Method for identifying gravity moment and friction moment of horizontal three-axis hydraulic flight turntable outer frame

Abstract

The present disclosure provides a horizontal three-axis hydraulic flight turntable outer frame gravity moment and friction moment identification method, comprising: the outer frame takes zero angular displacement as the initial position, rotates within a certain range, and selects multiple different time instants when the outer frame rotates forward and reversely to the same position for force analysis; a motion equation is obtained through force analysis; the motion equation is operated to obtain expressions of the friction moment and the gravity moment; and the gravity moment and the friction moment at the corresponding positions can be obtained through experiments at different positions. The expression of the friction moment and the expression of the gravity moment are coupled with each other, so that the mutual relationship between the friction moment and the gravity moment is fully considered, the accuracy of the mathematical model is improved, and the design difficulty of the controller is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flight simulation, in particular to a method, system, device and readable storage medium for identifying the gravity moment and friction moment of an outer frame of a horizontal three-axis hydraulic flight turntable. BACKGROUND

[0002] A horizontal hydraulic flight motion simulator (HHFMS) is a key device for semi-physical simulation in the field of aerospace and is widely used in high-power and high-maneuverability scenarios. However, the three mismatched model uncertainties of the nonlinear friction moment, the unbalanced gravity moment and the unknown inertia moment existing in the outer frame of the HHFMS bring certain difficulties to obtaining a high-precision outer frame position control effect.

[0003] The prior art generally identifies the friction moment by giving a constant-speed rotation instruction to the motor, so that the acceleration is zero and the inertia moment can be considered as zero, thereby excluding the influence of the inertia moment. However, the prior art does not consider the influence of the frame gravity moment and only identifies the friction moment. Therefore, it is still difficult to overcome the control difficulties brought by the three mismatched model uncertainties of the nonlinear friction moment, the unbalanced gravity moment and the unknown inertia moment to high-precision outer frame position control. SUMMARY

[0004] To solve the problem that the prior art does not consider the influence of the frame gravity moment and only identifies the friction moment, the present disclosure provides a method for identifying the gravity moment and friction moment of an outer frame of a horizontal three-axis hydraulic flight turntable, comprising:

[0005] The outer frame is initially positioned at zero angular displacement and rotates within a certain range, and force analysis is performed on multiple different time instants when the outer frame rotates forward and reversely to the same position;

[0006] A motion equation is obtained through force analysis;

[0007] The motion equation is operated to obtain expressions of the friction moment and the gravity moment;

[0008] The gravity moment and the friction moment at the corresponding positions can be obtained through experiments at different positions.

[0009] The present disclosure can obtain the expressions of the friction moment and the gravity moment through force analysis and operation of the motion equation, thereby obtaining the mechanical parameters of the outer frame at different positions through experiments and obtaining the friction moment and the gravity moment according to the expressions of the friction moment and the gravity moment, thereby effectively reducing the burden on the observer. The expression of the friction moment and the expression of the gravity moment of the present disclosure are mutually coupled, so that the mutual relationship between the friction moment and the gravity moment is fully considered, the accuracy of the mathematical model is improved, and the design difficulty of the controller is reduced.

[0010] The present disclosure exemplarily provides a force analysis method, comprising: performing mechanical analysis on angular displacement, angular velocity, force direction of multiple different time instants at the same position.

[0011] The present disclosure exemplarily provides a force analysis: performing force analysis on two different time instants at the same position.

[0012] The present disclosure exemplarily provides a motion equation, comprising:

[0013]

[0014]

[0015] In the formula, J(y a ) is the inertia value at point a, J(y b ) is the inertia value at point b, y a is the displacement of the middle frame at point a, y b is the displacement of the middle frame at point b, x 1a is the displacement of the outer frame at point a, x 1b is the displacement of the outer frame at point b, x 2a is the angular velocity of the outer frame at point a, x 2b is the angular velocity of the outer frame at point b, is the angular acceleration of the outer frame at point a, is the angular acceleration of the outer frame at point b, x 3a is the load pressure of the outer frame at point a, x 3b is the load pressure of the outer frame at point b, A is the load pressure adjustment coefficient, f ra is the friction torque of the outer frame at point a, f rb is the friction torque of the outer frame at point b, f ga is the gravity torque of the outer frame at point a, f gb is the gravity torque of the outer frame at point b, f ea is the unmodeled torque of the outer frame at point a, f eb is the unmodeled torque of the outer frame at point b.

[0016] The present disclosure exemplarily provides a method for obtaining gravity torque, which is: by bringing the middle frame displacement, outer frame displacement, angular velocity, angular acceleration, load pressure data at point a and point b as shown in formula 2 into formula 1, and adding formula and two formulas to eliminate the friction torques f ra and f rb , the gravity torque expression of the outer frame position under any displacement is obtained.

[0017] Since point a and point b are a set of displacement points with the same displacement but opposite directions, the relationships between the middle frame displacement, the outer frame displacement, the angular velocity, the angular acceleration, and the load pressure of point a and point b are as shown in formula 2, so the friction torque f of the point can be obtained by bringing the middle frame displacement, the outer frame displacement, the angular velocity, the angular acceleration, and the load pressure of point a and point b in formula 2 into formula 1 and adding formula 1 ra and f rb , to obtain the expression of the gravity torque of the point. Since point a and point b are displacement points at different times of any point, the expression of the gravity torque of the outer frame at any displacement can be obtained.

[0018] The disclosure exemplarily provides a method for obtaining the friction torque, which is: based on the obtained gravity torque expression, any formula in is brought in to calculate and determine the friction torque of the current point.

[0019] The disclosure also provides a horizontal three-axis hydraulic flight turntable outer frame gravity torque and friction torque identification system, which comprises an input module, an analysis module, an output module, and a storage module. The input module receives system external information and inputs information to the analysis module. The analysis module analyzes and processes the input information according to the received input information to obtain output information by using the above-mentioned horizontal three-axis hydraulic flight turntable outer frame gravity torque and friction torque identification method. The output module receives the output information of the analysis module and outputs the information to the outside of the system. The storage module is used to store the information that needs to be stored.

[0020] The disclosure also provides a horizontal three-axis hydraulic flight turntable outer frame gravity torque and friction torque identification device, which comprises a memory and a processor. The memory stores a computer program that can be run on the processor. When the processor executes the program, the steps of the above-mentioned horizontal three-axis hydraulic flight turntable outer frame gravity torque and friction torque identification method are implemented.

[0021] The disclosure also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above-mentioned horizontal three-axis hydraulic flight turntable outer frame gravity torque and friction torque identification method are implemented.

[0022] The disclosure has at least one of the following advantages:

[0023] 1. The disclosure solves the model uncertainty problem of the mismatch between the nonlinear friction torque and the unbalanced gravity torque in the outer frame of the HHFMS.

[0024] 2. The disclosure can obtain the friction torque and the gravity torque of the outer frame at different positions, effectively reducing the burden on the observer, improving the accuracy of the mathematical model, and reducing the design difficulty of the controller. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a turntable block diagram model diagram.

[0026] Figure 2 It is a slope position control instruction diagram.

[0027] Figure 3 It is a gravity moment identification curve diagram.

[0028] Figure 4 It is a friction moment identification curve diagram. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and technical effects to be solved by the present application more clear, the technical solutions of the present application are described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0030] For a horizontal three-axis flight turntable, the inertia moment of the outer frame is the largest among the three frames, and there is a serious mismatch uncertainty. The first mismatch uncertainty is the nonlinear friction moment, which is usually required to be identified due to its difficulty in accurate modeling. The second mismatch uncertainty is the unbalanced gravity moment, which is unbalanced due to the asymmetric installation of the middle frame. In theory, when the load mass and shape are determined, if the middle frame and the inner frame remain unchanged, the gravity moment applied to the outer frame is only related to its own angular displacement. Although the gravity moment acting on the outer frame can be obtained by theoretical derivation, in practice, due to unknown load shape or asymmetric installation of the middle frame hydraulic motor, the middle frame structure is not completely symmetric, which may cause eccentric gravity moment. The last mismatched uncertainty is the unknown inertia moment of the outer frame, which is also caused by different load mass and shape.

[0031] The traditional PID control has low precision and cannot meet the tracking requirements, so nonlinear control needs to be used. In order to reduce the asymmetry of tracking, the nonlinear control needs to compensate for the gravity moment, which requires identification of the gravity moment, but the existing control method does not identify the gravity moment.

[0032] In order to solve the problems existing in the prior art, the identification method of the outer frame gravity moment and friction moment of the horizontal three-axis hydraulic flight turntable provided by the present disclosure can identify the gravity moment and the friction moment, and effectively reduce the asymmetry of tracking. The following is further described in combination with specific embodiments.

[0033] Embodiment 1

[0034] With Figure 1Based on the shown turntable block model, the identification method of the outer frame gravity moment and friction moment of the horizontal three-axis hydraulic flight turntable is used to identify the gravity moment and friction moment, including the following steps:

[0035] The outer frame takes zero angular displacement as the initial position, rotates within a certain range, and selects multiple different time points of the outer frame rotating forward and reverse to the same position for force analysis; force analysis is performed on the same position at two different time points. Among them, the zero angular displacement of the outer frame is the initial relative position of the outer frame, middle frame and inner frame without additional control rotation, and the range of the outer frame rotating motion can be between positive and negative 55°.

[0036] The motion equation is obtained through force analysis.

[0037] By applying a PI controller, the outer frame controls the maximum amplitude of a triangular wave signal of 0.125 Hz to execute a closed-loop position control command, as shown in Figure 2 Select Figure 2 points a and b, which have the same angular displacement and the same angular velocity, but the directions are opposite. When the angular velocity is not zero, the friction torque is an odd function, so the friction torque at points a and b is equal in size but opposite in direction. Since the middle frame and the inner frame are fixed, theoretically, the gravitational moment applied to the outer frame forms a cosine relationship with its own angular displacement. Therefore, the gravitational moments of points a and b are the same. Secondly, due to the constant angular velocity of the outer frame, it can be considered that the acceleration is zero, and when the unmodeled disturbance is ignored, the above force analysis can be represented by equation 1 and equation 2.

[0038]

[0039]

[0040] In the formula, J(y a ) is the inertia value at point a, J(y b ) is the inertia value at point b, y a is the displacement of the middle frame at point a, y b is the displacement of the middle frame at point b, x 1a is the displacement of the outer frame at point a, x 1b is the displacement of the outer frame at point b, x 2a is the angular velocity of the outer frame at point a, x 2b is the angular velocity of the outer frame at point b, is the angular acceleration of the outer frame at point a, is the angular acceleration of the outer frame at point b, x 3a is the load pressure at point a of the outer frame, x 3b is the load pressure at point b of the outer frame, A is the load pressure adjustment coefficient, f raf is the frictional torque of the outer frame at point a. rb f is the frictional torque of the outer frame at point b. ga f is the gravitational moment of the outer frame at point a. gb f is the gravitational moment of the outer frame at point b. ea f is the unmodeled moment of the outer frame at point a. eb It is the unmodeled torque of the outer frame at point b.

[0041] By performing calculations on the equations of motion, we obtain expressions for the frictional torque and the gravitational torque.

[0042] By substituting the displacement of the middle frame, the displacement of the outer frame, the angular velocity, the angular acceleration, and the load pressure data at points a and b as shown in Equation 2 into Equation 1, and then... Formula and Add the two equations together to eliminate the frictional torque f. ra and f rb This yields the expression for the gravitational moment at any displacement of the outer frame position.

[0043] Since points a and b are a pair of displacement points with the same displacement but opposite directions, the relationships between the middle frame displacement, outer frame displacement, angular velocity, angular acceleration, and load pressure of points a and b are shown in Equation 2. Therefore, by substituting the parameters of the middle frame displacement, outer frame displacement, angular velocity, angular acceleration, and load pressure of points a and b in Equation 2 into Equation 1 and adding Equation 1 together, the frictional torque f can be eliminated. ra and f rb This yields the expression for the gravitational moment. Since points a and b are displacement points at two different times from any point, the expression for the gravitational moment at any displacement of the outer frame can be obtained. For example... Figure 3 As shown in the figure, "*" represents the experimentally measured data, and the solid line in the figure represents the fitted curve y=-[GL1cos(θ)+GL2sin(θ)], where G=850, L1=0.73, and L2=0.58.

[0044] Based on the obtained expression for the gravitational torque, substituting: The expression for the friction torque at the current point can be obtained from any of the equations in the equation.

[0045] After obtaining the expression for the gravitational torque, refer to the last two equations of Equation 2. The expression for the frictional torque can be determined. A PI controller was used to implement a series of closed-loop position control commands based on a 0.25Hz triangular wave signal. The amplitude range of these command signals is 1° to 60°, meaning each amplitude represents an angular velocity. The step size is 5° when the step size is between 10° and 60°, and 1° when the step size is less than 10°. Since the gravitational torque is known at any angular displacement, the frictional torque at each angular velocity can be obtained, such as... Figure 4The experimental data is indicated by "*" and the fitted curve is indicated by a solid line, where y = l1[tanh(c1w) - tanh(c2w)] + l2tanh(c2w) + l3w, and l1 = 130, l2 = 230, l3 = 110, c1 = 18, c2 = 7, and c3 = 70.

[0046] The experiment is performed at different positions to obtain the gravity moment and the friction moment at the corresponding positions.

[0047] After obtaining the expression of the gravity moment and the expression of the friction moment, the displacement of the middle frame, the displacement of the outer frame, the angular velocity, the angular acceleration, and the load pressure parameters at the target position are obtained when the outer frame is at other different positions, for example, the load pressure can be measured by a pressure sensor, and the displacement of the middle frame and the displacement of the outer frame are obtained from the rotation parameters of the hydraulic motor. The measurable parameters are brought into the obtained expression of the gravity moment and the expression of the friction moment to determine the gravity moment and the friction moment at the position.

[0048] It can be seen that the present disclosure solves the model uncertainty of the mismatch between the nonlinear friction moment and the unbalanced gravity moment of the outer frame of the HHFMS. Through experiments, the friction moment and the gravity moment of the outer frame at different positions can be obtained, the burden on the observer is effectively reduced, the accuracy of the mathematical model is improved, and the design difficulty of the controller is reduced.

[0049] Embodiment 2

[0050] A system for identifying the gravity moment and the friction moment of the outer frame of a horizontal three-axis hydraulic flight turntable includes an input module, an analysis module, an output module, and a storage module. The input module inputs information to the analysis module after receiving external information of the system. Figure 1 Based on the turntable block diagram model shown in the figure, the input information includes the experimental data in embodiment 1 and the displacement parameters of the PI controller, the pressure sensor, and the hydraulic motor.

[0051] The analysis module analyzes and processes the input information according to the received input information by using the method for identifying the gravity moment and the friction moment of the outer frame of the horizontal three-axis hydraulic flight turntable in embodiment 1 to obtain output information. The output module receives the output information of the analysis module and outputs the information to the outside of the system. The output information can be the friction moment and the gravity moment at the target position according to the turntable block diagram model shown in the figure. Figure 1

[0052] Embodiment 3

[0053] A device for identifying the gravity moment and the friction moment of the outer frame of a horizontal three-axis hydraulic flight turntable includes a memory and a processor. The memory stores a computer program that can run on the processor. Figure 1 ​The processor, when executing the program, implements the steps in the horizontal three-axis hydraulic flight turntable outer frame gravity moment and friction moment identification method of embodiment 1 based on the turntable block diagram model.

[0054] Embodiment 4

[0055] A computer readable storage medium, having stored thereon a computer program. Figure 1 The computer program, when executed by the processor, implements the steps in the horizontal three-axis hydraulic flight turntable outer frame gravity moment and friction moment identification method based on the turntable block diagram model.

[0056] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for identifying the gravitational torque and frictional torque of the outer frame of a horizontal three-axis hydraulic flight turntable, characterized in that, include: The outer frame starts at zero angular displacement and rotates within a certain range. Force analysis is performed at multiple different moments when the outer frame rotates to the same position in both the forward and reverse directions. The force analysis is performed at two different moments at the same position. The equations of motion are obtained through force analysis; By performing calculations on the equations of motion, we obtain the expressions for the frictional torque and the gravitational torque; Experiments were conducted at different locations to obtain the gravitational torque and frictional torque at the corresponding locations; The equations of motion obtained through force analysis include: In the formula, J(y) a J(y) is the moment of inertia at point a. b y is the moment of inertia at point b. a It is the displacement of the middle frame at point a, y b It is the displacement of the middle frame at point b, x 1a x is the displacement of the outer frame at point a. 1b x is the displacement of the outer frame at point b. 2a The angular velocity of the outer frame at point a is x. 2b It is the angular velocity of the outer frame at point b. It is the angular acceleration of the outer frame at point a. It is the angular acceleration of the outer frame at point b, x 3a It is the load pressure on the outer frame at point a, x 3b Here, A is the load pressure on the outer frame at point b, and f is the load pressure adjustment coefficient. ra f is the frictional torque of the outer frame at point a. rb f is the frictional torque of the outer frame at point b. ga f is the gravitational moment of the outer frame at point a. gb f is the gravitational moment of the outer frame at point b. ea f is the unmodeled moment of the outer frame at point a. eb It is the unmodeled torque of the outer frame at point b. The angular displacements at points a and b are exactly the same, the magnitudes of the angular velocities are the same, and the directions of the angular velocities are opposite.

2. The method for identifying the gravitational torque and frictional torque of the outer frame of the horizontal triaxial hydraulic flight turntable according to claim 1, characterized in that, The force analysis includes: performing mechanical analysis on the angular displacement, angular velocity, and force direction at multiple different times at the same location.

3. The method for identifying the gravitational torque and frictional torque of the outer frame of the horizontal triaxial hydraulic flight turntable according to claim 1, characterized in that, By performing calculations on the equations of motion, we obtain the expressions for the frictional torque and the gravitational torque. The method for obtaining the gravitational torque is as follows: By substituting the displacement of the middle frame, the displacement of the outer frame, the angular velocity, the angular acceleration, and the load pressure data at points a and b as shown in Equation 2 into Equation 1, and then... Formula and Add the two equations together to eliminate the frictional torque f. ra and f rb This yields the expression for the gravitational moment at the position of the outer frame under any displacement.

4. The method for identifying the gravitational torque and frictional torque of the outer frame of the horizontal triaxial hydraulic flight turntable according to claim 3, characterized in that, By performing calculations on the equations of motion, we obtain the expressions for frictional torque and gravitational torque. The method for obtaining frictional torque is as follows: Based on the obtained expression for the gravitational torque, substituting: Use any one of the formulas to calculate and determine the frictional torque at the current point.

5. A system for identifying the gravitational torque and frictional torque of the outer frame of a horizontal three-axis hydraulic flight turntable, comprising an input module, an analysis module, an output module, and a storage module; characterized in that, After receiving information from outside the system, the input module inputs information to the analysis module. The analysis module analyzes and processes the input information based on the received input information using the identification method of gravity torque and friction torque of the outer frame of the horizontal three-axis hydraulic flight turntable as described in any one of claims 1 to 4, and then obtains output information. The output module receives the output information from the analysis module and outputs the information to outside the system. The storage module is used to store preset information that needs to be stored.

6. A device for identifying the gravitational torque and frictional torque of the outer frame of a horizontal three-axis hydraulic flight turntable, comprising a memory and a processor, wherein the memory stores a computer program that can run on the processor, characterized in that, When the processor executes the program, it implements the steps in the method for identifying the gravitational torque and frictional torque of the outer frame of the horizontal three-axis hydraulic flight turntable as described in any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps in the method for identifying the gravitational torque and frictional torque of the outer frame of the horizontal triaxial hydraulic flight turntable as described in any one of claims 1 to 4.

Images