Disclosure of Invention
The invention aims to provide an electro-hydraulic actuator and a control method thereof, which aim to improve the integration of the electro-hydraulic actuator, and the electro-hydraulic actuator is provided with a matched motion controller and a control algorithm so as to provide a highly integrated intelligent electro-hydraulic actuator.
In order to achieve the purpose, the invention provides the following scheme:
an electro-hydraulic actuator comprises a servo cylinder, a nozzle baffle servo valve, a force sensor, a displacement sensor and a motion controller;
an oil inlet bionic flow passage, a rodless cavity bionic flow passage, a rod cavity bionic flow passage and an oil return bionic flow passage are integrally arranged on the cylinder body of the servo cylinder;
the nozzle baffle servo valve is arranged outside a cylinder body of the servo cylinder;
an oil inlet of the nozzle baffle servo valve is communicated with an oil inlet pipeline through an oil inlet bionic flow passage; a first control oil port of the nozzle baffle servo valve is communicated with a rodless cavity of the servo cylinder through a rodless cavity bionic flow passage; a second control oil port of the nozzle baffle servo valve is communicated with a rod cavity of the servo cylinder through a rod cavity bionic flow passage, and an oil return port of the nozzle baffle servo valve is communicated with an oil tank through an oil return bionic flow passage;
the force sensor is arranged at the front end of a cylinder rod of the servo cylinder; the outer cylinder of the displacement sensor is fixed on the cylinder body of the servo cylinder, and the inner sleeve of the displacement sensor is fixedly connected with one side of the cylinder rod of the servo cylinder;
the force sensor and the displacement sensor are both connected with the motion controller, the force sensor is used for collecting a cylinder rod output value of the servo cylinder, and the displacement sensor is used for collecting a cylinder rod displacement value of the servo cylinder;
the motion controller is connected with the control end of the nozzle baffle servo valve and used for controlling the states of the first control oil port and the second control oil port of the nozzle baffle servo valve according to the cylinder rod output value and the cylinder rod displacement value so as to adjust the output displacement of the cylinder rod of the servo cylinder and enable the output displacement of the cylinder rod of the servo cylinder to be expected displacement.
Optionally, the servo cylinder comprises a cylinder body and a cylinder rod; a rod cavity and a rodless cavity are arranged in the cylinder body, and the cylinder rod is arranged in the rod cavity.
Optionally, the oil inlet bionic flow passage, the rodless cavity bionic flow passage, the rod cavity bionic flow passage and the oil return bionic flow passage are arranged on the cylinder body of the servo cylinder by adopting a laser melting manufacturing process.
Optionally, the electro-hydraulic actuator further comprises a filter element;
the filter element is arranged at an oil inlet of the nozzle baffle servo valve.
Optionally, the electro-hydraulic actuator further includes a first pressure sensor and a second pressure sensor, and the first pressure sensor and the second pressure sensor are respectively disposed in the rodless cavity and the rod cavity of the servo cylinder.
Optionally, the motion controller includes a position impedance control module and a state observation module;
the position impedance control module is used for adopting an impedance characteristic formula according to the output value of the cylinder rod
Calculating an impedance control outer ring position deviation signal Xe; wherein, F
LIndicating the cylinder rod output value, C
DIndicating desired damping of electrohydraulic actuator, K
DThe expected rigidity of the electro-hydraulic actuator is obtained, and s is a state variable; comparing the impedance control outer ring position deviation signals to obtain an expected position of a cylinder rod of the servo cylinder, and calculating a difference value between the expected position and a cylinder rod displacement value obtained through collection to serve as a position control inner ring deviation signal;
and the state observation module is used for correcting the position control inner ring deviation signal by adopting a state observation algorithm and controlling the states of the first control oil port and the second control oil port of the nozzle baffle control valve by using the corrected position control inner ring deviation signal.
A control method of an electro-hydraulic actuator, the control method comprising the steps of:
collecting a cylinder rod output value and a cylinder rod displacement value of a servo cylinder;
calculating an impedance control outer ring position deviation signal by adopting an impedance characteristic formula according to the cylinder rod output value;
comparing the impedance control outer ring position deviation signals to obtain an expected position of a cylinder rod of the servo cylinder, and calculating a difference value between the expected position and a cylinder rod displacement value obtained through collection to serve as a position control inner ring deviation signal;
and correcting the position control inner ring deviation signal by adopting a state observation algorithm, and controlling the states of a first control oil port and a second control oil port of the nozzle baffle control valve by using the corrected position control inner ring deviation signal.
Optionally, the impedance characteristic formula is:
wherein, XeRepresenting an impedance-controlled outer loop position deviation signal, FLIndicating the cylinder rod output value, CDIndicating desired damping of electrohydraulic actuator, KDS is the desired stiffness of the electro-hydraulic actuatorAnd (4) state variables.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides an electro-hydraulic actuator and a control method thereof, wherein the electro-hydraulic actuator comprises a servo cylinder, a nozzle baffle servo valve, a force sensor, a displacement sensor and a motion controller; an oil inlet bionic flow passage, a rodless cavity bionic flow passage, a rod cavity bionic flow passage and an oil return bionic flow passage are integrally arranged on the cylinder body of the servo cylinder; the invention realizes high-density integration of a plurality of components through the integrated arrangement of the servo cylinder, the nozzle baffle servo valve, the force sensor, the displacement sensor and the motion controller, has small volume and light weight, realizes the communication between the servo cylinder and the nozzle baffle servo valve by utilizing a bionic runner, does not need to arrange a connecting pipeline, realizes no external pipeline between the nozzle baffle servo valve and the servo cylinder, reduces the occurrence rate of damage and leakage faults of a pipeline joint of high-end mobile equipment, and realizes the control of the servo cylinder through the motion controller, the force sensor and the displacement sensor which are arranged in a matched way.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide an electro-hydraulic actuator and a control method thereof, which aim to improve the integration of the electro-hydraulic actuator, and the electro-hydraulic actuator is provided with a matched motion controller and a control algorithm so as to provide a highly integrated intelligent electro-hydraulic actuator.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the invention provides an electro-hydraulic actuator, which comprises a filter element 1, a nozzle baffle servo valve 2, a motion controller 3, a force sensor 4, a displacement sensor 5, a pressure sensor 6, a servo cylinder 7 and a bionic flow channel, wherein the bionic flow channel is integrated on a cylinder body of the servo cylinder 7 and is used for communicating the servo valve and the servo cylinder.
As shown in fig. 1, a nozzle baffle servo valve 2 and a motion controller 3 are fixedly arranged on the upper part of a cylinder body of a servo cylinder 7 in parallel through bolts, an inner sleeve of a displacement sensor 5 is fixedly connected with one side of a cylinder rod of the servo cylinder through a connecting plate, the other side of the top end of the cylinder rod of the servo cylinder 7 is connected with a force sensor 4, an outer cylinder of the displacement sensor 5 is fixed on the cylinder body of the servo cylinder 7 through two cylinder ring fixing pieces, a pressure sensor 6 is fixedly connected at the joint of one end of the cylinder body of the servo cylinder 7 and the nozzle baffle servo valve 2 through bolts, and a filter element 1 is fixedly connected in an oil inlet of the;
the motion controller is a motion controller which is independently developed and has small volume, light weight and better human-computer interaction interface, the controller takes a DSP as a core control chip to design the motion controller, a bottom layer driving module of the controller is created based on a TLC language of MATLAB, automatic generation of MATLAB/Simulink control codes is realized, seamless connection of software and hardware of a control method is facilitated, the value access efficiency of the control method is improved, and an upper computer debugging interface is developed based on Labview software.
The cylinder body structure of the servo cylinder of the electro-hydraulic actuator can be printed out in a lighter weight mode by utilizing the function of rapid prototype manufacturing of the 3D printing technology, and the 3D printing technology provides powerful technical support for manufacturing of the integrated electro-hydraulic actuator.
As shown in fig. 2, the servo cylinder is a single-rod hydraulic cylinder, a rodless cavity bionic flow passage 9 and a rod cavity bionic flow passage 11 are arranged on a cylinder body at the joint of the servo cylinder 7 and the nozzle baffle servo valve 2, and an oil inlet bionic flow passage 8 and an oil return bionic flow passage 10 are respectively arranged at the joint of the nozzle baffle servo valve 2, the filter element 1 and the oil return pipeline. The nozzle baffle servo valve is provided with an oil inlet P, a first control oil port A, a second control oil port B and an oil return port T.
As shown in fig. 3, the pressure sensor 6 is used for detecting the fluid pressure value of the flow passage between the nozzle flapper servo valve 2 and the servo cylinder 7, and the pressure sensor 6 converts the pressure value into a signal in the form of weak current to be transmitted to the motion controller 3; the displacement sensor 5 is used for detecting a real-time displacement value of a cylinder rod of the servo cylinder 7, and the displacement sensor 5 converts the displacement value of the cylinder rod into a weak voltage type signal which is amplified by the displacement amplification plate and then transmitted to the motion controller 3; the force sensor 4 is used for detecting a real-time output value of a cylinder rod of the servo cylinder 7, and the force sensor 4 converts the output value of the cylinder rod into a weak voltage form signal and transmits the weak voltage form signal to the motion controller 3 after the weak voltage form signal is amplified by the displacement amplification plate.
As shown in fig. 1-3, two pressure sensors 6 are respectively fixed on the left and right sides of a servo cylinder 7 of the electro-hydraulic actuator, namely, a first pressure sensor is arranged on the servo cylinder close to one side of a nozzle baffle servo valve, and a second pressure sensor is arranged on one side of a cylinder cover of the servo cylinder and is used for detecting the oil pressure of two cavities of the servo cylinder; the force sensor 4 is fixedly arranged at the top end of the cylinder rod of the servo cylinder 7 and is used for detecting a real-time force output value of the cylinder rod of the servo cylinder 7; the fixed part of the displacement sensor 5 is fixed on one side of the cylinder body of the servo cylinder 7 through two cylinder ring fixing pieces, and the top end of the cylinder rod of the servo cylinder 7 is connected with the moving part of the displacement sensor 5 through a connecting plate and used for detecting the real-time displacement value of the cylinder rod of the servo cylinder 7.
The motion controller comprises a position impedance control module and a state observation module; the position impedance control module is used for adopting an impedance characteristic formula according to the output value of the cylinder rod
Calculating an impedance control outer loop position deviation signal X
e(ii) a Wherein, F
LIndicating the cylinder rod output value, C
DIndicating desired damping of electrohydraulic actuator, K
DThe expected rigidity of the electro-hydraulic actuator is obtained, and s is a state variable; comparing the impedance control outer ring position deviation signals to obtain an expected position of a cylinder rod of the servo cylinder, and calculating a difference value between the expected position and a cylinder rod displacement value obtained through collection to serve as a position control inner ring deviation signal; and the state observation module is used for correcting the position control inner ring deviation signal by adopting a state observation algorithm and controlling the states of the first control oil port and the second control oil port of the nozzle baffle control valve by using the corrected position control inner ring deviation signal.
Specifically, as shown in fig. 3-5, the motion controller 3 includes a state observation module and a position impedance control module, the motion controller 3 calculates a state quantity change characteristic through a position impedance control algorithm according to signals such as a pressure displacement load force detected by a sensor, so as to realize online correction of control parameters in the motion controller, so as to improve control robustness of the integrated electro-hydraulic actuator under the conditions of displacement, speed, load and two-cavity pressure change, the motion controller 3 is used by matching the state observation module, the position impedance control module and a multi-sensor detection element, the state quantity of the dynamic process of the integrated electro-hydraulic actuator can be detected in real time, the control parameters in the motion controller are corrected online by using a position impedance control method, and the control performance of the integrated electro-hydraulic actuator is improved.
The invention also provides a control method of the electro-hydraulic actuator. The control method of the invention has the following working procedures:
step 1: the force sensor acquires a force output value F of a cylinder rod of the servo cylinderLData; the displacement sensor acquires a displacement value X of a cylinder rod of the servo cylinderPAnd (4) data.
Step 2: the output value F collected in the
step 1 is processed
LData passing impedance characteristic formula
The position deviation signal X in the impedance control outer ring can be obtained after calculation
eData and control the impedance by an outer loop position deviation signal X
eThe data is processed by a comparator to obtain the expected position X of the cylinder rod of the servo cylinder
dData; in the formula: x
eIs the impedance position deviation (m), F
LThe external load force (N) (the collected output force value), C
DDesired damping (N.s/m), K for the system
DIs the desired stiffness of the system (N/m). Further using the displacement value X collected in
step 1
PThe data is amplified and biased by a displacement amplifying plate and a comparator to obtain a position control inner ring bias signal X
d-X
PAnd (4) data.
And step 3: for the position control inner ring deviation signal X obtained in the step 2
d-X
PThe data is observed by the state observation module in the motion controller and adopts the state observation algorithm
After correction, where X ═ X
d-X
PAnd the corrected inner ring deviation signal y outputs a feedback control voltage signal from the nozzle baffle servo valve amplification plate to control the corresponding opening and closing of a PTAB port of the nozzle baffle servo valve, so that the output displacement of a cylinder rod of the servo cylinder is adjusted, and the joint driving of the foot robot is realized. In the formula: a is the system state matrix and B is the system input momentAnd C is a system output matrix, G is a state observer output error feedback matrix, x 'is a state vector of the state observer, is an estimated value of x, and y' is an output vector of the state observer and is an estimated value of y.
The working process of the electro-hydraulic actuator is as follows:
(1) electrohydraulic actuator extension movement
Oil inlet: oil flows to the nozzle baffle servo valve 2 through the filter element 1 through the oil inlet bionic flow passage 8, then flows into the nozzle baffle servo valve 2 through an oil inlet of the nozzle baffle servo valve, flows out of the nozzle baffle servo valve 2 through a first control oil A port of the nozzle baffle servo valve, enters a rodless cavity bionic flow passage 9 between the nozzle baffle servo valve 2 and the servo cylinder 7, and then enters a rodless cavity of a servo cylinder body through the rodless cavity bionic flow passage 9.
Oil return: the oil liquid flows out from a rod cavity of the servo cylinder 7, flows to a second control oil port B of the nozzle baffle servo valve 2 through a rod cavity bionic runner 11 of the servo cylinder 7 and the nozzle baffle servo valve 2, flows into the nozzle baffle servo valve 2 through a second control oil port B of the nozzle baffle servo valve, flows out of the nozzle baffle servo valve 2 through an oil return port T of the nozzle baffle servo valve, and flows back to an oil tank through an oil return bionic runner 10 to complete the stretching motion of the integrated intelligent electro-hydraulic actuator.
(2) An electro-hydraulic actuator retracting movement
Oil inlet: the system oil flows in through the bionic oil inlet flow channel 8 on the oil inlet pipeline, flows to the nozzle baffle servo valve 2 through the filter element 1, flows into the nozzle baffle servo valve through an oil inlet P port of the nozzle baffle servo valve, flows out of the nozzle baffle servo valve 2 through a second control oil port B port of the nozzle baffle servo valve, enters the bionic rod cavity flow channel 11 between the nozzle baffle servo valve 2 and the servo cylinder 7, and enters the rod cavity of the servo cylinder body through the bionic rod cavity flow channel 11.
Oil return: the oil liquid flows out from a rodless cavity of the servo cylinder 7, flows to a first control oil port A of the nozzle baffle servo valve 2 through a rodless cavity bionic runner 9 of the servo cylinder 7 and the nozzle baffle servo valve 2, flows into the nozzle baffle servo valve 2 through a first control oil port A of the nozzle baffle servo valve, flows out of the nozzle baffle servo valve 2 through an oil return port T of the nozzle baffle servo valve, and flows back to an oil tank through an oil return bionic runner 10 to complete the retraction motion of the integrated intelligent electro-hydraulic actuator.
Compared with the prior art, the invention has the beneficial effects that:
1. the electro-hydraulic actuator realizes high-density integration of multiple elements, has small volume and light weight, has no external pipeline between the servo valve and the servo cylinder, reduces the occurrence rate of damage and leakage faults of a pipeline joint of high-end mobile equipment, and improves the dynamic response of movement. The performance requirement of high-end mobile equipment is met to a certain extent, and the device can be widely applied to engineering machinery, metallurgical machinery, aircrafts, power-assisted exoskeletons and robots.
2. The autonomously developed motion controller matched with the electro-hydraulic actuator is small in size, light in weight and better in man-machine interaction interface, realizes automatic generation of MATLAB/Simulink control codes, facilitates seamless connection of software and hardware of a control method, and improves the value-in efficiency of the control method.
3. By applying the electro-hydraulic servo control theory, the modern control theory and the theoretical thought and method of a linear system, the artificial intelligence control theory is fused, the state quantity of the dynamic process of the integrated electro-hydraulic actuator can be detected in real time by designing a state observation module, a state feedback control module and a multi-sensing detection element in the motion controller, and the control parameter in the controller is corrected on line by adopting state feedback, so that the control performance of the integrated electro-hydraulic actuator is improved.
The equivalent embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts between the equivalent embodiments can be referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In summary, this summary should not be construed to limit the present invention.