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

Abstract

The invention relates to the technical field of vehicle dynamics control, and discloses a vehicle control method and system for a double-closed-loop adjustable magneto-rheological semi-active suspension, and the method comprises the steps: S1, obtaining the state information of a vehicle based on a sensor, building a vibration control model, and calculating and outputting the expected damping force of vibration control; s2, establishing a vehicle body attitude control model, and calculating and outputting vehicle body attitude control expected damping force; s3, calculating the expected damping force obtained in the step S1 and the expected damping force obtained in the step S2 to obtain the total expected damping force; and S4, according to the total expected damping force, the relative speed of the wheels and the vehicle body and the dynamic deflection information of the suspension, a suspension inverse model is established, and expected current is output. According to the method, the control system is optimized by combining the design parameters of the shock absorber and the test parameters of the real vehicle, the current loop adjustment is designed on the basis of the damping loop control, and the tracking compensation control of the current is mainly realized, so that the response speed and the accuracy of the control are improved, and the performance of the magneto-rheological semi-active suspension is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle dynamics control, and in particular to a vehicle control method and system of a double closed-loop adjustable magnetorheological semi-active suspension. Background Art

[0002] The quality of automobile suspension design directly affects the driving stability, comfort and safety of the vehicle. Since the damping force of passive suspension cannot be adjusted and the comfort is poor, 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. The research on using semi-active control suspension system to improve the ride comfort and handling stability of the vehicle has received widespread attention from academia and industry.

[0003] Magnetorheological semi-active suspension changes the damping coefficient of the shock absorber by adjusting the current input, thereby adjusting the damping force. It has the characteristics of low energy consumption, fast response, wide damping force adjustment range and high safety. Its excellent high-frequency response characteristics have significantly expanded its application field, but at the same time, it is easy to cause vibration 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, and adjust the damping coefficient. The control system algorithm does not consider the process loss of hardware implementation and the interference of the previous control quantity, which is prone to problems such as slow response speed, low control accuracy and current distortion. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a vehicle control method and system for a dual closed-loop adjustable magnetorheological semi-active suspension to solve the above technical problems.

[0005] In a first aspect, a vehicle control method of a dual closed-loop adjustable magnetorheological semi-active suspension is provided, comprising a damping closed-loop adjustment step:

[0006] S1: Acquire vehicle status information based on sensors, establish a vibration control model, calculate and output the desired damping force for vibration control;

[0007] S2: Establish a vehicle body posture control model, calculate and output the desired damping force for vehicle body posture control;

[0008] S3: Calculate the expected damping force obtained in steps S1 and S2 to obtain the total expected damping force;

[0009] S4: According to the total expected damping force, the relative speed between the wheel and the vehicle body, and the suspension dynamic deflection information, an inverse suspension model is established to output the expected current.

[0010] Furthermore, the current closed-loop regulation step is also included:

[0011] The current flowing through the shock absorber coil is collected, filtered, and amplified through precision resistors, and the feedback voltage is output to the main control chip;

[0012] 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;

[0013] The algorithm is optimized and controlled with the minimum error as the control target, the compensation current is output, and the hysteresis correction is performed to obtain the final output current.

[0014] Furthermore, the method further includes the step of determining the expected current and the current threshold:

[0015] comparing the desired current with a current threshold of the shock absorber and a maximum current of the circuit;

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

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

[0018] In a second aspect, a vehicle control system of a dual closed-loop adjustable magnetorheological semi-active suspension is provided. A vehicle control method of a dual closed-loop adjustable magnetorheological semi-active suspension based on any one of the above-mentioned items includes:

[0019] A vehicle status acquisition module is used to obtain vehicle status information;

[0020] A control calculation module is used to establish a vibration control model and a body posture control model, calculate the desired damping force, and output the desired current;

[0021] The driving module is used to control the current output of the magnetorheological damper according to the desired current.

[0022] Furthermore, the control calculation module also includes a current collection and feedback unit, which is used to collect the current in the shock absorber coil, output feedback voltage, and calculate the actual current.

[0023] Furthermore, it also includes a current threshold determination module, which is used to compare the expected current with the current threshold of the shock absorber and the maximum current of the circuit, and output the actual current according to the comparison result.

[0024] Furthermore, the driving module includes a PWM signal generating 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 driving circuit through the MOSFET high-frequency switch.

[0025] Furthermore, it also includes a power supply module, which is used to convert the voltage of the battery into the voltage required by the control calculation module and the drive module, and perform voltage stabilization and filtering processing.

[0026] Furthermore, it also includes a communication interface module for connecting to a host computer to burn algorithms, match signals, observe control effects, and analyze data.

[0027] The invention adopting the above technical solution has the following advantages:

[0028] The present invention combines the shock absorber design parameters and actual vehicle test parameters to optimize the control system, and designs the current loop adjustment based on the damping loop control, mainly to achieve current tracking compensation control, thereby improving the control response speed and accuracy, and further improving the performance of the magnetorheological semi-active suspension. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0030] Figure 1 It is a flow chart of the vehicle control method of the double closed-loop adjustable magnetorheological semi-active suspension of the present invention;

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

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

[0033] Figure 4 A vehicle control system diagram of the double closed-loop adjustable magnetorheological semi-active suspension of the present invention;

[0034] Figure 5 It is an equivalent circuit diagram of a magnetorheological damper in a vehicle control method of a double closed-loop adjustable magnetorheological semi-active suspension of the present invention;

[0035] Figure 6 A positive model diagram of a magnetorheological damper in a vehicle control method of a double closed-loop adjustable magnetorheological semi-active suspension of the present invention;

[0036] Figure 7 The inverse model diagram of the magnetorheological damper in the vehicle control method of the double closed-loop adjustable magnetorheological semi-active suspension of the present invention. DETAILED DESCRIPTION

[0037] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0038] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should be the common meanings understood by technicians in the field to which the present invention belongs. The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to implement the embodiments of the present disclosure described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. Unless otherwise specified, the term "multiple" means two or more. In the embodiments of the present disclosure, the character " / " indicates that the objects before and after are in an "or" relationship. For example, A / B means: A or B. The term "and / or" is a description of the association relationship of objects, indicating that there can be three relationships. For example, A and / or B means: A or B, or, A and B. The term "corresponding" can refer to an association relationship or a binding relationship, and A and B correspondingly refer to an association relationship or a binding relationship between A and B.

[0039] like Figure 1 to Figure 7 As shown, the vehicle control method of the dual closed-loop adjustable magnetorheological semi-active suspension of the present invention includes the damping closed-loop adjustment step:

[0040] Step S1: acquiring vehicle state information based on sensors, establishing a vibration control model, and calculating and outputting a desired damping force for vibration control;

[0041] Step S2: establishing a vehicle body posture control model, calculating and outputting the desired damping force for vehicle body posture control;

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

[0043] Step S4: According to the total expected damping force, the relative speed between the wheel and the vehicle body and the suspension dynamic deflection information, an inverse suspension model is established to output the expected current.

[0044] Specifically, based on the vehicle status information obtained by the sensor, a vibration control model is established, an algorithm calculation is performed with the control target of reducing the sprung mass acceleration, and the desired damping force of the vibration control is output;

[0045] Based on the vehicle status information, a body posture control model is established, and the algorithm calculation is performed with the control objectives of reducing the sprung acceleration and reducing the body posture angular acceleration, and the desired damping force for body posture control is output;

[0046] Performing algorithmic calculation on the expected damping force of vibration control and the expected damping force of attitude control to obtain the total expected damping force;

[0047] Based on the desired damping force output from the above steps, the relative speed between the wheel and the vehicle body, and the suspension dynamic deflection information, an inverse suspension model is established to output the desired current.

[0048] In some embodiments, the current closed-loop regulation step is also included:

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

[0050] 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;

[0051] The algorithm is optimized and controlled with the minimum error as the control target, the compensation current is output, and the hysteresis correction is performed to obtain the final output current.

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

[0053] The current acquisition module collects, filters, and amplifies the current flowing through the shock absorber coil through precision resistors, outputs a 0-5V feedback voltage to the main control chip, and calculates the actual current based on the calibration curve fitted by the designed sampling circuit;

[0054] The current in the magnetorheological shock absorber piston is converted by the AD module and input into the current tracking algorithm module in the MCU. The difference with the expected current is calculated. After the error is calculated, the algorithm is optimized to control the output compensation current with the minimum error as the control target. The hysteresis loop correction is performed to obtain the final output current, thereby realizing the correction of the damping force brought by the current loop.

[0055] In some embodiments, the step of determining the expected current and the current threshold is also included:

[0056] comparing the desired current with a current threshold of the shock absorber and a maximum current of the circuit;

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

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

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

[0060] In some other embodiments, a vehicle control system of a dual closed-loop adjustable magnetorheological semi-active suspension is provided. A vehicle control method of a dual closed-loop adjustable magnetorheological semi-active suspension based on any one of the above includes:

[0061] A vehicle status acquisition module is used to obtain vehicle status information;

[0062] A control calculation module is used to establish a vibration control model and a body posture control model, calculate the desired damping force, and output the desired current;

[0063] The driving module is used to control the current output of the magnetorheological damper according to the desired current.

[0064] In some embodiments, the control calculation module further includes a current acquisition and feedback unit for acquiring the current in the shock absorber coil, outputting a feedback voltage, and calculating the actual current.

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

[0066] Specifically, the vehicle forward model and inverse model are established. The forward model is mainly established through the movement rate, displacement, and current of the shock absorber piston, and the expected damping force is output; the inverse model is established through the expected damping force output, the relative movement rate and displacement of the piston, and the expected current is output;

[0067] The sensor module includes:

[0068] The vehicle status acquisition module obtains the vehicle status coding information through the installed sensors, transmits it to the MCU in the controller for decoding of CAN and IIC protocols, and outputs the actual vehicle status information.

[0069] like Figure 1The vehicle state information is obtained based on the sensor, and the vehicle suspension model is used as the basis. The control algorithm takes reducing the acceleration of the sprung mass as the control target, calculates and outputs the expected damping force, which is used to control the vehicle vibration state and the body posture; the above-mentioned expected damping force is input into the inverse model to calculate the current, and the main control circuit controls and outputs the shock absorber coil current to achieve vibration suppression of the damping ring. On the other hand, the current of the shock absorber coil is calculated by the controller recovery module, and the error between the current and the expected current is optimized by the algorithm to achieve follow-up control, completing the optimization control of the current loop.

[0070] like Figure 1 As shown, the present invention is based on the acceleration sensor installed on the test vehicle to transmit the sprung mass acceleration in real time. The angle sensor transmits the suspension dynamic deflection z s -z u ,The gyroscope calculates the roll angle and pitch angle of the vehicle, and obtains useful vehicle status information after decoding and data processing and filtering the sensor data.

[0071] Establish as Figure 2 The vibration control model of the two-degree-of-freedom 1 / 4 vehicle magnetorheological semi-active suspension shown in the figure obtains the dynamic equation of the system according to Newton's law of motion:

[0072]

[0073] Where m s and m u and unsprung mass respectively; z s and z u sprung and unsprung displacements respectively; and sprung and unsprung speeds respectively; and and unsprung acceleration respectively; k s is the suspension stiffness; C s is the damping coefficient of the shock absorber; F d is the shock absorber damping force.

[0074] According to the information of sprung mass acceleration, relative speed between wheel and vehicle body, suspension dynamic deflection, etc., the control law of shock absorber damping coefficient is used to calculate the algorithm with the control target of reducing sprung mass acceleration, and the desired damping force F of vibration control from road excitation of four wheels is output. sus,FL1 , F sus,FR1 , F sus,RL1 , F sus,RR1 .

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

[0076] Vertical motion equation:

[0077]

[0078] Rolling motion equation:

[0079]

[0080] Pitch motion equation:

[0081]

[0082] Where m s and m u and unsprung mass respectively; is the sprung acceleration; sprung roll angular acceleration; is the sprung pitching acceleration; F sus,FL2 , F sus,FR2 , F sus,RL2 , F sus,RR2 They are the left front damping force, the right front damping force, the left rear damping force and the right rear damping force respectively; I xx is the roll moment of inertia; I yy Pitch moment of inertia; w is wheelbase; L a is the distance from the center of mass to the front axle; L b is the distance from the center of mass to the rear axle.

[0083] According to the information of gyroscope and sprung mass acceleration, the algorithm control output is obtained by taking roll angle and pitch angle as control quantity to obtain the desired control damping force F of the vehicle body posture. sus,FL2 , F sus,FR2 , F sus,RL2 , F sus,RR2 .

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

[0085] The expected damping force outputted above, the relative speed between the wheel and the vehicle body, and the suspension dynamic deflection information are input into the inverse model of the magnetorheological shock absorber to calculate the expected current, and the expected current and the current threshold of the controller driving circuit are used to determine the circuit safety;

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

[0087] By fitting the corresponding relationship between the driving circuit current and the duty cycle in the designed controller, a pulse width modulation signal (PWM) is obtained. The PWM controls the high-frequency switching of the MOSFET to control the output of the desired current in the driving circuit to achieve the adjustment of the damping force.

[0088] Based on the above damping loop adjustment, the current loop is corrected. The specific method is as follows:

[0089] Establish Figure 5 The equivalent circuit of the magnetorheological damper is shown in the figure. The equivalent circuit is mathematically modeled and the state equation is established:

[0090]

[0091] Where: 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 Indicates the voltage of the module power supply, V o and It represents the voltage divided by the load resistance R and the voltage change rate, i L and Indicates the current flowing through the inductor L and the rate of change of the current.

[0092] According to the characteristics of electronic components, current is often obtained through voltage acquisition, and the voltage is read after filtering through the ADC channel. The calculation formula for the instantaneous current and voltage of the shock absorber is obtained by deformation:

[0093]

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

[0095] E=I0-I

[0096] The control algorithm is built with the goal of minimizing the control current error E to obtain the theoretical optimal control current I q Considering the inevitable time lag in the hardware implementation of the circuit, the correction parameters are introduced to correct the hysteresis loop. The empirical parameters a and b are obtained by formula fitting based on the data calibration results, and the final output control current I is obtained. S :

[0097] I S =aI q +b

[0098] The final output control current I S The circuit safety is determined by the current threshold of the controller driving circuit. If the final output control current I SIf it is less than the maximum current of the circuit, it will be output directly, otherwise it will be output according to the maximum current of the circuit.

[0099] Through the designed driving circuit and the corresponding relationship between the calibration fitting current and the duty cycle of the actual vehicle, I s Converted into a pulse width modulation signal (PWM), PWM controls the high-frequency on and off of MOSFET to achieve the output of the corrected current and complete the corrected damping force adjustment.

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

[0101] Specifically, the driving module includes:

[0102] Through the designed driving circuit and the corresponding relationship between the calibration fitting current and the duty cycle of the actual vehicle, a pulse width modulation signal (PWM) is obtained. The PWM controls the high-frequency switching of the MOSFET to control the output of the desired current in the driving circuit and realize the adjustment of the damping force.

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

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

[0105] Specifically, the power module includes:

[0106] Design a power module. The DC-DC circuit converts the +12V power supply of the battery into +5V, which is then used to power the control calculation circuit of the MCU after voltage stabilization and filtering. At the same time, the +12V voltage is stabilized and filtered to power the drive module.

[0107] In some embodiments, a communication interface module is also included for connecting to a host computer to burn algorithms, match signals, observe control effects, and analyze data.

[0108] Specifically, the controller is connected to the host computer through an external J-Link serial port for algorithm burning and signal matching; and is connected to the external CH340 serial port for control effect observation and data analysis.

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

[0110] The present invention obtains vehicle body acceleration information through a sprung acceleration sensor, obtains suspension dynamic deflection information through an angle sensor, and obtains vehicle body posture information through a gyroscope.

[0111] Based on the basic information of the vehicle and the real-time status information transmitted by the sensor, the damping ring establishes a vehicle model with the reduction of the sprung mass acceleration as the control target, and outputs the desired damping force; the desired current is calculated through the constructed shock absorber inverse model, and the control circuit and the drive circuit realize the output of the current to adjust the damping force; the real-time current is collected through the controller, and the error between the real-time current and the desired current is used as the control quantity for algorithm compensation control, thereby achieving accurate control of the damping force of the magnetorheological suspension system and improving the magnetorheological fluid suspension system's ability to suppress vehicle vibration.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A vehicle control method for a dual closed-loop adjustable magnetorheological semi-active suspension, characterized in that: Including damping closed loop adjustment steps: S1: Acquire vehicle status information based on sensors, establish a vibration control model, calculate and output the desired damping force for vibration control; S2: Establish a vehicle body posture control model, calculate and output the desired damping force for vehicle body posture control; S3: Calculate the expected damping force obtained in steps S1 and S2 to obtain the total expected damping force; S4: According to the total expected damping force, the relative speed between the wheel and the vehicle body, and the suspension dynamic deflection information, an inverse suspension model is established to output the expected current.

2. The vehicle control method according to claim 1, characterized in that: It also includes the current closed-loop regulation steps: The current flowing through the shock absorber coil is collected, filtered, and amplified through precision resistors, 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 and controlled with the minimum error as the control target, the compensation current is output, and the hysteresis correction is performed to obtain the final output current.

3. The vehicle control method according to claim 2, characterized in that: It also includes the steps of determining the expected current and the current threshold: comparing the desired current with a current threshold of the shock absorber and a maximum current of the circuit; If the expected current is less than the current threshold of the shock absorber and the maximum current of the circuit, the actual output is used; If the expected current is greater than the current threshold of the shock absorber or the maximum current of the circuit, the output is based on the shock absorber current threshold.

4. A vehicle control system of a double closed-loop adjustable magnetorheological semi-active suspension, characterized in that: A vehicle control method based on the dual closed-loop adjustable magnetorheological semi-active suspension according to any one of claims 1 to 3, comprising: A vehicle status acquisition module is used to obtain vehicle status information; A control calculation module is used to establish a vibration control model and a body posture control model, calculate the desired damping force, and output the desired current; The driving module is used to control the current output of the magnetorheological damper according to the desired current.

5. The vehicle control system according to claim 4, characterized in that: The control calculation module also includes a current collection and feedback unit, which is used to collect the current in the shock absorber coil, output feedback voltage, and calculate the actual current.

6. The vehicle control system according to claim 5, characterized in that: It also includes a current threshold determination module, which is used to compare the expected current with the current threshold of the shock absorber and the maximum current of the circuit, and output the actual current according to the comparison result.

7. The vehicle control system according to claim 6, characterized in that: The driving module includes a PWM signal generating unit and a MOSFET high-frequency switch control unit, which is used to generate a PWM signal according to a desired current and control the output of the desired current in the driving circuit through the MOSFET high-frequency switch.

8. The vehicle control system according to claim 7, characterized in that: It also includes a power supply module, which is used to convert the voltage of the battery into the voltage required by the control calculation module and the drive module, and perform voltage stabilization and filtering.

9. The vehicle control system according to claim 8, characterized in that: It also includes a communication interface module for connecting to a host computer to burn algorithms, match signals, observe control effects, and analyze data.

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