Valve control cylinder high-precision force control method based on elastic modulus modeling

Abstract

The invention discloses a valve control cylinder high-precision force control method based on elastic modulus modeling. The method comprises the following steps: establishing an elastic modulus-based dynamic model of the valve-controlled cylinder, and further designing a robust force controller of the valve-controlled cylinder, wherein the robust force controller comprises a feedforward model compensation item, a nonlinear robust control item and a linear stability feedback item; the expected total pressure of the valve-controlled cylinder and the displacement of the piston rod are input into a robust force controller to be processed to obtain a valve control voltage signal, voltage flow mapping is carried out to obtain a valve control flow signal, then the contact force of the piston rod of the valve-controlled cylinder and the external environment is controlled, and high-precision force control of the valve-controlled cylinder is achieved. According to the method, the high-precision force control performance of the valve control cylinder under various pressure conditions can be achieved, and the force tracking precision and robustness under complex working conditions are improved.

Description

Technical Field

[0001] The present invention relates to a valve-controlled cylinder control method, and in particular to a high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling. Background Art

[0002] As the core power execution unit of industrial equipment, the dynamic control accuracy of the output force of the valve-controlled hydraulic cylinder system directly affects the precise calibration of underwater instruments, high-pressure environment simulation, precision injection molding, aerospace actuators, intelligent engineering machinery and other high-end equipment fields. Traditional force control methods are subject to the time-varying characteristics of the elastic modulus of hydraulic oil, the nonlinear flow characteristics of the valve port and the coupling of multiple physical fields, and there are significant control deviations under complex working conditions such as variable loads. In the existing technology, the proportional-integral-derivative (PID) control strategy based on a fixed parameter model is difficult to adapt to the dynamic characteristics of the elastic modulus changing with pressure, resulting in inaccurate estimation of the system stiffness; the force control method using feedforward compensation does not establish a mapping relationship between the elastic modulus and the dynamic characteristics of the system, and the compensation efficiency is significantly reduced when the parameters are perturbed, which restricts the force tracking accuracy and robustness improvement of the system under complex working conditions. Summary of the Invention

[0003] In order to solve the problems existing in the background technology, the present invention provides a high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling.

[0004] The technical solution adopted in the present invention is:

[0005] The high-precision force control method of a valve-controlled cylinder based on elastic modulus modeling of the present invention comprises:

[0006] First, a dynamic model of a valve-controlled cylinder based on the elastic modulus is established. Based on this dynamic model, a robust force controller for the valve-controlled cylinder is designed, which includes a feedforward model compensation term, a nonlinear robust control term, and a linear stable feedback term. The desired total pressure of the valve-controlled cylinder, as well as the actual intracavity pressure and piston rod displacement after filtering, are input into the feedforward model compensation term to obtain the feedforward model compensation part. The desired pressure difference of the valve-controlled cylinder is input into the nonlinear robust control term and the linear stable feedback term in real time, and the nonlinear feedback part and the linear stable feedback part are output. The valve control voltage signal of the valve-controlled cylinder is obtained based on the feedforward model compensation, nonlinear feedback, and linear stable feedback parts. After voltage-flow mapping, the valve control flow signal is obtained, and the contact force between the piston rod of the valve-controlled cylinder and the external environment is controlled to achieve high-precision force control of the valve-controlled cylinder. During control, the valve-controlled cylinder outputs the actual total pressure, actual intracavity pressure, and piston rod displacement in real time. The desired pressure difference is obtained based on the actual total pressure, and then the next step of high-precision force control of the valve-controlled cylinder is carried out to achieve closed-loop force control.

[0007] The valve-controlled cylinder dynamics model based on elastic modulus is specifically as follows:

[0008]

[0009] Among them, F and They represent the active input force of the valve-controlled cylinder and its derivative, F d Indicates the expected output force of the valve-controlled cylinder, F d =A·p d , A represents the output force contact surface area of ​​the valve-controlled cylinder, p and p d Respectively represent the total pressure of the valve-controlled cylinder and its expected total pressure; A u 、B u 、C u 、X u and Y u represent the first, second, third, fourth and fifth intermediate quantities respectively; and They represent the first and second derivatives of the displacement of the piston rod respectively; u represents the actual voltage of the valve-controlled cylinder; A1 and A2 represent the force application area of ​​the rodless cavity and the rod cavity of the valve-controlled cylinder respectively, and p1 and Represent the pressure of the rodless chamber of the valve-controlled cylinder and its derivative, p2 and Respectively represent the pressure of the rod chamber of the valve-controlled cylinder and its derivative, V1 and V2 represent the volume of the rodless chamber and the rod chamber of the valve-controlled cylinder, q1 and q2 represent the flow rate of the rodless chamber and the rod chamber of the valve-controlled cylinder, respectively; E oe ( ) and ΔE oe ( ) represent the effective bulk elastic modulus of the hydraulic oil and its bounded deviation value, that is, the actual value can deviate from the standard value, but will never exceed a certain fixed range; E on ( ) represents the effective bulk elastic modulus E of the hydraulic oil oe ( ) slowly changing nominal value, that is, a certain standard value or normal value slowly changes slightly over a long period of time; K t represents the valve flow gain coefficient; s( ) represents the smooth transition function; p s and p r Respectively represent the oil supply pressure and the pressure when the hydraulic oil returns to the tank; C ip and C ipn They represent the amount of hydraulic oil leakage and its slowly changing nominal value, that is, a certain standard value or normal value slowly changes slightly over a long period of time, ΔC ip Indicates the amount of hydraulic oil leakage C ip The bounded deviation value of ΔD means that the actual value can deviate from the standard value, but it will never exceed a certain fixed range; 21 and ΔD 22represents the first and second model uncertainties; m represents the piston rod mass of the valve-controlled cylinder; f n sgn( ) represents Coulomb friction; D 1n represents the nominal value of the slow change produced by the dynamic model of the valve-controlled cylinder, ΔD1 represents the model error; Ω D Represents the set of model uncertainty and model error, here is about ΔD j The set of ΔD that satisfies specific conditions can be understood as j The set of all possible values ​​of ; D1 , δ D21 and δ D22 Represent the model error ΔD1, the first model uncertainty term ΔD 21 and the second model uncertainty term ΔD 22 All uncertainties are bounded in real scenarios.

[0010] The hydraulic oil effective bulk elastic modulus E oe ( ) and the nominal value E of the slow change of the effective bulk elastic modulus of the hydraulic oil on ( ) The details are as follows:

[0011] E oe (y) = E on (y)+ΔE oe (y)

[0012] E on (y) = ab·exp(-cy)

[0013] Where y represents the input quantity; a, b, and c represent the first, second, and third fitting parameters, respectively.

[0014] Before the valve-controlled cylinder dynamics model is established, the dynamic mapping relationship between the elastic modulus of the hydraulic oil and the pressure is first established. Specifically, the relationship between the elastic modulus and the pressure is fitted by an exponential function.

[0015] The feedforward model compensation term is as follows:

[0016]

[0017] Among them, u da represents the compensation part of the feedforward model; represents the third derivative of the displacement x of the piston rod; represents the desired total pressure p of the valve-controlled cylinder d The derivative of .

[0018] The actual cavity pressure includes the pressure of the rodless cavity and the rod cavity of the valve-controlled cylinder; the pressure of the rodless cavity and the rod cavity of the valve-controlled cylinder and the displacement of the piston rod input into the feedforward model compensation term are all filtered values.

[0019] The nonlinear robust control term is specifically as follows:

[0020] zu ds2 ≤0,

[0021]

[0022] z=pp d

[0023] Where z represents the expected pressure difference of the valve-controlled cylinder; u ds2 represents the nonlinear feedback part; ΔD1 represents the model error; ε represents an arbitrarily small constant coefficient; p and p d Represent the actual total pressure and expected total pressure of the valve-controlled cylinder respectively.

[0024] The linear stability feedback term is as follows:

[0025] u ds1 =-kz

[0026] Among them, u ds1 represents the linear stable feedback part; k represents the positive stable feedback gain; z represents the expected pressure difference of the valve-controlled cylinder.

[0027] The valve control voltage signal u of the valve-controlled cylinder d The details are as follows:

[0028] u d =u da +u ds1 +u ds2

[0029] Among them, u da 、u ds1 and u ds2 They represent the feedforward model compensation part, the linear stability feedback part and the nonlinear feedback part respectively.

[0030] Through the valve control voltage signal u d Control the actual voltage u of the valve-controlled cylinder; control the flow rate flowing into the rodless chamber and the rod chamber of the valve-controlled cylinder through the valve control flow signal.

[0031] The beneficial effects of the present invention are:

[0032] The method of the present invention enables the valve-controlled cylinder to achieve high-precision force control performance under various pressure conditions, and improves the force tracking accuracy and robustness under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a control block diagram of the present invention;

[0034] Figure 2 This is a specialized design diagram of a valve-controlled cylinder when the present invention is implemented;

[0035] Figure 3 It is a graph of the change of elastic modulus of a certain type of hydraulic oil with pressure using an exponential function fitted in a specific embodiment of the present invention;

[0036] Figure 4 is a reference trajectory curve diagram of the experimental setting when the present invention is implemented, wherein, Figure 4 (a) is a pressure curve diagram of the experimental setting when the present invention is implemented, Figure 4 (b) is a first-order pressure change rate curve diagram of the experimental setting when the present invention is implemented. Figure 4 (c) is a graph showing the second-order rate of change of pressure in the experimental setting during the specific implementation of the present invention. Figure 4 (d) is a graph of the third-order rate of change of pressure in the experimental setting during the specific implementation of the present invention;

[0037] Figure 5 is a reference trajectory tracking error curve diagram when the present invention is specifically implemented;

[0038] Figure 6 It is an enlarged view of the reference trajectory tracking error curve during the specific implementation of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1 As shown, the high-precision force control method of the valve-controlled cylinder based on elastic modulus modeling of the present invention is specifically as follows:

[0041] First, a valve-controlled cylinder dynamic model based on elastic modulus is established as follows:

[0042]

[0043] F=A1p1-A2p2

[0044]

[0045] The voltage-flow mapping is as follows:

[0046]

[0047] Among them, F and They represent the active input force of the valve-controlled cylinder and its derivative, F d Indicates the expected output force of the valve-controlled cylinder, F d =A·p d , A represents the output force contact surface area of ​​the valve-controlled cylinder, p and p dRespectively represent the total pressure of the valve-controlled cylinder and its expected total pressure; A u 、B u 、C u 、X u and Y u represent the first, second, third, fourth and fifth intermediate quantities respectively; and They represent the first and second derivatives of the displacement of the piston rod respectively; u represents the actual voltage of the valve-controlled cylinder; A1 and A2 represent the force application area of ​​the rodless cavity and the rod cavity of the valve-controlled cylinder respectively, and p1 and Represent the pressure of the rodless chamber of the valve-controlled cylinder and its derivative, p2 and They represent the pressure of the rod chamber of the valve-controlled cylinder and its derivative respectively. The pressure value is collected in real time by the pressure sensor installed on the valve-controlled cylinder. V1 and V2 represent the volume of the rodless chamber and the rod chamber of the valve-controlled cylinder respectively. q1 and q2 represent the flow rate flowing into the rodless chamber and the rod chamber of the valve-controlled cylinder respectively. E oe ( ) and ΔE oe ( ) represent the effective bulk elastic modulus of the hydraulic oil and its bounded deviation value, that is, the actual value can deviate from the standard value, but will never exceed a certain fixed range; E on ( ) represents the effective bulk elastic modulus E of the hydraulic oil oe ( ) slowly changing nominal value, that is, a certain standard value or normal value slowly changes slightly over a long period of time; K t represents the valve flow gain coefficient; s( ) represents the smooth transition function, s(·)=atan(600·); p s and p r Respectively represent the oil supply pressure and the pressure when the hydraulic oil returns to the tank; C ip and C ipn They represent the amount of hydraulic oil leakage and its slowly changing nominal value, that is, a certain standard value or normal value slowly changes slightly over a long period of time, ΔC ip Indicates the amount of hydraulic oil leakage C ip The bounded deviation value of ΔD means that the actual value can deviate from the standard value, but it will never exceed a certain fixed range; 21 and ΔD 22 represents the first and second model uncertainties; m represents the piston rod mass of the valve-controlled cylinder; f n sgn( ) represents the Coulomb friction force, which should be modeled as However, considering the requirements of the subsequent controller design for the differentiability and continuity of the equation, it is replaced by a smooth transition function s( ); D 1n represents the nominal value of the slow change produced by the dynamic model of the valve-controlled cylinder, ΔD1 represents the model error; Ω D Represents the set of model uncertainty and model error, here is about ΔDj The set of ΔD that satisfies specific conditions can be understood as j The set of all possible values ​​of ; D1 , δ D21 and δ D22 Represent the model error ΔD1, the first model uncertainty term ΔD 21 and the second model uncertainty term ΔD 22 All uncertainties are bounded in real scenarios.

[0048] Hydraulic oil effective bulk elastic modulus E oe ( ) and the nominal value E of the slow change of the effective bulk elastic modulus of the hydraulic oil on ( ) The details are as follows:

[0049] E oe (y) = E on (y)+ΔE oe (y)

[0050] E on (y) = ab·exp(-cy)

[0051] Where y represents the input quantity; a, b, and c represent the first, second, and third fitting parameters, respectively.

[0052] Before the valve-controlled cylinder dynamics model is established, the dynamic mapping relationship between the elastic modulus of the hydraulic oil and the pressure is first established. Specifically, the relationship between the elastic modulus and the pressure is fitted by an exponential function.

[0053] Based on the dynamic model of the valve-controlled cylinder, a robust force controller of the valve-controlled cylinder is designed, which includes a feedforward model compensation term, a nonlinear robust control term, and a linear stable feedback term. The feedforward model compensation term is as follows:

[0054]

[0055] Among them, u da represents the compensation part of the feedforward model; represents the third derivative of the displacement x of the piston rod; represents the desired total pressure p of the valve-controlled cylinder d The derivative of .

[0056] The actual cavity pressure includes the pressure of the rodless cavity and the rod cavity of the valve-controlled cylinder; the pressure of the rodless cavity and the rod cavity of the valve-controlled cylinder and the displacement of the piston rod input into the feedforward model compensation term are all filtered values.

[0057] The nonlinear robust control terms are as follows:

[0058] zu ds2 ≤0,

[0059]

[0060] z=pp d

[0061]

[0062] Where z represents the expected pressure difference of the valve-controlled cylinder, The derivative of the expected pressure difference of the valve-controlled cylinder; u ds2 represents the nonlinear feedback part; ΔD1 represents the model error; ε represents an arbitrarily small constant coefficient; p and p d Represent the actual total pressure and expected total pressure of the valve-controlled cylinder respectively.

[0063] The linear stabilization feedback term is as follows:

[0064] u ds1 =-kz

[0065] Among them, u ds1 represents the linear stable feedback part; k represents the positive stable feedback gain; z represents the expected pressure difference of the valve-controlled cylinder.

[0066] The expected total pressure of the valve-controlled cylinder, the actual intracavity pressure after filter processing, and the displacement of the piston rod are input into the feedforward model compensation term to obtain the feedforward model compensation part. The filter is specifically selected as a second-order bandpass filter. The expected pressure difference of the valve-controlled cylinder is input into the nonlinear robust control term and the linear stable feedback term in real time, and the nonlinear feedback part and the linear stable feedback part are output after processing. The valve control voltage signal u of the valve-controlled cylinder is obtained according to the feedforward model compensation part, the nonlinear feedback part and the linear stable feedback part. d ,as follows:

[0067] u d =u da +u ds1 +u ds2

[0068] Among them, u da 、u ds1 and u ds2 They represent the feedforward model compensation part, the linear stability feedback part and the nonlinear feedback part respectively.

[0069] After voltage-flow mapping, the valve control flow signal is obtained to control the contact force between the piston rod of the valve control cylinder and the external environment. dControl the actual voltage u of the valve-controlled cylinder; control the flow rate into the rodless chamber and the rod chamber of the valve-controlled cylinder through the valve control flow signal to achieve high-precision force control of the valve-controlled cylinder. During control, the valve-controlled cylinder outputs the actual total pressure, the actual cavity pressure and the displacement of the piston rod in real time, and obtains the expected pressure difference based on the actual total pressure, and continues to the next step of high-precision force control of the valve-controlled cylinder to achieve force closed-loop control.

[0070] The present invention constructs the feedforward model compensation term based on the elastic modulus modeling of the hydraulic oil, realizes the system voltage design through the linear stable feedback term and the nonlinear robust feedback term, and realizes high-precision force control, which is equivalent to the pressure control of this special system. The hydraulic system used in the specific implementation of the present invention is an electro-hydraulic actuator. The output force of the hydraulic cylinder of this special structure causes the water pressure of the controlled system to change according to the desired trajectory, and the force closed-loop control is realized through the pressure sensor. Figure 2 As shown, in the specific implementation of the present invention, chambers 1 and 2 of the electro-hydraulic actuator are connected to the valve, chamber 3 is connected to the air, and chamber 4 is connected to a high-pressure tank filled with water. The valve is used to control the inflow and outflow of hydraulic oil to achieve high-precision force control.

[0071] like Figure 3 The figure below shows the curve of the elastic modulus of a certain type of hydraulic oil fitting with pressure using an exponential function proposed in a specific embodiment of the present invention. B0 represents the data measured in an experiment with a certain type of hydraulic oil. It can be seen that at low pressures, the effective bulk modulus varies greatly with pressure. At high pressures, the variation gradually becomes stable. Among them, B1 represents the exponential function fitting method proposed in the present invention, and B2 represents the piecewise function fitting method. The maximum, average, and standard error values ​​of the fitting results for the exponential function fitting method B1 and the piecewise function fitting method B2 are shown in Table 1 below:

[0072] Table 1

[0073]

[0074] From the perspective of maximum error, the fitting effect of B1 is 1 / 7 of that of B2. From the perspective of average error, the fitting effect of B1 is 1 / 6600 of that of B2. From the perspective of standard error, the fitting effect of B1 is 1 / 3 of that of B2. The B1 proposed in this paper has a much better fitting effect than B2.

[0075] like Figure 4 (a) Figure 4 (b) Figure 4 (c) and Figure 4 As shown in (d), it is a reference trajectory curve diagram for the specific implementation of the present invention, including four groups of pressure p, pressure first-order change rate pdot, pressure second-order change rate pdotdot and pressure third-order change rate pdotdotdot, for specific experiments. Figure 5As shown in FIG, the reference trajectory tracking error curve of the specific implementation of the present invention is shown. C1 is to track the desired trajectory by using PID control, C2 is to model the elastic modulus by using the exponential function fitting method B1 to track the desired trajectory, that is, the method of the present invention, C3 is to track the desired trajectory by fixing the elastic modulus to a value, and C4 is to model the elastic modulus by using the piecewise function fitting method B2 to track the desired trajectory. Figure 6 The figure below is an enlarged view of the reference trajectory tracking error curve during implementation. Because the pressure errors corresponding to C2, C3, and C4 are much smaller than those for C1, they are plotted separately. The evaluation results for C1, C2, C3, and C4 are shown in Table 2 below.

[0076] Table 2

[0077]

[0078] As can be seen, from the perspective of maximum error, the C2 maximum error is the smallest among the four data sets, at only 1.2513e-5. From the perspective of average error, the C2 average error is the smallest among the four data sets, at only 8.2738e-10. From the perspective of standard error, the C2 standard error is the smallest among the four data sets, at only 9.4174e-6. Therefore, the C2 control proposed in this paper has the best effect.

[0079] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling, characterized in that: include: Firstly, a dynamic model of the valve-controlled cylinder based on the elastic modulus is established. Based on the dynamic model, a robust force controller of the valve-controlled cylinder is designed, which includes a feedforward model compensation term, a nonlinear robust control term, and a linear stability feedback term. The expected total pressure of the valve-controlled cylinder and the actual intra-cavity pressure and displacement of the piston rod after filter processing are input into the feedforward model compensation item for processing to obtain the feedforward model compensation part. The expected pressure difference of the valve-controlled cylinder is input into the nonlinear robust control item and the linear stable feedback item in real time, and the nonlinear feedback part and the linear stable feedback part are output after processing. The valve control voltage signal of the valve-controlled cylinder is obtained according to the feedforward model compensation part, the nonlinear feedback part and the linear stable feedback part. The valve control flow signal is obtained after voltage-flow mapping, and then the contact force between the piston rod of the valve-controlled cylinder and the external environment is controlled to realize high-precision force control of the valve-controlled cylinder. During control, the valve-controlled cylinder outputs the actual total pressure, the actual intra-cavity pressure and the displacement of the piston rod in real time. The expected pressure difference is obtained according to the actual total pressure, and the next step of high-precision force control of the valve-controlled cylinder is continued to realize force closed-loop control.

2. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 1 is characterized in that: The valve-controlled cylinder dynamics model based on elastic modulus is specifically as follows: Among them, F and They represent the active input force of the valve-controlled cylinder and its derivative, F d Indicates the expected output force of the valve-controlled cylinder, F d =A·p d , A represents the output force contact surface area of ​​the valve-controlled cylinder, p and p d Respectively represent the total pressure of the valve-controlled cylinder and its expected total pressure; A u 、B u 、C u 、X u and Y u represent the first, second, third, fourth and fifth intermediate quantities respectively; and They represent the first and second order derivatives of the displacement of the piston rod respectively; u represents the actual voltage of the valve-controlled cylinder; A1 and A2 represent the force action area of ​​the rodless cavity and the rod cavity of the valve-controlled cylinder respectively; p1 and p1 represent the pressure of the rodless cavity of the valve-controlled cylinder and its derivative respectively; p2 and Respectively represent the pressure of the rod chamber of the valve-controlled cylinder and its derivative, V1 and V2 represent the volume of the rodless chamber and the rod chamber of the valve-controlled cylinder, q1 and q2 represent the flow rate of the rodless chamber and the rod chamber of the valve-controlled cylinder, respectively; E oe () and ΔE oe () represent the effective bulk elastic modulus of hydraulic oil and its bounded deviation value, E on () represents the effective bulk elastic modulus E of the hydraulic oil oe () slowly changing nominal value; K t represents the valve flow gain coefficient; s() represents the smooth transition function; p s and p r Respectively represent the oil supply pressure and the pressure when the hydraulic oil returns to the tank; C ip and C ipn They represent the nominal value of hydraulic oil leakage and its slow change, ΔC ip Indicates the amount of hydraulic oil leakage C ip The bounded deviation value of ΔD 21 and ΔD 22 represents the first and second model uncertainties; m represents the piston rod mass of the valve-controlled cylinder; f n sgn() represents Coulomb friction; D 1n represents the nominal value of the slow change produced by the dynamic model of the valve-controlled cylinder, ΔD1 represents the model error; Ω D represents the set of model uncertainty and model error; δ D1 , δ D21 and δ D22 Represent the model error ΔD1, the first model uncertainty term ΔD 21 and the second model uncertainty term ΔD 22 The threshold or limit value.

3. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 2 is characterized in that: The hydraulic oil effective bulk elastic modulus E oe () and the nominal value of the slow change of the effective bulk elastic modulus of the hydraulic oil E on () The details are as follows: E oe (y)=E on (y)+ΔE oe (y) E on (y)=a-b·exp(-cy) Where y represents the input quantity; a, b, and c represent the first, second, and third fitting parameters, respectively.

4. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 2 is characterized in that: The feedforward model compensation term is as follows: Among them, u da Represents the compensation part of the feedforward model; represents the third-order derivative of the displacement x of the piston rod; represents the desired total pressure p of the valve-controlled cylinder d The derivative of The actual cavity pressure includes the pressure of the rodless cavity and the rod cavity of the valve-controlled cylinder.

5. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 2 is characterized in that: The nonlinear robust control term is specifically as follows: to ds2 ≤0, z=p-p d Where z represents the expected pressure difference of the valve-controlled cylinder; u ds2 represents the nonlinear feedback part; ΔD1 represents the model error; ε represents the constant coefficient; p and p d Represent the actual total pressure and expected total pressure of the valve-controlled cylinder respectively.

6. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 1 is characterized in that: The linear stability feedback term is as follows: u ds1 =-kz Among them, u ds1 represents the linear stable feedback part; k represents the positive stable feedback gain; z represents the expected pressure difference of the valve-controlled cylinder.

7. The high-precision force control method for a valve-controlled cylinder based on elastic modulus modeling according to claim 1 is characterized in that: The valve control voltage signal u of the valve-controlled cylinder d The details are as follows: in d =in da +in ds1 +in ds2 Among them, u da 、u ds1 and u ds2 They represent the compensation part of the feedforward model, the linear stable feedback part and the nonlinear feedback part respectively; Through the valve control voltage signal u d Control the actual voltage u of the valve-controlled cylinder; control the flow rate flowing into the rodless chamber and the rod chamber of the valve-controlled cylinder through the valve control flow signal.

Images