A disturbance compensation control method for underwater electro-hydrostatic actuator

Abstract

The present invention discloses a disturbance compensation control method for an underwater electric hydrostatic actuator. The method comprises: a first expanded observer outputs an estimated value of an external load force to a state space model; a second expanded observer outputs an estimated value of a seawater pressure compensator disturbance and a total leakage to a state space model; a backstepping controller outputs a second-step backstepping virtual control quantity; and the second-step backstepping virtual control quantity is used as the speed of a motor of the underwater electric hydrostatic actuator, thereby achieving control of the underwater electric hydrostatic actuator to accurately track a preset position. The method of the present invention solves the problem of low control accuracy of the underwater electric hydrostatic actuator, reduces the influence of disturbances through feedforward compensation of the expanded observer, improves the position control accuracy of the underwater electric hydrostatic actuator, ensures the stability and robustness of the overall system through the backstepping controller, and provides a guarantee for underwater operations.

Description

Technical Field

[0001] The invention relates to a compensation control method, in particular to an interference compensation control method for an underwater electric hydrostatic actuator. Background Art

[0002] The electric hydrostatic actuator (EHA) is a direct-drive volume control (pump control) electro-hydraulic servo system. Compared with the traditional valve-controlled hydraulic system, it has the advantages of high energy utilization efficiency and low throttling loss. Compared with the electric mechanical transmission system, it has high fault tolerance, so it is widely used.

[0003] In the field of marine equipment, traditional hydraulic systems have been widely used. Most traditional hydraulic control systems can theoretically be replaced by EHA, especially in places with high integration requirements. In some application scenarios, not only integration is required, but also the position control accuracy of EHA is required, such as underwater connector plugging and unplugging operations, underwater welding operations, underwater gate driving, underwater emergency cable cutting, underwater cable laying, or multiple EHAs are combined into lifting platforms, and multi-joint manipulators are mounted on the vehicle to cooperate in completing operations. In this application scenario, in order to provide guarantees for underwater fine operations, the control accuracy is generally required to reach millimeter-level or above position control accuracy. Millimeter-level control accuracy can basically be achieved in EHA on land, but due to the interaction between the underwater EHA shell and the seawater environment, there are problems such as interference from additional seawater pressure, which is more difficult to control than EHA on land, so the control accuracy is difficult to guarantee. At present, there is little research on underwater EHA. The structural composition can be referenced from the terrestrial EHA. In order to meet the underwater environment and compensate for the seawater pressure, a seawater pressure compensator is added for adaptive modification to make the pressure of the return oil chamber approximately equal to the pressure of seawater. Due to the changes in the structure and use environment of the underwater EHA, if high-precision motion control is to be achieved, the system modeling and motion control algorithm of the underwater electric hydrostatic actuator need to be reconsidered. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a relatively complete state space model covering the dynamic model of the seawater pressure compensator for the newly emerging underwater electric hydrostatic actuator. In order to improve the operating accuracy of the underwater electric hydrostatic actuator, a disturbance compensation control method for the underwater electric hydrostatic actuator is proposed, which solves the problem of low control accuracy caused by the pressure fluctuation of the seawater pressure compensator and the disturbances generated by the external seawater environment and load. This method aims at the pressure disturbance existing in the seawater pressure compensator part and the disturbance of unknown external environmental forces faced by the underwater electric hydrostatic actuator, reduces the influence of the disturbance by the feedforward compensation of the expanded observer, improves the position control accuracy of the underwater electric hydrostatic actuator, and designs the backstepping controller by the backstepping control method to ensure the stability and robustness of the disturbance compensation system.

[0005] The technical solution adopted by the present invention is:

[0006] The interference compensation control method of the present invention comprises the following steps:

[0007] 1) Establish the state space model of the underwater electric hydrostatic actuator.

[0008] 2) A low-order first expanded observer and a low-order second expanded observer are designed based on the underwater electro-hydrostatic actuator, taking into account the external load force of the underwater electro-hydrostatic actuator, the seawater pressure compensator disturbance and the total leakage; wherein the low order is below the second-order derivative.

[0009] Obtain the measured value of the displacement of the actuator rod of the underwater electric hydrostatic actuator, the measured value of the speed of the actuator rod of the underwater electric hydrostatic actuator, and the measured value of the output force of the underwater electric hydrostatic actuator; input the measured value of the speed of the actuator rod of the underwater electric hydrostatic actuator and the measured value of the output force of the underwater electric hydrostatic actuator into a first extended observer, and the first extended observer outputs an estimated value of the external load force to the state space model in a feedforward manner.

[0010] The measured values ​​of the displacement of the actuator rod of the electro-hydrostatic actuator and the measured values ​​of the speed of the actuator rod of the electro-hydrostatic actuator are input to the second expanded observer, and the second expanded observer outputs the common estimated values ​​of the seawater pressure compensator disturbance and the total leakage to the state space model in a feedforward manner.

[0011] 3) Through the state space model, use the backstepping control method to design a backstepping controller, input the preset displacement, preset speed, displacement measurement value, speed measurement value and output force measurement value of the underwater electric hydrostatic actuator into the backstepping controller, and the backstepping controller outputs the second backstepping method virtual control quantity.

[0012] 4) The backstepping controller performs compensation control on the motor of the underwater electric hydrostatic actuator through the virtual control quantity of the second backstepping method, that is, the virtual control quantity of the second backstepping method is used as the speed of the motor of the underwater electric hydrostatic actuator, thereby realizing precise control of the underwater electric hydrostatic actuator, so as to realize precise tracking of the preset position by controlling the underwater electric hydrostatic actuator.

[0013] That is, compensation control is performed on the compensation control system composed of the backstepping controller, the first expanded observer, the second expanded observer and the state space model to ensure the overall stability of the compensation control system.

[0014] In the step 1), the underwater electro-hydrostatic actuator is mainly composed of a seawater pressure compensator and an electro-hydrostatic actuator. The electro-hydrostatic actuator mainly includes a hydraulic cylinder, a hydraulic pump and a motor. The seawater pressure compensator is installed on the motor of the electro-hydrostatic actuator.

[0015] The motor of the electro-hydrostatic actuator is connected to the hydraulic pump, and the hydraulic pump is connected to the hydraulic cylinder through a valve block.

[0016] The seawater pressure compensator is specifically a rolling diaphragm pressure compensator.

[0017] In the step 1), the state space model of the underwater electro-hydrostatic actuator is established as follows:

[0018]

[0019] in, is the acceleration of the actuator rod of the electro-hydrostatic actuator, is the speed of the actuator rod of the electro-hydrostatic actuator; m L F is the total mass of the inertial load of the electro-hydrostatic actuator and the piston of the hydraulic cylinder; l is the output force of the electric hydrostatic actuator; B m is the damping coefficient of the hydraulic cylinder of the electro-hydrostatic actuator; F(t) is the external load force of the electro-hydrostatic actuator at time t; is the first-order derivative of the output force of the electro-hydrostatic actuator; β e is the elastic modulus of the oil; the hydraulic cylinder of the electric hydrostatic actuator includes a rodless chamber and a rod chamber, A1 and A2 are the piston area of ​​the rodless chamber and the piston area of ​​the rod chamber of the hydraulic cylinder respectively; V1 and V2 are the volume of the rodless chamber and the volume of the rod chamber of the hydraulic cylinder respectively; Q p is the outlet flow rate of the hydraulic pump of the electro-hydrostatic actuator; is the speed of the seawater pressure compensator; V c is the volume of the seawater pressure compensator, V c =V c0 -A e x c , Vc0 is the initial volume of the seawater pressure compensator, x c is the displacement of the seawater pressure compensator; K x A is the composite stiffness of the rolling diaphragm and spring of the seawater pressure compensator; e is the equivalent area of ​​the rolling diaphragm of the seawater pressure compensator; L1 is the sum of the external leakage of the rodless cavity and the rod cavity, and L2 is the sum of the internal leakage of the rodless cavity and the rod cavity.

[0020] The output force F of the electro-hydrostatic actuator is l as follows:

[0021] F l =(P1-P s0 )A1-(P2-P s0 )A2

[0022] Among them, the hydraulic cylinder of the electric hydrostatic actuator mainly includes a rodless chamber and a rod chamber, and P1 and P2 are the pressure of the rodless chamber and the pressure of the rod chamber of the hydraulic cylinder of the electric hydrostatic actuator respectively; P s0 is the external seawater pressure.

[0023] The outlet flow rate Q of the hydraulic pump of the electro-hydrostatic actuator is p The details are as follows:

[0024] Q p =D p ·wL p

[0025] Among them, D p is the displacement of the hydraulic pump, w is the speed of the hydraulic pump, L p It is the sum of the internal leakage and external leakage of the hydraulic pump.

[0026] In the step 2), the external load force of the underwater electrostatic hydraulic actuator is the external load force of the electrostatic hydraulic actuator; the electrostatic hydraulic actuator is equipped with a displacement sensor, a speed sensor and two pressure sensors, the displacement sensor measures the displacement of the actuator rod of the electrostatic hydraulic actuator, that is, the displacement of the actuator rod of the underwater electrostatic hydraulic actuator; the speed sensor observes the speed of the actuator rod of the electrostatic hydraulic actuator, that is, the speed of the actuator rod of the underwater electrostatic hydraulic actuator;

[0027] The two pressure sensors respectively observe and obtain the measured value of the pressure of the rodless chamber and the measured value of the pressure of the rod chamber of the hydraulic cylinder of the electric hydrostatic actuator, and then obtain the measured value of the output force of the electric hydrostatic actuator, that is, the measured value of the output force of the underwater electric hydrostatic actuator; the displacement sensor and the speed sensor are installed inside the hydraulic cylinder, and the two pressure sensors are respectively installed at the oil inlet and the oil outlet of the hydraulic cylinder;

[0028] The total leakage of the underwater electric hydrostatic actuator is the sum of the external leakage and internal leakage of the two chambers of the hydraulic cylinder and the sum of the external leakage and internal leakage of the hydraulic pump.

[0029] A low-order first expanded observer and a low-order second expanded observer are designed based on the underwater electro-hydrostatic actuator, taking into account the external load disturbance, seawater pressure compensator disturbance and total leakage of the electro-hydrostatic actuator.

[0030] The first extended observer is as follows:

[0031]

[0032] in, The speed of the actuator rod of the electro-hydrostatic actuator The first derivative of the estimate of , The speed of the actuator rod of the electro-hydrostatic actuator The estimated value of F is the external load force of the electro-hydrostatic actuator. is the estimated value of the external load force of the electro-hydrostatic actuator; λ1 and λ2 are the gain coefficients of the first extended observer and the second extended observer, respectively, and the characteristic polynomial s is satisfied. 2 +sλ1+λ2=0, which satisfies the Hurwitz stability condition, and the real part of the characteristic root of the characteristic polynomial is less than 0; ε1 is the compensation parameter of the first expanded observer and the second expanded observer, and its value range is 0-1.

[0033] R1(y2,y3,t,w) is the system state function of the first extended observer at time t, and the formula is as follows:

[0034]

[0035] Where y2 is the speed of the actuator rod of the electro-hydrostatic actuator The measured value of y3 is the output force F of the electro-hydrostatic actuator. l The measured value.

[0036] The second extended observer is as follows:

[0037]

[0038] in, is the output force F of the electro-hydrostatic actuator l The first derivative of the estimate of , is the output force F of the electro-hydrostatic actuator l An estimated value of Combined estimate of seawater pressure compensator disturbance and total leakage.

[0039] R2(y1,y2,t,w) is the system state function of the second extended observer at time t, and the formula is as follows:

[0040] R2(y1,y2,t,w)=-α(t,y1)y2+β(t,y1)D p w

[0041] Where y1 is the displacement x of the actuator rod of the electro-hydrostatic actuator L The measured values ​​of α(t,y1) and β(t,y1) are the displacement x of the actuator rod of the electrostatic actuator at time t. L Related nonlinear time-varying parameters; D p is the displacement of the hydraulic pump of the electro-hydrostatic actuator, and w is the speed of the hydraulic pump of the electro-hydrostatic actuator.

[0042] The external load force is observed by the first extended observer, and an estimated value of the external load force is output in a feedforward manner To the state space model; observe the seawater pressure compensator disturbance and total leakage through the second extended observer, and output the common estimated value of the seawater pressure compensator disturbance and total leakage in a feedforward manner to the state-space model.

[0043] In the step 3), the backstepping control method is used through the state space model to obtain the backstepping controller as follows:

[0044] w d =w d1 +w d2

[0045]

[0046] z3=y3-F ld

[0047] z3(w d2 +Δd2)≤ε3

[0048] 3W d2 ≤0

[0049]

[0050] F ld =F ld1 +F ld2

[0051]

[0052] z2(F ld2 +Δd1)≤ε2

[0053] zF ld2 ≤0

[0054]

[0055] Among them, w d is the virtual control quantity of the second backstepping method, w d1 is the second backstepping control parameter used for state space model compensation and compensating control system stability; w d2 The second robust parameter to eliminate observation errors; is the virtual control quantity F of the first step backstepping method ld The first derivative of ld is the virtual control quantity of the first step backstepping method; k3 is the preset second feedback gain, z3 is the output force F of the electric hydrostatic actuator l The measured value y3 and the first step backstepping method virtual control quantity F ld , ε3 is the compensation parameter of the second robust control rate; γ is the disturbance and total leakage of the seawater pressure compensator, is the estimated value of the seawater pressure compensator disturbance and total leakage, Δd2 is the error between the seawater pressure compensator disturbance and total leakage and the estimated value of the seawater pressure compensator disturbance and total leakage at time t; F ld1 is the first backstepping control parameter used for disturbance state space model compensation and compensating control system stability, F ld2 is the first robust parameter to eliminate observation errors; is the preset acceleration of the actuator rod of the electrostatic hydraulic actuator; k2 is the preset second feedback gain; z2 is the measured value y2 of the speed of the actuator rod of the electrostatic hydraulic actuator and the preset speed x of the actuator rod of the electrostatic hydraulic actuator 2eq The error, z2 = y2-x 2eq ; ε2 is the compensation parameter of the first robust control rate; Δd1 is the external load force of the electro-hydrostatic actuator and the estimated value of the external load force of the electro-hydrostatic actuator The error between .

[0056] The preset speed x of the actuator rod of the electro-hydrostatic actuator 2eq as follows:

[0057] x 2eq =x 1d -k1z1

[0058] z1=y1-x 1d

[0059] Among them, x 1d is the preset displacement of the actuator rod of the electrostatic hydraulic actuator, k1 is the preset first feedback gain, z1 is the displacement x of the actuator rod of the electrostatic hydraulic actuator L The measured value y1 and the preset displacement x1d of error.

[0060] Set the preset displacement x of the actuator rod of the electro-hydrostatic actuator 1d , preset speed x 2eq , displacement x L The measured value y1, speed The measured value y2 and the output force F of the electro-hydrostatic actuator l The measured value y3 is input into the backstepping controller, which then outputs the second backstepping method virtual control quantity w d .

[0061] The beneficial effects of the present invention are:

[0062] Compared with the prior art, the present invention establishes a state-space model covering the seawater pressure compensator for the underwater electric hydrostatic actuator, and based on the model, designs two low-order extended observers for observing unknown external load forces and unmeasurable pressure disturbances of the seawater pressure compensator, etc. The stability of the overall system is ensured by the backstepping controller, and the position control accuracy of the underwater electric hydrostatic actuator is improved by the feedforward compensation of the observation values ​​of the extended observer, thereby providing a guarantee for underwater operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of the compensation control system of the present invention;

[0064] Figure 2 It is a schematic diagram of interference observation results of the first extended observer of the present invention;

[0065] Figure 3 It is a schematic diagram of interference observation results of the second extended observer of the present invention;

[0066] Figure 4 This is a schematic diagram for comparing the position tracking results of the present invention;

[0067] Figure 5 It is a schematic diagram for comparing the position tracking error results of the present invention. DETAILED DESCRIPTION

[0068] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] The interference compensation control method of the present invention comprises the following steps:

[0070] 1) Establish the state space model of the underwater electro-hydrostatic actuator; The underwater electro-hydrostatic actuator is mainly composed of a seawater pressure compensator and an electro-hydrostatic actuator. The electro-hydrostatic actuator mainly includes a hydraulic cylinder, a hydraulic pump and a motor. The seawater pressure compensator is installed on the motor of the electro-hydrostatic actuator. The motor of the electro-hydrostatic actuator is connected to the hydraulic pump, and the hydraulic pump is connected to the hydraulic cylinder through a valve block. The seawater pressure compensator is specifically a rolling diaphragm pressure compensator.

[0071] The state space model of the underwater electro-hydrostatic actuator is established as follows:

[0072]

[0073] in, is the acceleration of the actuator rod of the electro-hydrostatic actuator, is the speed of the actuator rod of the electro-hydrostatic actuator; m L F is the total mass of the inertial load of the electro-hydrostatic actuator and the piston of the hydraulic cylinder; l is the output force of the electric hydrostatic actuator; B m is the damping coefficient of the hydraulic cylinder of the electro-hydrostatic actuator; F(t) is the external load force of the electro-hydrostatic actuator at time t; is the first-order derivative of the output force of the electro-hydrostatic actuator; β e is the elastic modulus of the oil; the hydraulic cylinder of the electric hydrostatic actuator includes a rodless chamber and a rod chamber, A1 and A2 are the piston area of ​​the rodless chamber and the piston area of ​​the rod chamber of the hydraulic cylinder respectively; V1 and V2 are the volume of the rodless chamber and the volume of the rod chamber of the hydraulic cylinder respectively; Q p is the outlet flow rate of the hydraulic pump of the electro-hydrostatic actuator; is the speed of the seawater pressure compensator; V c is the volume of the seawater pressure compensator, V c =V c0 -A e x c , V c0 is the initial volume of the seawater pressure compensator, x c is the displacement of the seawater pressure compensator; K x A is the composite stiffness of the rolling diaphragm and spring of the seawater pressure compensator; e is the equivalent area of ​​the rolling diaphragm of the seawater pressure compensator; L1 is the sum of the external leakage of the rodless cavity and the rod cavity, and L2 is the sum of the internal leakage of the rodless cavity and the rod cavity.

[0074] Output force F of electro-hydrostatic actuator l as follows:

[0075] F l =(P1-P s0 )A1-(P2-Ps0 )A2

[0076] Among them, the hydraulic cylinder of the electric hydrostatic actuator mainly includes a rodless chamber and a rod chamber, and P1 and P2 are the pressure of the rodless chamber and the pressure of the rod chamber of the hydraulic cylinder of the electric hydrostatic actuator respectively; P s0 is the external seawater pressure.

[0077] Outlet flow rate Q of the hydraulic pump of the electrostatic actuator p The details are as follows:

[0078] Q p =D p ·wL p

[0079] Among them, D p is the displacement of the hydraulic pump, w is the speed of the hydraulic pump, L p It is the sum of the internal leakage and external leakage of the hydraulic pump.

[0080] 2) A low-order first expanded observer and a low-order second expanded observer are designed based on the underwater electro-hydrostatic actuator, taking into account the external load force of the underwater electro-hydrostatic actuator, the seawater pressure compensator disturbance and the total leakage; wherein the low order is below the second-order derivative.

[0081] Obtain the measured value of the displacement of the actuator rod of the underwater electric hydrostatic actuator, the measured value of the speed of the actuator rod of the underwater electric hydrostatic actuator, and the measured value of the output force of the underwater electric hydrostatic actuator; input the measured value of the speed of the actuator rod of the underwater electric hydrostatic actuator and the measured value of the output force of the underwater electric hydrostatic actuator into a first extended observer, and the first extended observer outputs an estimated value of the external load force to the state space model in a feedforward manner.

[0082] The measured values ​​of the displacement of the actuator rod of the electro-hydrostatic actuator and the measured values ​​of the speed of the actuator rod of the electro-hydrostatic actuator are input to the second expanded observer, and the second expanded observer outputs the common estimated values ​​of the seawater pressure compensator disturbance and the total leakage to the state space model in a feedforward manner.

[0083] The external load force of the underwater electric hydrostatic actuator is the external load force of the electric hydrostatic actuator; the electric hydrostatic actuator is equipped with a displacement sensor, a speed sensor and two pressure sensors, the displacement sensor measures the displacement of the actuating rod of the electric hydrostatic actuator, that is, the displacement of the actuating rod of the underwater electric hydrostatic actuator; the speed sensor observes the speed of the actuating rod of the electric hydrostatic actuator, that is, the speed of the actuating rod of the underwater electric hydrostatic actuator.

[0084] The two pressure sensors respectively observe and obtain the measured values ​​of the pressure of the rodless chamber and the pressure of the rod chamber of the hydraulic cylinder of the electrostatic hydrostatic actuator, and then obtain the measured value of the output force of the electrostatic hydrostatic actuator, that is, the measured value of the output force of the underwater electrostatic hydrostatic actuator; the displacement sensor and the speed sensor are installed inside the hydraulic cylinder, and the two pressure sensors are installed at the oil inlet and the oil outlet of the hydraulic cylinder respectively. The total leakage of the underwater electrostatic hydrostatic actuator is the sum of the external leakage and internal leakage of the two chambers of the hydraulic cylinder and the sum of the external leakage and internal leakage of the hydraulic pump.

[0085] A low-order first expanded observer and a low-order second expanded observer are designed based on the underwater electro-hydrostatic actuator, taking into account the external load disturbance, seawater pressure compensator disturbance and total leakage of the electro-hydrostatic actuator.

[0086] The first extended observer is as follows:

[0087]

[0088] in, The speed of the actuator rod of the electro-hydrostatic actuator The first derivative of the estimate of , The speed of the actuator rod of the electro-hydrostatic actuator The estimated value of F is the external load force of the electro-hydrostatic actuator. is the estimated value of the external load force of the electro-hydrostatic actuator; λ1 and λ2 are the gain coefficients of the first extended observer and the second extended observer, respectively, and the characteristic polynomial s is satisfied. 2 +sλ1+λ2=0, which satisfies the Hurwitz stability condition, and the real part of the characteristic root of the characteristic polynomial is less than 0; ε1 is the compensation parameter of the first expanded observer and the second expanded observer, and its value range is 0-1.

[0089] R1(y2,y3,t,w) is the system state function of the first extended observer at time t, and the formula is as follows:

[0090]

[0091] Where y2 is the speed of the actuator rod of the electro-hydrostatic actuator The measured value of y3 is the output force F of the electro-hydrostatic actuator. l The measured value.

[0092] The second extended observer is as follows:

[0093]

[0094] in, is the output force F of the electro-hydrostatic actuatorl The first derivative of the estimate of , is the output force F of the electro-hydrostatic actuator l An estimated value of Combined estimate of seawater pressure compensator disturbance and total leakage.

[0095] R2(y1,y2,t,w) is the system state function of the second extended observer at time t, and the formula is as follows:

[0096] R2(y1,y2,t,w)=-α(t,y1)y2+β(t,y1)D p w

[0097] Where y1 is the displacement x of the actuator rod of the electro-hydrostatic actuator L The measured values ​​of α(t,y1) and β(t,y1) are the displacement x of the actuator rod of the electrostatic actuator at time t. L Related nonlinear time-varying parameters; D p is the displacement of the hydraulic pump of the electro-hydrostatic actuator, and w is the speed of the hydraulic pump of the electro-hydrostatic actuator.

[0098] The external load force is observed by the first extended observer, and an estimated value of the external load force is output in a feedforward manner To the state space model; observe the seawater pressure compensator disturbance and total leakage through the second extended observer, and output the common estimated value of the seawater pressure compensator disturbance and total leakage in a feedforward manner to the state-space model.

[0099] 3) Through the state space model, use the backstepping control method to design a backstepping controller, input the preset displacement, preset speed, displacement measurement value, speed measurement value and output force measurement value of the actuator rod of the underwater electric hydrostatic actuator into the backstepping controller, and the backstepping controller outputs the second step backstepping method virtual control quantity.

[0100] Through the state space model, using the backstepping control method, the backstepping controller is designed as follows:

[0101] w d =w d1 +w d2

[0102]

[0103] z3=y3-F ld

[0104] z3(w d2 +Δd2)≤ε3

[0105] 3W d2 ≤0

[0106]

[0107] F ld =F ld1 +F ld2

[0108]

[0109] z2(F ld2 +Δd1)≤ε2

[0110] zF ld2 ≤0

[0111]

[0112] Among them, w d is the virtual control quantity of the second backstepping method, w d1 is the second backstepping control parameter used for state space model compensation and compensating control system stability; w d2 The second robust parameter to eliminate observation errors; is the virtual control quantity F of the first step backstepping method ld The first derivative of ld is the virtual control quantity of the first step backstepping method; k3 is the preset second feedback gain, z3 is the output force F of the electric hydrostatic actuator l The measured value y3 and the first step backstepping method virtual control quantity F ld , ε3 is the compensation parameter of the second robust control rate; γ is the disturbance and total leakage of the seawater pressure compensator, is the estimated value of the seawater pressure compensator disturbance and total leakage, Δd2 is the error between the seawater pressure compensator disturbance and total leakage and the estimated value of the seawater pressure compensator disturbance and total leakage; F ld1 is the first backstepping control parameter used for disturbance state space model compensation and compensating control system stability, F ld2 is the first robust parameter to eliminate observation errors; is the preset acceleration of the actuator rod of the electrostatic hydraulic actuator; k2 is the preset second feedback gain; z2 is the measured value y2 of the speed of the actuator rod of the electrostatic hydraulic actuator and the preset speed x of the actuator rod of the electrostatic hydraulic actuator 2eq The error, z2 = y2-x 2eq ; ε2 is the compensation parameter of the first robust control rate; Δd1 is the external load force of the electro-hydrostatic actuator and the estimated value of the external load force of the electro-hydrostatic actuator The error between .

[0113] The preset speed x of the actuator rod of the electro-hydrostatic actuator 2eq as follows:

[0114] x 2eq =x 1d -k1z1

[0115] z1=y1-x 1d

[0116] Among them, x 1d is the preset displacement of the actuator rod of the electrostatic hydraulic actuator, k1 is the preset first feedback gain, z1 is the displacement x of the actuator rod of the electrostatic hydraulic actuator L Measured value y1 and preset displacement x 1d of error.

[0117] Set the preset displacement x of the actuator rod of the electro-hydrostatic actuator 1d , preset speed x 2eq , displacement x L The measured value y1, speed The measured value y2 and the output force F of the electro-hydrostatic actuator l The measured value y3 is input into the backstepping controller, which then outputs the second backstepping method virtual control quantity w d .

[0118] 4) The backstepping controller performs compensation control on the motor of the underwater electric hydrostatic actuator through the virtual control quantity of the second backstepping method, that is, the virtual control quantity of the second backstepping method is used as the speed of the motor of the underwater electric hydrostatic actuator, thereby realizing precise control of the underwater electric hydrostatic actuator, so as to realize precise tracking of the preset position by controlling the underwater electric hydrostatic actuator.

[0119] like Figure 1 As shown, compensation control is performed on the compensation control system composed of the backstepping controller, the first expanded observer, the second expanded observer and the state space model to ensure the overall stability of the compensation control system. Specific embodiment:

[0121] The present invention simulates the above method based on the electric hydrostatic actuator model, analyzes the observation effect of the two expanded observers and the control effect of the backstepping controller, and compares it with the backstepping controller without the expanded observer, verifying the effectiveness of the control method of the present invention.

[0122] In terms of parameter establishment of the backstepping controller and the extended observer, the controller feedback gain parameter selection of the established backstepping controller based on disturbance compensation is as follows: the preset first feedback gain k1=30, the preset second feedback gain k2=80, the preset third feedback gain k3=200; the compensation parameter ε2=0.001 of the first robust control rate, the compensation parameter ε3=0.001 of the second robust control rate; the gain parameter selection of the two extended observers: the gain coefficient λ1=10.8 of the first extended observer, the gain coefficient λ2=20.8 of the second extended observer; the compensation parameter selection of the extended observer: the compensation parameter ε1=0.01 of the first extended observer and the second extended observer.

[0123] In terms of simulation parameter setting: the assumed input of the external load force F(t) of the electro-hydrostatic actuator at time t is:

[0124]

[0125] The specific simulation parameters of the underwater electric hydrostatic actuator are as follows:

[0126]

[0127]

[0128] Among them, L 1,2,p Total leakage of the underwater electro-hydrostatic actuator.

[0129] like Figure 2 As shown, it is the interference observation result of the first extended observer; Figure 3 As shown, the disturbance observation result of the seawater pressure compensator in the disturbance observation result of the second expanded observer.

[0130] like Figure 4 and Figure 5 As shown in the figure, it is the position tracking effect of the backstepping controller based on disturbance compensation, as shown in Figure 4 For position tracking comparison between the backstepping controller based on disturbance observation and the backstepping controller without disturbance observation, Figure 5 Comparison of position tracking error between the backstepping controller based on disturbance observation and the backstepping controller without disturbance observation.

[0131] The simulation results show that the underwater electric hydrostatic actuator and backstepping controller based on interference observation can achieve good position tracking under the interference of time-varying external load force and unknown seawater pressure compensator pressure fluctuation. Compared with the backstepping controller without expansion observer, it overcomes the pressure fluctuation interference of seawater pressure compensator, unknown external load force interference and total leakage, improves the position tracking accuracy by about 100 times, and makes the position tracking error smaller, reaching about 0.01mm, which shows that the tracking effect is good.

Claims

1. A disturbance compensation control method for an underwater electro-hydrostatic actuator, characterized in that: The steps include: 1) Establish the state space model of underwater electro-hydrostatic actuator; 2) Considering the external load force of the underwater electro-hydrostatic actuator, the disturbance of the seawater pressure compensator and the total leakage, a first expansion observer and a second expansion observer are designed based on the underwater electro-hydrostatic actuator; Obtaining a measured value of the displacement of an actuator rod of an underwater electric hydrostatic actuator, a measured value of the speed of an actuator rod of an underwater electric hydrostatic actuator, and a measured value of the output force of the underwater electric hydrostatic actuator; inputting the measured value of the speed of the actuator rod of the underwater electric hydrostatic actuator and the measured value of the output force of the underwater electric hydrostatic actuator into a first extended observer, and the first extended observer outputs an estimated value of the external load force to a state space model in a feedforward manner; Inputting the measured value of the displacement of the actuator rod of the underwater electro-hydrostatic actuator and the measured value of the speed of the actuator rod of the underwater electro-hydrostatic actuator into the second expanded observer, the second expanded observer outputs the common estimated value of the seawater pressure compensator disturbance and the total leakage to the state space model in a feedforward manner; 3) By using the state space model and the backstepping control method, a backstepping controller is designed, and the preset displacement, preset speed, displacement measurement value, speed measurement value and output force measurement value of the underwater electric hydrostatic actuator are input into the backstepping controller, and the backstepping controller outputs the second backstepping method virtual control quantity; 4) The backstepping controller performs compensation control on the motor of the underwater electric hydrostatic actuator through the second-step backstepping method virtual control quantity, that is, the second-step backstepping method virtual control quantity is used as the speed of the motor of the underwater electric hydrostatic actuator, thereby realizing precise control of the underwater electric hydrostatic actuator, so as to control the underwater electric hydrostatic actuator to track the preset position; In the step 1), the underwater electro-hydrostatic actuator is mainly composed of a seawater pressure compensator and an electro-hydrostatic actuator, the electro-hydrostatic actuator mainly includes a hydraulic cylinder, a hydraulic pump and a motor, and the seawater pressure compensator is installed on the motor of the electro-hydrostatic actuator; In the step 1), the state space model of the underwater electro-hydrostatic actuator is established as follows: in, is the acceleration of the actuator rod of the electro-hydrostatic actuator, is the speed of the actuator rod of the electro-hydrostatic actuator; m L F is the total mass of the inertial load of the electro-hydrostatic actuator and the piston of the hydraulic cylinder; l is the output force of the electric hydrostatic actuator; B m is the damping coefficient of the hydraulic cylinder of the electro-hydrostatic actuator; F(t) is the external load force of the electro-hydrostatic actuator at time t; is the first-order derivative of the output force of the electro-hydrostatic actuator; β e is the elastic modulus of the oil; the hydraulic cylinder of the electric hydrostatic actuator includes a rodless chamber and a rod chamber, A1 and A2 are the piston area of ​​the rodless chamber and the piston area of ​​the rod chamber of the hydraulic cylinder respectively; V1 and V2 are the volume of the rodless chamber and the volume of the rod chamber of the hydraulic cylinder respectively; Q p is the outlet flow rate of the hydraulic pump of the electro-hydrostatic actuator; is the speed of the seawater pressure compensator; V c is the volume of the seawater pressure compensator, V c =V c0 -A e x c , V c0 is the initial volume of the seawater pressure compensator, x c is the displacement of the seawater pressure compensator; K x A is the composite stiffness of the rolling diaphragm and spring of the seawater pressure compensator; e is the equivalent area of ​​the rolling diaphragm of the seawater pressure compensator; L1 is the sum of the external leakage of the rodless cavity and the cavity with rod, and L2 is the sum of the internal leakage of the rodless cavity and the cavity with rod; The output force F of the electro-hydrostatic actuator is l as follows: F l =(P1-P s0 )A1-(P2-P s0 )A2 Among them, the hydraulic cylinder of the electric hydrostatic actuator mainly includes a rodless chamber and a rod chamber, and P1 and P2 are the pressure of the rodless chamber and the pressure of the rod chamber of the hydraulic cylinder of the electric hydrostatic actuator respectively; P s0 is the external seawater pressure; The outlet flow rate Q of the hydraulic pump of the electro-hydrostatic actuator is p The details are as follows: Q p =D p ·w-L p Among them, D p is the displacement of the hydraulic pump, w is the speed of the hydraulic pump, L p It is the sum of the internal leakage and external leakage of the hydraulic pump; In the step 2), the external load force of the underwater electrostatic hydraulic actuator is the external load force of the electrostatic hydraulic actuator; the electrostatic hydraulic actuator is equipped with a displacement sensor, a speed sensor and two pressure sensors, the displacement sensor measures the displacement of the actuator rod of the electrostatic hydraulic actuator, that is, the displacement of the actuator rod of the underwater electrostatic hydraulic actuator; the speed sensor observes the speed of the actuator rod of the electrostatic hydraulic actuator, that is, the speed of the actuator rod of the underwater electrostatic hydraulic actuator; The two pressure sensors respectively observe and obtain the measured value of the pressure of the rodless chamber and the measured value of the pressure of the rod chamber of the hydraulic cylinder of the electrostatic hydrostatic actuator, and then obtain the measured value of the output force of the electrostatic hydrostatic actuator, that is, the measured value of the output force of the underwater electrostatic hydrostatic actuator; The total leakage of the underwater electric hydrostatic actuator is the sum of the external leakage and internal leakage of the two chambers of the hydraulic cylinder and the sum of the external leakage and internal leakage of the hydraulic pump; Under the condition of considering the external load disturbance of the electro-hydrostatic actuator, the disturbance of the seawater pressure compensator and the total leakage, the first expansion observer and the second expansion observer are designed based on the underwater electro-hydrostatic actuator respectively; The first extended observer is as follows: in, The speed of the actuator rod of the electro-hydrostatic actuator The first derivative of the estimate of , The speed of the actuator rod of the electro-hydrostatic actuator The estimated value of F is the external load force of the electro-hydrostatic actuator. is the estimated value of the external load force of the electro-hydrostatic actuator; λ1 and λ2 are the gain coefficients of the first extended observer and the second extended observer, respectively, and the characteristic polynomial s is satisfied. 2 +sλ1+λ2=0, and the real part of the characteristic root of the characteristic polynomial is less than 0; ε1 is the compensation parameter of the first expanded observer and the second expanded observer, and its value range is 0-1; R1(y2,y3,t,w) is the system state function of the first extended observer at time t, and the formula is as follows: Where y2 is the speed of the actuator rod of the electro-hydrostatic actuator The measured value of y3 is the output force F of the electro-hydrostatic actuator. l The measured value of The second extended observer is as follows: in, is the output force F of the electro-hydrostatic actuator l The first derivative of the estimate of , is the output force F of the electro-hydrostatic actuator l An estimated value of is the combined estimate of the seawater pressure compensator disturbance and total leakage; R2(y1,y2,t,w) is the system state function of the second extended observer at time t, and the formula is as follows: R2(y1,y2,t,w)=-α(t,y1)y2+β(t,y1)D p w Where y1 is the displacement x of the actuator rod of the electro-hydrostatic actuator L The measured values ​​of α(t,y1) and β(t,y1) are the displacement x of the actuator rod of the electrostatic actuator at time t. L Related nonlinear time-varying parameters; D p is the displacement of the hydraulic pump of the electro-hydrostatic actuator, w is the speed of the hydraulic pump of the electro-hydrostatic actuator; The external load force is observed by the first extended observer, and the estimated value of the external load force is output in a feedforward manner To the state space model; observe the seawater pressure compensator disturbance and total leakage through the second extended observer, and output the common estimated value of the seawater pressure compensator disturbance and total leakage in a feedforward manner to the state-space model; In step 3), the backstepping control method is used through the state space model to obtain the backstepping controller as follows: In d =in d1 +in d2 <h2 style=";text-align:left;direction:ltr">z3 = y3-F<h2 style=";text-align:left;direction:ltr"> ld z3(w d2 +Δd2)≤ε3 <h2 style=";text-align:left;direction:ltr">z3w<h2 style=";text-align:left;direction:ltr"> d2 <h2 style=";text-align:left;direction:ltr"> ≤0 F ld =F ld1 +F ld2 z2(F ld2 +Δd1)≤ε2 z2F ld2 ≤0 Among them, w d is the virtual control quantity of the second backstepping method, w d1 is the second backstepping control parameter; w d2 The second robust parameter to eliminate observation errors; is the virtual control quantity F of the first step backstepping method ld The first derivative of ld is the virtual control quantity of the first step backstepping method; k3 is the preset second feedback gain, z3 is the output force F of the electric hydrostatic actuator l The measured value y3 and the first step backstepping method virtual control quantity F ld , ε3 is the compensation parameter of the second robust control rate; γ is the disturbance and total leakage of the seawater pressure compensator, is the estimated value of the seawater pressure compensator disturbance and total leakage, Δd2 is the error between the water pressure compensator disturbance and total leakage and the estimated value of the seawater pressure compensator disturbance and total leakage; F ld1 is the first backstepping control parameter, F ld2 is the first robust parameter to eliminate observation errors; is the preset acceleration of the actuator rod of the electrostatic hydraulic actuator; k2 is the preset second feedback gain; z2 is the measured value y2 of the speed of the actuator rod of the electrostatic hydraulic actuator and the preset speed x of the actuator rod of the electrostatic hydraulic actuator 2eq The error, z2 = y2-x 2eq ; ε2 is the compensation parameter of the first robust control rate; Δd1 is the external load force of the electro-hydrostatic actuator and the estimated value of the external load force of the electro-hydrostatic actuator The error between The preset speed x of the actuator rod of the electro-hydrostatic actuator 2eq as follows: x 2eq =x 1d -k1z1 z1=y1-x 1d Among them, x 1d is the preset displacement of the actuator rod of the electrostatic hydraulic actuator, k1 is the preset first feedback gain, z1 is the displacement measurement value y1 and x of the actuator rod of the electrostatic hydraulic actuator 1d is the error of the preset displacement; Set the preset displacement x of the actuator rod of the electro-hydraulic actuator 1d , preset speed x 2eq , displacement x L The measured value y1, speed The measured value y2 and the output force F of the electro-hydrostatic actuator l The measured value y3 is input into the backstepping controller, which then outputs the second backstepping method virtual control quantity w d .

2. The method for controlling disturbance compensation of an underwater electro-hydrostatic actuator according to claim 1, characterized in that: The seawater pressure compensator is specifically a rolling diaphragm pressure compensator.

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