Magnetorheological suspension control method and system based on IMU solution

Abstract

The invention belongs to the technical field of vehicle attitude control, and discloses a magneto-rheological suspension control method and system based on IMU resolving, and the method comprises the following steps: obtaining measurement data of an inertial sensor at an initial installation position of a vehicle body, building a vehicle body coordinate system, and determining space coordinate positions of four corners of a suspension; decomposing the motion process of the vehicle body to obtain a resolving formula, and analyzing the obtained vertical acceleration of the four-corner measuring points of the vehicle suspension; calculating the vertical acceleration of the four corners of the vehicle suspension through a resolving formula in combination with the measured data and the spatial positions of the four corners of the vehicle suspension; and an expected force value is obtained through an H-infinity control algorithm, the magneto-rheological damper is controlled in real time, and the magneto-rheological suspension is controlled. By the adoption of the magneto-rheological suspension control method and system based on IMU calculation, the arrangement process is simplified, the precision and response speed of the system are improved, and the high-precision control requirement of the magneto-rheological suspension system under various road conditions and driving working conditions is met in combination with a control algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle posture control, and in particular to a magnetorheological suspension control method and system based on IMU solution. Background Art

[0002] The suspension system is a key powertrain component that connects the vehicle body and wheels. It is responsible for transmitting the force exerted by the road on the wheels to the vehicle body, which directly affects the ride comfort, handling stability and comfort of the vehicle. The suspension system is generally composed of elastic elements, shock absorbers and guide mechanisms. The performance parameters of the traditional passive suspension system are fixed when the vehicle leaves the factory, and cannot cope with complex load changes, road characteristics and different driving conditions. Therefore, it cannot be adjusted and optimized in real time during actual driving. In contrast, the semi-active suspension system can adjust the damping force within a certain range, thereby improving the ride comfort and handling performance of the vehicle within the dissipation range of the damping force. Unlike traditional vehicle suspension systems, the damping characteristics of the magnetorheological suspension can be precisely adjusted by the electronic control system, with higher response speed and better adaptability.

[0003] In the control system of magnetorheological suspension, it is crucial to obtain the body attitude angular velocity and four-way acceleration signals and four-way suspension relative displacement signals in real time. The traditional sensor layout method usually arranges four acceleration sensors at the left front, right front, left rear and right rear corner suspension positions of the body and four relative displacement sensors at the suspension. However, this layout method requires the installation of multiple sensors, which increases the complexity of the system and may introduce calibration errors, resulting in increased experimental complexity and data errors. The current sensor layout method still faces multiple challenges, especially in magnetorheological suspension systems. In order to further optimize the real-time control performance of magnetorheological suspension, a magnetorheological suspension control method and system based on IMU solution is urgently needed to solve the problems of too many sensors, complex experiments and large data errors in the traditional layout method, thereby optimizing the performance of magnetorheological suspension and achieving more efficient vehicle smoothness and handling adjustment. Summary of the invention

[0004] The purpose of the present invention is to provide a magnetorheological suspension control method and system based on IMU solution, which reduces the number of sensors and wiring harness connections by combining a single IMU with a four-way displacement sensor, and controls the magnetorheological suspension in real time through an H∞ control algorithm, thereby improving the comfort and handling stability of the vehicle.

[0005] To achieve the above object, the present invention provides a magnetorheological suspension control method based on IMU solution, comprising the following steps:

[0006] Step S1, obtaining measurement data of the inertial sensor IMU at the initial installation position of the vehicle body, and establishing a vehicle body coordinate system based on the measured data, and then determining the spatial coordinate positions of the four corners of the suspension;

[0007] Step S2, based on the vehicle body coordinate system, decompose the motion process of the vehicle body, obtain a solution formula, and analyze the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension;

[0008] Step S3, combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension, and calculating the vertical acceleration of the four corners of the vehicle suspension by solving the formula;

[0009] Step S4: combining the vertical accelerations of the four corners of the vehicle obtained by solving and the measurement values ​​of the four relative displacement sensors, the desired force value is obtained through the H∞ control algorithm, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension.

[0010] Preferably, in step S1, the measurement data of the inertial sensor IMU at the initial installation position of the vehicle body is obtained, and a vehicle body coordinate system is established based on the measured data, and then the spatial coordinate positions of the four corners of the suspension are determined. The specific process is as follows:

[0011] Step S11, first, install the IMU on the sprung mass of the vehicle body, that is, the center of mass of the vehicle, to obtain the three-axis acceleration and three-axis angular velocity data of the sprung mass of the vehicle body in real time; install four relative displacement sensors to measure the relative displacement between the vehicle body and the tire in real time, reflecting the dynamic movement between the wheel and the vehicle body;

[0012] Step S12: Secondly, establish a vehicle body coordinate system with the IMU as the origin, ensure that the IMU installation surface is parallel to the vehicle horizontal reference plane, and the IMU coordinate axis is parallel to the vehicle body coordinate system, and obtain the spatial coordinate positions of the four corners of the suspension in the vehicle body coordinate system;

[0013] Step S13: Finally, under different road surface excitations, the three-axis angular velocity and three-axis acceleration measured by the IMU are obtained.

[0014] Preferably, in step S2, based on the vehicle body coordinate system, the motion process of the vehicle body is decomposed to obtain a solution formula, and the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension are analyzed. The specific process is as follows:

[0015] Step S21, fusing the three-axis acceleration and three-axis angular velocity data measured by the IMU, and combining the spatial positions of the four corner measurement points of the vehicle suspension to obtain the vertical acceleration data of the four corner measurement points of the vehicle suspension;

[0016] Among them, four relative displacement sensors are installed between the body and the tires, and provide displacement data of the suspension system by measuring the relative displacement between the body and the wheels;

[0017] Step S22: Determine the rotation coordinate matrix according to the order in which the vehicle body rotates around the axis in space, and analyze the obtained velocities and vertical accelerations of the four corner measurement points of the vehicle suspension.

[0018] Preferably, the vehicle body is assumed to be a six-degree-of-freedom rigid body, wherein three degrees of freedom are used to describe the position of the center of mass of the vehicle body relative to the inertial coordinate system, and the other three degrees of freedom are used to describe the posture of the vehicle body, namely, the yaw angle ψ, the pitch angle θ and the roll angle Establish three coordinate systems as follows:

[0019] OXYZ is an inertial coordinate system fixed to the ground; a X a Y a Z a It is an intermediate coordinate system whose origin coincides with the IMU installation position and whose three-axis directions are the same as the inertial coordinate system; b X b Y b Z b It is the body coordinate system fixedly connected to the IMU, and its three-axis directions are the acceleration directions directly measured by the IMU; point H is the measurement point.

[0020] Preferably, the order in which the vehicle body rotates around the axis in space is as follows:

[0021] First, rotate ψ around the Z axis of the fixed body coordinate system; then rotate θ around the Y axis; finally, rotate around the X axis

[0022] Preferably, the inertial coordinate system OXYZ and the vehicle body coordinate system O b X b Y b Z b The rotation matrix A for the transformation between is as follows:

[0023]

[0024] Among them, A ψ , A θ、 They are the corresponding rotation matrices when the car body rotates relative to the base point.

[0025] Preferably, according to Euler's theorem of rigid body motion, the motion of point H in the inertial coordinate system OXYZ is divided into the vector sum of the translation displacement with the base point and the rotation around the base point, as shown below:

[0026]

[0027] Among them, A is the rotation matrix, e is the coordinate system in the vehicle body O bX b Y b Z b The position of the lower H point, e b is the projection of e on each coordinate axis, f is the translation displacement vector; g is the vector sum;

[0028] Perform velocity analysis on point H, take derivative of the motion displacement, and the rotation matrix A has regularity. The velocity of H is obtained as the sum of the base point translation vector velocity and the rotation vector of the point in the vehicle body coordinate system.

[0029] Analyze the acceleration of point H. The acceleration expression is obtained by the base point translation vector acceleration Tangential acceleration (β b ×e b ) and centripetal acceleration (ω b ×ω b ×e b )constitute;

[0030] Among them, ω b is the three-axis angular velocity in the vehicle body coordinate system.

[0031] Preferably, in step S3, the vertical acceleration of the four corners of the vehicle suspension is calculated by combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension through a solution formula, and the specific process is as follows:

[0032] Step S31: The absolute acceleration vector obtained by IMU calculation is calculated along the vehicle body coordinate system O b X b Y b Z b Project the Z axis of the vehicle plane and use the coordinate rotation matrix to transform the unit normal vector of the vehicle plane into the absolute coordinate system;

[0033] Step S32, performing an inner product operation on the absolute acceleration of any point on the vehicle body and the unit normal vector in the absolute coordinate system, so as to obtain the vertical acceleration of the point perpendicular to the plane of the vehicle body;

[0034] Among them, the vertical acceleration a1 of the measuring point H perpendicular to the plane of the vehicle body is as follows:

[0035]

[0036] in, is the acceleration of the Z axis in the vehicle body coordinate system; They are the three-axis accelerations in the vehicle body coordinate system; x b ,y b 、z b They are the three-axis coordinates of point H in the vehicle body coordinate system; They are the angular acceleration values ​​along the X and Y axes in the vehicle body coordinate system; is the pitch angular acceleration; is the roll angular acceleration.

[0037] Preferably, in step S4, the desired force value is obtained by combining the vertical acceleration of the four corners of the vehicle and the measurement values ​​of the four relative displacement sensors obtained by solving the calculation, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension. The specific process is as follows:

[0038] Step S41: Establish a quarter vehicle suspension dynamics model. The kinematic equation of the model is as follows:

[0039]

[0040] Among them, m s is the sprung mass (sprung mass); m u is the unsprung mass (unsprung mass); k s is the suspension spring stiffness; k t is the tire stiffness; z s is the vertical vibration displacement of the sprung mass; z u is the vertical vibration displacement of the unsprung mass; z r is the vertical displacement of the road surface excitation; in semi-active control, c s is the uncontrollable damping of the MR damper, and u is the controllable damping force generated by the MR damper;

[0041] Step S42, defining the state variables and system disturbances of the system, and obtaining the state space expression of the system;

[0042] The state variables of the system are:

[0043] x1=z s -z u ;

[0044] x2=z u -z r ;

[0045]

[0046] The system disturbance is:

[0047]

[0048] Therefore, the state space expression of the system is as follows:

[0049]

[0050] in,

[0051] The control output of the system is:

[0052]

[0053] in, δ>0, λ>0 are weight coefficients;

[0054] Step S43: Design measurement variables as follows:

[0055] Y = EX;

[0056] in,

[0057] The H∞ controller is designed as:

[0058] u=K h EX;

[0059] Among them, K h Gains designed for the controller;

[0060] Step S44, by solving the matrix inequality in the LMI toolbox in MATLAB, the gain of the H∞ controller is obtained, thereby obtaining the desired force value, converting the desired force value into a current value, and controlling the current to achieve real-time control of the magnetorheological damper.

[0061] A magnetorheological suspension control system based on IMU solution, including a coordinate system establishment module, a measurement solution module and a control module;

[0062] A coordinate system establishment module is used to obtain the initial measurement data of the inertial sensor at the initial installation position of the vehicle body, and to build a vehicle body coordinate system based on the measured initial data; based on four relative displacement sensors, the relative displacement between the vehicle body and the wheel is measured and real-time displacement data is provided;

[0063] The measurement and solution module is used to analyze the vehicle motion process in the vehicle body coordinate system and obtain the solution data corresponding to the current measurement result;

[0064] The control module is used to control the magnetorheological damper. Through the sensor data and solution data, combined with the control algorithm, the control data is obtained to adjust the damping characteristics of the magnetorheological damper and optimize the vibration reduction performance of the vehicle.

[0065] Therefore, the present invention adopts the above-mentioned magnetorheological suspension control method and system based on IMU solution, and the beneficial effects are as follows:

[0066] (1) The present invention calculates the vertical acceleration of the four corners of the vehicle body suspension, combines it with the relative displacement sensor data of the four wheels of the vehicle suspension, and obtains control data through the H∞ control algorithm, thereby controlling the vehicle magnetorheological suspension;

[0067] (2) The present invention has the advantages of easy installation, accurate calculation, and clear physical characteristics, and solves the problems of too many sensors, complex experiments, and large data errors in the traditional arrangement method, thereby optimizing the performance of the magnetorheological suspension and achieving more efficient vehicle ride comfort and controllability adjustment;

[0068] (3) The present invention adjusts the damping coefficient of the damper in real time according to the vehicle driving conditions, thereby improving the vehicle's ride comfort and handling, and providing a better experience for the driver and passengers.

[0069] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a flow chart of a magnetorheological suspension control method based on IMU solution of the present invention;

[0071] Figure 2 It is a schematic diagram of a sensor arrangement scheme of a magnetorheological suspension control method and system based on IMU solution of the present invention;

[0072] Figure 3 It is a schematic diagram of coordinate system conversion in IMU data solution analysis of a magnetorheological suspension control method and system based on IMU solution of the present invention;

[0073] Figure 4 It is a quarter vehicle suspension dynamics model diagram of a magnetorheological suspension control method and system based on IMU solution of the present invention. DETAILED DESCRIPTION

[0074] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0075] like Figure 1 As shown, a magnetorheological suspension control method based on IMU solution includes the following steps:

[0076] Step S1, obtaining measurement data of an inertial sensor (IMU) at an initial installation position of a vehicle body, and establishing a vehicle body coordinate system based on the measured data, thereby determining the spatial coordinate positions of the four corners of the suspension;

[0077] Step S2, based on the vehicle body coordinate system, decompose the motion process of the vehicle body, obtain a solution formula, and analyze the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension;

[0078] Step S3, combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension, and calculating the vertical acceleration of the four corners of the vehicle suspension by solving the formula;

[0079] Step S4: combining the vertical accelerations of the four corners of the vehicle obtained by solving and the measurement values ​​of the four relative displacement sensors, the desired force value is obtained through the H∞ control algorithm, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension.

[0080] Based on the above method, the present invention also proposes a magnetorheological suspension control system based on IMU solution, including a coordinate system establishment module, a measurement solution module and a control module.

[0081] The coordinate system establishment module is used to obtain the initial measurement data of the inertial sensor at the initial installation position of the vehicle body, and to build the body coordinate system based on the measured initial data; based on four relative displacement sensors, it measures the relative displacement between the body and the wheel and provides real-time displacement data.

[0082] The measurement and solution module is used to analyze the vehicle motion process in the vehicle body coordinate system and obtain the solution data corresponding to the current measurement result.

[0083] The control module is used to control the magnetorheological damper. Through the sensor data and solution data, combined with the control algorithm, the control data is obtained to adjust the damping characteristics of the magnetorheological damper and optimize the vibration reduction performance of the vehicle.

[0084] The system simplifies the complexity of traditional suspension systems by reducing the number and cost of body sensors. At the same time, the system optimizes the control accuracy and responsiveness of the suspension system through the coordinated work of the IMU and four relative displacement sensors. It automatically adjusts the damping coefficient of the magnetorheological damper according to different road conditions, vehicle load, vehicle speed and driving mode, and optimizes the dynamic response of the suspension in real time to ensure the stability, comfort and handling of the vehicle under different working conditions.

[0085] Example

[0086] Step S1, obtaining measurement data of an inertial sensor (IMU) at an initial installation position of a vehicle body, and establishing a vehicle body coordinate system based on the measured data, and then determining the spatial coordinate positions of the four corners of the suspension.

[0087] Step S11, first, install the IMU on the sprung mass of the vehicle body, that is, the center of mass of the vehicle, to obtain the three-axis acceleration and three-axis angular velocity data of the sprung mass of the vehicle body in real time; install four relative displacement sensors to measure the relative displacement between the vehicle body and the tire in real time to reflect the dynamic movement between the wheel and the vehicle body.

[0088] Step S12: Secondly, establish a vehicle body coordinate system with the IMU as the origin, ensure that the IMU installation surface is parallel to the vehicle horizontal reference plane, and the IMU coordinate axis is parallel to the vehicle body coordinate system, and obtain the spatial coordinate positions of the four corners of the suspension in the vehicle body coordinate system.

[0089] Step S13: Finally, under different road surface excitations, the three-axis angular velocity and three-axis acceleration measured by the IMU are obtained.

[0090] Step S2: Based on the vehicle body coordinate system, the motion process of the vehicle body is decomposed to obtain a solution formula, and the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension are obtained by analysis.

[0091] Step S21, fusing the three-axis acceleration and three-axis angular velocity data measured by the IMU, and combining the spatial positions of the four corner measurement points of the vehicle suspension to obtain the vertical acceleration data of the four corner measurement points of the vehicle suspension.

[0092] Among them, four relative displacement sensors are installed between the body and the tires. They provide displacement data of the suspension system by measuring the relative displacement between the body and the wheels, which is further calculated and fed back to the control algorithm to optimize the damping effect.

[0093] Step S22: Determine the rotation coordinate matrix according to the order in which the vehicle body rotates around the axis in space, and analyze and obtain the speed and vertical acceleration of the four corner measurement points of the vehicle suspension.

[0094] Assume the vehicle body is a six-degree-of-freedom rigid body and establish three coordinate systems in the IMU solution system. Among them, the sensor layout scheme is as follows Figure 2 The coordinate system transformation diagram is shown in Figure 3 shown.

[0095] As a rigid body in space, the vehicle body has six degrees of freedom, three of which are used to describe the position of the center of mass of the vehicle body relative to the inertial coordinate system, and the other three are used to describe the posture of the vehicle body, namely the yaw angle ψ, the pitch angle θ and the roll angle Also called Euler angle coordinates.

[0096] Among them, OXYZ is the inertial coordinate system fixed to the ground; a X a Y a Z a It is an intermediate coordinate system whose origin coincides with the IMU installation position and whose three-axis directions are the same as the inertial coordinate system; b X b Y b Z b It is the body coordinate system fixedly connected to the IMU, and its three-axis directions are the acceleration directions directly measured by the IMU; point H is the measurement point.

[0097] In practical applications, the rotation of a vehicle is usually a combination of multiple axes. The commonly used combination is the ZYX Euler angle sequence:

[0098] First, rotate ψ (yaw angle) around the Z axis of the fixed body coordinate system; then, rotate θ (pitch angle) around the Y axis; finally, rotate around the X axis (Roll angle).

[0099] Therefore, the inertial coordinate system OXYZ and the body coordinate system O b X b Y b Z b The rotation matrix A for the transformation between is as follows:

[0100]

[0101] Among them, A ψ , A θ、 They are the corresponding rotation matrices when the car body rotates relative to the base point.

[0102] According to Euler's theorem of rigid body motion, the motion of point H in the inertial coordinate system OXYZ can be divided into the vector sum of the translation displacement with the base point and the rotation around the base point, as shown below:

[0103]

[0104] Among them, A is the rotation matrix, e is the coordinate system in the vehicle body O b X b Y b Z b The position of the lower H point, e b is the projection of e on each coordinate axis, f is the translation displacement vector; g is the vector sum.

[0105] Perform velocity analysis on point H, differentiate the motion displacement, consider the regularity of the rotation matrix A, and obtain the velocity of H as the sum of the base point translation vector velocity and the rotation velocity vector of the point in the vehicle body coordinate system.

[0106] Analyze the acceleration of point H. The acceleration expression is obtained by the base point translation vector acceleration Tangential acceleration (β b ×e b ) and centripetal acceleration (ω b ×ω b ×e b )constitute.

[0107] Among them, ω b is the three-axis angular velocity in the vehicle body coordinate system.

[0108] Step S3, combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension, and calculating the vertical acceleration of the four corners of the vehicle suspension by solving the formula.

[0109] Step S31: The absolute acceleration vector obtained by IMU calculation is calculated along the vehicle body coordinate system O b X b Y b Z b The Z axis is projected and the unit normal vector of the vehicle plane is transformed into the absolute coordinate system using the coordinate rotation matrix.

[0110] Step S32: perform an inner product operation on the absolute acceleration of any point on the vehicle body and the unit normal vector in the absolute coordinate system, so as to obtain the vertical acceleration of the point perpendicular to the plane of the vehicle body.

[0111] In the first embodiment, the measurement point H is taken as an example, and the inner product of the absolute acceleration at the point H and the unit normal vector in the absolute coordinate system is calculated to obtain the vertical acceleration a1 of the point H perpendicular to the plane of the vehicle body, as shown below:

[0112]

[0113] in, is the acceleration of the Z axis in the vehicle body coordinate system; They are the three-axis accelerations in the vehicle body coordinate system; x b ,y b 、z b They are the three-axis coordinates of point H in the vehicle body coordinate system; They are the angular acceleration values ​​along the X and Y axes in the vehicle body coordinate system; is the pitch angular acceleration; is the roll angular acceleration.

[0114] Among them, only the pitch angular acceleration and roll angular acceleration It needs to be obtained through data conversion, and other quantities can be obtained through IMU readings or installation positions.

[0115] Step S4: combining the vertical accelerations of the four corners of the vehicle obtained by solving and the measurement values ​​of the four relative displacement sensors, the desired force value is obtained through the H∞ control algorithm, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension.

[0116] Step S41: Establish a quarter-car suspension dynamics model and derive the motion equation of the model.

[0117] like Figure 4 As shown, a quarter vehicle suspension dynamics model is established, and the kinematic equation of the model is as follows:

[0118]

[0119] Among them, m s is the sprung mass (sprung mass); mu is the unsprung mass (unsprung mass); k s is the suspension spring stiffness; k t is the tire stiffness; z s is the vertical vibration displacement of the sprung mass; z u is the vertical vibration displacement of the unsprung mass; z r is the vertical displacement of the road surface excitation; in semi-active control, c s is the uncontrollable damping of the MR damper, and u is the controllable damping force generated by the MR damper.

[0120] Step S42: define the state variables and system disturbances of the system to obtain the state space expression of the system.

[0121] The state variables of the system are:

[0122] x1=z s -z u ;

[0123] x2=z u -z r ;

[0124]

[0125] The system disturbance is:

[0126]

[0127] Therefore, the state space expression of the system is as follows:

[0128]

[0129] in,

[0130] The control output of the system is:

[0131]

[0132] in, δ>0, λ>0 are weight coefficients.

[0133] Step S43: Design the measurement variables to obtain the design of the H∞ controller.

[0134] It can be seen from the actual situation that the relative displacement sensor between the tire and the road and the vertical velocity sensor of the tire are very difficult to install. In order to reduce the sensors for measuring state quantities, in this controller design, only the sprung acceleration value calculated by the IMU and the relative displacement values ​​of the four relative displacement sensors are required to simplify the implementation of the controller.

[0135] After the data from the IMU and four relative displacement sensors are input into the control system, real-time calculation and feedback adjustment are performed to ensure that the suspension system can effectively adapt and provide the best vibration reduction effect under complex road conditions. Therefore, the measured variables are as follows:

[0136] Y = EX;

[0137] in,

[0138] The H∞ controller is designed as:

[0139] u=K h EX;

[0140] Among them, K h Gains designed for the controller.

[0141] Step S44, by solving the matrix inequality in the LMI toolbox in MATLAB, the gain of the H∞ controller is obtained, thereby obtaining the desired force value, converting the desired force value into a current value, thereby controlling the current to achieve the effect of real-time control of the magnetorheological damper.

[0142] In terms of design, the H∞ controller uses the Lyapunov equation to verify its stability in robust control, and the controller gain K h The system matrix inequality is satisfied to ensure the stability of the vehicle suspension system within a certain range when subjected to external excitation.

[0143] Step S441, define a positive definite matrix P=P T >0, then the linear matrix inequality is expressed as:

[0144]

[0145] where I represents the identity matrix of appropriate dimension.

[0146] Step S442: define Q=P -1 , WE=EQ,Y h =K h Q, multiply it by diag(Q,I,I) on the left and right respectively, and we get:

[0147]

[0148] Step S443, define WE=EQ, which can be solved equivalently as follows:

[0149] tr[(WE-EQ) T (WE-EQ)] = 0;

[0150] Step S444: introduce the following conditions:

[0151] (WE-EQ)T (WE-EQ)≤μI;

[0152] Among them, μ>0 is defined as a very small positive number, which can be obtained:

[0153]

[0154] Step S445, by solving the above inequality and using the LMI toolbox of MATLAB to ensure that Q>0, the controller state feedback gain is obtained as shown below:

[0155] K h =Y h W -1 ;

[0156] The controller state feedback gain determines the output of the controller, which is output to four magnetorheological dampers respectively. The magnetorheological dampers are controlled by controlling the current respectively, thereby optimizing the performance of the magnetorheological suspension and achieving more efficient vehicle smoothness and handling adjustment.

[0157] Therefore, the present invention adopts the above-mentioned magnetorheological suspension control method and system based on IMU solution. Under different road excitation conditions, the robust H∞ control algorithm dynamically optimizes the damping coefficient in real time and uses the feedback signal of the suspension system to adjust the magnetorheological damper to ensure that the suspension system automatically adjusts the control strategy of the suspension system according to the vehicle load, vehicle speed, driving mode and road conditions under different working conditions. The response of the magnetorheological damper is adjusted by the real-time feedback signal to achieve the best vibration reduction effect, ride comfort and driving stability, especially under uneven road conditions or sudden road conditions, and can balance the vibration reduction effect and vehicle response.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A magnetorheological suspension control method based on IMU solution, characterized in that: The following steps are involved: Step S1, obtaining measurement data of the inertial sensor IMU at the initial installation position of the vehicle body, and establishing a vehicle body coordinate system based on the measured data, and then determining the spatial coordinate positions of the four corners of the suspension; Step S2, based on the vehicle body coordinate system, decompose the motion process of the vehicle body, obtain a solution formula, and analyze the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension; Step S3, combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension, and calculating the vertical acceleration of the four corners of the vehicle suspension by solving the formula; Step S4: combining the vertical accelerations of the four corners of the vehicle obtained by solving and the measurement values ​​of the four relative displacement sensors, the desired force value is obtained through the H∞ control algorithm, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension.

2. The magnetorheological suspension control method based on IMU solution according to claim 1, characterized in that: In step S1, the measurement data of the inertial sensor IMU at the initial installation position of the vehicle body is obtained, and the vehicle body coordinate system is established based on the measured data, and then the spatial coordinate positions of the four corners of the suspension are determined. The specific process is as follows: Step S11, first, install the IMU on the sprung mass of the vehicle body, that is, the center of mass of the vehicle, to obtain the three-axis acceleration and three-axis angular velocity data of the sprung mass of the vehicle body in real time; install four relative displacement sensors to measure the relative displacement between the vehicle body and the tire in real time, reflecting the dynamic movement between the wheel and the vehicle body; Step S12: Secondly, establish a vehicle body coordinate system with the IMU as the origin, ensure that the IMU installation surface is parallel to the vehicle horizontal reference plane, and the IMU coordinate axis is parallel to the vehicle body coordinate system, and obtain the spatial coordinate positions of the four corners of the suspension in the vehicle body coordinate system; Step S13: Finally, under different road surface excitations, the three-axis angular velocity and three-axis acceleration measured by the IMU are obtained.

3. The magnetorheological suspension control method based on IMU solution according to claim 1, characterized in that: In step S2, based on the vehicle body coordinate system, the motion process of the vehicle body is decomposed to obtain the solution formula, and the velocities and vertical accelerations of the four corner measurement points of the vehicle suspension are analyzed. The specific process is as follows: Step S21, fusing the three-axis acceleration and three-axis angular velocity data measured by the IMU, and combining the spatial positions of the four corner measurement points of the vehicle suspension to obtain the vertical acceleration data of the four corner measurement points of the vehicle suspension; Among them, four relative displacement sensors are installed between the body and the tires, and provide displacement data of the suspension system by measuring the relative displacement between the body and the wheels; Step S22: Determine the rotation coordinate matrix according to the order in which the vehicle body rotates around the axis in space, and analyze the obtained velocities and vertical accelerations of the four corner measurement points of the vehicle suspension.

4. The magnetorheological suspension control method based on IMU solution according to claim 3 is characterized in that: Assume that the vehicle body is a rigid body with six degrees of freedom, of which three degrees of freedom are used to describe the position of the center of mass of the vehicle body relative to the inertial coordinate system, and the other three degrees of freedom are used to describe the posture of the vehicle body, namely the yaw angle ψ, the pitch angle θ and the roll angle Establish three coordinate systems as follows: OXYZ is an inertial coordinate system fixed to the ground; a X a Y a Z a It is an intermediate coordinate system whose origin coincides with the IMU installation position and whose three-axis directions are the same as the inertial coordinate system; b X b Y b Z b It is the body coordinate system fixedly connected to the IMU, and its three-axis directions are the acceleration directions directly measured by the IMU; point H is the measurement point.

5. The magnetorheological suspension control method based on IMU solution according to claim 4 is characterized in that: The order in which the body rotates around the axis in space is as follows: First, rotate ψ around the Z axis of the fixed body coordinate system; then rotate θ around the Y axis; finally, rotate around the X axis 6. The magnetorheological suspension control method based on IMU solution according to claim 5, characterized in that: Inertial coordinate system OXYZ and body coordinate system O b X b Y b Z b The rotation matrix A for the transformation between is as follows: in, They are the corresponding rotation matrices when the car body rotates relative to the base point.

7. The magnetorheological suspension control method based on IMU solution according to claim 6, characterized in that: According to Euler's theorem of rigid body motion, the motion of point H in the inertial coordinate system OXYZ is divided into the vector sum of the translation displacement along the base point and the rotation around the base point, as shown below: Among them, A is the rotation matrix, e is the coordinate system in the vehicle body O b X b Y b Z b The position of the lower H point, e b is the projection of e on each coordinate axis, f is the translation displacement vector; g is the vector sum; Perform velocity analysis on point H, take derivative of the motion displacement, and the rotation matrix A has regularity. The velocity of H is obtained as the sum of the base point translation vector velocity and the rotation vector of the point in the vehicle body coordinate system. Analyze the acceleration of point H. The acceleration expression is obtained by the base point translation vector acceleration Tangential acceleration (β b ×e b ) and centripetal acceleration (ω b ×ω b ×e b )constitute; Among them, ω b is the three-axis angular velocity in the vehicle body coordinate system.

8. The magnetorheological suspension control method based on IMU solution according to claim 1, characterized in that: In step S3, the vertical acceleration of the four corners of the vehicle suspension is calculated by combining the IMU measurement data and the spatial positions of the four corners of the vehicle suspension through the solution formula. The specific process is as follows: Step S31: The absolute acceleration vector obtained by IMU calculation is calculated along the vehicle body coordinate system O b X b Y b Z b Project the Z axis of the vehicle plane and use the coordinate rotation matrix to transform the unit normal vector of the vehicle plane into the absolute coordinate system; Step S32, performing an inner product operation on the absolute acceleration of any point on the vehicle body and the unit normal vector in the absolute coordinate system, so as to obtain the vertical acceleration of the point perpendicular to the plane of the vehicle body; Among them, the vertical acceleration a1 of the measuring point H perpendicular to the plane of the vehicle body is as follows: in, is the acceleration of the Z axis in the vehicle body coordinate system; They are the three-axis accelerations in the vehicle body coordinate system; x b ,y b 、z b They are the three-axis coordinates of point H in the vehicle body coordinate system; They are the angular acceleration values ​​along the X and Y axes in the vehicle body coordinate system; is the pitch angular acceleration; is the roll angular acceleration.

9. The magnetorheological suspension control method based on IMU solution according to claim 1, characterized in that: In step S4, the desired force value is obtained by combining the calculated vertical acceleration of the four corners of the vehicle and the measured values ​​of the four relative displacement sensors through the H∞ control algorithm, and the magnetorheological damper is controlled in real time, thereby controlling the magnetorheological suspension. The specific process is as follows: Step S41: Establish a quarter vehicle suspension dynamics model. The kinematic equation of the model is as follows: Among them, m s is the sprung mass (sprung mass); m u is the unsprung mass (unsprung mass); k s is the suspension spring stiffness; k t is the tire stiffness; z s is the vertical vibration displacement of the sprung mass; z u is the vertical vibration displacement of the unsprung mass; z r is the vertical displacement of the road surface excitation; in semi-active control, c s is the uncontrollable damping of the MR damper, and u is the controllable damping force generated by the MR damper; Step S42, defining the state variables and system disturbances of the system, and obtaining the state space expression of the system; The state variables of the system are: x1=z s -z u ; x2=z u -With r ; The system disturbance is: Therefore, the state space expression of the system is as follows: in, The control output of the system is: in, δ>0, λ>0 are weight coefficients; Step S43: Design measurement variables as follows: Y = EX; in, The H∞ controller is designed as: u=K h EX; Among them, K h Gains designed for the controller; Step S44, by solving the matrix inequality in the LMI toolbox in MATLAB, the gain of the H∞ controller is obtained, thereby obtaining the desired force value, converting the desired force value into a current value, and controlling the current to achieve real-time control of the magnetorheological damper.

10. A control system of a magnetorheological suspension control method based on IMU solution according to any one of claims 1 to 9, characterized in that: It includes coordinate system establishment module, measurement and solution module and control module; A coordinate system establishment module is used to obtain the initial measurement data of the inertial sensor at the initial installation position of the vehicle body, and to build a vehicle body coordinate system based on the measured initial data; based on four relative displacement sensors, the relative displacement between the vehicle body and the wheel is measured and real-time displacement data is provided; The measurement and solution module is used to analyze the vehicle motion process in the vehicle body coordinate system and obtain the solution data corresponding to the current measurement result; The control module is used to control the magnetorheological damper. Through the sensor data and solution data combined with the control algorithm, the control data is obtained to adjust the damping characteristics of the magnetorheological damper and optimize the vibration reduction performance of the vehicle.

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