A compliant continuous variable structure control method for servo loop of four-axis inertially stabilized platform

Abstract

The application discloses a compliance continuous variable structure control method for a four-axis inertial stabilization platform servo loop, which comprises the following steps: obtaining the angular velocity components of a platform body on X, Y and Z axes and the angles of internal relative rotation of a four-axis inertial stabilization platform according to the angular velocity output by a gyroscope installed on the platform body; calculating the angular velocity correction value of the compliance continuous variable structure according to the value of a given compliance continuous variable structure parameter k; calculating ωx, ωy, ωz and ω according to βx, βy, βz, βxy, βxz, βyz and Δω; feeding back the calculated ωx, ωy, ωz and ω to a four-axis inertial stabilization platform servo loop controller to realize the compliance continuous variable structure control of the loop. p p p xk yk zk xk yk zk z y x yk′ z y x yk′ The method can ensure the relative inertial space stabilization of the platform body of the four-axis inertial stabilization platform and has the advantages of full attitude and high precision.​​​​​​​​​​​​​​​​

Description

Technical Field

[0001] This invention belongs to the field of inertial measurement technology, and particularly relates to a compliant continuous variable structure control method for a servo loop of a four-axis inertial stabilization platform. Background Technology

[0002] Because three-axis inertial platforms suffer from "frame locking," they cannot meet the requirements for large-scale maneuvering of the platform. Therefore, four-axis inertial platforms were developed. Compared to three-axis inertial platforms, four-axis inertial platforms add an outer frame to the platform body, inner frame, and middle frame. The outer frame is located between the middle frame and the base of the platform.

[0003] In engineering applications, to ensure the stability of the quadcopter platform relative to inertial space, limiting pins are installed on the inner frame axis to restrict the range of the inner frame angle (generally not exceeding ±45°). When β xk When the angle is ±90°, the inner frame angle will change with the movement of the carrier and cannot be kept at zero.

[0004] One solution is as follows: "Rotating the outer frame by 90° brings the inner frame angle back to near zero, while simultaneously moving the middle frame away from the ±90° position, thus allowing the three-frame four-axis platform to re-meet the working conditions of the traditional servo loop," see the literature "Research on the Control Strategy of the Servo Frame for a Four-Axis Inertial Platform, Navigation and Control, 2017, No. 4." However, this method results in the inner frame angle and the middle frame angle being in different ranges. During the inner frame's limit movement, the compliant continuous variable structure control involves switching between different control signals, which can cause momentary jitter in the platform at the switching moment, leading to relative swaying of the platform in space.

[0005] Therefore, there is an urgent need in this field to study a new decoupling method to improve the shortcomings of compliant continuous variable structure control when the inner frame is constrained. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform. This method overcomes the influence of compliant continuous variable structure control on the stability of the platform during the transition process when the inner frame is limited, thereby enhancing the stability of the platform relative to the inertial space and improving the accuracy of navigation calculation for the four-axis inertial stabilization platform.

[0007] To address the aforementioned technical problems, this invention discloses a compliant continuous variable structure control method for a four-axis inertial stabilization platform servo loop, comprising:

[0008] Based on the angular velocity output by the gyroscope mounted on the platform, the position of the platform in the X direction is obtained. p Axis, Y p Axis and Z p angular velocity component ω on the axis xpω yp and ω zp ;

[0009] The measured angle of relative rotation inside the four-axis inertial stabilized platform is: β xk β yk and β zk ; where β xk Represents the X coordinate of the outer frame around the body coordinate system of the middle frame. p2 The angle of rotation of the axis, β yk Represents the Y-axis of the middle frame around the inner frame's body coordinate system. p1 The angle of rotation of the axis, β zk The Z-axis represents the coordinate system of the inner frame around the body of the platform. p The angle of rotation of the shaft;

[0010] Given the value of the compliant continuous variable structure parameter k;

[0011] Based on the given value of the compliant continuous variable structure parameter k, the angular velocity correction value Δω of the compliant continuous variable structure is calculated.

[0012] According to β xk β yk β zk ω xp ω yp ω zp And Δω, calculate ω z ω y ω x and ω yk′ ; where ω z Represents the Z-shaped platform. p The resultant rotational angular velocity of the shaft, ω y Indicates the inner frame Y p1 The resultant rotational angular velocity of the shaft, ω x Representing the frame X p2 The resultant rotational angular velocity of the shaft, ω yk′ Represents the outer frame Y p3 The resultant rotational angular velocity of the shaft;

[0013] The calculated ω z ω y ω x and ω yk′ Feedback is sent to the servo loop controller of the four-axis inertial stabilization platform to achieve compliant continuous variable structure control.

[0014] In the above-mentioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, this method is used to achieve compliant continuous variable structure control when the inner frame of the servo loop of the four-axis inertial stabilization platform is limited.

[0015] In the aforementioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, this method is based on a four-axis inertial stabilization platform. The four-axis inertial stabilization platform includes: a base, an outer frame, a middle frame, an inner frame, and a platform. The respective body coordinate systems of the base, outer frame, middle frame, inner frame, and platform are: base body coordinate system X1Y1Z1, outer frame body coordinate system X... p3 Y p3 Z p3 , Medium frame body coordinate system X p2 Y p2 Z p2 The inner frame body coordinate system X p1 Y p1 Z p1 and the X coordinate system of the platform body p Y p Z p Among them, the origins of the five body coordinate systems coincide, and: the Z-axis of the frustum body coordinate system... p Z-axis and the coordinate system of the inner frame p1 The axes coincide, and the Y-axis of the middle frame body coordinate system is... p2 Y-axis and the coordinate system of the inner frame p1 The axes coincide, and the X coordinate of the outer frame body coordinate system is... p3 The X-axis of the axis and the body coordinate system of the middle frame p2 The axes coincide, the X1 axis of the base body coordinate system and the Y axis of the outer frame body coordinate system. p3 The axes coincide; wherein, the base is fixedly connected to the carrier, and when the four-axis inertial stabilization platform undergoes internal relative rotation under the drive of the carrier, the base revolves around the Y-axis of the outer frame's body coordinate system. p3 The axis rotates, and the outer frame revolves around the X coordinate system of the middle frame. p2 The axis rotates, and the middle frame revolves around the Y-axis of the inner frame's body coordinate system. p1 The axis rotates, and the inner frame rotates around the Z-axis of the platform's coordinate system. p The shaft rotates.

[0016] In the above-mentioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, the formula for calculating Δω is as follows:

[0017]

[0018] Where, β m This indicates the limit value of the inner frame.

[0019] In the aforementioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, ω z ω y ω x and ω yk′ The calculation formula is as follows:

[0020]

[0021] In the above-mentioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, the measured relative rotation angles inside the four-axis inertial stabilization platform include:

[0022] X in the outer frame p2 Angle sensor A is mounted on the shaft, and β is obtained by measuring angle sensor A. xk ;

[0023] Y in the inner frame p1 Angle sensor B is installed on the shaft, and β is obtained by measuring angle sensor B. yk ;

[0024] In the Z of the platform p An angle sensor C is mounted on the shaft, and β is obtained by measuring the angle sensor C. zk .

[0025] In the aforementioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, β yk The range of values ​​for is: -β m ~β m .

[0026] In the aforementioned compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, β zk β xk The range of values ​​is -180° to 180°.

[0027] The present invention has the following advantages:

[0028] (1) This invention discloses a compliant continuous variable structure control method for a four-axis inertial stabilization platform servo loop, which overcomes the influence of compliant continuous variable structure control on the stability of the platform during the transition process when the inner frame is limited, eliminates the dynamic error caused by frequent shaking caused by interval switching, and thus improves the accuracy of inertial navigation.

[0029] (2) This invention discloses a compliant continuous variable structure control method for a four-axis inertial stabilization platform servo loop, which has the characteristic of low output energy and is conducive to saving control energy.

[0030] (3) This invention discloses a compliant continuous variable structure control method for a servo loop of a four-axis inertial stabilization platform, which has the characteristics of small overshoot, no need for partitioning, simple control algorithm, and easy engineering implementation. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the steps of a compliant continuous variable structure control method for a servo loop of a four-axis inertial stabilization platform according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram illustrating the relationship between the five body coordinate systems in a four-axis inertial stabilization platform according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a region divided according to the angles of the inner frame and the middle frame when using variable structure zoning control in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram illustrating the change of frame angle over time when using variable structure partitioning control in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the area where the angles of the inner frame and the middle frame are located when using variable structure zoning control in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram illustrating the change of the platform's angular velocity over time when using variable structure partition control in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram illustrating the change of the angle of the platform relative to the inertial space over time when using variable structure partition control in an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram illustrating the change of the frame angle over time when using the compliant continuous variable structure control with the inner frame limiting of the present invention in an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the angle regions of the inner frame and the middle frame when using the compliant continuous variable structure control with the inner frame limiting method in an embodiment of the present invention.

[0040] Figure 10 This is a schematic diagram illustrating the change of the platform's angular velocity over time when using the compliant continuous variable structure control with the inner frame of this invention in an embodiment of the invention.

[0041] Figure 11 This is a schematic diagram illustrating the change of the angle of the platform relative to the inertial space over time when using the compliant continuous variable structure control with the inner frame limiting of this invention in an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed herein will be described in further detail below with reference to the accompanying drawings.

[0043] This invention discloses a compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform, mainly used to achieve compliant continuous variable structure control when the inner frame of the servo loop of the four-axis inertial stabilization platform is limited. This compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform is implemented based on a four-axis inertial stabilization platform. The four-axis inertial stabilization platform includes: a base, an outer frame, a middle frame, an inner frame, and a platform body; the positions and connection relationships of the base, outer frame, middle frame, inner frame, and platform body are similar to those of existing four-axis inertial stabilization platforms and will not be described in detail here.

[0044] like Figure 1 In this embodiment, the compliant continuous variable structure control method for the servo loop of the four-axis inertial stabilization platform includes:

[0045] Step 101: Based on the angular velocity output by the gyroscope mounted on the platform, obtain the angular velocity of the platform in the X direction. p Axis, Y p Axis and Z p angular velocity components on the axis and

[0046] In this embodiment, as Figure 2 The corresponding body coordinate systems for the base, outer frame, middle frame, inner frame, and platform are as follows: base body coordinate system X1Y1Z1, outer frame body coordinate system X... p3 Y p3 Z p3 , Medium frame body coordinate system X p2 Y p2 Z p2 The inner frame body coordinate system X p1 Y p1 Z p1 and the X coordinate system of the platform body p Y p Z p The origins of the five body coordinate systems coincide, and they satisfy the following relationship: the Z-axis of the tabletop body coordinate system... p Z-axis and the coordinate system of the inner frame p1 The axes coincide, and the Y-axis of the middle frame body coordinate system is... p2 Y-axis and the coordinate system of the inner frame p1 The axes coincide, and the X coordinate of the outer frame body coordinate system is... p3 The X-axis of the axis and the body coordinate system of the middle frame p2 The axes coincide, the X1 axis of the base body coordinate system and the Y axis of the outer frame body coordinate system. p3 The axes coincide. The base is fixed to the carrier. When the four-axis inertial stabilization platform undergoes internal relative rotation under the drive of the carrier, the base rotates around the Y-axis of the outer frame's body coordinate system. p3 The axis rotates, and the outer frame revolves around the X coordinate system of the middle frame.p2 The axis rotates, and the middle frame revolves around the Y-axis of the inner frame's body coordinate system. p1 The axis rotates, and the inner frame rotates around the Z-axis of the platform's coordinate system. p The shaft rotates.

[0047] Step 102: Measure the angle of relative rotation inside the four-axis inertial stabilized platform: β xk β yk and β zk .

[0048] In this embodiment, β xk Represents the X coordinate of the outer frame around the body coordinate system of the middle frame. p2 The angle of rotation of the axis, β yk Represents the Y-axis of the middle frame around the inner frame's body coordinate system. p1 The angle of rotation of the axis, β zk The Z-axis represents the coordinate system of the inner frame around the body of the platform. p The angle of rotation of the axis. Specifically, it can be measured in the X-axis of the outer frame. p2 Angle sensor A is mounted on the shaft, and β is obtained by measuring angle sensor A. xk ; in the inner frame Y p1 Angle sensor B is installed on the shaft, and β is obtained by measuring angle sensor B. yk ; in the Z of the platform p An angle sensor C is mounted on the shaft, and β is obtained by measuring the angle sensor C. zk .

[0049] Preferred, β yk The range of values ​​for is: -β m ~β m . β zk β xk The range of values ​​for β is -180° to 180°. m This indicates the limit value of the inner frame.

[0050] Step 103: Given the value of the compliant continuous variable structure parameter k.

[0051] Step 104: Calculate the angular velocity correction value Δω of the compliant continuous variable structure based on the given value of the compliant continuous variable structure parameter k.

[0052] In this embodiment, the formula for calculating Δω is as follows:

[0053]

[0054] Step 105, according to β xk β yk β zk , And Δω, calculate ω zω y ω x and ω yk′ .

[0055] In this embodiment, ω z Represents the Z-shaped platform. p The resultant rotational angular velocity of the shaft, ω y Indicates the inner frame Y p1 The resultant rotational angular velocity of the shaft, ω x Representing the frame X p2 The resultant rotational angular velocity of the shaft, ω yk′ Represents the outer frame Y p3 The resultant rotational angular velocity of the shaft.

[0056] Preferably, ω z ω y ω x and ω yk′ The calculation formula is as follows:

[0057]

[0058] Step 106, calculate ω z ω y ω x and ω yk′ Feedback is sent to the servo loop controller of the four-axis inertial stabilization platform to achieve compliant continuous variable structure control.

[0059] To further illustrate the high precision of the compliant continuous variable structure control method for the four-axis inertial stabilization platform servo loop described in this invention, an example is provided below.

[0060] Reference: "Research on Control Strategy of Four-Axis Inertial Platform Follower Frame, Navigation and Control, 2017, No. 4", assuming the inner frame limit value β. m =45°, the area controlled by the locking partition discrete variable structure when the inner frame angle is limited is as follows: Figure 3 As shown. The main problem with this method is that the motion trajectory cannot cross from region 32 to region 31; it can only move forward by constantly switching along the boundary, causing the platform to shake.

[0061] Let β yk′ β xk β yk β zk The initial values ​​are 0°, 90°, 0°, and 0° respectively. When using variable structure zoning control, the initial position is in region 32. Let the platform base angular velocity...

[0062] The time-varying process of the frame angle in the locking-type discrete variable structure partition control when using inner frame angle limiting is as follows: Figure 4As shown, the areas where the inner and outer frames are located are as follows: Figure 5 As shown, the change of the angular velocity of the platform with time is as follows: Figure 6 As shown, the angle θ between the platform and the inertial space x θ y θ z The process of change over time is as follows Figure 7 As shown. Throughout the entire operation, the inner frame angle never exceeded the limit of 45°, but during the switching process, both the platform's angular velocity and angle exhibited high-frequency vibrations. Specifically, the platform's angular velocity ω... xp The maximum value is approximately -291° / s. At the switching moment, the maximum value is approximately -167° / s, and the angle θ of the platform relative to the inertial space is... x At instantaneous closure at time zero, the maximum value can reach 1.983°, θ y The maximum value at the switching moment is approximately 0.96°.

[0063] When using the compliant continuous variable structure control method for inner frame limiting as described in this paper, the change process of the frame angle over time is as follows: Figure 8 As shown, the areas where the inner frame and middle frame angles are located are as follows: Figure 9 As shown, the change of the angular velocity of the platform with time is as follows: Figure 10 As shown, the angle θ between the platform and the inertial space x θ y θ z The process of change over time is as follows Figure 11 As shown. During operation, the angular velocity of the platform... The maximum is -2.9° / s. The maximum value is above -4.8° / s, and the angle θ of the platform relative to the inertial space is... x The maximum is -0.08°, θ y The maximum is 0.16°.

[0064] By comparing the partitioned discrete variable structure control with the compliant continuous variable structure control method of the present invention, it can be seen that by using the compliant continuous variable structure control method of the present invention, the overshoot of the angle and angular velocity of the platform relative to the inertial space is significantly reduced, and there is no continuous swaying process. The method of the present invention has higher accuracy.

[0065] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0066] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A compliant continuous variable structure control method for a servo loop of a four-axis inertial stabilization platform, characterized in that, include: Based on the angular velocity output by the gyroscope mounted on the platform, the position of the platform in the X direction is obtained. p Axis, Y p Axis and Z p angular velocity components on the axis , and ; The relative rotation angles inside the four-axis inertial stabilized platform were measured: , and ;in, Represents the X coordinate of the outer frame around the body coordinate system of the middle frame. p2 The angle of rotation of the shaft, Represents the Y-axis of the middle frame around the inner frame's body coordinate system. p1 The angle of rotation of the shaft, The Z-axis represents the coordinate system of the inner frame around the body of the platform. p The angle of rotation of the shaft; Given compliant continuous variable structure parameters k The value; Based on the given compliant continuous variable structure parameters k The value was used to calculate the angular velocity correction value of the compliant continuous variable structure. : in, Indicates the limit value of the inner frame; according to , , , , , and Calculations yielded , , and : in, Represents the Z-shaped platform. p The resultant rotational angular velocity of the shaft, Indicates the inner frame Y p1 The resultant rotational angular velocity of the shaft, Representing the frame X p2 The resultant rotational angular velocity of the shaft, Represents the outer frame Y p3 The resultant rotational angular velocity of the shaft; The calculated , , and Feedback is sent to the servo loop controller of the four-axis inertial stabilization platform to achieve compliant continuous variable structure control.

2. The compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform according to claim 1, characterized in that, This method is used to achieve compliant continuous variable structure control when the frame is limited within the servo loop of a four-axis inertial stabilization platform.

3. The compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform according to claim 1, characterized in that, This method is implemented based on a four-axis inertial stabilization platform; A four-axis inertial stabilization platform includes: a base, an outer frame, a middle frame, an inner frame, and a platform; the respective body coordinate systems of the base, outer frame, middle frame, inner frame, and platform are: base body coordinate system X1Y1Z1, outer frame body coordinate system X... p3 Y p3 Z p3 , Medium frame body coordinate system X p2 Y p2 Z p2 The inner frame body coordinate system X p1 Y p1 Z p1 and the X coordinate system of the platform body p Y p Z p Among them, the origins of the five body coordinate systems coincide, and: the Z-axis of the frustum body coordinate system... p Z-axis and the coordinate system of the inner frame p1 The axes coincide, and the Y-axis of the middle frame body coordinate system is... p2 Y-axis and the coordinate system of the inner frame p1 The axes coincide, and the X coordinate of the outer frame body coordinate system is... p3 The X-axis of the axis and the body coordinate system of the middle frame p2 The axes coincide, the X1 axis of the base body coordinate system and the Y axis of the outer frame body coordinate system. p3 The axes coincide; wherein, the base is fixedly connected to the carrier, and when the four-axis inertial stabilization platform undergoes internal relative rotation under the drive of the carrier, the base revolves around the Y-axis of the outer frame's body coordinate system. p3 The axis rotates, and the outer frame revolves around the X coordinate system of the middle frame. p2 The axis rotates, and the middle frame revolves around the Y-axis of the inner frame's body coordinate system. p1 The axis rotates, and the inner frame rotates around the Z-axis of the platform's coordinate system. p The shaft rotates.

4. The compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform according to claim 1, characterized in that, The relative rotation angles inside the four-axis inertial stabilized platform were measured, including: X in the outer frame p2 Angle sensor A is installed on the shaft, and the angle is measured by angle sensor A. ; Y in the inner frame p1 Angle sensor B is installed on the shaft, and the angle is measured by angle sensor B. ; In the Z of the platform p An angle sensor C is mounted on the shaft, and the angle is measured by the angle sensor C. .

5. The compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform according to claim 1, characterized in that, The range of values ​​for is: ~ .

6. The compliant continuous variable structure control method for the servo loop of a four-axis inertial stabilization platform according to claim 1, characterized in that, , The value range is -180° to 180°.

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