parameter c corresponding to a target fault of the intelligent line control chassis systemmThe parameter relation determining unit in the fault diagnosis module utilizes the simulation variation deltas and the actual of the response parameter of the intelligent drive-by-wire chassis systemThe variation Δ a characterizing the first state parameter cmObtaining the first state parameter cmA corresponding response parameter characterization function; the response parameter characterization function constructed based on the digital twin model is expressed as:
Figure GDA0003295068630000062
the response parameter characterization function constructed based on the actual running state of the intelligent drive-by-wire chassis system is expressed as:
Figure GDA0003295068630000063
in the formula,. DELTA.cjRepresenting the variation of the jth first state parameter; m represents the number of first state parameters; n represents the number of response parameters; Δ sjiRepresenting the ith response parameter obtained based on the digital twin model with respect to Δ cjThe simulation variation of (2); Δ ajiRepresenting the ith response parameter relative to Δ cjThe actual amount of change in; f. ofjiRepresents Δ sjiAnd Δ cjFunctional relationship between; gjiDenotes Δ ajiAnd Δ cjFunctional relationship between;
57) a second difference function construction unit in the fault diagnosis module constructs the actual variation delta a of the response parameter before and after the fault occurrence based on the response parameter characterization functionjiWith a simulation variation Δ s determined based on the digital twin modeljiA second difference function therebetween; the second difference function is expressed as:
Figure GDA0003295068630000064
the variation amount determining unit in the failure diagnosis module applies the second difference function E2Carrying out minimization processing to obtain the variation delta c of the first state parameter, and carrying out linear control chassis system according to the variation delta c of the first state parameterDiagnosing the fault;
58) updating the digital twin model according to the variation delta c of the first state parameter to obtain a first digital twin model, and taking an L value meeting the following fault position identification model as the position of the fault:
Figure GDA0003295068630000065
wherein L represents a failure position, ai(L) actual value of response parameter when fault occurs at L position, si(L) a simulated value of a response parameter obtained based on the digital twin model when a fault occurs at the L position, and n a fault measurement point.
Further, the selecting of the operating modes of the drive-by-wire system, the brake-by-wire system, and the steer-by-wire system according to the operating state of the intelligent chassis-by-wire system in the step 5) specifically includes:
511) the fault diagnosis unit monitors the working state of the intelligent line-control chassis system by using the method for detecting the fault of the intelligent line-control chassis system based on the digital twin method; the chassis decision unit outputs an instruction to the chassis driving unit according to the working state of the intelligent line-control chassis system to drive the line-control driving system, the line-control braking system and the line-control steering system to work;
512) if the steer-by-wire system is in failure, the steer motor stops working when the drive-by-wire system and the brake-by-wire system both work normally; the drive-by-wire system participates in the steering work, the left front wheel hub motor and the right front wheel hub motor output different motor rotating speeds, the front wheel differential power-assisted steering is realized, and a driver is assisted to reach a desired turning angle of the front wheel; after the steering work is finished, the vehicle reaches a stable running state, at the moment, the fault alarm unit reminds a driver of a fault and reminds the driver of braking operation, the brake-by-wire system outputs corresponding braking force according to a brake pedal signal given by the driver to brake the vehicle stably, and the intelligent drive-by-wire chassis system is subjected to fault elimination;
513) if the brake-by-wire system breaks down, when the steer-by-wire system and the drive-by-wire system both work normally, the method specifically comprises the following steps:
5131) when one brake motor of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor breaks down, the fault alarm unit reminds a driver of breaking down and reminds the driver of brake operation, the fault brake motor stops working, the brake motors arranged in a crossed mode stop working, the normal brake motors brake, and the drive-by-wire system participates in brake operation, the hub motors at the positions of the fault brake motors and the hub motors arranged in a crossed mode reverse rotation at the moment, and brake torque identical to that of the normal brake motors is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5132) when one of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor which are positioned on different sides fails, the failure alarm unit reminds a driver of the failure and reminds the driver of performing brake operation, the failure brake motor stops working, and the normal brake motor performs brake; when the pedal signal output by the driver is slow and small in amplitude, the brake operation is finished only by the brake-by-wire system; under the condition that pedal signals output by a driver are rapid and large in amplitude, the brake work is simultaneously completed by the line control brake system and the line control drive system, the hub motor at the position where the fault brake motor is located is reversed, and the same brake torque as that of a normal brake motor is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5133) under other fault conditions, the fault alarm unit reminds a driver of fault and reminds the driver of brake operation, all brake motors stop working, the drive-by-wire system completes brake work, and the four hub motors reversely rotate to output corresponding brake torque according to brake pedal signals output by the driver; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
514) if the drive-by-wire system fails, when the steer-by-wire system and the brake-by-wire system both work normally, the failure alarm unit directly reminds the driver of the failure and reminds the driver of brake operation, all the hub motors stop working, and the brake-by-wire system outputs proper brake torque to complete brake work according to the brake pedal signal of the driver; meanwhile, the wire control steering system outputs a yaw moment to compensate the yaw motion in the vehicle braking process in real time, and assists a driver to complete vehicle braking.
The invention has the beneficial effects that:
the intelligent drive-by-wire chassis architecture based on the digital twin integrates a drive-by-wire system, a steer-by-wire system and a brake-by-wire system, and provides a platform for researching the coupling among a plurality of subsystems; meanwhile, the mechanical structure connection is reduced, the actuator can respond to the instruction of the driver more quickly, and the driving safety is enhanced;
the intelligent drive-by-wire chassis architecture active fault-tolerant method based on the digital twin realizes the integrated cooperative control among the drive-by-wire system, the steer-by-wire system and the brake-by-wire system, enhances the reliability of the whole drive-by-wire chassis system and further improves the driving safety of a driver;
the invention diagnoses the possible faults of the intelligent line control chassis system by using a digital twin technology, detects the actual running state of the intelligent line control chassis system in real time, updates the corresponding digital twin model, diagnoses and predicts the possible faults, and prevents in advance to eliminate potential safety hazards.
Drawings
FIG. 1 is a block diagram of the structural principles of the intelligent drive-by-wire chassis system of the present invention;
FIG. 2 is a schematic block diagram of an active fault tolerance method for an intelligent line control chassis architecture according to the present invention;
FIG. 3 is an active fault-tolerant flow chart of the intelligent line-control chassis architecture of the present invention;
FIG. 4 is a schematic diagram of a fault diagnosis method according to the present invention;
in the drawing, 1-a steering wheel, 2-a rotation angle sensor, 3-a torque sensor, 4-a steering column, 5-a road feel simulation means, 6-a left front wheel brake motor, 7-a left front wheel brake motor rotation speed sensor, 8-a left front wheel speed sensor, 9-a left front wheel hub motor, 10-a left front wheel brake cylinder, 11-a left front wheel reduction mechanism, 12-a left front wheel ball screw, 13-a left front wheel, 14-a left rear wheel brake motor, 15-a left rear wheel brake motor rotation speed sensor, 16-a left rear wheel speed sensor, 17-a left rear wheel hub motor, 18-a left rear wheel brake cylinder, 19-a left rear wheel reduction mechanism, 20-a left rear wheel ball screw, 21-a left rear wheel, 22-a line control controller, 23-drive-by-wire controller, 24-right rear wheel, 25-right rear wheel ball screw, 26-right rear wheel reduction mechanism, 27-right rear wheel brake cylinder, 28-right rear wheel hub motor, 29-right rear wheel speed sensor, 30-right rear wheel brake motor speed sensor, 31-right rear wheel brake motor, 32-right front wheel, 33-right front wheel ball screw, 34-right front wheel reduction mechanism, 35-right front wheel brake cylinder, 36-right front wheel hub motor, 37-right front wheel speed sensor, 38-right front wheel brake motor speed sensor, 39-right front wheel brake motor, 40-vehicle other status unit, 41-steer-by-wire controller, 42-chassis-by-wire integrated controller, 43-steer ladder, 44-brake pedal position sensor, 45-brake pedal, 46-accelerator pedal, 47-accelerator pedal position sensor, 48-steering tie rod, 49-steering ball screw, 50-steering speed reducing mechanism, 51-steering motor speed sensor and 52-steering motor;
a-angle signal, B-torque signal, C-steer-by-wire system status signal, C1Steering motor speed signal, D-brake pedal position signal, E-accelerator pedal position signal, F1Left front wheel brake motor speed signal, F2-right front wheel brake motor speed signal, F3Left rear wheel brake motor speed signal, F4-a right rear wheel brake motor speed signal, F-brake-by-wire system status signal, G1Left front wheel speed signal, G2Right front wheel speed signal, G3Left rear wheel speed signal, G4Right rear wheel speed signal, G-lineA control drive system state signal, an H-road feel control signal, an I-brake-by-wire system control signal, a J-steering-by-wire system control signal, a K-drive-by-wire system control signal, an N-vehicle speed signal and a P-yaw rate signal.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.
Referring to fig. 1, a digital twin based intelligent drive-by-wire chassis architecture comprises: an intelligent line control chassis system and a digital twin diagnosis system;
intelligent drive-by-wire chassis system, comprising: the system comprises a drive-by-wire system, a steer-by-wire system, a brake-by-wire system, a chassis control unit, a drive-by-wire controller, a steer-by-wire controller and a control controller; wherein the content of the first and second substances,
the drive-by-wire system includes: an accelerator pedal 46, an accelerator pedal position sensor 47, a left front wheel hub motor 9, a right front wheel hub motor 36, a left rear wheel hub motor 17, a right rear wheel hub motor 28, a left front wheel speed sensor 8, a right front wheel speed sensor 37, a left rear wheel speed sensor 16, a right rear wheel speed sensor 29, a left front wheel 13, a right front wheel 32, a left rear wheel 21, a right rear wheel 24; an accelerator pedal position sensor 47 is fixedly mounted on the accelerator pedal 46; a left front wheel hub motor 9 and a left front wheel speed sensor 8 are arranged in a left front wheel 13; a right front wheel hub motor 36 and a right front wheel speed sensor 37 are mounted in the right front wheel 32; the left rear wheel hub motor 17 and the left rear wheel speed sensor 16 are arranged in the left rear wheel 21; a right rear wheel hub motor 28 and a right rear wheel speed sensor 29 are installed in the right rear wheel 24; the rotary motion output by the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor and the right rear wheel hub motor is respectively converted into the rotary motion of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel to drive the vehicle to run;
the steer-by-wire system includes: the device comprises a steering wheel 1, a steering column 4, a road feel simulation device 5 and a steering assembly;
the steering wheel 1 is connected with a steering column 4, a corner sensor 2 and a torque sensor 3 are respectively and fixedly installed on the steering column 4, and acting force input by the steering wheel acts on a road feel simulation device 5 through the steering column 4;
the steering assembly includes: a steering motor 52, a steering motor speed sensor 51, a steering speed reducing mechanism 50, a steering ball screw 49, a steering tie rod 48 and a steering trapezoid 43; the output end of the steering motor 52 is connected to the nut of the steering ball screw 49 through a steering motor speed sensor 51 and a steering speed reducing mechanism 50 in sequence; the screw end of the steering ball screw 49 breaks the tie rod 48, and the two ends of the steering ball screw 49 are axially and fixedly connected with the two broken ports of the tie rod 48; the rotary motion output by the steering motor 52 is converted into the displacement motion of the tie rod 48 through the steering reduction mechanism 50 and the steering ball screw 49, and the displacement motion of the tie rod 48 completes the steering action of the vehicle through the steering trapezoid 43 and the wheels;
the brake-by-wire system includes: a brake pedal 45, a brake pedal position sensor 44, a left front wheel brake motor 6, a left front wheel brake motor rotation speed sensor 7, a left front wheel reduction mechanism 11, a left front wheel ball screw 12, a left front wheel brake cylinder 10, a right front wheel brake motor 39, a right front wheel brake motor rotation speed sensor 38, a right front wheel reduction mechanism 34, a right front wheel ball screw 33, a right front wheel brake cylinder 35, a left rear wheel brake motor 14, a left rear wheel brake motor rotation speed sensor 15, a left rear wheel reduction mechanism 19, a left rear wheel ball screw 20, a left rear wheel brake cylinder 18, a right rear wheel brake motor 31, a right rear wheel brake motor rotation speed sensor 30, a right rear wheel reduction mechanism 26, a right rear wheel ball screw 25 and a right rear wheel brake cylinder 27; a brake pedal position sensor 44 is fixedly mounted on a brake pedal 45; the output end of a left front wheel brake motor 6 is connected to a left front wheel ball screw 12 through a left front wheel brake motor rotating speed sensor 7 and a left front wheel speed reducing mechanism 11 in sequence, and one end of the left front wheel ball screw 12 is connected to a left front wheel brake cylinder 10; the output end of a right front wheel brake motor 39 is connected to a right front wheel ball screw 33 through a right front wheel brake motor rotating speed sensor 38 and a right front wheel speed reducing mechanism 34 in sequence, and one end of the right front wheel ball screw 33 is connected to a right front wheel brake cylinder 35; the output end of the left rear wheel brake motor 14 is connected to a left rear wheel ball screw 20 through a left rear wheel brake motor wheel speed sensor 15 and a left rear wheel speed reducing mechanism 19 in sequence, and one end of the left rear wheel ball screw 20 is connected to a left rear wheel brake wheel cylinder 18; the output end of a right rear wheel brake motor 31 is connected to a right rear wheel ball screw 25 through a right rear wheel brake motor rotating speed sensor 30 and a right rear wheel speed reducing mechanism 26 in sequence, and one end of the right rear wheel ball screw 25 is connected to a right rear wheel brake cylinder 27; the rotary motion of the left front wheel brake motor 6, the right front wheel brake motor 39, the left rear wheel brake motor 14 and the right rear wheel brake motor 31 respectively passes through the left front wheel speed reduction mechanism 11 and the left front wheel ball screw 12, the right front wheel speed reduction mechanism 34 and the right front wheel ball screw 33, the left rear wheel speed reduction mechanism 19 and the left rear wheel ball screw 20, the right rear wheel speed reduction mechanism 26 and the right rear wheel ball screw 25 to be converted into the displacement motion of the screw rod end of the left front wheel ball screw, the screw rod end of the right front wheel ball screw, the screw rod end of the left rear wheel ball screw and the screw rod end of the right rear wheel ball screw, and the displacement motion respectively acts on the left front wheel brake cylinder, the right front wheel brake master cylinder, the left rear wheel brake master cylinder and the right rear wheel brake master cylinder to generate brake torque, and the brake operation of the vehicle is completed;
the wire-controlled chassis control unit includes: a drive-by-wire chassis integrated controller 42, a vehicle other status unit 40; the input end of the drive-by-wire chassis integrated controller 42 is connected with the corner sensor 2, the torque sensor 3, the steer-by-wire controller 41, the brake pedal displacement sensor 44, the accelerator pedal displacement sensor 47, the line control controller 22, the drive-by-wire controller 23 and the other vehicle state unit 40 through the vehicle-mounted communication line; the other state units of the vehicle are used for acquiring the vehicle speed and the yaw rate;
the input end of the steer-by-wire controller 41 is connected with a steering motor rotating speed sensor 51 through a vehicle-mounted communication line, and the output end of the steer-by-wire controller 41 is connected with the chassis-by-wire integrated controller 42;
the input end of the drive-by-wire controller 23 is connected with the left front wheel speed sensor 8, the right front wheel speed sensor 37, the left rear wheel speed sensor 16 and the right rear wheel speed sensor 29 through vehicle-mounted communication lines, and the output end of the drive-by-wire controller is connected with the chassis integrated controller 42;
the input end of the line control controller 22 is connected with the left front wheel brake motor rotating speed sensor 7, the right front wheel brake motor rotating speed sensor 38, the left rear wheel brake motor rotating speed sensor 15 and the right rear wheel brake motor rotating speed sensor 30 through a vehicle-mounted communication line, and the output end of the line control controller 22 is connected with the line control chassis integrated controller 42.
The chassis-by-wire integrated controller 42 includes: the system comprises a signal processing unit, a chassis decision database, a fault diagnosis unit, a fault alarm unit and a chassis driving unit;
referring to fig. 2, the signal processing unit is electrically connected to the corner sensor, the torque sensor, the brake pedal position sensor, the accelerator pedal position sensor, the drive-by-wire controller, the steer-by-wire controller, and the wire control controller, respectively, to obtain signals collected by the sensors in real time and signals output by the drive-by-wire controller, the steer-by-wire controller, and the wire control controller, and is electrically connected to other state units of the vehicle to obtain a vehicle speed signal N and a yaw rate signal P of the vehicle; the input end of the fault diagnosis unit is electrically connected with the signal processing unit, the sensor information and the vehicle state information are obtained, and the state information of the wire-controlled chassis is output to the chassis decision unit through the vehicle-mounted communication line after calculation; the fault alarm unit receives a control instruction of the chassis decision unit through a vehicle-mounted communication line;
the chassis decision unit receives input signals of the signal processing unit, the chassis decision database and the fault diagnosis unit through a vehicle-mounted communication line respectively, and outputs instructions to the chassis driving unit and the fault alarm unit through the vehicle-mounted communication line after calculation; the chassis driving unit respectively outputs control signals of the road feel simulation device, the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor, the right rear wheel hub motor, the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor; the fault alarm unit reminds a driver of the fault information of the current drive-by-wire chassis according to the received control instruction; and finishing the integrated control process of the drive-by-wire chassis.
The digital twin diagnostic system includes: the system comprises an initial model building module, a correction parameter determining module, a correction quantity determining module, a model updating module and a fault diagnosis module;
the initial model building module is used for obtaining initial state parameters and initial response parameters of the intelligent drive-by-wire chassis system so as to build an initial twin model of the intelligent drive-by-wire chassis system;
the correction parameter determining module is used for acquiring target response parameters of the intelligent line control chassis system and corresponding update parameters thereof, calculating the sensitivity of each update parameter relative to the target response parameters, and taking the update parameters with the sensitivity meeting the preset requirements as the correction parameters;
the correction quantity determining module is used for constructing a response surface model between the target response parameter and the correction parameter and determining the correction value of the correction parameter based on the response surface model;
the model updating module is used for updating the initial digital twin model by using the correction value of the correction parameter to obtain a digital twin model of the intelligent line control chassis system;
and the fault diagnosis module is used for diagnosing faults of the intelligent drive-by-wire chassis system by utilizing the digital twin model.
Wherein the fault diagnosis unit includes: the device comprises a parameter obtaining unit, a parameter relation determining unit, a first difference function constructing unit, a second difference function constructing unit and a variation determining unit;
the parameter acquisition unit is used for acquiring a first state parameter corresponding to a target fault of the intelligent line control chassis system;
the parameter relation determining unit is used for representing the first state parameter by using the response parameter of the intelligent line control chassis system to obtain a response parameter representation function corresponding to the first state parameter;
the first difference function building unit is used for building a first difference function between an actual value of a response parameter and a simulated value obtained based on the initial digital twin model;
the second difference function construction unit is used for constructing a second difference function between the actual variation of the response parameter before and after the fault and the simulation variation determined based on the digital twin model based on the response parameter characterization function;
and the variable quantity determining unit is used for carrying out minimization processing on the second difference function to obtain the variable quantity of the first state parameter, and further determining the fault diagnosis result of the intelligent line control chassis system.
Referring to fig. 1 and fig. 3, the active fault-tolerant method of the intelligent drive-by-wire chassis architecture based on the digital twin according to the present invention includes the following steps based on the above architecture:
1) accelerating, braking or steering according to the current running condition of the vehicle;
2) the drive-by-wire controller receives the left front wheel rotating speed signal G in real time1Right front wheel rotation speed signal G2Left rear wheel rotation speed signal G3And a right rear wheel rotation speed signal G4Integrating the received signals to obtain a drive-by-wire system state signal G, and transmitting the drive-by-wire system state signal G to a drive-by-wire chassis integrated controller; the line control controller receives the rotating speed signal F of the left front wheel brake motor in real time1Front right wheel brake motor speed signal F2Left rear wheel brake motor speed signal F3And a rotating speed signal F of a brake motor of the right rear wheel4Integrating the received signals to obtain a brake-by-wire system state signal F, and transmitting the brake-by-wire system state signal F to a chassis integrated controller by wire control; the steer-by-wire controller receives a rotating speed signal of a steering motor in real time, integrates the received signal to obtain a state signal C of the steer-by-wire system, and transmits the state signal C to the integrated controller of the steer-by-wire chassis;
3) the signal processing unit receives a corner signal A, a torque signal B, a steer-by-wire system state signal C, a brake pedal position signal D, an accelerator pedal position signal E, a brake-by-wire system state signal I and a drive-by-wire system state signal K in real time, integrates the signals to obtain a current chassis state signal, and transmits the current chassis state signal to the chassis decision unit;
4) the chassis decision unit carries out decision calculation on the chassis state signals according to the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle in each chassis state stored in the chassis decision database to obtain the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle at the next moment; meanwhile, the expected driving road feeling at the next moment is obtained, and the steering column torque corresponding to the expected driving road feeling at the next moment is calculated; and outputting instructions to the drive unit;
5) the chassis driving unit selects the working modes of a drive-by-wire system, a brake-by-wire system and a steer-by-wire system in the drive-by-wire chassis system according to an instruction output by the chassis decision unit, and respectively outputs a road feel control signal H, a brake-by-wire system control signal, a drive-by-wire system control signal K and a steer-by-wire system control signal J to complete driving road feel feedback, brake torque output, drive torque output and steering assistance torque output, so that integrated cooperative control of the drive-by-wire chassis system is realized.
Referring to fig. 4, the step 5) of performing fault detection on the drive-by-wire chassis system based on the digital twin method specifically includes:
51) the intelligent drive-by-wire chassis system is used as a physical model in an actual working environment, a digital twin model matched with the physical model is built on a simulation platform based on a digital twin technology, the simulation working environment of the digital twin model is configured to keep consistent with the actual working environment of the physical model, the collected physical data generated by the operation of the physical model and the collected virtual data generated by the operation of the digital twin model are received through a communication line, and a large amount of heterogeneous physical data and virtual data are subjected to data analysis and fusion processing;
52) initial state parameter c of intelligent drive-by-wire chassis system is obtained by initial model building module0Data and initial response parameter t0Obtaining an initial twin model of the intelligent drive-by-wire chassis system through data;
53) the correction parameter determining module obtains a target response parameter t and the target response parameter u of the intelligent line control chassis system, and calculates each update parameter uiWith respect to the target response parameter tiSensitivity S ofiTaking an updated parameter with the sensitivity meeting a preset requirement as a correction parameter d; for n update parameters u ═ u1,u2,...,un]TThe corresponding target response parameter is t ═ t1,t2,...,tm]TThen, the sensitivity of the jth target response parameter corresponding to the ith update parameter is approximately expressed as:
Figure GDA0003295068630000121
wherein h is the assumed amount of change;
the integrated sensitivity corresponding to the ith update parameter is expressed as:
Figure GDA0003295068630000131
setting a threshold value T when S (u)i) When the value is more than or equal to T, the parameter u is considered to be updatediFor target response parameter tiIs determined as the correction parameter di；
54) A correction quantity determining module constructs a response surface model between a response parameter t and a correction parameter d of the intelligent drive-by-wire chassis system, and the construction method of the response surface model comprises a full factor method, an orthogonal method, a uniform method and the like; determining a correction value d of the correction parameter based on the response surface model; the model updating module updates the digital twin model by using the correction value d of the correction parameter to obtain a digital twin model with a real-time updated working state;
55) a first difference function construction unit in the fault diagnosis module constructs an actual value a of a response parameter of the intelligent drive-by-wire chassis systemiAnd a simulation value s obtained based on the initial digital twin modeliA first difference function therebetween, the first difference function being expressed as:
Figure GDA0003295068630000132
a correction quantity determining module for determining the first difference function E based on the response surface model1Performing minimization processing, and searching the value d of the correction parameter satisfying the above formula in the response surface space1；
56) A parameter acquisition unit in a fault diagnosis module acquires a first state parameter c corresponding to a target fault of the intelligent line control chassis systemmThe parameter relation determining unit in the fault diagnosis module represents the first state parameter c by using the simulation variation deltas and the actual variation deltaa of the response parameter of the intelligent drive-by-wire chassis systemmObtaining the first state parameter cmA corresponding response parameter characterization function; the response parameter characterization function constructed based on the digital twin model is expressed as:
Figure GDA0003295068630000133
the response parameter characterization function constructed based on the actual running state of the intelligent drive-by-wire chassis system is expressed as:
Figure GDA0003295068630000134
in the formula,. DELTA.cjRepresenting the variation of the jth first state parameter; m represents the number of first state parameters; n represents the number of response parameters; Δ sjiRepresenting the ith response parameter obtained based on the digital twin model with respect to Δ cjThe simulation variation of (2); Δ ajiRepresenting the ith response parameter relative to Δ cjThe actual amount of change in; f. ofjiRepresents Δ sjiAnd Δ cjFunctional relationship between; gjiDenotes Δ ajiAnd Δ cjFunctional relationship between;
57) a second difference function construction unit in the fault diagnosis module constructs the actual variation delta a of the response parameter before and after the fault occurrence based on the response parameter characterization functionjiWith a simulation variation Δ s determined based on the digital twin modeljiA second difference function therebetween; the second difference function is expressed as:
Figure GDA0003295068630000141
the variation amount determining unit in the failure diagnosis module applies the second difference function E2Carrying out minimization processing to obtain the variation delta c of the first state parameter, and diagnosing the fault of the line control chassis system according to the variation delta c of the first state parameter;
58) updating the digital twin model according to the variation delta c of the first state parameter to obtain a first digital twin model, and taking an L value meeting the following fault position identification model as the position of the fault:
Figure GDA0003295068630000142
wherein L represents a failure position, ai(L) actual value of response parameter when fault occurs at L position, si(L) a simulated value of a response parameter obtained based on the digital twin model when a fault occurs at the L position, and n a fault measurement point.
The step 5) of selecting the working modes of the drive-by-wire system, the brake-by-wire system and the steer-by-wire system according to the working state of the intelligent drive-by-wire chassis system specifically comprises the following steps:
511) the fault diagnosis unit monitors the working state of the drive-by-wire chassis by using the method for detecting the fault of the intelligent drive-by-wire chassis system based on the digital twin method; the working state signal of the line-control chassis system is transmitted to a chassis decision unit, and the chassis decision unit outputs an instruction to a chassis driving unit according to the working state of the line-control chassis system to drive the line-control driving system, the line-control braking system and the line-control steering system to work;
512) if the steer-by-wire system is in failure, the steer motor stops working when the drive-by-wire system and the brake-by-wire system both work normally; the drive-by-wire system participates in the steering work, the left front wheel hub motor and the right front wheel hub motor output different motor rotating speeds, the front wheel differential power-assisted steering is realized, and a driver is assisted to reach a desired turning angle of the front wheel; after the steering work is finished, the vehicle reaches a stable running state, at the moment, the fault alarm unit reminds a driver of a fault and reminds the driver of braking operation, the brake-by-wire system outputs corresponding braking force according to a brake pedal signal given by the driver to brake the vehicle stably, and the fault of the chassis-by-wire system is eliminated;
513) if the brake-by-wire system breaks down, when the steer-by-wire system and the drive-by-wire system both work normally, the method specifically comprises the following steps:
5131) when one brake motor of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor breaks down, the fault alarm unit reminds a driver of breaking down and reminds the driver of brake operation, the fault brake motor stops working, the brake motors arranged in a crossed mode stop working, the normal brake motors brake, and the drive-by-wire system participates in brake operation, the hub motors at the positions of the fault brake motors and the hub motors arranged in a crossed mode reverse rotation at the moment, and brake torque identical to that of the normal brake motors is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5132) when one of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor which are positioned on different sides fails, the failure alarm unit reminds a driver of the failure and reminds the driver of performing brake operation, the failure brake motor stops working, and the normal brake motor performs brake; when the pedal signal output by the driver is slow and small in amplitude, the brake operation is finished only by the brake-by-wire system; under the condition that pedal signals output by a driver are rapid and large in amplitude, the brake work is simultaneously completed by the line control brake system and the line control drive system, the hub motor at the position where the fault brake motor is located is reversed, and the same brake torque as that of a normal brake motor is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5133) under other fault conditions, the fault alarm unit reminds a driver of fault and reminds the driver of brake operation, all brake motors stop working, the drive-by-wire system completes brake work, and the four hub motors reversely rotate to output corresponding brake torque according to brake pedal signals output by the driver; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
514) if the drive-by-wire system fails, when the steer-by-wire system and the brake-by-wire system both work normally, the failure alarm unit directly reminds the driver of the failure and reminds the driver of brake operation, all the hub motors stop working, and the brake-by-wire system outputs proper brake torque to complete brake work according to the brake pedal signal of the driver; meanwhile, the wire control steering system outputs a yaw moment to compensate the yaw motion in the vehicle braking process in real time, and assists a driver to complete vehicle braking.
While the invention has been described in terms of its preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (6)

1. A digital twin based intelligent drive-by-wire chassis architecture, comprising: an intelligent line control chassis system and a digital twin diagnosis system;
the intelligent drive-by-wire chassis system comprises: the system comprises a drive-by-wire system, a steer-by-wire system, a brake-by-wire system, a chassis control unit, a drive-by-wire controller, a steer-by-wire controller and a control controller;
the drive-by-wire system includes: the system comprises an accelerator pedal, an accelerator pedal position sensor, a left front wheel hub motor, a right front wheel hub motor, a left rear wheel hub motor, a right rear wheel hub motor, a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor, a right rear wheel speed sensor, a left front wheel, a right front wheel, a left rear wheel and a right rear wheel; the accelerator pedal position sensor is fixedly arranged on the accelerator pedal; the left front wheel hub motor and the left front wheel speed sensor are arranged in the left front wheel; the right front wheel hub motor and the right front wheel speed sensor are arranged in the right front wheel; the left rear wheel hub motor and the left rear wheel speed sensor are arranged in the left rear wheel; a right rear wheel hub motor and a right rear wheel speed sensor are arranged in the right rear wheel; the rotary motion output by the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor and the right rear wheel hub motor is respectively converted into the rotary motion of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel to drive the vehicle to run;
the steer-by-wire system includes: the steering wheel, the steering column, the road feel simulation device and the steering assembly;
the steering wheel is connected with a steering column, a corner sensor and a torque sensor are respectively and fixedly installed on the steering column, and acting force input by the steering wheel acts on the road feel simulation device through the steering column;
the steering assembly includes: the steering motor, the steering motor rotating speed sensor, the steering speed reducing mechanism, the steering ball screw, the steering tie rod and the steering trapezoid; the output end of the steering motor is connected to a nut of the steering ball screw through a steering motor rotating speed sensor and a steering speed reducing mechanism in sequence; a screw rod end of the steering ball screw breaks the tie rod, and two ends of the steering ball screw are axially and fixedly connected with two broken ports of the tie rod; the rotary motion output by the steering motor is converted into the displacement motion of a steering tie rod through a steering speed reducing mechanism and a steering ball screw, and the displacement motion of the steering tie rod completes the steering action of the vehicle through a steering trapezoid and wheels;
the brake-by-wire system includes: a brake pedal, a brake pedal position sensor, a left front wheel brake motor speed sensor, a left front wheel speed reduction mechanism, a left front wheel ball screw, a left front wheel brake cylinder, a right front wheel brake motor speed sensor, a right front wheel speed reduction mechanism, a right front wheel ball screw, a right front wheel brake cylinder, a left rear wheel brake motor speed sensor, a left rear wheel speed reduction mechanism, a left rear wheel ball screw, a left rear wheel brake cylinder, a right rear wheel brake motor speed sensor, a right rear wheel speed reduction mechanism, a right rear wheel ball screw, a right rear wheel brake cylinder; the brake pedal position sensor is fixedly arranged on the brake pedal; the output end of the left front wheel brake motor is connected to a left front wheel ball screw through a left front wheel brake motor rotating speed sensor and a left front wheel speed reducing mechanism in sequence, and one end of the left front wheel ball screw is connected to a left front wheel brake cylinder; the output end of the right front wheel brake motor is connected to a right front wheel ball screw through a right front wheel brake motor rotating speed sensor and a right front wheel speed reducing mechanism in sequence, and one end of the right front wheel ball screw is connected to a right front wheel brake cylinder; the output end of the left rear wheel brake motor is connected to a left rear wheel ball screw through a left rear wheel brake motor wheel speed sensor and a left rear wheel speed reducing mechanism in sequence, and one end of the left rear wheel ball screw is connected to a left rear wheel brake cylinder; the output end of the right rear wheel brake motor is connected to a right rear wheel ball screw through a right rear wheel brake motor rotating speed sensor and a right rear wheel speed reducing mechanism in sequence, and one end of the right rear wheel ball screw is connected to a right rear wheel brake cylinder; the rotary motion of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor respectively passes through the left front wheel speed reduction mechanism and the left front wheel ball screw, the right front wheel speed reduction mechanism and the right front wheel ball screw, the left rear wheel speed reduction mechanism and the left rear wheel ball screw, the right rear wheel speed reduction mechanism and the right rear wheel ball screw in sequence and is converted into the displacement motion of the screw rod end of the left front wheel ball screw, the screw rod end of the right front wheel ball screw, the screw rod end of the left rear wheel ball screw and the screw rod end of the right rear wheel ball screw, and the displacement motion respectively acts on the left front wheel brake cylinder, the right front wheel brake master cylinder, the left rear wheel brake master cylinder and the right rear wheel brake master cylinder to generate brake torque, so as to finish the brake operation of the vehicle;
the wire-controlled chassis control unit includes: the drive-by-wire chassis integrated controller and other state units of the vehicle; the input end of the drive-by-wire chassis integrated controller is connected with a corner sensor, a torque sensor, a drive-by-wire steering controller, a brake pedal displacement sensor, an accelerator pedal displacement sensor, a drive-by-wire controller, and other state units of the vehicle through a vehicle-mounted communication line; the other state units of the vehicle are used for acquiring the vehicle speed and the yaw rate;
the input end of the steer-by-wire controller is connected with a steering motor rotating speed sensor through a vehicle-mounted communication line, and the output end of the steer-by-wire controller is connected with the steer-by-wire chassis integrated controller;
the input end of the drive-by-wire controller is connected with a left front wheel speed sensor, a right front wheel speed sensor, a left rear wheel speed sensor and a right rear wheel speed sensor through a vehicle-mounted communication line, and the output end of the drive-by-wire controller is connected with a drive-by-wire chassis integrated controller;
the input end of the line control controller is connected with a left front wheel brake motor rotating speed sensor, a right front wheel brake motor rotating speed sensor, a left rear wheel brake motor rotating speed sensor and a right rear wheel brake motor rotating speed sensor through a vehicle-mounted communication line, and the output end of the line control controller is connected with a line control chassis integrated controller;
the digital twin diagnostic system includes: the system comprises an initial model building module, a correction parameter determining module, a correction quantity determining module, a model updating module and a fault diagnosis module;
the initial model building module is used for obtaining initial state parameters and initial response parameters of the intelligent drive-by-wire chassis system so as to build an initial twin model of the intelligent drive-by-wire chassis system;
the correction parameter determining module is used for acquiring target response parameters of the intelligent line control chassis system and corresponding update parameters thereof, calculating the sensitivity of each update parameter relative to the target response parameters, and taking the update parameters with the sensitivity meeting the preset requirements as the correction parameters;
the correction quantity determining module is used for constructing a response surface model between the target response parameter and the correction parameter and determining the correction value of the correction parameter based on the response surface model;
the model updating module is used for updating the initial digital twin model by using the correction value of the correction parameter to obtain a digital twin model of the intelligent line control chassis system;
and the fault diagnosis module is used for diagnosing faults of the intelligent drive-by-wire chassis system by utilizing the digital twin model.
2. The digital twin based intelligent chassis-by-wire architecture of claim 1, wherein the chassis-by-wire integrated controller comprises: the system comprises a signal processing unit, a chassis decision database, a fault diagnosis unit, a fault alarm unit and a chassis driving unit;
the signal processing unit is respectively electrically connected with the corner sensor, the torque sensor, the brake pedal position sensor, the accelerator pedal position sensor, the drive-by-wire controller, the steer-by-wire controller and the wire control controller to acquire signals acquired by the sensors in real time and signals output by the drive-by-wire controller, the steer-by-wire controller and the wire control controller, and is electrically connected with other state units of the vehicle to acquire a vehicle speed signal and a yaw velocity signal of the vehicle; the input end of the fault diagnosis unit is electrically connected with the signal processing unit, the sensor information and the vehicle state information are obtained, and the state information of the wire-controlled chassis is output to the chassis decision unit through the vehicle-mounted communication line after calculation; the fault alarm unit receives a control instruction of the chassis decision unit through a vehicle-mounted communication line;
the chassis decision unit receives input signals of the signal processing unit, the chassis decision database and the fault diagnosis unit through a vehicle-mounted communication line respectively, and outputs instructions to the chassis driving unit and the fault alarm unit through the vehicle-mounted communication line after calculation; the chassis driving unit respectively outputs control signals of the road feel simulation device, the left front wheel hub motor, the right front wheel hub motor, the left rear wheel hub motor, the right rear wheel hub motor, the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor; the fault alarm unit reminds a driver of the fault information of the current drive-by-wire chassis according to the received control instruction; and finishing the integrated control process of the drive-by-wire chassis.
3. The intelligent twin-based chassis-by-wire architecture of claim 2, wherein the fault diagnosis unit comprises: the device comprises a parameter obtaining unit, a parameter relation determining unit, a first difference function constructing unit, a second difference function constructing unit and a variation determining unit;
the parameter acquisition unit is used for acquiring a first state parameter corresponding to a target fault of the intelligent line control chassis system;
the parameter relation determining unit is used for representing the first state parameter by using the response parameter of the intelligent line control chassis system to obtain a response parameter representation function corresponding to the first state parameter;
the first difference function building unit is used for building a first difference function between an actual value of a response parameter and a simulated value obtained based on the initial digital twin model;
the second difference function construction unit is used for constructing a second difference function between the actual variation of the response parameter before and after the fault and the simulation variation determined based on the digital twin model based on the response parameter characterization function;
and the variable quantity determining unit is used for carrying out minimization processing on the second difference function to obtain the variable quantity of the first state parameter, and further determining the fault diagnosis result of the intelligent line control chassis system.
4. An active fault tolerance method of a digital twin-based intelligent drive-by-wire chassis architecture, based on the architecture of any one of claims 2-3, characterized by comprising the following steps:
1) accelerating, braking or steering according to the current running condition of the vehicle;
2) the drive-by-wire controller receives the left front wheel rotating speed signal, the right front wheel rotating speed signal, the left rear wheel rotating speed signal and the right rear wheel rotating speed signal in real time, integrates the received signals to obtain a drive-by-wire system state signal, and transmits the drive-by-wire system state signal to the drive-by-wire chassis integrated controller; the line control controller receives a rotating speed signal of a left front wheel brake motor, a rotating speed signal of a right front wheel brake motor, a rotating speed signal of a left rear wheel brake motor and a rotating speed signal of a right rear wheel brake motor in real time, integrates the received signals to obtain a state signal of a line control brake system, and transmits the state signal to the line control chassis integrated controller; the steer-by-wire controller receives a rotating speed signal of a steering motor in real time, integrates the received signal to obtain a state signal of the steer-by-wire system, and transmits the state signal to the steer-by-wire chassis integrated controller;
3) the signal processing unit receives a corner signal, a torque signal, a steer-by-wire system state signal, a brake pedal position signal, an accelerator pedal position signal, a brake-by-wire system state signal and a drive-by-wire system state signal in real time, integrates the signals to obtain a current chassis state signal, and transmits the current chassis state signal to the chassis decision unit;
4) the chassis decision unit carries out decision calculation on the chassis state signals according to the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle in each chassis state stored in the chassis decision database to obtain the expected front wheel rotation angle, the expected driving force and the expected braking force of the vehicle at the next moment; meanwhile, the expected driving road feeling at the next moment is obtained, and the steering column torque corresponding to the expected driving road feeling at the next moment is calculated; and outputting instructions to the drive unit;
5) the chassis driving unit selects the working modes of a drive-by-wire system, a brake-by-wire system and a steer-by-wire system in the drive-by-wire chassis system according to an instruction output by the chassis decision unit, and respectively outputs a road feel control signal, a brake-by-wire system control signal, a drive-by-wire system control signal and a steer-by-wire system control signal to complete driving road feel feedback, brake torque output, drive torque output and steering assistance torque output, thereby realizing integrated cooperative control of the drive-by-wire chassis system.
5. The active fault tolerance method for the intelligent drive-by-wire chassis architecture based on the digital twin according to claim 4, wherein the fault detection of the intelligent drive-by-wire chassis system based on the digital twin in the step 5) specifically comprises:
51) the intelligent drive-by-wire chassis system is used as a physical model in an actual working environment, a digital twin model matched with the physical model is built on a simulation platform based on a digital twin technology, the simulation working environment of the digital twin model is configured to keep consistent with the actual working environment of the physical model, the collected physical data generated by the operation of the physical model and the collected virtual data generated by the operation of the digital twin model are received through a communication line, and a large amount of heterogeneous physical data and virtual data are subjected to data analysis and fusion processing;
52) obtaining initial state parameter c of intelligent line control chassis system0Data and initial response parameter t0Obtaining an initial twin model of the intelligent drive-by-wire chassis system through data;
53) obtaining a target response parameter t of the intelligent line control chassis system and an update parameter u corresponding to the target response parameter t, and calculating each update parameter uiWith respect to the target response parameter tiSensitivity S ofiTaking an updated parameter with the sensitivity meeting a preset requirement as a correction parameter d; for n update parameters u ═ u1,u2,...,un]TThe corresponding target response parameter is t ═ t1,t2,...,tm]TThen, the sensitivity of the jth target response parameter corresponding to the ith update parameter is approximately expressed as:
Figure FDA0003295068620000041
wherein h is the assumed amount of change;
the integrated sensitivity corresponding to the ith update parameter is expressed as:
Figure FDA0003295068620000042
setting a threshold value T when S (u)i) When the value is more than or equal to T, the parameter u is considered to be updatediFor target response parameter tiIs determined as the correction parameter di；
54) Constructing a response surface model between the response parameter t and the correction parameter d of the intelligent line control chassis system, wherein the construction method of the response surface model comprises a full factor method, an orthogonal method and a uniform method; determining a correction value d of the correction parameter based on the response surface model; updating the digital twin model by using the correction value d of the correction parameter to obtain a digital twin model with a real-time updated working state;
55) constructing an actual value a of a response parameter of the intelligent line-control chassis systemiAnd a simulation value s obtained based on the initial digital twin modeliA first difference function therebetween, the first difference function being expressed as:
Figure FDA0003295068620000051
the first difference function E is based on the response surface model1Performing minimization processing, and searching the value d of the correction parameter satisfying the above formula in the response surface space1；
56) Obtaining a first state parameter c corresponding to a target fault of the intelligent line control chassis systemmAnd representing the first state parameter c by using the simulation variation deltas and the actual variation deltaa of the response parameter of the intelligent line-control chassis systemmObtaining the first state parameter cmA corresponding response parameter characterization function; the response parameter characterization function constructed based on the digital twin model is expressed as:
Figure FDA0003295068620000052
the response parameter characterization function constructed based on the actual running state of the intelligent drive-by-wire chassis system is expressed as:
Figure FDA0003295068620000053
in the formula,. DELTA.cjRepresenting the variation of the jth first state parameter; m represents the number of first state parameters; n represents the number of response parameters; Δ sjiRepresenting the ith response parameter obtained based on the digital twin model with respect to Δ cjThe simulation variation of (2); Δ ajiRepresenting the ith response parameter relative to Δ cjThe actual amount of change in; f. ofjiRepresents Δ sjiAnd Δ cjFunctional relationship between; gjiDenotes Δ ajiAnd Δ cjFunctional relationship between;
57) constructing the actual variation delta a of the response parameter before and after the fault based on the response parameter characterization functionjiWith a simulation variation Δ s determined based on the digital twin modeljiA second difference function therebetween; the second difference function is expressed as:
Figure FDA0003295068620000054
for the second difference function E2Carrying out minimization processing to obtain the variation delta c of the first state parameter, and diagnosing the fault of the line control chassis system according to the variation delta c of the first state parameter;
58) updating the digital twin model according to the variation delta c of the first state parameter to obtain a first digital twin model, and taking an L value meeting the following fault position identification model as the position of the fault:
Figure FDA0003295068620000061
wherein L represents a failure position, ai(L) actual value of response parameter when fault occurs at L position, si(L) a simulation value of a response parameter obtained based on the digital twin model when the fault occurs at the L position, and n represents the faultAnd (6) measuring points.
6. The active fault-tolerant method for the intelligent drive-by-wire chassis architecture based on the digital twin according to claim 5, wherein the selecting the operation modes of the drive-by-wire system, the brake-by-wire system and the steer-by-wire system according to the operation state of the intelligent drive-by-wire chassis system in the step 5) specifically comprises:
511) the fault diagnosis unit monitors the working state of the intelligent line-control chassis system by using the method for detecting the fault of the intelligent line-control chassis system based on the digital twin method; the chassis decision unit outputs an instruction to the chassis driving unit according to the working state of the intelligent line-control chassis system to drive the line-control driving system, the line-control braking system and the line-control steering system to work;
512) if the steer-by-wire system is in failure, the steer motor stops working when the drive-by-wire system and the brake-by-wire system both work normally; the drive-by-wire system participates in the steering work, the left front wheel hub motor and the right front wheel hub motor output different motor rotating speeds, the front wheel differential power-assisted steering is realized, and a driver is assisted to reach a desired turning angle of the front wheel; after the steering work is finished, the vehicle reaches a stable running state, at the moment, the fault alarm unit reminds a driver of a fault and reminds the driver of braking operation, the brake-by-wire system outputs corresponding braking force according to a brake pedal signal given by the driver to brake the vehicle stably, and the intelligent drive-by-wire chassis system is subjected to fault elimination;
513) if the brake-by-wire system breaks down, when the steer-by-wire system and the drive-by-wire system both work normally, the method specifically comprises the following steps:
5131) when one brake motor of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor breaks down, the fault alarm unit reminds a driver of breaking down and reminds the driver of brake operation, the fault brake motor stops working, the brake motors arranged in a crossed mode stop working, the normal brake motors brake, and the drive-by-wire system participates in brake operation, the hub motors at the positions of the fault brake motors and the hub motors arranged in a crossed mode reverse rotation at the moment, and brake torque identical to that of the normal brake motors is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5132) when one of the left front wheel brake motor, the right front wheel brake motor, the left rear wheel brake motor and the right rear wheel brake motor which are positioned on different sides fails, the failure alarm unit reminds a driver of the failure and reminds the driver of performing brake operation, the failure brake motor stops working, and the normal brake motor performs brake; when the pedal signal output by the driver is slow and small in amplitude, the brake operation is finished only by the brake-by-wire system; under the condition that pedal signals output by a driver are rapid and large in amplitude, the brake work is simultaneously completed by the line control brake system and the line control drive system, the hub motor at the position where the fault brake motor is located is reversed, and the same brake torque as that of a normal brake motor is output; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
5133) under other fault conditions, the fault alarm unit reminds a driver of fault and reminds the driver of brake operation, all brake motors stop working, the drive-by-wire system completes brake work, and the four hub motors reversely rotate to output corresponding brake torque according to brake pedal signals output by the driver; meanwhile, the wire-controlled steering system outputs a yaw moment to compensate the yaw motion in the braking process of the vehicle in real time, so as to assist a driver to complete the braking of the vehicle;
514) if the drive-by-wire system fails, when the steer-by-wire system and the brake-by-wire system both work normally, the failure alarm unit directly reminds the driver of the failure and reminds the driver of brake operation, all the hub motors stop working, and the brake-by-wire system outputs proper brake torque to complete brake work according to the brake pedal signal of the driver; meanwhile, the wire control steering system outputs a yaw moment to compensate the yaw motion in the vehicle braking process in real time, and assists a driver to complete vehicle braking.
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