Vehicle control method and system for double-loop adjustable magneto-rheological semi-active suspension

Abstract

The application relates to the technical field of vehicle dynamics control, and discloses a vehicle control method and system of a double-closed-loop adjustable magneto-rheological semi-active suspension, which comprises a damping closed-loop adjustment step: S1: obtaining vehicle state information based on a sensor, establishing a vibration control model, calculating and outputting expected damping force of vibration control; S2: establishing a vehicle body posture control model, calculating and outputting expected damping force of vehicle body posture control; S3: performing operation on the expected damping force obtained in the steps S1 and S2 to obtain total expected damping force; and S4: establishing a suspension inverse model according to the total expected damping force, the relative speed of the wheel and the vehicle body and suspension dynamic deflection information, and outputting expected current. The above application combines damper design parameters and real vehicle test parameters to optimize the control system, and designs current loop adjustment on the basis of the damping loop control, mainly realizes tracking compensation control of the current, thereby improving the response speed and precision of the control, and further improving the performance of the magneto-rheological semi-active suspension.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle dynamics control, in particular to a vehicle control method and system of a double-closed-loop adjustable magneto-rheological semi-active suspension. BACKGROUND

[0002] The design of automobile suspension directly affects the driving stability, comfort and safety of the automobile. Since the damping force of passive suspension is not adjustable, the comfort is poor, and it is gradually replaced by active suspension and semi-active suspension. The high cost and high energy consumption of active suspension greatly limit its application, and the application of semi-active control suspension system to improve the ride comfort and handling stability of vehicles has attracted widespread attention from academia and industry.

[0003] The magneto-rheological semi-active suspension changes the damping coefficient of the shock absorber by adjusting the current input, thereby realizing the adjustment of the damping force, and has the characteristics of low energy consumption, fast response, wide damping force adjustment range and safety, etc. Its excellent high-frequency response characteristics significantly expand its application field, but at the same time, chattering phenomenon is easy to occur when the control system switches at high frequency, which may reduce the overall performance of the suspension system. In addition, most of the controls use vehicle control algorithms based on vehicle state information, output the expected damping force based on a certain optimization target, obtain the suspension control current through the inverse model to realize the adjustment of the damping coefficient, and the control system algorithm does not consider the process loss and previous control quantity disturbance of hardware implementation, etc. Slow response speed, low control accuracy and current distortion problems are easy to occur. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides a vehicle control method and system of a double-closed-loop adjustable magneto-rheological semi-active suspension to solve the above technical problems.

[0005] In a first aspect, a vehicle control method of a double-closed-loop adjustable magneto-rheological semi-active suspension is provided, which includes a damping closed-loop adjustment step:

[0006] S1: obtaining vehicle state information based on sensors, establishing a vibration control model, calculating and outputting expected damping force for vibration control;

[0007] S2: establishing a vehicle body attitude control model, calculating and outputting expected damping force for vehicle body attitude control;

[0008] S3: performing operation on the expected damping forces obtained in steps S1 and S2 to obtain total expected damping force;

[0009] S4: establishing a suspension inverse model according to the total expected damping force, the relative speed of the wheel and the vehicle body and the suspension deflection information, and outputting expected current.

[0010] Further, it further includes a current closed-loop adjustment step:

[0011] The current flowing through the shock absorber coil is collected, filtered, and amplified by a precision resistor, and a feedback voltage is output to the master control chip.

[0012] The actual current is calculated according to the calibration curve fitted by the designed sampling circuit, and the difference between the actual current and the expected current is calculated.

[0013] The algorithm optimization control is performed with the minimum error as the control target, the compensation current is output, and the final output current is obtained through hysteresis correction.

[0014] Further, it further includes the determination steps of the expected current and the current threshold value:

[0015] The expected current is compared with the current threshold value of the shock absorber and the maximum current of the circuit.

[0016] If the expected current is less than the current threshold value of the shock absorber and the maximum current of the circuit, the actual output is performed.

[0017] If the expected current is greater than the current threshold value of the shock absorber or the maximum current of the circuit, the current threshold value of the shock absorber is output.

[0018] In a second aspect, a vehicle control system of a double-loop adjustable magneto-rheological semi-active suspension is provided, based on the vehicle control method of the double-loop adjustable magneto-rheological semi-active suspension of any one of the preceding aspects, comprising:

[0019] A vehicle state acquisition module is configured to acquire vehicle state information.

[0020] A control calculation module is configured to establish a vibration control model and a vehicle body attitude control model, calculate an expected damping force, and output an expected current.

[0021] A driving module is configured to control the current output of the magneto-rheological shock absorber according to the expected current.

[0022] Further, the control calculation module further includes a current collection and feedback unit configured to collect the current in the shock absorber coil, output a feedback voltage, and calculate an actual current.

[0023] Further, it further includes a current threshold value determination module configured to compare the expected current with the current threshold value of the shock absorber and the maximum current of the circuit, and output the actual current according to the comparison result.

[0024] Further, the driving module includes a PWM signal generation unit and a MOSFET high-frequency switch control unit configured to generate a PWM signal according to the expected current, and control the output of the expected current in the driving circuit through the MOSFET high-frequency switch.

[0025] Further, the power module is further included for converting the voltage of the storage battery into the voltage required by the control calculation module and the driving module, and performing voltage stabilization and filtering processing.

[0026] Further, the communication interface module is further included for connecting the host computer to perform algorithm burning, signal matching, control effect observation and data analysis.

[0027] The application adopting the technical scheme has the following advantages:

[0028] The application combines the shock absorber design parameters and the real vehicle test parameters to optimize the control system, and designs the current loop regulation on the basis of the damping loop control, mainly realizes the current tracking compensation control, thereby improving the response speed and precision of the control, and further improving the performance of the magneto-rheological semi-active suspension. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the application, the drawings needed in the specific embodiments will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0030] Figure 1 A flow chart of the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0031] Figure 2 A two-degree-of-freedom 1 / 4 vehicle vibration control model diagram in the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0032] Figure 3 A whole vehicle seven-degree-of-freedom vehicle body posture control model diagram in the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0033] Figure 4 A vehicle control system diagram of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0034] Figure 5 An equivalent circuit diagram of the magneto-rheological shock absorber in the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0035] Figure 6 A positive model diagram of the magneto-rheological shock absorber in the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application;

[0036] Figure 7 An inverse model diagram of the magneto-rheological shock absorber in the vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the application. DETAILED DESCRIPTION

[0037] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0038] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present application should be the general meanings understood by the skilled in the art to which the present application belongs. The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-described drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so as to implement the embodiments of the present disclosure described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. Unless otherwise specified, the term "multiple" means two or more. In the embodiments of the present disclosure, the character " / " represents a "or" relationship between the preceding and following objects. For example, A / B represents: A or B. The term "and / or" is a description of the association between objects, which means that there can be three relationships. For example, A and / or B, which means: A or B, or, A and B, the three relationships. The term "corresponding" can refer to an association or binding relationship, A corresponding to B means that there is an association or binding relationship between A and B.

[0039] As shown in Figures 1-7 The vehicle control method of the double-closed-loop adjustable magneto-rheological semi-active suspension of the present application includes a damping closed-loop adjustment step:

[0040] Step S1: based on the sensor-acquired vehicle state information, a vibration control model is established, and the expected damping force of vibration control is calculated and output;

[0041] Step S2: a vehicle body attitude control model is established, and the expected damping force of vehicle body attitude control is calculated and output;

[0042] Step S3: the expected damping forces obtained in steps S1 and S2 are operated to obtain the total expected damping force;

[0043] Step S4: based on the total expected damping force, the relative speed of the wheel and the vehicle body, and the suspension deflection information, a suspension inverse model is established, and the expected current is output.

[0044] Specifically, based on the sensor-acquired vehicle state information, a vibration control model is established, and the expected damping force of vibration control is output by algorithm calculation with the reduction of the sprung mass acceleration as the control target;

[0045] Based on the vehicle state information, a vehicle body attitude control model is established, and the expected damping force of vehicle body attitude control is output by algorithm calculation with the reduction of the sprung acceleration and the reduction of the vehicle body attitude angular acceleration as the control target;

[0046] The desired damping force of the vibration control and the desired damping force of the attitude control are algorithmically operated to obtain a total desired damping force;

[0047] The desired damping force output from the above step, the obtained relative speed of the wheel and the vehicle body, and the suspension deflection information are used to establish a suspension inverse model, and a desired current is output.

[0048] In some embodiments, the current closed-loop regulation step further comprises:

[0049] The current flowing through the shock absorber coil is collected by a precision resistor, filtered, amplified, and output as a feedback voltage to the main control chip;

[0050] The actual current is calculated according to the calibration curve fitted by the designed sampling circuit, and the difference between the actual current and the desired current is calculated;

[0051] The algorithm optimization control is performed with the minimum error as the control target, the compensation current is output, and the final output current is obtained after hysteresis correction.

[0052] Specifically, the current closed-loop regulation comprises:

[0053] The current flowing through the shock absorber coil is collected by a precision resistor, filtered, amplified, and output as a feedback voltage to the main control chip, and the actual current is calculated according to the calibration curve fitted by the designed sampling circuit;

[0054] The current in the magnetorheological shock absorber piston is converted by an AD module and input into the current tracking algorithm module of the MCU, the difference between the actual current and the desired current is calculated, the error is calculated, the algorithm optimization control is performed with the minimum error as the control target, the compensation current is output, and the final output current is obtained after hysteresis correction to realize the correction of the damping force caused by the current loop.

[0055] In some embodiments, the desired current and the current threshold determination step further comprises:

[0056] The desired current is compared with the current threshold of the shock absorber and the maximum current of the circuit;

[0057] If the desired current is less than the current threshold of the shock absorber and the maximum current of the circuit, the actual output is performed;

[0058] If the desired current is greater than the current threshold of the shock absorber or the maximum current of the circuit, the current threshold of the shock absorber is output.

[0059] Specifically, the expected current is compared with the current threshold of the shock absorber, the circuit current threshold, the output damping force and the circuit safety judgment, if the expected current is less than the current threshold of the shock absorber and the circuit maximum current, it is output according to the actual output; if the expected current is greater than the current threshold of the shock absorber or the circuit maximum current, it is output according to the current threshold of the shock absorber.

[0060] In some embodiments, a vehicle control system of a double closed loop adjustable magneto-rheological semi-active suspension is provided, a vehicle control method of a double closed loop adjustable magneto-rheological semi-active suspension based on any one of the preceding embodiments, comprising:

[0061] A vehicle state acquisition module is configured to acquire vehicle state information.

[0062] A control calculation module is configured to establish a vibration control model and a vehicle body posture control model, calculate an expected damping force, and output an expected current.

[0063] A driving module is configured to control the current output of the magneto-rheological shock absorber according to the expected current.

[0064] In some embodiments, the control calculation module further comprises a current acquisition and feedback unit configured to acquire the current in the shock absorber coil, output a feedback voltage, and calculate an actual current.

[0065] In some embodiments, a current threshold determination module is further included, configured to compare the expected current with the current threshold of the shock absorber and the circuit maximum current, and output the actual current according to the comparison result.

[0066] Specifically, the vehicle positive model and inverse model are established, the positive model is mainly established by the movement speed, displacement of the shock absorber piston and the input current of the shock absorber, and the expected damping force is output; the inverse model is established by the output expected damping force, relative movement speed and displacement of the piston, and the expected current is output.

[0067] The sensor module comprises:

[0068] The vehicle state acquisition module acquires vehicle state code information through the added sensors, and transmits the information into the MCU in the controller for CAN and IIC protocol decoding, and outputs the actual vehicle state information.

[0069] As Figure 1The shown sensor-based vehicle state information is acquired, a vehicle suspension model is used as the basis, a control algorithm takes the sprung mass acceleration as the control target, calculates the expected damping force, and is used for vehicle vibration state control and vehicle body posture control; the above expected damping force is input into the inverse model to calculate the current, and the main control circuit realizes the control and output of the shock absorber coil current, and realizes the vibration suppression of the damping ring. On the other hand, the current of the shock absorber coil is calculated through the controller back sampling module, and the error between the expected current is optimized through the algorithm to realize follow-up control, and complete the optimization control of the current loop.

[0070] As shown in Figure 1 , the present application is based on the real-time transmission of the sprung mass acceleration of the test vehicle installed acceleration sensor s -z u , the suspension deflection z s is transmitted by the angle sensor, and the roll angle and pitch angle of the whole vehicle are calculated by the gyroscope. After decoding and data processing filtering of the sensor data, useful vehicle state information is obtained.

[0071] A two-degree-of-freedom 1 / 4 vehicle magnetorheological semi-active suspension vibration control model is established as shown in Figure 2 , and the dynamic equation of the system is obtained according to Newton's motion theorem:

[0072]

[0073] In the formula, m s and m u are the sprung mass and the unsprung mass respectively; z s and z u are the sprung displacement and the unsprung displacement respectively; and are the sprung speed and the unsprung speed respectively; and are the sprung acceleration and the unsprung acceleration respectively; k s is the suspension stiffness; C s is the shock absorber damping coefficient; F d is the shock absorber damping force.

[0074] According to the processed sprung mass acceleration, the relative speed of the wheel and the vehicle body, the suspension deflection and other information, the control law of the shock absorber damping coefficient, the control target of reducing the sprung mass acceleration is calculated, and the expected damping force F sus,FL1 , F sus,FR1 , F sus,RL1 , F sus,RR1 of the vibration control of the four wheels from the road excitation is output.

[0075] The vehicle body posture control model is established as follows:

[0076] The vertical motion equation is:

[0077]

[0078] Rolling motion equation:

[0079]

[0080] Pitch motion equation:

[0081]

[0082] Where m s and m u are sprung and unsprung mass respectively; is sprung acceleration; sprung roll angle acceleration; is sprung pitch angle acceleration; F sus,FL2 , F sus,FR2 , F sus,RL2 , F sus,RR2 are left front, right front, left rear and right rear damping forces respectively; I xx is roll moment of inertia; I yy pitch moment of inertia; w is wheel base; L a is distance from mass center to front axle; L b is distance from mass center to rear axle.

[0083] According to the information of gyro and sprung mass acceleration, the expected damping forces F sus,FL2 , F sus,FR2 , F sus,RL2 , F sus,RR2 are obtained by algorithm control output taking roll angle and pitch angle as control variables.

[0084] The expected damping forces of vibration control and the expected damping forces of attitude control are summed to obtain the total expected damping forces F sus,FL , F sus,FR , F sus,RL , F sus,RR .

[0085] The expected damping forces output above, the relative speed of wheel and vehicle body obtained, and the suspension deflection information are input into the inverse model of magneto-rheological damper to calculate expected current, and the expected current is compared with the current threshold of controller driving circuit to determine circuit safety.

[0086] If the expected current is less than the maximum current of circuit, the actual output is performed; if the expected current is greater than the maximum current allowed, the maximum current of circuit is output.

[0087] The current and duty cycle of the driving circuit in the designed controller are fitted to obtain a pulse width modulation signal (PWM), which controls the high-frequency switching of the MOSFET to control the output of the expected current in the driving circuit, so as to realize the adjustment of the damping force.

[0088] On the basis of the above damping ring adjustment, the current loop correction is carried out, and the specific mode is as follows:

[0089] Establish Figure 5 The equivalent circuit of the magneto-rheological damper shown in the figure is established, and the state equation is established by mathematical modeling of the equivalent circuit:

[0090]

[0091] In the formula: V L represents the voltage across the inductor L, L and C represent the inductance and capacitance of the energy storage inductor L and the filter capacitor C, V in represents the voltage of the module power supply, V o and represents the voltage and voltage change rate shared by the load resistor R, i L and represents the current and current change rate flowing through the inductor L.

[0092] According to the characteristics of electronic components, the current is often obtained by voltage acquisition, and the voltage is read after being filtered by the ADC channel. The calculation formula of the instantaneous current and voltage of the damper is obtained by deformation:

[0093]

[0094] According to the sampling calculation, the actual current I can be obtained, and the real-time current I is compared with the expected current I o calculated by the damping ring control algorithm to obtain the current error E.

[0095] E = I0-I

[0096] The control algorithm is built to minimize the current error E to obtain the theoretical optimal control current I q . Considering the inevitable time delay of the hardware implementation of the circuit, a correction parameter is introduced for hysteresis correction, and the empirical parameters a and b are obtained by formula fitting according to the data calibration results, and the final output control current I S :

[0097] I S = aI q +b

[0098] The final output control current I S is compared with the current threshold of the driving circuit of the controller to determine the safety of the circuit, and if the final output control current I SIf the current is less than the maximum current of the circuit, the current is directly output; otherwise, the current is output according to the maximum current of the circuit.

[0099] The designed driving circuit and the real vehicle are calibrated to fit the corresponding relationship between the current and the duty cycle, so that the pulse width modulation signal (PWM) is obtained, the high-frequency switching of the MOSFET is controlled by the PWM, and the output of the expected current in the driving circuit is controlled to realize the adjustment of the damping force. s The pulse width modulation signal (PWM) is converted into a pulse width modulation signal (PWM), and the high-frequency switching of the MOSFET is controlled to realize the output of the corrected current and complete the adjustment of the damping force.

[0100] In some embodiments, the driving module includes a PWM signal generation unit and a MOSFET high-frequency switching control unit, which is used to generate a PWM signal according to the expected current and control the output of the expected current in the driving circuit through the MOSFET high-frequency switching.

[0101] Specifically, the driving module includes:

[0102] The designed driving circuit and the real vehicle are calibrated to fit the corresponding relationship between the current and the duty cycle, so that the pulse width modulation signal (PWM) is obtained, the high-frequency switching of the MOSFET is controlled by the PWM, and the output of the expected current in the driving circuit is controlled to realize the adjustment of the damping force.

[0103] A triode discharge channel is provided in the driving circuit to further improve the response speed of the controller.

[0104] In some embodiments, the power module is also included, which is used to convert the voltage of the storage battery into the voltage required by the control calculation module and the driving module, and perform voltage stabilization and filtering processing.

[0105] Specifically, the power module includes:

[0106] The DC-DC circuit converts the +12V power supply of the storage battery into +5V, and supplies power to the control calculation circuit of the MCU after voltage stabilization and filtering; at the same time, the +12V voltage is stabilized and filtered, and the driving module is powered.

[0107] In some embodiments, the communication interface module is also included, which is used to connect the host computer to burn the algorithm, match the signal, and observe the control effect and analyze the data.

[0108] Specifically, the controller is connected to the J-Link serial port to access the host computer to burn the algorithm and match the signal; the CH340 serial port is connected to observe the control effect and analyze the data.

[0109] In other embodiments, a test vehicle equipped with four magnetorheological shock absorbers and a suspension controller is used to verify the effectiveness of the double-closed-loop adjustable magnetorheological semi-active suspension control method and the stability of the controller.

[0110] The application obtains the body acceleration information through a spring-loaded acceleration sensor, obtains the suspension deflection information through an angle sensor, and obtains the body posture information through a gyroscope.

[0111] The damping ring establishes a vehicle model with the control target of reducing the spring mass acceleration according to the basic information of the vehicle and the real-time state information transmitted by the sensor, and outputs the expected damping force; the expected current is calculated through the built shock absorber inverse model, and the output of the current is realized by the control circuit and the driving circuit to adjust the damping force; the real-time current is collected by the controller, and the error between the real-time current and the expected current is used as the control amount for algorithm compensation control, so that the accurate control of the damping force of the magnetorheological suspension system is realized, and the suppression performance of the magnetorheological fluid suspension system on the vehicle vibration is improved.

[0112] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. A vehicle control method for a dual-closed-loop adjustable magnetorheological semi-active suspension, characterized in that, Includes damping closed-loop adjustment steps: S1: Based on the vehicle state information obtained by the sensor, establish a vibration control model, calculate and output the desired damping force for vibration control; S2: Establish a vehicle body attitude control model, calculate and output the desired damping force for vehicle body attitude control; S3: Calculate the desired damping force obtained in steps S1 and S2 to obtain the total desired damping force; S4: Based on the total desired damping force, the relative speed between the wheel and the vehicle body, and the suspension dynamic deflection information, establish the suspension inverse model and output the desired current; It also includes a current closed-loop regulation step: The current flowing through the damper coil is collected, filtered, and amplified by a precision resistor, and the feedback voltage is output to the main control chip. The actual current is calculated based on the calibration curve fitted by the designed sampling circuit, and the difference between the actual current and the expected current is calculated. The algorithm is optimized to minimize the error, output compensation current, and hysteresis correction is performed to obtain the final output current. It also includes steps for determining the expected current and the current threshold: Compare the desired current with the current threshold of the damper and the maximum current of the circuit. If the desired current is less than the current threshold of the damper and the maximum current of the circuit, then the actual output shall apply. If the desired current is greater than the current threshold of the damper or the maximum current of the circuit, then the output will be based on the current threshold of the damper.

2. A vehicle control system for a dual-closed-loop adjustable magnetorheological semi-active suspension, characterized in that, The vehicle control method based on the dual-closed-loop adjustable magnetorheological semi-active suspension according to claim 1 includes: The vehicle status acquisition module is used to acquire vehicle status information; The control calculation module is used to establish vibration control models and vehicle body attitude control models, calculate the desired damping force, and output the desired current. The drive module is used to control the current output of the magnetorheological damper according to the desired current.

3. The vehicle control system according to claim 2, characterized in that, The control calculation module also includes a current acquisition and feedback unit, which is used to acquire the current in the damper coil, output feedback voltage, and calculate the actual current.

4. The vehicle control system according to claim 3, characterized in that, It also includes a current threshold determination module, which compares the desired current with the current threshold of the damper and the maximum current of the circuit, and outputs the actual current based on the comparison result.

5. The vehicle control system according to claim 4, characterized in that, The drive module includes a PWM signal generation unit and a MOSFET high-frequency switch control unit, which are used to generate a PWM signal according to the desired current and control the output of the desired current in the drive circuit through the MOSFET high-frequency switch.

6. The vehicle control system according to claim 5, characterized in that, It also includes a power supply module, which converts the battery voltage into the voltage required by the control computing module and drive module, and performs voltage regulation and filtering.

7. The vehicle control system according to claim 6, characterized in that, It also includes a communication interface module, which is used to connect to a host computer for algorithm programming, signal matching, and observation of control effects and data analysis.

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