Single-leg hydraulic power-assisted exoskeleton control method, control device and exoskeleton under heavy load

Abstract

The present application relates to a kind of heavy load under single leg hydraulic power exoskeleton control method, control device and exoskeleton.The heavy load under single leg hydraulic power exoskeleton control method includes the desired flow α of the rod cavity of the hydraulic cylinder in each joint 2p , the desired flow Q of the rod cavity 1m , carries out the pump valve flow distribution of each joint, and then obtains the control voltage of the variable speed pump and servo valve corresponding to each joint, controls the action of single leg hydraulic power exoskeleton;The method of pump valve flow distribution includes determining the control voltage of the variable speed pump corresponding to hydraulic cylinder i and determining the control voltage of the servo valve corresponding to hydraulic cylinder i, according to control voltage, pump control part and valve control part are controlled.The heavy load under single leg hydraulic power exoskeleton control method, flow distribution uses the scheme that pump provides low frequency flow, and valve provides high frequency flow, solves the difficult problem of flow distribution caused by the compressibility of oil under heavy load, and reduces the system energy consumption under heavy load.

Description

Technical Field

[0001] The present invention relates to the technical field of exoskeletons, and in particular to a control method, a control device and an exoskeleton for a single-leg hydraulically assisted exoskeleton under heavy load. Background Art

[0002] A wearable lower-limb assisted exoskeleton is a human-machine integrated device that enhances the wearer's load-bearing capacity and can be used in emergency rescue, defense, and other fields. Hydraulic actuators, with their high output force and torque, and high power-to-weight ratio, are ideally suited for compact, heavy-duty systems like these. In an assisted exoskeleton system, reducing human-machine forces allows the exoskeleton to accurately track human movement, allowing the wearer to effortlessly carry loads. Therefore, the design of a high-precision human-machine force control algorithm is crucial for achieving the exoskeleton's assisted function. On the other hand, the energy supply system for a lower-limb assisted exoskeleton must be portable, and energy sources are very limited. To ensure a long operating time, system energy efficiency is also crucial. Achieving both high-precision and high-efficiency control of a lower-limb hydraulic assisted exoskeleton is a key technology for improving exoskeleton performance.

[0003] Achieving high-precision, high-energy-efficiency control of hydraulic exoskeletons requires addressing two key issues. The first is the design of a high-precision, high-energy-efficiency electro-hydraulic system for the hydraulic exoskeleton. Conventional electro-hydraulic systems for lower-limb hydraulic-assisted exoskeletons often utilize valve-controlled systems. However, due to throttling and overflow losses, these systems exhibit low energy efficiency. The second challenge is designing a corresponding high-precision, high-energy-efficiency control algorithm for the exoskeleton based on the selected electro-hydraulic system. Existing control methods for hydraulic-assisted exoskeletons focus on addressing the inherent strong coupling, high-order nonlinearities, and modeling uncertainty inherent in hydraulic exoskeleton systems. These methods only achieve high-precision force control without considering energy consumption, resulting in high system energy consumption. Furthermore, the compressibility of hydraulic oil, particularly under heavy loads, cannot be ignored, which complicates flow distribution within the pump and valve systems. Summary of the Invention

[0004] Based on this, it is necessary to provide a single-leg hydraulic assisted exoskeleton control method, control device and exoskeleton under heavy load to address the problem that under heavy load, the hydraulic oil has oil compressibility, which makes it difficult to distribute the flow of the pump valve.

[0005] A method for controlling a single-leg hydraulically assisted exoskeleton under heavy loads is disclosed. The three hydraulic systems of the exoskeleton's ankle, knee, and hip joints all employ parallel pump-valve coordinated electro-hydraulic systems. Each parallel pump-valve coordinated electro-hydraulic system comprises a parallel coordinated pump control section and a valve control section. The pump control section comprises a variable speed pump and two switch valves SV1 and SV2 that determine the flow direction of the variable speed pump outlet. The valve control section comprises four servo valves PV1, PV2, PV3, and PV4. The desired flow rate α of the rod chamber of the hydraulic cylinder in each joint is determined based on the desired flow rate α of the rod chamber.2p , rodless cavity expected flow Q 1m , distribute the pump and valve flow of each joint, and then obtain the control voltage of the variable speed pump and servo valve corresponding to each joint to control the movement of the single-leg hydraulic power-assisted exoskeleton;

[0006] The method for distributing pump and valve flow includes determining a control voltage u of a variable speed pump corresponding to a hydraulic cylinder i. pi and determine the control voltage u of the servo valve corresponding to the hydraulic cylinder i pv1i ,u pv2i ,u pv3i ,u pv4i , the pump control part and the valve control part are controlled according to the control voltage;

[0007] Among them, determine the control voltage u of the variable speed pump corresponding to the hydraulic cylinder i pi The method comprises the following steps:

[0008] Determine whether the variable speed pump provides flow to the rodless chamber of hydraulic cylinder i or the rod chamber of hydraulic cylinder i, and control the switching state of the corresponding switching valve accordingly:

[0009] Calculate Q 1madi and α 2padi :Let Q 1mad =[Q 1mad1 Q 1mad2 Q 1mad3 ] T ;

[0010]

[0011] If Q 1mi Q 1madi ≤0, then Q 1madi =0;

[0012] If α 2pi α 2padi ≤0, then α 2padi =0;

[0013] Where Q 1madi It's Q 1mad The i-th element of Q 1madi and α 2padi They represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint, respectively, di represents the motion reference trajectory of hydraulic cylinder i, is x di about The first-order partial derivative of V 1di =V h1i +A1i x di and V 2di =V h2i -A 2i x di are the compressible volume V at the i-th hydraulic cylinder 1i and V 2i Using motion reference trajectory x di Replace x Li The expression form, is an estimate of the elastic modulus,

[0014] N 1d =diag{A 11 / V 1d1 ,A 12 / V 1d2 ,A 13 / V 1d3}, N 2d =diag{A 21 / V 2d1 ,A 22 / V 2d2 ,A 23 / V 2d3},

[0015] α 2pad =[α 2pad1 α 2pad2 α 2pad3 ] T ,

[0016]

[0017] φ 4cd =[0 3×7 0 3×3 0 3×3 N 2d α 2pad -q vd I 3×3 ] T , is the estimated value of the exoskeleton system parameters, F Ldad is the expected compensation driving force of the hydraulic cylinder at each joint, and F Ldad about and the partial derivatives of t, is the estimated value of the constant part of the uncertainty of the rod cavity model in hydraulic cylinder i, is the derivative of the desired pressure in the rod chamber of the i-th hydraulic cylinder, Q 1mi is the expected flow rate of the rodless cavity of the i-th joint, α 2pi is the expected flow rate of the rod cavity of the i-th joint;

[0018] Calculate the expected output flow Q of the variable speed pump corresponding to hydraulic cylinder i pdi :Q pdi =sw 1i Q 1madi -sw 2i α 2padi ;

[0019] If 0≤Q pdi ≤Q pbound , then Q pdi =0;

[0020] Where Q pbound Indicates the minimum boundary flow rate for using a variable speed pump;

[0021] Calculate the control voltage of the variable speed pump corresponding to the hydraulic cylinder i as follows: Where k p is the flow gain coefficient.

[0022] The present invention also provides a heavy-load single-leg hydraulically assisted exoskeleton control device, which adopts the heavy-load single-leg hydraulically assisted exoskeleton control method described above; the control device includes:

[0023] Multiple parallel pump-valve coordinated electro-hydraulic systems; each parallel pump-valve coordinated electro-hydraulic system includes a parallel coordinated pump control section and a valve control section; the pump control section includes a variable speed pump PS1 and two two-way switch valves SV1 and SV2 that determine the outlet flow direction of the variable speed pump PS1; the valve control section includes four two-way electro-hydraulic servo valves PV1, PV2, PV3, and PV4 and a hydraulic oil source PS2. The electro-hydraulic servo valves PV1 and PV2 control the flow of hydraulic oil from the hydraulic source PS2 to the two chambers of the corresponding hydraulic cylinder, and the electro-hydraulic servo valves PV3 and PV4 control the flow of hydraulic oil from the two chambers of the corresponding hydraulic cylinder to the oil tank;

[0024] The flow acquisition module is used to coordinate the electro-hydraulic system of the parallel pump valves of each joint of the single-leg hydraulic power-assisted exoskeleton, according to the reference rotation angle of each joint Reference angular velocity Reference angular acceleration Actual driving force F of hydraulic cylinder L , actual rotation angle q, actual rotation angular velocity Get the expected flow rate α of the rod cavity of each joint 2p =[α 2p1 α 2p2 α 2p3 ] T and the desired flow rate Q of the rodless cavity 1m =[Q 1m1 Q 1m2 Q1m3 ] T ; wherein, i represents the serial number of three joints, the expected flow of the rod cavity of the i-th joint is 2pi , and the expected flow of the rodless cavity of the i-th joint is Q 1mi ;

[0025] a control voltage acquisition module configured to calculate the control voltage of PS1, PV1, PV2, PV3 and PV4 corresponding to each joint according to 2p , Q 1m , so as to perform pump valve flow distribution of each joint.

[0026] The application further provides a single-leg hydraulic assistance exoskeleton under heavy load, which adopts the single-leg hydraulic assistance exoskeleton control method under heavy load as described above.

[0027] Compared with the existing exoskeleton control method, the single-leg hydraulic assistance exoskeleton control method and device under heavy load has the following beneficial effects:

[0028] 1. The single-leg hydraulic assistance exoskeleton control method under heavy load adopts a hydraulic driving mode for the exoskeleton driving system, and has the characteristics of being able to output larger force or torque, having sensitive motion response, being easy to control, having small volume and compact structure, etc.

[0029] 2. The single-leg hydraulic assistance exoskeleton control method under heavy load adopts a parallel pump valve coordination electro-hydraulic system scheme, and constructs an independently operated pump control part and a valve control part, so that the pump control part provides main flow and the valve control part provides small flow, thereby improving the energy efficiency level of the electro-hydraulic system of the lower limb assistance exoskeleton without losing accuracy.

[0030] 3. The single-leg hydraulic assistance exoskeleton control method under heavy load mainly realizes reliable human-computer interaction by the back force sensor and the joint encoder in the sensor system.

[0031] 4. The single-leg hydraulic assistance exoskeleton control method under heavy load adopts a force control method. An adaptive robust control algorithm (ARC) is used to design upper and lower controllers, so as to effectively overcome the influence of high-order nonlinearity and model uncertainty of the single-leg hydraulic assistance exoskeleton. The rodless cavity of the hydraulic cylinder in the lower controller adopts position tracking control, and the rod cavity of the hydraulic cylinder adopts pressure tracking control, so that the pressure of the hydraulic cylinder cavity is always in the minimum pressure state. The technical problem of large energy consumption of the existing exoskeleton control method is solved, not only the hydraulic assistance exoskeleton can well follow and assist human movement, but also the system energy consumption is reduced, the longer endurance time is realized, and the application value is high.

[0032] 5. This method for controlling a single-leg hydraulically assisted exoskeleton under heavy load adopts a flow distribution scheme in which a pump provides low-frequency flow and a valve provides high-frequency flow. This solves the flow distribution problem caused by the non-negligible compressibility of the oil under heavy load and reduces the system energy consumption under heavy load.

[0033] 6. This heavy-load, single-leg hydraulically assisted exoskeleton control method uses human motion as the external input for the entire exoskeleton system, ensuring balance during walking. Furthermore, a cascaded force control algorithm is employed to enable the exoskeleton to follow the user's trajectory. This control method is simple to implement, easy to engineer, and offers flexible control.

[0034] 7. The beneficial effects of the heavy-load single-leg hydraulic-assisted exoskeleton control device and the heavy-load single-leg hydraulic-assisted exoskeleton are the same as the beneficial effects of the heavy-load single-leg hydraulic-assisted exoskeleton control method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the overall shape and structure of a single-leg hydraulically assisted exoskeleton provided in a preferred embodiment of the present invention;

[0036] Figure 2 for Figure 1 Schematic diagram of the single-joint parallel pump-valve coordinated electro-hydraulic system used in the single-leg hydraulic power-assisted exoskeleton;

[0037] Figure 3 for Figure 1 The block diagram of the design concept of the control method of the single-leg hydraulic power-assisted exoskeleton under heavy load;

[0038] Figure 4 for Figure 1 Control flow chart of the control method of the single-leg hydraulically assisted exoskeleton under heavy load adopted by the medium single-leg hydraulically assisted exoskeleton. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] See also Figure 1 , which is a schematic diagram of the overall shape and structure of a single-leg hydraulic power-assisted exoskeleton provided by a preferred embodiment of the present invention. Figure 1 It can be seen that the single-leg hydraulic power-assisted exoskeleton includes a foot 1, an ankle joint encoder 2, an ankle joint hydraulic cylinder rod cavity pressure sensor 3, an ankle joint hydraulic cylinder 4, an ankle joint hydraulic cylinder rodless cavity pressure sensor 5, a calf rod 6, a knee joint encoder 7, a knee joint hydraulic cylinder rod cavity pressure sensor 8, a thigh rod 9, a knee joint hydraulic cylinder 10, a knee joint hydraulic cylinder rodless cavity pressure sensor 11, a hip joint encoder 12, a hip joint hydraulic cylinder rod cavity pressure sensor 13, a hip joint hydraulic cylinder rodless cavity pressure sensor 1 4. Base plate 15, hip joint hydraulic cylinder 16, on-off valve 17 of ankle joint pump control part, servo valve 18 of ankle joint valve control part, on-off valve 19 of knee joint pump control part, servo valve 20 of knee joint valve control part, on-off valve 21 of hip joint pump control part, servo valve 22 of hip joint valve control part, back plate 23, back force sensor 24, back strap 25, waist strap 26, servo amplifier board (not shown in the figure), variable speed pump corresponding to each joint (not shown in the figure), and real-time controller (not shown in the figure).

[0042] The foot 1 of the exoskeleton serves as the contact part with the ground, and supports the entire exoskeleton through the foot, which functions similarly to a human foot. The bottom end of the calf rod 6 is rotatably connected to the foot 1, which can be a hinge connection. The bottom end of the thigh rod 9 is rotatably connected to the top end of the calf rod 6, which can also be a hinge connection. The ankle joint hydraulic cylinder 4 is used to drive the foot 1 and the calf rod 6 to rotate relative to each other. The ankle joint encoder 2 is installed at the ankle joint (can be installed at the hinge connection). The knee joint hydraulic cylinder 10 is used to drive the calf rod 6 and the thigh rod 9 to rotate relative to each other. The knee joint encoder 7 is installed at the knee joint (can be installed at the hinge connection). The top end of the thigh rod 9 is rotatably connected to the base plate 15, and the hip joint hydraulic cylinder 16 is used to drive the thigh rod 9 and the base plate 15 to rotate relative to each other. The hip joint encoder 12 is installed at the hip joint (can be installed at the hinge connection). The bottom plate 15 is connected to the back plate 23 by bolts, the back force sensor 24 is installed between the back plate 23 and the back strap 25, and the waist strap 26 is connected to the lower end of the back plate 23.

[0043] The rod cavity pressure sensor 3 of the ankle joint hydraulic cylinder is used to detect the rod cavity pressure of the ankle joint hydraulic cylinder 4, and the rodless cavity pressure sensor 5 of the ankle joint hydraulic cylinder is used to detect the rodless cavity pressure of the ankle joint hydraulic cylinder 4. The ankle joint encoder is used to detect the rotation angle at the ankle joint. The rod cavity pressure sensor 8 of the knee joint hydraulic cylinder is used to detect the rod cavity pressure of the knee joint hydraulic cylinder 10, and the rodless cavity pressure sensor 11 of the knee joint hydraulic cylinder is used to detect the rodless cavity pressure of the knee joint hydraulic cylinder 10. The knee joint encoder is used to detect the rotation angle at the knee joint. The rod cavity pressure sensor 13 of the hip joint hydraulic cylinder is used to detect the rod cavity pressure of the hip joint hydraulic cylinder 16, and the rodless cavity pressure sensor 14 of the hip joint hydraulic cylinder is used to detect the rodless cavity pressure of the hip joint hydraulic cylinder 16. The hip joint encoder is used to detect the rotation angle at the hip joint.

[0044] The switch valve 17 of the ankle joint pump control part and the servo valve 18 of the ankle joint valve control part are used to control the ankle joint hydraulic cylinder 4, the switch valve 19 of the knee joint pump control part and the servo valve 20 of the knee joint valve control part are used to control the knee joint hydraulic cylinder 10, and the switch valve 21 of the hip joint pump control part and the servo valve 22 of the hip joint valve control part are used to control the hip joint hydraulic cylinder 16. The real-time controller is electrically connected to the ankle joint encoder 2, the ankle joint hydraulic cylinder rod cavity pressure sensor 3, the ankle joint hydraulic cylinder rodless cavity pressure sensor 5, the knee joint encoder 7, the knee joint hydraulic cylinder rod cavity pressure sensor 8, the knee joint hydraulic cylinder rodless cavity pressure sensor 11, the hip joint encoder 12, the hip joint hydraulic cylinder rod cavity pressure sensor 13, the hip joint hydraulic cylinder rodless cavity pressure sensor 14, the ankle joint pump control unit switch valve 17, the ankle joint valve control unit servo valve 18, the knee joint pump control unit switch valve 19, the knee joint valve control unit servo valve 20, the hip joint pump control unit switch valve 21, the hip joint valve control unit servo valve 22, and the back force sensor 24. The real-time controller model can be, but is not limited to, the NI cRIO-9031. The servo valve amplifier board can be, but is not limited to, the Star WO36829 / 1 product.

[0045] To overcome the high energy consumption of the single-leg hydraulic-assisted exoskeleton's electro-hydraulic system, the hydraulic system uses a parallel pump-valve coordinated electro-hydraulic system solution, constructing independently operated pump-controlled and valve-controlled components, with the pump-controlled component providing the main flow and the valve-controlled component providing a small flow. To overcome the high-order nonlinearity and model uncertainty of the single-leg hydraulic-assisted exoskeleton, the adaptive robust control algorithm (ARC) is used to design upper and lower-level controllers, achieving excellent tracking and assistance effects of the single-leg hydraulic-assisted exoskeleton in response to human movement. To overcome the flow distribution problem caused by the non-negligible compressibility of the oil under heavy loads, the flow distribution solution uses a pump to provide low-frequency flow and a valve to provide high-frequency flow, reducing system energy consumption under heavy loads.

[0046] In this embodiment, the present invention changes the original power system of the ankle joint, knee joint and hip joint, and improves the original power system of each joint into a parallel pump valve coordinated electro-hydraulic system. Figure 2 Each parallel pump-valve coordinated electro-hydraulic system includes a parallel coordinated pump control part and a valve control part; the pump control part includes a variable speed pump PS1 and two two-way switch valves SV1 and SV2 that determine the outlet flow direction of the variable speed pump PS1; the valve control part includes four two-way electro-hydraulic servo valves PV1, PV2, PV3 and PV4 and a hydraulic oil source PS2. The electro-hydraulic servo valves PV1 and PV2 control the flow of the hydraulic oil source PS2 to the two chambers of the corresponding hydraulic cylinder, and the electro-hydraulic servo valves PV3 and PV4 control the flow of the two chambers of the corresponding hydraulic cylinder to the oil tank.

[0047] Of course, the present invention not only improves the power systems of the ankle, knee, and hip joints, but also requires the coordinated movement of the three joints through the corresponding single-leg hydraulically assisted exoskeleton control method. The present invention's single-leg hydraulically assisted exoskeleton control method under heavy loads utilizes an adaptive robust control algorithm (ARC) that effectively overcomes the effects of model uncertainty. This algorithm employs an adaptive law to continuously adjust the system model parameters, applies feedforward compensation to the control model to ensure zero tracking error under static conditions, and employs robust feedback to ensure the dynamic characteristics and stability of the single-leg hydraulically assisted exoskeleton system. Simultaneously, utilizing a cascaded force control method, an upper-level controller is designed to obtain the single-leg exoskeleton joint reference trajectory. The lower-level rodless cavity position tracking controller, the lower-level rod-type cavity pressure planner, and the lower-level rod-type cavity pressure tracking controller implement tracking of the joint reference trajectory and reduce system energy consumption. Furthermore, the flow distribution scheme uses a pump to provide low-frequency flow and a valve to provide high-frequency flow, reducing system energy consumption under heavy loads. The control algorithm is simple to implement, easy to implement in engineering, and offers flexible control.

[0048] In specific applications, the single-leg hydraulic-assisted exoskeleton control method can be implemented in the form of software, such as a standalone program designed and installed on a computer terminal, which can be a computer, smartphone, control system, or other IoT device. Alternatively, it can be designed as an embedded program and installed on a computer terminal, such as a single-chip microcomputer. A computer terminal generally includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the single-leg hydraulic-assisted exoskeleton control method under heavy loads are implemented. In specific applications, the single-leg hydraulic-assisted exoskeleton control method under heavy loads can be implemented in the form of software, such as a standalone program designed on a computer-readable storage medium, such as a USB flash drive or USB shield, which is designed to activate the entire method through an external trigger. A USB flash drive is a type of computer-readable storage medium that stores a computer program. When the program is executed by the processor, the steps of the single-leg hydraulic-assisted exoskeleton control method are implemented.

[0049] Regardless of the application of the heavy-load single-leg hydraulic-assisted exoskeleton control method, its functional design can be categorized as a single-leg hydraulic-assisted exoskeleton device. This device primarily includes a flow acquisition module, a control voltage acquisition module, a module for acquiring the actual hydraulic cylinder driving force, a module for acquiring the actual joint driving torque, and a module for acquiring the rotational angular velocity.

[0050] Next, combine Figure 3 and Figure 4 The present invention provides a detailed description of the control method for a single-leg hydraulically assisted exoskeleton under heavy load. When applying the control method for a single-leg hydraulically assisted exoskeleton under heavy load, the following preparations must be made for the exoskeleton in advance:

[0051] (1) The exoskeleton is fixed to the human body by means of the back strap 25 and the waist strap 26. The sampling period T of the real-time controller is initialized according to the actual situation. The sampling period T is set to be between 10 and 20 milliseconds.

[0052] (2) Rotate the foot 1 to a horizontal position, and rotate the calf rod 6, thigh rod 9, and back plate 23 to a vertical position. At this time, initialize the ankle joint encoder 2, knee joint encoder 7, and hip joint encoder 12, and set the joint encoder values ​​to zero;

[0053] (3) Initializing the back force sensor 24 and adjusting the value of the back force sensor 24 to zero;

[0054] (4) Design a schematic diagram of the pump-valve coordination electro-hydraulic system for a single-leg hydraulically assisted exoskeleton.

[0055] The principle scheme of the pump valve coordination electro-hydraulic system of the single-leg hydraulic power-assisted exoskeleton is as follows Figure 2 As shown, Figure 2 This is the schematic diagram of the single-joint parallel pump-valve coordinated electro-hydraulic system. The principle scheme of the pump-valve coordinated electro-hydraulic system for the single-leg hydraulic assisted exoskeleton is to apply the single-joint parallel pump-valve coordinated electro-hydraulic system to the ankle joint, knee joint and hip joint of the exoskeleton respectively.

[0056] The structure of a parallel pump-valve coordinated electro-hydraulic system is primarily divided into a pump control section and a valve control section. The pump control section consists of a variable-speed pump PS1 and two two-way on-off valves SV1 and SV2. The direction of the oil source's outlet flow is determined by the on-off valves. The valve control section comprises four two-way electro-hydraulic servovalves PV1, PV2, PV3, and PV4, and a hydraulic oil source PS2. The electro-hydraulic servovalves PV1 and PV2 control the flow of oil to the two chambers of the hydraulic cylinder, while the electro-hydraulic servovalves PV3 and PV4 control the flow of oil from the two chambers of the hydraulic cylinder to the oil tank. The pump control section's oil source is not limited to variable-speed pumps. Variable displacement pumps with similar functions, as well as combinations of variable-speed and variable displacement pumps, can also be used in the pump control section, which requires real-time adjustment of output flow based on a given input signal. PV1, PV2, PV3, and PV4 are also not limited to electro-hydraulic servovalves. Proportional servovalves and proportional cartridge valves with similar functions can also be used in the valve control section. Their fundamental function is to continuously adjust the flow through the valve ports, with a bandwidth greater than that of the pump control section. The flow of the pump control part and the flow of the valve control part are superimposed in parallel at N1 and N2 to jointly control the flow to the two chambers of the hydraulic cylinder.

[0057] (5) Establishing a physical model of a single-leg hydraulically assisted exoskeleton and converting it into a state equation; wherein the physical model includes a human-machine interface model, a motion model of the exoskeleton mechanical body, and a dynamic model of the hydraulic actuator;

[0058] The upper-level human-machine interface model expression is:

[0059]

[0060] Among them, F hm =[F hmx F hmy τ hmz ] T is the human-machine force at the contact point between the human and the exoskeleton robot, x, y, z are the symbols of the three coordinate axes of the world coordinate system; K = diag{K x ,K y ,K z} is the stiffness of the human-machine interface, x h =[x hx x hy x hz ] T is the Cartesian coordinate position of the contact point of the strap 25 on the back of the person, x e =[xex x ey x ez ] T is the Cartesian position of the contact point of the exoskeleton back plate 23; It is about concentrated interference and modeling uncertainty at the human-machine interface.

[0061] When transforming the physical model, the integration of human-machine forces Replace F hm , the state equation is obtained as:

[0062]

[0063] The motion model of the exoskeleton mechanical body is:

[0064]

[0065] Where, τ act =[τ1 τ2 τ3] T is the joint driving torque at the ankle, knee and hip joints, J is the Jacobian matrix of the system at the force sensor, q = [q1 q2 q3] T are the rotation angles of the ankle, knee and hip joints respectively, M sp3 (q) is the inertia matrix of the system, is the centrifugal force and Coriolis force matrix of the system, G sp3 (q) is the gravity matrix of the system, B = diag{B1, B2, B3} is the damping matrix of the system, It is a concentrated disturbance of the system;

[0066] The dynamic model of the hydraulic actuator is:

[0067]

[0068] Q 1i =Q 1vi +Q 1pi , Q 2i =Q 2vi -Q 2pi

[0069] Q 1vi =Q pv1i -Q pv3i , Q 2vi =-Q pv2i +Q pv4i

[0070]

[0071] ΔP pv1i =P s -P1i , ΔP pv2i =P s -P 2i , ΔP pv3i =P 1i -P r , ΔP pv4i =P 2i -P r

[0072] x pvji =u pvji ,i=1,2,3

[0073] Q 1pi =sw 1i Q pi , Q 2pi =sw 2i Q pi

[0074]

[0075] Q pi =k pi u pi ,i=1,2,3

[0076] Where x Li is the displacement of hydraulic cylinder i, is x Li About q i The first-order partial derivative of P 1i and P 2i Indicates the actual pressure of the rodless chamber and the rod chamber in the hydraulic cylinder i, A 1i and A 2i V represents the effective area of ​​the rodless cavity and the rod cavity in the hydraulic cylinder i. 1i =V h1i +A 1i x Li and V 2i =V h2i -A 2i x Li are the total volume of the two chambers in the hydraulic cylinder i, V h1i ,V h2i It's q i = 0, the volume of the two chambers of the hydraulic cylinder i, β e Represents the bulk elastic modulus. Q 1i , Q 2i are the oil inlet flow rate of the rodless chamber and the oil outlet flow rate of the rod chamber in the hydraulic cylinder i, and represents the concentrated modeling error and uncertain disturbance in the hydraulic actuator dynamics model, Q 1vi and Q 2viThey represent the oil flow rate from the rodless chamber to the valve control part and the oil flow rate from the rod chamber in the hydraulic cylinder i, respectively. 1pi and Q 2pi They represent the oil flow rate of the rodless chamber and the rod chamber from the pump control part in the hydraulic cylinder i, respectively, and Q pvji represents the flow rate of the jth servo valve corresponding to the hydraulic cylinder i, k qpvji is the flow gain coefficient of the jth servo valve corresponding to the hydraulic cylinder i, x pvji is the valve core displacement of the jth servo valve corresponding to hydraulic cylinder i, P s With P r They are the oil supply pressure of the valve control part and the pressure of the oil tank, ΔP pv1i and ΔP pv2i Respectively represent the oil supply pressure P of the valve control part in the hydraulic cylinder i s The actual pressure of the rodless chamber P 1i And the actual pressure of the rod chamber P 2i Pressure difference, ΔP pv3i and ΔP pv4i They represent the actual pressure P in the rodless chamber of hydraulic cylinder i. 1i And the actual pressure of the rod chamber P 2i With the tank pressure P r The pressure difference, u pvji is the control voltage of the jth servo valve corresponding to hydraulic cylinder i, Q pi represents the output flow of the variable speed pump corresponding to the hydraulic cylinder i, k pi and u pi They represent the flow gain coefficient and control voltage of the variable speed pump corresponding to the hydraulic cylinder i respectively.

[0077] The method of converting the physical model into the equation of state includes the following steps:

[0078] (5.1) Define state variables:

[0079]

[0080] x2=q

[0081]

[0082] x4=P1=[P 11 P 12 P 13 ] T

[0083] x5=P2=[P 21 P 22 P 23 ] T

[0084] x=[x1T x2 T x3 T x4 T x5 T ] T

[0085] The centralized model uncertainty is defined as:

[0086]

[0087] (5.2) The centralized model uncertainty is divided into two parts, constant and time-varying function, and the following equation is obtained Δ in and Δ i represent the constant and time-varying parts of , respectively;

[0088] (5.3) Let θ q = [β T B θ T Δ 2n T β e Δ 3n T ] T , θ p2i = [β e Δ 4ni ] T where, Δ 1n = [Δ 1nx Δ 1ny Δ 1nz ] T , β = [Y2 Y3 Y4 X4 J2 J3 J4] T is the system parameter of the single leg of the exoskeleton, B θ = [B1 B2 B3] T is the system damping, Δ 2n = [Δ 2n1 Δ 2n2 Δ 2n3 ] T , Δ 3n = [Δ 3n1 Δ 3n2 Δ 3n3 ] T , Δ 4n = [Δ 4n1 Δ 4n2 Δ 4n3 ] T .

[0089] The state equation of the physical model of the single leg hydraulic power-assisted exoskeleton is:

[0090]

[0091]

[0092]

[0093] in, A2=diag{A 21 ,A 22 ,A 23} , F L =A1P1-A2P2, Q v =N1Q1+N2Q2, Q v =[Q 11 A 11 / V 11 +Q 21 A 21 / V 21 ,Q 12 A 12 / V 12 +Q 22 A 22 / V 22 ,Q 13 A 13 / V 13 +Q 23 A 23 / V 23 ] T , Q1=[Q 11 ,Q 12 ,Q 13 ] T ,Q2=[Q 21 ,Q 22 ,Q 23 ] T ,N1=diag{A 11 / V 11 ,A 12 / V 12 ,A 13 / V 13},

[0094] (6) Connecting the wearer to the back force sensor 24 via the back strap 25, measuring the human-machine interaction force of the back force sensor 24, and obtaining the reference rotation angle of each joint of the single-leg hydraulic power-assisted exoskeleton through the upper controller;

[0095] According to the state equation of the physical model in step (5), let the first tracking error z1 = x1-x 1d , where x 1d is the integral of the desired human-machine force in the x, y, and z directions, which is zero;e As a virtual control input, x e Design control law x m The first tracking error z1 of the human-machine force quickly approaches zero;

[0096] Let x m =x ma +x ms +x msn ,in x ms =K1z1, and By x ma After parameter linearization, we get is the desired human-machine force in the x, y, and z directions, K1 = diag{K 1x ,K 1y ,K 1z} is the linear feedback gain, in this example, K1 = diag{8,8,8}; is θ F The estimated value of is in the range of: In this embodiment, the initial value is in is the parameter θ F Estimated value of The minimum value of is the parameter θ F Estimated value of In this embodiment, take Estimated value In the upper controller, the adaptive law It is found that Γ1 is a positive definite gain matrix. In this embodiment, Γ1=diag{0,0,0,2,15,2} is taken. The mapping function is:

[0097]

[0098] Where, i is the independent variable, the nonlinear robust feedback term x msn satisfy:

[0099]

[0100] in, is an estimate Subtract the actual value θ F , ε1 is a threshold value and is any non-negative number. In this example, ε1 =

[111] T , x msn=

[000] T .

[0101] According to the design of x m , and the inverse kinematics model of the single-leg hydraulic assisted exoskeleton to obtain the expected rotation angle q of each joint of the exoskeleton m =[q m1 q m2 q m3 ] T :

[0102] q m =invkine(x m )

[0103] Where invkine stands for inverse kinematics. According to the expected rotation angle q of each joint of the exoskeleton mi , i = 1, 2, 3, and smoothed by a fourth-order filter to obtain the reference rotation angle, reference rotation angular velocity, reference rotation angular acceleration and reference rotation angular jerk of each joint of the exoskeleton; wherein, the state equation of the fourth-order filter is as follows:

[0104]

[0105] i=1,2,3

[0106] Where, Represent the filtered reference rotation angle, reference rotation angular velocity, reference rotation angular acceleration and reference rotation angular jerk respectively, from q mi to η 1i The transfer function is:

[0107]

[0108] Through the above transfer function, we can obtain q mi Converted into the required smooth reference rotation angle η of each joint of the exoskeleton 1i Wherein, a1, a2, a3, and a4 in the transfer function are obtained by pole placement. In this embodiment, the closed-loop pole is set to 20 radians per second, and the values ​​of a1, a2, a3, and a4 are respectively a1 = 80, a2 = 2400, a3 = 32000, and a4 = 160000. In practice, the values ​​are not limited to this.

[0109] (7) The actual rotation angle values ​​of the joints of the single-leg hydraulic power-assisted exoskeleton are obtained through the ankle joint encoder 2, the knee joint encoder 7 and the hip joint encoder 12; the reference rotation angles of the joints are obtained according to step (6), and the actual rotation angles and the reference rotation angles are used as inputs of the lower-layer rodless cavity position tracking controller. The outputs of the lower-layer rodless cavity position tracking controller are the desired driving forces at the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10 and the hip joint hydraulic cylinder 16 in the single-leg hydraulic power-assisted exoskeleton and the desired flow rate of the rodless cavity; the design method of the lower-layer rodless cavity position tracking controller includes the following steps:

[0110] Assume the second tracking error in Define a transformation equation:

[0111]

[0112] Where K2 is the positive feedback gain matrix. In this example, K2 = diag{85,85,85}. z3 is the third tracking error. The transfer function of z2 and z3 is G p (s)=z2(s) / z3(s)=diag{1 / (s+K 2i ),i=1,2,3},

[0113]

[0114] Let Bx3 = Y B B θ , Where β = [Y2 Y3 Y4 X4 J2 J3 J4] T , Y2, Y3, Y4, X4, J2, J3, J4 are all model parameters of the mechanical structure, B θ =[B1B2 B3] T is the damping of the system;

[0115] (7.1) L As a virtual control input, F L Design control law F Ld Make the second tracking error z2 quickly approach zero;

[0116] Let F Ld =F Lda +F Lds +F Ldsn ,in, F Lds =-h -1 K3z3, K3 is the linear feedback gain. In this example, K3=diag{85,85,85}; is the parameter β,Bθ ,Δ 2n the estimate of θ q = [β T B θ T Δ 2n T β e Δ 3n T ] T In this example, the initial value of

[0117] is the estimate of θ q , and the range of the estimate is: where is the minimum value of the estimate of θ q is the maximum value of the estimate of θ q ; in this example, we take

[0118]

[0119] The estimate of is obtained in the lower layer pole-free cavity position tracking controller by the adaptive law , τ4 is obtained by step (7.3), Γ2 is a positive definite gain matrix, in this example, we take Γ2 = diag{10, 0, 0, 0, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, The mapping function of

[0120]

[0121] where · i is the argument, let φ3 = [-Y-Y B I 3×3 0 3×1 0 3×3 ] T where I 3×3 = diag{1, 1, 1}, 0 3×1 =

[000] T , 0 3×3 = diag{0, 0, 0}, F Ldsn satisfies:

[0122]

[0123] where is the estimate of minus the actual value θ​​​q , ε2 is a threshold value and is any non-negative number; in this example, ε2 =

[111] T , F Ldsn =

[000] T .

[0124] (7.2) Design an adaptive robust observer to estimate the joint rotation angular velocity and angular acceleration.

[0125] Assume that the observation error e o1 =x2-y, where y is the estimated value of the joint angle, and a transformation equation is defined:

[0126]

[0127] Among them, K o1 is the positive feedback gain matrix. In this example, K o1 =[606060] T ; is the estimated value of the joint angular velocity, the estimated value of the joint angular acceleration Designed to:

[0128]

[0129] in, Is to use θ q Another set of parameter estimates for The obtained M sp3 、C sp3 , G sp3 The estimated value of K o2 is the linear positive definite feedback gain matrix. In this example, K o2 =[400200200] T ;K o2s is the nonlinear positive definite feedback gain matrix. In this example, K o2s =

[000] T ;T os is the robust feedback term of the observer error; let In this example, the initial value The range of estimated values ​​that can be obtained is: make φ o =[-Y o -Y Bo I 3×3 0 3×1 0 3×3 ] T ; Estimated value In the adaptive robust observer, the adaptive law We get, where Γ o is a positive definite gain matrix. In this example, we take Γ o =diag{10,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0}, The mapping function is:

[0130]

[0131] Where, i is the independent variable,

[0132] The following two conditions are met:

[0133]

[0134] Where, is an estimate Subtract the actual value θ q , ε o is a threshold value and is any non-negative number. In this embodiment, ε is selected o =

[111] T , select T os =

[000] T .

[0135] Defining the fourth tracking error in, That is, in the control law F Ld Chinese replace To calculate

[0136] (7.3) Consider Q1 as a virtual control input and design the control law Q for Q1. 1m The fourth tracking error Rapidly approaches zero;

[0137] Let Q 1m =Q 1ma +Q 1ms +Q 1msn ,in,

[0138] φ 4c =[0 3×7 0 3×3 0 3×3 N2α 2p -q v I 3×3 ] T , α 2p From step (9), K4>0 is the linear feedback gain. In this example, K4=[858585] T Let φ4=[0 3×7 0 3×3 0 3×3 Q1 1ma +N2α 2p -q v I 3×3 ] T , Q 1msn The following two conditions must be met:

[0139]

[0140] Where, is an estimate Subtract the actual value θ q , ε3 is a threshold value and is any non-negative number; in this embodiment, ε3 =

[111] T , select Q 1msn =

[000] T .

[0141] (8) The desired driving force of the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10, and the hip joint hydraulic cylinder 16 in the single-leg hydraulic power-assisted exoskeleton obtained in step (7) is used as the input of the lower-layer rod cavity pressure planner, and the output of the lower-layer rod cavity pressure planner is the desired rod cavity pressure of the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10, and the hip joint hydraulic cylinder 16 of the single-leg hydraulic power-assisted exoskeleton; the design of the lower-layer rod cavity pressure planner includes the following steps:

[0142] Considering that good control design can ensure that the system error is within a small range, the model compensation term F in step (7.1) Lda Can basically characterize the expected driving force F Ld In addition, in order to obtain a more continuous and smooth desired pressure in the rod cavity and to avoid the negative influence of noise, the joint reference trajectory is used instead of the measurement signal of the state quantity.

[0143] set up

[0144] Among them, F Ldad =[F Ldad1 F Ldad2 F Ldad3 ] T .

[0145] The desired pressure P of the rod chamber of the i-th hydraulic cylinder2di Designed to:

[0146]

[0147] Where, P c is the set minimum working pressure. In this example, P c =0.1×10 6 Pa. The derivative of the desired pressure in the rod chamber of the i-th hydraulic cylinder Designed to:

[0148]

[0149] (9) The actual pressure values ​​of the rod chambers of the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10 and the hip joint hydraulic cylinder 16 are obtained through the ankle joint hydraulic cylinder rod chamber pressure sensor 3, the knee joint hydraulic cylinder rod chamber pressure sensor 8 and the hip joint hydraulic cylinder rod chamber pressure sensor 13; according to the desired rod chamber pressures of the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10 and the hip joint hydraulic cylinder 16 in the single-leg hydraulic power-assisted exoskeleton obtained in step (8), the desired rod chamber pressures and the actual rod chamber pressures are used as inputs of the lower-level rod chamber pressure tracking controller, and the output of the lower-level rod chamber pressure tracking controller is the desired rod chamber flow of the ankle joint hydraulic cylinder 4, the knee joint hydraulic cylinder 10 and the hip joint hydraulic cylinder 16. In this example, the lower-level rod chamber pressure tracking controller method includes the following steps:

[0150] Define the fifth tracking error z 5i =p 2i -p 2di , Q 2i As a virtual control input, Q 2i Design control law α 2pi So that the fifth tracking error z 5i =p 2i -p 2di Rapidly approaches zero;

[0151] Let α 2pi =α 2pai +α 2ps1i +α 2ps2i ,in α 2p =[α 2p1 α 2p2 α 2p3 ] T ,K p2i >0 is the linear feedback gain. In this example, take K p21 =200,K p22 =100,K p23 =100; They are β e , Δ4ni The estimated value of θ p2i =[β e Δ 4ni ] T , is θ p2i In this example, the estimated value is And the estimated values ​​range from: in is the parameter θ p2i Estimated value of The minimum value of is the parameter θ p2i Estimated value of In this example, take the maximum value of make Estimated value In the lower pressure tracking controller, the adaptive law Get, Γ p2i is a positive definite gain matrix. In this example, we take Γ p2i =

[00] T , The mapping function is:

[0152]

[0153] Where, i is the independent variable, the nonlinear robust feedback term α 2ps2i The following two conditions must be met:

[0154]

[0155] in, is an estimate Subtract the actual value θ p2i , ε p2i is a threshold value and is any non-negative number. In this embodiment, ε is selected p2i =1, select α 2ps2i =0.

[0156] (10) The expected flow rates of the rodless chambers of the ankle joint hydraulic cylinder, the knee joint hydraulic cylinder, and the hip joint hydraulic cylinder in the single-leg hydraulic power-assisted exoskeleton obtained in step (7) and the expected flow rates of the rod chambers of the ankle joint hydraulic cylinder, the knee joint hydraulic cylinder, and the hip joint hydraulic cylinder in the single-leg hydraulic power-assisted exoskeleton obtained in step (9) are used as inputs of a pump-valve flow distribution module, and the output of the pump-valve flow distribution module is the control voltage of the electro-hydraulic servo valve of each hydraulic cylinder and the control voltage of the variable speed pump; the pump-valve flow distribution includes the following steps:

[0157] (10.1) Determine the control voltage u of the variable speed pump corresponding to hydraulic cylinder i pi.

[0158] Step 1: Determine whether the pump provides flow to the rodless chamber of the hydraulic cylinder or to the rod chamber of the hydraulic cylinder.

[0159] If Q 1mi >0,α 2pi ≥0, then sw 1i =1,sw 2i =0;

[0160] If Q 1mi >0,α 2pi <0;

[0161] If |Q 1madi |≥|α 2padi |, sw 1i =1,sw 2i =0;

[0162] If |Q 1madi |<|α 2padi |, sw 1i =0, sw 2i =1;

[0163] If Q 1mi ≤0,α 2pi ≥0, then sw 1i =0, sw 2i =0;

[0164] If Q 1mi ≤0,α 2pi <0, then sw 1i =0, sw 2i =1;

[0165] Among them, sw 1i and sw 2i They represent the switch state of the switch valve when the flow of the pump control part in the hydraulic cylinder i enters the rodless chamber of the hydraulic cylinder and the switch state of the switch valve when entering the rod chamber of the hydraulic cylinder, respectively. Q 1madi and α 2padi They represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint. The joint reference trajectory includes the reference rotation angle after the above filtering. Reference angular velocity and the reference angular acceleration The expected flow rate of the low-frequency part is the value calculated by removing the part directly related to the measurement error from the compensation term of the expected flow model of each joint and replacing the actual trajectory with the joint reference trajectory. Specifically, for the rodless cavity expected flow rate Q 1m =Q 1ma +Q1ms +Q 1msn , the so-called desired flow rate Q of the low-frequency part required by the rodless cavity pump control part of each joint 1mad is the compensation term Q for the above adaptive model 1ma The portion directly related to the measurement error is removed (i.e., the term related to the third tracking error z3, which is directly related to the measurement error and has a higher frequency). The remaining portion is calculated using the joint reference trajectory instead of the actual trajectory. Similarly, the desired low-frequency flow rate required for the rodless chamber pump control can be compared to that of the rodless chamber.

[0166] Step 2: Determine the expected output flow rate Q of the pump pdi .

[0167] 1) Calculate Q 1madi and α 2padi ;

[0168] Let Q 1mad =[Q 1mad1 Q 1mad2 Q 1mad3 ] T ;

[0169]

[0170]

[0171] If Q 1mi Q 1madi ≤0, then Q 1madi =0;

[0172] If α 2pi α 2padi ≤0, then α 2padi =0;

[0173] Among them, Q 1madi It's Q 1mad The i-th element of Q 1madi and α 2padi They represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint, respectively, di represents the motion reference trajectory of hydraulic cylinder i, is x di about The first-order partial derivative of V 1di =V h1i +A 1i x di and V 2di =V h2i -A 2i x diare the compressible volume V at the i-th hydraulic cylinder 1i and V 2i Using motion reference trajectory x di Replace x Li The expression form, is an estimate of the elastic modulus, N 1d =diag{A 11 / V 1d1 ,A 12 / V 1d2 ,A 13 / V 1d3}, N 2d =diag{A 21 / V 2d1 ,A 22 / V 2d2 ,A 23 / V 2d3}, α 2pad =[α 2pad1 α 2pad2 α 2pad3 ] T ,

[0174] φ 4cd =[0 3×7 0 3×3 0 3×3 N 2d α 2pad -q vd I 3×3 ] T , is the estimated value of the exoskeleton system parameters, F Ldad is the expected compensation driving force of the hydraulic cylinder at each joint, and F Ldad about and the partial derivatives of t, is the estimated value of the constant part of the uncertainty of the rod cavity model in hydraulic cylinder i, is the derivative of the desired pressure in the rod chamber of the i-th hydraulic cylinder, Q 1mi is the expected flow rate of the rodless cavity of the i-th joint, α 2pi is the desired flow rate in the rod chamber of joint i. It's worth noting that the values ​​in the above formulas are calculated using the joint reference trajectory instead of the actual trajectory. The joint reference trajectory is used to avoid the influence of state measurement noise and to avoid state-to-measurement correlation, which results in lower frequencies. Since the pump can only receive low-frequency signals, the filtered joint reference trajectory is used here.

[0175] 2) Calculate Q pdi .

[0176] Q pdi =sw 1i Q 1madi -sw 2i α 2padi ;

[0177] If 0≤Q pdi ≤Q pbound , then Q pdi =0;

[0178] Among them, Q pbound Indicates the minimum boundary flow rate when using a variable speed pump. In this example, Q pbound =1×10 - 6 m 3 / s,Q pdi represents the expected output flow of the variable speed pump corresponding to hydraulic cylinder i.

[0179] Step 3: Calculate the control voltage of the pump.

[0180] The control voltage of the variable speed pump corresponding to the hydraulic cylinder i is Among them, the flow gain coefficient k p =8.3×10 -5 m 3 / (s·V).

[0181] (10.2) Determine the control voltage u of the servo valve corresponding to hydraulic cylinder i pv1i ,u pv2i ,u pv3i ,u pv4i .

[0182] Q 1pdi =sw 1i Q pdi , Q 2pdi =sw 2i Q pdi , Q 1vdi =Q 1mi -Q 1pdi , Q 2vdi =α 2pi +Q 2pdi ,

[0183] where Q 1pdi and Q 2pdi They represent the expected oil flow rate of the rodless chamber and the rod chamber from the pump control part in the hydraulic cylinder i, respectively, and Q 1vdi and Q 2vdi They represent the expected oil inlet flow rate of the rodless chamber and the expected oil outlet flow rate of the rod chamber from the valve control part in the hydraulic cylinder i respectively.

[0184] If Q 1vdi >0, then u pv3i =0;

[0185] If Q 1vdi <0, then u pv1i =0,

[0186] If Q 1vdi =0, then u pv1i =0,u pv3i =0;

[0187] If Q 2vdi >0, then u pv2i =0,

[0188] If Q 2vdi <0, then u pv4i =0;

[0189] If Q 2vdi =0, then u pv2i =0,u pv4i =0;

[0190] in,

[0191] In summary, the control input signals of the pump control part and the valve control part can be obtained.

[0192] (11) converting the control voltage of the electro-hydraulic servo valve obtained in step (10) into the control current of the corresponding servo valve through the amplifier board of the ankle joint electro-hydraulic servo valve, the amplifier board of the knee joint electro-hydraulic servo valve, and the amplifier board of the hip joint electro-hydraulic servo valve;

[0193] (12) The valve core opening displacement of the corresponding servo valve 18 of the ankle joint valve control part, the servo valve 20 of the knee joint valve control part, and the servo valve 22 of the hip joint valve control part is controlled by the control current of each servo valve, and the speed of the servo motor of the corresponding variable speed pump of the ankle joint pump control part, the variable speed pump of the knee joint pump control part, and the variable speed pump of the hip joint pump control part is controlled by the control voltage of each variable speed pump, so as to control the pressure at both ends of the hydraulic cylinder, promote the movement of each hydraulic cylinder, and then drive the rotation of each joint of the single-leg hydraulic power-assisted exoskeleton to achieve the following movement of the single-leg hydraulic power-assisted exoskeleton. Compared with the existing technology, the flow of the existing exoskeleton pump control part adopts the "hydraulic cylinder speed × area" distribution method, which does not take into account the compressibility of the oil. In the present invention, the flow of the pump control part is calculated based on the low-frequency part of the model compensation term, taking into account the compressibility of the oil. Under heavy load conditions, the compressibility of the oil cannot be ignored. At this time, the flow rate of the two chambers of the hydraulic cylinder and the speed of the hydraulic cylinder cannot be simply regarded as an algebraic relationship, but there is a dynamic relationship. At this time, the existing flow distribution scheme will no longer be applicable. The control method provided by the present invention solves this problem, so that under heavy load conditions, the variable speed pump can provide most of the flow rate, achieving energy saving.

[0194] In summary, in this embodiment, the single-leg hydraulically assisted exoskeleton control method of the present invention can be summarized into the following steps.

[0195] In the first step, the three hydraulic systems applied to the ankle, knee, and hip joints of the exoskeleton, respectively, all adopt parallel pump-valve coordinated electro-hydraulic systems. Each parallel pump-valve coordinated electro-hydraulic system includes a parallel coordinated pump control section and a valve control section. The pump control section includes a variable speed pump PS1 and two two-way switching valves SV1 and SV2 that determine the direction of the outlet flow of the variable speed pump PS1. The valve control section includes four two-way electro-hydraulic servo valves PV1, PV2, PV3, and PV4 and a hydraulic oil source PS2. The electro-hydraulic servo valves PV1 and PV2 control the flow of hydraulic oil from the hydraulic source PS2 to the two chambers of the corresponding hydraulic cylinders, while the electro-hydraulic servo valves PV3 and PV4 control the flow of hydraulic oil from the two chambers of the corresponding hydraulic cylinders to the oil tank.

[0196] This step requires installing three corresponding hydraulic systems on the exoskeleton for the ankle, knee and hip joints.

[0197] The second step is to coordinate the electro-hydraulic system of the parallel pump valves of each joint of the single-leg hydraulic assisted exoskeleton according to the reference rotation angle of each joint. Reference angular velocity Reference angular acceleration Actual driving force F of hydraulic cylinder L , actual rotation angle q, actual rotation angular velocity Get the expected flow rate α of the rod cavity of each joint2p =[α 2p1 α 2p2 α 2p3 ] T and the desired flow rate Q of the rodless cavity 1m =[Q 1m1 Q 1m2 Q 1m3 ] T ; where i represents the serial number of the three joints, the expected flow rate of the rod cavity of the i-th joint is α 2pi , the expected flow rate of the rodless cavity of the i-th joint is Q 1mi .

[0198] This step can be performed by the traffic acquisition module.

[0199] Among them, (1) The method for obtaining includes the following steps:

[0200] According to the human-machine force F hm and the Cartesian position x of the exoskeleton at the contact point e Design an upper-layer controller, which is x m =x ma +x ms +x msn , thus obtaining the Cartesian expected position x of the exoskeleton at the contact point m Where x ma is x m The adaptive model compensation term, x ms is x m The linear robust feedback term, x msn is x m The nonlinear robust feedback term of ;

[0201] According to the design of x m , based on the inverse kinematics model of the single-leg hydraulically assisted exoskeleton q m =invkine(x m ), and thus the expected rotation angle q of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained m =[q m1 q m2 q m3 ] T ,q mi represents the expected rotation angle of the i-th joint;

[0202] The expected rotation angle q of the i-th joint of the single-leg hydraulic assisted exoskeleton mi, i = 1, 2, 3, and smoothed by a fourth-order filter to obtain the reference rotation angle, reference rotation angular velocity, reference rotation angular acceleration and reference rotation angular jerk of the i-th joint of the exoskeleton; wherein the state equation of the fourth-order filter is as follows:

[0203]

[0204] i=1,2,3

[0205] Where, Represent the reference rotation angle, reference rotation angular velocity, reference rotation angular acceleration and reference rotation angular jerk of the i-th joint of the exoskeleton after filtering, respectively. mi to η 1i The transfer function is:

[0206]

[0207] Through the above transfer function, we can obtain q mi Converted into the required smooth reference rotation angle η of the i-th joint of the exoskeleton 1i ; Among them, a1, a2, a3, and a4 in the transfer function are obtained by pole configuration;

[0208] The reference rotation angles of each joint of the single-leg hydraulic assisted exoskeleton are obtained Reference angular velocity Reference angular acceleration

[0209] (2) Expected flow rate Q of the rodless cavity of each joint of the single-leg hydraulic power-assisted exoskeleton 1m =[Q 1m1 Q 1m2 Q 1m3 ] T The calculation method includes the following steps:

[0210] according to q、 α 2p 、F L Design a rodless cavity position tracking controller, the rodless cavity position tracking controller is Q 1m =Q 1ma +Q 1ms +Q 1msn , thus obtaining the expected flow Q of the rodless cavity of each joint of the single-leg hydraulic power-assisted exoskeleton 1m , where Q 1ma Q 1m The adaptive model compensation term, Q 1ms Q 1m The linear robust feedback term, Q 1msn Q1m The nonlinear robust feedback term.

[0211] (3) Expected flow rate α of the rod cavity of each joint of the single-leg hydraulic power-assisted exoskeleton 2p =[α 2p1 α 2p2 α 2p3 ] T The calculation method includes the following steps:

[0212] according to q、 α 2p 、F L Design a rodless cavity position tracking controller, the rodless cavity position tracking controller is F Ld =F Lda +F Lds +F Ldsn , and thus the expected driving force F of the hydraulic cylinder of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained Ld Where, F Lda F Ld The adaptive model compensation term, F Lds F Ld The linear robust feedback term, F Ldsn F Ld The nonlinear robust feedback term of ;

[0213] According to F Ld =[F Ld1 F Ld2 F Ld3 ] T Design the rod cavity pressure planner for each joint. Considering that a good control design can ensure that the system error is within a small range, the adaptive model compensation term F Lda Can basically characterize the expected driving force F of the hydraulic cylinder Ld In addition, in order to obtain a more continuous and smooth desired pressure in the rod cavity and avoid the negative influence of noise, the joint reference trajectory is used instead of the measurement signal of the state quantity, that is, the hydraulic cylinder expected compensation driving force F Ldad =[F Ldad1 F Ldad2 F Ldad3 ] T , the expected compensation driving force of the hydraulic cylinder of the i-th joint is F Ldadi ;

[0214] F at the i-th joint Ldadi , the rod cavity pressure planner of the i-th joint is The expected pressure P of the rod cavity of the i-th joint is obtained 2di Where, P c is the set minimum working pressure, A1i and A 2i They represent the effective areas of the rodless cavity and the rod cavity in the i-th joint respectively;

[0215] According to P 2di and the actual pressure P of the rod cavity of the i-th joint 2i , design the rod cavity pressure tracking controller of the i-th joint, the rod cavity pressure tracking controller of the i-th joint is α 2pi =α 2pai +α 2ps1i +α 2ps2i , thus we get the expected flow rate α of the rod cavity of the i-th joint 2pi Where, α 2pai is α 2pi The adaptive model compensation term, α 2ps1i is α 2pi The linear robust feedback term, α 2ps2i is α 2pi The nonlinear robust feedback term of ;

[0216] The expected flow rate α of the rod cavity of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained from this 2p =[α 2p1 α 2p2 α 2p3 ] T .

[0217] The third step is to 2p , Q 1m Calculate the control voltages of PS1, PV1, PV2, PV3, and PV4 corresponding to each joint to distribute the pump and valve flow of each joint.

[0218] This step can be performed by the control voltage acquisition module, thus solving the technical problems of high-order nonlinearity, model uncertainty, and high energy consumption of existing single-leg hydraulic power-assisted exoskeletons.

[0219] (1) The calculation method of the control voltages of PS1, PV1, PV2, PV3, and PV4 corresponding to each joint includes the following steps:

[0220] According to α 2p , Q 1m Distribute pump and valve flow to each joint;

[0221] For the i-th joint, the control voltage u of the variable speed pump PS1 of the i-th joint pi for:

[0222] Step 1: Determine whether the pump provides flow to the rodless chamber of the hydraulic cylinder or to the rod chamber of the hydraulic cylinder.

[0223] If Q 1mi >0,α2pi ≥0, then sw 1i =1,sw 2i =0;

[0224] If Q 1mi >0,α 2pi <0;

[0225] If |Q 1madi |≥|α 2padi |, sw 1i =1,sw 2i =0;

[0226] If |Q 1madi |<|α 2padi |, sw 1i =0, sw 2i =1;

[0227] If Q 1mi ≤0,α 2pi ≥0, then sw 1i =0, sw 2i =0;

[0228] If Q 1mi ≤0,α 2pi <0, then sw 1i =0, sw 2i =1;

[0229] Among them, sw 1i and sw 2i They represent the switch state of the switch valve when the flow of the pump control part in the hydraulic cylinder i enters the rodless chamber of the hydraulic cylinder and the switch state of the switch valve when entering the rod chamber of the hydraulic cylinder, respectively. Q 1madi and α 2padi They respectively represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint.

[0230] Step 2: Determine the expected output flow rate Q of the pump pdi .

[0231] 1) Calculate Q 1madi and α 2padi .

[0232] Let Q 1mad =[Q 1mad1 Q 1mad2 Q 1mad3 ] T ;

[0233]

[0234]

[0235] If Q 1mi Q 1madi ≤0, then Q 1madi =0;

[0236] If α 2pi α 2padi ≤0, then α 2padi =0;

[0237] Among them, Q 1madi It's Q 1mad The i-th element of Q 1madi and α 2padi They represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint, respectively, di represents the motion reference trajectory of hydraulic cylinder i, is x di about The first-order partial derivative of V 1di =V h1i +A 1i x di and V 2di =V h2i -A 2i x di are the compressible volume V at the i-th hydraulic cylinder 1i and V 2i Using motion reference trajectory x di Replace x Li The expression form, N 1d =diag{A 11 / V 1d1 ,A 12 / V 1d2 ,A 13 / V 1d3}, N 2d =diag{A 21 / V 2d1 ,A 22 / V 2d2 ,A 23 / V 2d3}, α 2pad =[α 2pad1 α 2pad2 α 2pad3 ] T ,

[0238] φ 4cd =[0 3×7 0 3×3 0 3×3 N 2d α2pad -q vd I 3×3 ] T , is the estimated value of the exoskeleton system parameters, F Ldad is the expected compensation driving force of the hydraulic cylinder at each joint, and F Ldad about and the partial derivatives of t, is the estimated value of the constant part of the uncertainty of the rod cavity model in hydraulic cylinder i, is the derivative of the desired pressure in the rod chamber of the i-th hydraulic cylinder, Q 1mi is the expected flow rate of the rodless cavity of the i-th joint, α 2pi is the expected flow rate of the rod cavity of the i-th joint.

[0239] 2) Calculate Q pdi .

[0240] Q pdi =sw 1i Q 1madi -sw 2i α 2padi ;

[0241] If 0≤Q pdi ≤Q pbound , then Q pdi =0;

[0242] Among them, Q pbound Indicates the minimum boundary flow rate when using a variable speed pump. In this example, Q pbound =1×10 - 6 m 3 / s,Q pdi represents the expected output flow of the variable speed pump corresponding to hydraulic cylinder i.

[0243] Step 3: Calculate the control voltage of the pump.

[0244] The control voltage of the variable speed pump corresponding to the hydraulic cylinder i is Among them, the flow gain coefficient k p =8.3×10 -5 m 3 / (s·V).

[0245] The control voltage u of the servo valve of the i-th joint pv1i ,u pv2i ,u pv3i ,u pv4i for:

[0246] Q 1pdi =sw1i Q pdi , Q 2pdi = sw 2i Q pdi , Q 1vdi = Q 1mi - Q 1pdi , Q 2vdi = a 2pi + Q 2pdi , where Q 1pdi and Q 2pdi represent the desired oil inflow to the rodless chamber and the desired oil outflow from the rod chamber in the ith joint from the pump-controlled part, respectively, Q 1vdi and Q 2vdi represent the desired oil inflow to the rodless chamber and the desired oil outflow from the rod chamber in the ith joint from the valve-controlled part, respectively;

[0247] If Q 1vdi > 0, then u pv3i = 0;

[0248] If Q 1vdi < 0, then u pv1i = 0,

[0249] If Q 1vdi = 0, then u pv1i = 0, u pv3i = 0;

[0250] If Q 2vdi > 0, then u pv2i = 0,

[0251] If Q 2vdi < 0, then u pv4i = 0;

[0252] If Q 2vdi = 0, then u pv2i = 0, u pv4i = 0;

[0253] where u pv1i is the control voltage of PV1 in the ith joint; u pv2i is the control voltage of PV2 in the ith joint; u pv3i is the control voltage of PV3 in the ith joint; and u pv4i is the control voltage of PV4 in the ith joint.

[0254] Thus, the control voltages of PS1, PV1, PV2, PV3 and PV4 corresponding to each joint are obtained.

[0255] The fourth step is to calculate the dynamic model of the hydraulic actuator in the i-th joint according to the control voltages of PS1, PV1, PV2, PV3, and PV4 corresponding to each joint. The actual pressure P of the rod cavity corresponding to the hydraulic cylinder in the i-th joint is obtained 2i Where Q 2i is the oil flow rate out of the rod chamber of the hydraulic cylinder in the i-th joint; x Li is the displacement of the hydraulic cylinder in the i-th joint, is x Li About q i The first-order partial derivative of V 2i =V h2i -A 2i x Li is the total volume of the rod chamber of the hydraulic cylinder in the i-th joint, V h2i It is q i = 0, the volume of the rod chamber of the hydraulic cylinder in the i-th joint, β e represents the bulk elastic modulus; represents the concentrated modeling error and uncertain interference in the dynamic model of the hydraulic actuator in the i-th joint; thereby, the actual pressure P2 of the rod cavity corresponding to the hydraulic cylinder in each joint of the single-leg hydraulic power-assisted exoskeleton is obtained; according to the actual pressure P of the rodless cavity corresponding to the hydraulic cylinder in the i-th joint 1i And the actual pressure P of the rod chamber 2i , get the actual driving force F of the hydraulic cylinder in the i-th joint Li =P 1i A 1i -P 2i A 2i ; From this, we can get the actual driving force F of the hydraulic cylinder of each joint of the single-leg hydraulic power-assisted exoskeleton L =[F L1 F L2 F L3 ] T .

[0256] This step can be performed by the hydraulic cylinder actual driving force acquisition module.

[0257] The fifth step is to calculate the actual driving force F of the hydraulic cylinder of each joint of the single-leg hydraulic power-assisted exoskeleton. L ; For the i-th joint, the actual driving torque τ of the i-th joint is obtained i =F Li h i Where h i Represents the force arm between the rotation point of the i-th joint and the hydraulic cylinder; thus, the actual driving torque τ of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained act =[τ1 τ2τ3] T .

[0258] This step can be performed by the joint actual driving torque acquisition module.

[0259] Step 6: According to τ act , and based on the motion model of the exoskeleton mechanical body The actual rotation angle q and the actual rotation angular velocity of each joint are obtained from this. Among them, τ act =[τ1τ2τ3] T is the actual joint driving torque at the ankle, knee and hip joints, J is the Jacobian matrix of the system at the force sensor, M sp3 (q) is the inertia matrix of the system, is the centrifugal force and Coriolis force matrix of the system, G sp3 (q) is the gravity matrix of the system, B = diag{B1, B2, B3} is the damping matrix of the system, It is a concentrated interference of the system.

[0260] This step can be performed by the rotation angular velocity acquisition module. Among them, the fourth, fifth, and sixth steps introduce the steps after the pump valve flow distribution of each joint.

[0261] The present invention's single-leg hydraulically assisted exoskeleton control method under heavy load is suitable for single-leg use. The power system it uses is a hydraulic system with the characteristics of small size, light weight, flexible layout, compact structure, and the ability to output large force or torque, sensitive action response, and easy control. The hydraulic system adopts a parallel pump-valve coordinated electro-hydraulic system solution, allowing the pump control part to provide the main flow and the valve control part to provide a small flow, thereby improving the energy efficiency level of the lower limb power-assisted exoskeleton electro-hydraulic system. The present invention's single-leg hydraulically assisted exoskeleton control method adopts a force control method and uses the adaptive robust control algorithm (ARC) to design the upper and lower layer controllers, effectively overcoming the effects of high-order nonlinearity and model uncertainty of the single-leg hydraulically assisted exoskeleton. In the lower layer controller, the rodless cavity of the hydraulic cylinder adopts position tracking control, and the rod cavity of the hydraulic cylinder adopts pressure tracking control, which solves the technical problem of high energy consumption of existing exoskeleton control methods. The flow distribution adopts a solution in which the pump provides low-frequency flow and the valve provides high-frequency flow, which solves the problem of flow distribution caused by the non-negligible compressibility of the oil under heavy load. This invention not only enables the hydraulically assisted exoskeleton to effectively follow and assist human movement under heavy loads, but also reduces system energy consumption and achieves a longer battery life, demonstrating its high application value. This invention effectively overcomes the effects of the strong coupling of multiple joints, the high-order nonlinearity of the hydraulic drive, and model uncertainty in single-leg hydraulically assisted exoskeletons. It not only enables the hydraulically assisted exoskeleton to effectively follow and assist human movement under heavy loads, but also reduces system energy consumption and achieves a longer battery life.

[0262] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0263] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for controlling a single-leg hydraulically assisted exoskeleton under heavy loads, wherein the three hydraulic systems of the exoskeleton's ankle, knee, and hip joints all employ parallel pump-valve coordinated electro-hydraulic systems. Each parallel pump-valve coordinated electro-hydraulic system comprises a parallel coordinated pump control section and a valve control section. The pump control section comprises a variable speed pump and two on-off valves SV1 and SV2 that determine the flow direction of the variable speed pump outlet. The valve control section comprises four servo valves PV1, PV2, PV3, and PV4. The desired flow rate α of the rod chamber of the hydraulic cylinder in each joint is determined based on the desired flow rate α. 2p , rodless cavity expected flow Q 1m , distribute the pump and valve flow of each joint, and then obtain the control voltage of the variable speed pump and servo valve corresponding to each joint to control the movement of the single-leg hydraulic power-assisted exoskeleton; It is characterized by: The method for distributing pump and valve flow includes determining a control voltage u of a variable speed pump corresponding to a hydraulic cylinder i. pi and determine the control voltage u of the servo valve corresponding to the hydraulic cylinder i pv1i ,u pv2i ,u pv3i ,u pv4i , the pump control part and the valve control part are controlled according to the control voltage; Among them, determine the control voltage u of the variable speed pump corresponding to the hydraulic cylinder i pi The method comprises the following steps: Determine whether the variable speed pump provides flow to the rodless chamber of hydraulic cylinder i or the rod chamber of hydraulic cylinder i, and control the switching state of the corresponding switching valve accordingly: Calculate Q 1madi and α 2padi :Let Q 1mad =[Q 1mad1 Q 1mad2 Q 1mad3 ] T ; If Q 1mi Q 1madi ≤0, then Q 1madi =0; If α 2pi α 2padi ≤0, then α 2padi =0; Where Q 1madi It's Q 1mad The i-th element of Q 1madi and α 2padi They represent the expected flow of the low-frequency part of the hydraulic cylinder rodless cavity compensation and the expected flow of the low-frequency part of the hydraulic cylinder rod cavity compensation using the joint reference trajectory of the i-th joint, respectively, di represents the motion reference trajectory of hydraulic cylinder i, is x di about The first-order partial derivative of A 1i and A 2i V represents the effective area of ​​the rodless cavity and the rod cavity in the hydraulic cylinder i, 1di =V h1i +A 1i x di and V 2di =V h2i -A 2i x di are the compressible volume V at the i-th hydraulic cylinder 1i and V 2i Using motion reference trajectory x di Replace x Li The expression form, is an estimate of the elastic modulus, N 1d =diag{A 11 / V 1d1 ,A 12 / V 1d2 ,A 13 / V 1d3 }, N 2d =diag{A 21 / V 2d1 ,A 22 / V 2d2 ,A 23 / V 2d3 }, α 2pad =[α 2pad1 α 2pad2 α 2pad3 ] T , φ 4cd =[0 3×7 0 3×3 0 3×3 N 2d α 2pad -q vd I 3×3 ] T , is the estimated value of the exoskeleton system parameters, F Ldad is the expected compensation driving force of the hydraulic cylinder at each joint, and F Ldad about and the partial derivatives of t, is the estimated value of the constant part of the uncertainty of the rod cavity model in hydraulic cylinder i, is the derivative of the desired pressure in the rod chamber of the i-th hydraulic cylinder, Q 1mi is the expected flow rate of the rodless cavity of the i-th joint, α 2pi is the expected flow rate of the rod cavity of the i-th joint; Calculate the expected output flow Q of the variable speed pump corresponding to hydraulic cylinder i pdi :Q pdi =sw 1i Q 1madi -sw 2i α 2padi ; If 0≤Q pdi ≤Q pbound , then Q pdi =0; Where Q pbound Indicates the minimum boundary flow rate for using a variable speed pump; Calculate the control voltage of the variable speed pump corresponding to the hydraulic cylinder i as follows: Where k p is the flow gain coefficient.

2. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: The method for controlling the switching state of the corresponding switching valve comprises the following steps: If Q 1mi >0,α 2pi ≥0, then sw 1i =1,sw 2i =0; If Q 1mi >0,α 2pi <0; If |Q 1madi |≥|α 2padi |, sw 1i =1,sw 2i =0; If |Q 1madi |<|α 2padi |, sw 1i =0, sw 2i =1; If Q 1mi ≤0,α 2pi ≥0, then sw 1i =0, sw 2i =0; If Q 1mi ≤0,α 2pi <0, then sw 1i =0, sw 2i =1; Among them, sw 1i and sw 2i They respectively represent the switching state of the switch valve when the flow of the pump control part in the hydraulic cylinder i enters the rodless chamber of the hydraulic cylinder and the switching state of the switch valve when entering the rod chamber of the hydraulic cylinder.

3. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: The joint reference trajectory includes the reference rotation angle of each joint Reference angular velocity and the reference angular acceleration 4. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: The expected flow of the low-frequency part is the value calculated by replacing the actual trajectory with the joint reference trajectory for the remaining part after removing the part directly related to the measurement error from the compensation term of the expected flow model of each joint.

5. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: Determine the control voltage u of the servo valve corresponding to the hydraulic cylinder i pv1i ,u pv2i ,u pv3i ,u pv4i The method is: Q 1pdi =sw 1i Q pdi ,Q 2pdi =sw 2i Q pdi ,Q 1vdi =Q 1mi -Q 1pdi ,Q 2vdi =α 2pi +Q 2pdi Where Q 1pdi and Q 2pdi They represent the expected oil flow rate of the rodless chamber and the rod chamber from the pump control part in the hydraulic cylinder i, respectively, and Q 1vdi and Q 2vdi They represent the expected oil inlet flow rate of the rodless chamber and the expected oil outlet flow rate of the rod chamber from the valve control part in the hydraulic cylinder i respectively; If Q 1vdi >0, then u pv3i =0; If Q 1vdi <0, then u pv1i =0, If Q 1vdi =0, then u pv1i =0,u pv3i =0; If Q 2vdi >0, then u pv2i =0, If Q 2vdi <0, then u pv4i =0; If Q 2vdi =0, then u pv2i =0,u pv4i =0; Where k qpv1i 、k qpv2i 、k qpv3i 、k qpv4i They are the flow gain coefficient of the hydraulic cylinder i corresponding to a servo valve, ΔP pv1i and ΔP pv2i They represent the pressure difference between the oil supply pressure of the valve control part of the hydraulic cylinder i and the actual pressure of the rodless chamber and the actual pressure of the rod chamber, ΔP pv3i and ΔP pv4i They respectively represent the pressure difference between the actual pressure of the rodless chamber and the actual pressure of the rod chamber in hydraulic cylinder i and the tank pressure.

6. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: The control voltage u of the servo valve is increased by the amplifier board pv1i ,u pv2i ,u pv3i ,u pv4i Converted into the control current of the corresponding servo valve, the valve core opening displacement of the corresponding servo valve is controlled by the control current; the control voltage u of the variable speed pump is used pi Controls the speed of the servo motor of the variable speed pump.

7. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: Expected flow rate Q of the rodless chamber in each joint hydraulic cylinder 1m The calculation method includes the following steps: According to the reference rotation angle of each joint Reference angular velocity Reference angular acceleration Actual driving force F of hydraulic cylinder L 、Expected flow rate of the rod chamber of the hydraulic cylinder α 2p , actual rotation angle q, actual rotation angular velocity Design a rodless cavity position tracking controller; the rodless cavity position tracking controller is Q 1m =Q 1ma +Q 1ms +Q 1msn , thus obtaining the expected flow Q of the rodless cavity of each joint of the single-leg hydraulic power-assisted exoskeleton 1m , where Q 1ma Q 1m The adaptive model compensation term, Q 1ms Q 1m The linear robust feedback term, Q 1msn Q 1m The nonlinear robust feedback term.

8. The method for controlling a single-leg hydraulically assisted exoskeleton under heavy load according to claim 1, characterized in that: The expected flow rate α in the rod chamber of each joint hydraulic cylinder 2p The calculation method includes the following steps: According to the reference rotation angle of each joint Reference angular velocity Reference angular acceleration Actual driving force F of hydraulic cylinder L 、Expected flow rate of the rod chamber of the hydraulic cylinder α 2p , actual rotation angle q, actual rotation angular velocity Design a rodless cavity position tracking controller, the rodless cavity position tracking controller is F Ld =F Lda +F Lds +F Ldsn , and thus the expected driving force F of the hydraulic cylinder of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained Ld Where, F Lda F Ld The adaptive model compensation term, F Lds F Ld The linear robust feedback term, F Ldsn F Ld The nonlinear robust feedback term of ; According to F Ld =[F Ld1 F Ld2 F Ld3 ] T Design the rod cavity pressure planner for each joint. Considering that a good control design can ensure that the system error is within a small range, the adaptive model compensation term F Lda Can basically characterize the expected driving force F of the hydraulic cylinder Ld In addition, in order to obtain a more continuous and smooth desired pressure in the rod cavity and avoid the negative influence of noise, the joint reference trajectory is used instead of the measurement signal of the state quantity, that is, the hydraulic cylinder expected compensation driving force F Ldad =[F Ldad1 F Ldad2 F Ldad3 ] T , the expected compensation driving force of the hydraulic cylinder of the i-th joint is F Ldadi ; F at the i-th joint Ldadi , the rod cavity pressure planner of the i-th joint is The expected pressure P of the rod cavity of the i-th joint is obtained 2di Where, P c is the set minimum working pressure, A 1i and A 2i They represent the effective areas of the rodless cavity and the rod cavity in the i-th joint respectively; According to P 2di and the actual pressure P of the rod cavity of the i-th joint 2i , design the rod cavity pressure tracking controller of the i-th joint, the rod cavity pressure tracking controller of the i-th joint is α 2pi =α 2pai +α 2ps1i +α 2ps2i , thus we get the expected flow rate α of the rod cavity of the i-th joint 2pi Where, α 2pai is α 2pi The adaptive model compensation term, α 2ps1i is α 2pi The linear robust feedback term, α 2ps2i is α 2pi The nonlinear robust feedback term of ; The expected flow rate α of the rod cavity of each joint of the single-leg hydraulic power-assisted exoskeleton is obtained 2p =[α 2p1 α 2p2 α 2p3 ] T .

9. A heavy-load single-leg hydraulically assisted exoskeleton control device, characterized in that: It adopts the heavy-load single-leg hydraulic-assisted exoskeleton control method according to any one of claims 1 to 8, and the control device includes: Multiple parallel pump-valve coordinated electro-hydraulic systems; each parallel pump-valve coordinated electro-hydraulic system includes a parallel coordinated pump control section and a valve control section; the pump control section includes a variable speed pump PS1 and two two-way switch valves SV1 and SV2 that determine the outlet flow direction of the variable speed pump PS1; the valve control section includes four two-way electro-hydraulic servo valves PV1, PV2, PV3, and PV4 and a hydraulic oil source PS2. The electro-hydraulic servo valves PV1 and PV2 control the flow of hydraulic oil from the hydraulic source PS2 to the two chambers of the corresponding hydraulic cylinder, and the electro-hydraulic servo valves PV3 and PV4 control the flow of hydraulic oil from the two chambers of the corresponding hydraulic cylinder to the oil tank; The flow acquisition module is used to coordinate the electro-hydraulic system of the parallel pump valves of each joint of the single-leg hydraulic power-assisted exoskeleton, according to the reference rotation angle of each joint Reference angular velocity Reference angular acceleration Actual driving force F of hydraulic cylinder L , actual rotation angle q, actual rotation angular velocity Get the expected flow rate α of the rod cavity of each joint 2p =[α 2p1 α 2p2 α 2p3 ] T and the desired flow rate Q of the rodless cavity 1m =[Q 1m1 Q 1m2 Q 1m3 ] T ; where i represents the serial number of the three joints, the expected flow rate of the rod cavity of the i-th joint is α 2pi , the expected flow rate of the rodless cavity of the i-th joint is Q 1mi ; The control voltage acquisition module is used to obtain the voltage according to α 2p , Q 1m Calculate the control voltages of PS1, PV1, PV2, PV3, and PV4 corresponding to each joint to distribute the pump and valve flow of each joint.

10. A heavy-load single-leg hydraulically assisted exoskeleton, characterized in that: It adopts the heavy-load single-leg hydraulically assisted exoskeleton control method as described in any one of claims 1 to 8.

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