A powered ankle-foot prosthesis based on electro-hydraulic direct drive and control method

Abstract

A powered ankle-foot prosthesis and control method based on electro-hydraulic direct drive, belonging to the field of mechanical and hydraulic technology. The present invention solves the problem that the existing powered ankle-foot prosthesis has a low power density ratio and performs poorly in practical applications. The control module of the present invention is connected to the electro-hydraulic direct drive actuator, and fluid pipelines are distributed in the hydraulic valve block. The hydraulic cylinder, the first energy storage sensor and the first pressure sensor are connected to one fluid pipeline with one end oil port of the bidirectional gear pump, and the hydraulic cylinder, the second accumulator and the second pressure sensor are connected to another fluid pipeline with the other end oil port of the bidirectional gear pump, and the calf prosthesis is connected to the hydraulic cylinder. A powered ankle-foot prosthesis and control method based on electro-hydraulic direct drive of the present invention can absorb the negative work done by the human body on the ankle-foot prosthesis in the dorsiflexion control stage through bilateral accumulators, and reduce the peak power required by the prosthesis drive unit in the power plantar flexion stage, thereby realizing energy recovery and power amplification.

Description

Technical Field

[0001] The invention belongs to the field of mechanical and hydraulic technology, and in particular relates to a powered ankle-foot prosthesis based on electro-hydraulic direct drive and a control method thereof. Background Art

[0002] According to relevant surveys, the number of disabled people in the world has reached 650 million. What is not optimistic is that these numbers are still rising year by year. By increasing publicity efforts, popularizing safety knowledge, and issuing subsidies to the disabled, the lives of the disabled can be improved and the emergence of disabled people can be prevented to a certain extent. There are more and more attempts to fundamentally solve the difficulties of the disabled with scientific and technological means and help the disabled return to normal life. Medical assistive devices are becoming more and more common in social life. For disabled people with lower limb amputations, a prosthesis that can enable the disabled to regain the ability to walk normally is of great significance.

[0003] Most of the existing contouring prostheses that have appeared and are actually put into use are passive, that is, they only play a supporting function. Among them, some prostheses introduce special materials or energy storage elements to a certain extent, which can better restore the function of the human ankle. However, since they do not have the function of actively providing power, they cannot enable amputees to gain considerable walking ability. The use of these passive ankle-foot prostheses will have defects such as slow walking, small stride, and asymmetry. Powered ankle-foot prostheses can actively provide sufficient power for the wearer's walking, and at the same time have functions such as buffering and shock absorption. They are advanced equipment that make up for the defects of passive prostheses. However, the existing powered ankle-foot prostheses have a low power density ratio and perform poorly in practical applications.

[0004] Based on the above background, the present application proposes a powered ankle-foot prosthesis based on electro-hydraulic direct drive and a control method to solve the above problems. Summary of the invention

[0005] The purpose of the research and development of the present invention is to solve the problem that the existing powered ankle-foot prosthesis has a low power density ratio and performs poorly in practical applications. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0006] The technical solution of the present invention:

[0007] Solution 1: A powered ankle-foot prosthesis based on electro-hydraulic direct drive, comprising an electro-hydraulic direct drive actuator, a calf prosthesis and a control module. The control module is connected to the electro-hydraulic direct drive actuator in the form of an electrical signal. The electro-hydraulic direct drive actuator comprises a servo motor, a bidirectional gear pump, a first accumulator, a second accumulator, a hydraulic cylinder, a first pressure sensor, a second pressure sensor and a hydraulic valve block. The servo motor, the bidirectional gear pump, the first accumulator, the second accumulator, the hydraulic cylinder, the first pressure sensor and the second pressure sensor are respectively installed on the hydraulic valve block. The servo motor is connected to the bidirectional gear pump. Fluid pipelines are distributed in the hydraulic valve block. The hydraulic cylinder, the first accumulator and the first pressure sensor are connected to one fluid pipeline with one end oil port of the bidirectional gear pump. The hydraulic cylinder, the second accumulator and the second pressure sensor are connected to another fluid pipeline with the other end oil port of the bidirectional gear pump. The calf prosthesis is connected to the hydraulic cylinder.

[0008] Furthermore, the calf prosthesis includes an arch, a heel and a connecting frame, which are sequentially mounted at the bottom of the connecting frame. The connecting frame is connected to the hydraulic cylinder via a first connecting frame connecting shaft and a second connecting frame connecting shaft. The second connecting frame connecting shaft is connected to a piston rod connecting end, and the piston rod connecting end is connected to a cylinder body of the hydraulic cylinder via the piston rod connecting shaft.

[0009] Furthermore, a receiving cavity interface is installed on the upper sealing cover of the hydraulic cylinder.

[0010] Furthermore, the first pressure sensor and the second pressure sensor are connected to the control module via electrical signals.

[0011] Solution 2: A control method for a powered ankle-foot prosthesis based on electro-hydraulic direct drive, which is based on the control method for a powered ankle-foot prosthesis based on electro-hydraulic direct drive described in Solution 1 and includes the following stages:

[0012] Controlling plantar flexion: The heel touches the ground before the arch of the foot, and the bidirectional gear pump and the hydraulic cylinder form a closed circuit. The piston rod of the hydraulic cylinder will be passively retracted, and the oil will flow through the oil outlet at one end of the bidirectional gear pump and the oil port at one end of the hydraulic cylinder in turn, and flow back from the oil port at the other end of the hydraulic cylinder to the oil inlet at the other end of the bidirectional gear pump. In this process, the first accumulator and the second accumulator can adjust the circuit pressure, and the servo motor is controlled to drive the bidirectional gear pump to rotate, providing a certain damping for the hydraulic oil, simulating the damping of controlling the plantar flexion stage during human walking;

[0013] Control dorsiflexion: Driven by the knee, the calf moves forward, the piston rod of the hydraulic cylinder will be passively extended, and the oil will flow through the oil outlet at one end of the two-way gear pump and the oil port at one end of the hydraulic cylinder in turn, and flow back to the oil inlet at the other end of the two-way gear pump from the oil port at the other end of the hydraulic cylinder. In this process, the first accumulator and the second accumulator regulate the circuit pressure and store energy at the same time. The cooperation of the servo motor and the two-way gear pump simulates the damping of this stage during human walking;

[0014] Power plantar flexion: The power ankle-foot prosthesis actively provides power, the piston rod of the hydraulic cylinder actively retracts, and the oil flows through the oil outlet at one end of the bidirectional gear pump and the oil port at one end of the hydraulic cylinder in sequence, and flows back to the oil inlet at the other end of the bidirectional gear pump from the oil port at the other end of the hydraulic cylinder. In this process, the first accumulator and the second accumulator regulate the circuit pressure and release the stored energy at the same time to assist the bidirectional gear pump in providing power;

[0015] Swinging stage: the powered ankle-foot prosthesis actively returns to its initial position, and the piston rod of the hydraulic cylinder actively extends, allowing the powered ankle-foot prosthesis to complete the dorsiflexion movement. The oil flows through the oil outlet at one end of the two-way gear pump and the oil port at one end of the hydraulic cylinder in turn, and flows back to the oil inlet at the other end of the two-way gear pump from the oil port at the other end of the hydraulic cylinder. During this process, the first accumulator and the second accumulator adjust the circuit pressure.

[0016] The present invention has the following beneficial effects:

[0017] 1. The hydraulic circuit actuator of a powered ankle-foot prosthesis based on electro-hydraulic direct drive of the present invention has a first accumulator and a second accumulator on both sides, respectively. The accumulator, as a gas-liquid spring, can absorb the negative work done by the human body on the ankle-foot prosthesis in the dorsiflexion control stage, and reduce the peak power required by the prosthesis drive unit in the power plantar flexion stage, thereby realizing energy recovery and power amplification;

[0018] 2. The electro-hydraulic direct-drive powered ankle-foot prosthesis of the present invention can generate nonlinear impedance, which has a better reduction degree of the impedance of the human ankle-foot than the prosthesis using mechanical springs, thereby better matching the energy flow of the human ankle-foot and having higher operating efficiency;

[0019] 3. The dual accumulators provided in the electro-hydraulic direct-drive powered ankle-foot prosthesis of the present invention can eliminate the pressure pulsation and actuator speed pulsation caused by the pump flow pulsation to a certain extent, and the vibration absorption system is stable and reliable;

[0020] 4. The powered ankle-foot prosthesis based on electro-hydraulic direct drive of the present invention does not require an oil replenishing valve required by the electro-hydraulic direct drive system, thereby streamlining the hydraulic circuit, and has a simpler manufacturing process and lower manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a schematic diagram of the overall structure of a powered ankle-foot prosthesis based on electro-hydraulic direct drive;

[0022] Figure 2 It is the schematic diagram of the electro-hydraulic direct drive actuator;

[0023] Figure 3 This is a schematic diagram of the gait phase division of the ankle joint of a powered ankle-foot prosthesis based on electro-hydraulic direct drive technology;

[0024] Figure 4 This is the front view of the electro-hydraulic direct drive actuator;

[0025] Figure 5 It is a schematic diagram of the states of the electro-hydraulic direct-drive actuator in the dorsiflexion stage and the swing stage;

[0026] Figure 6 It is a schematic diagram of the state of the electro-hydraulic direct-drive actuator for controlling plantar flexion and power plantar flexion;

[0027] Figure 7 It is a simulation model diagram of a powered ankle-foot prosthesis based on electro-hydraulic direct drive;

[0028] Figure 8 It is a power simulation diagram of a powered ankle-foot prosthesis based on electro-hydraulic direct drive;

[0029] Fig. 9 It is a simulation comparison diagram of the flow pulsation elimination effect of a powered ankle-foot prosthesis based on electro-hydraulic direct drive and a powered ankle-foot prosthesis without a dual accumulator;

[0030] Fig.10 This is a stiffness comparison chart of the bilateral accumulators set up in a powered ankle-foot prosthesis based on electro-hydraulic direct drive and the traditional mechanical springs.

[0031] In the figure: 1-servo motor, 2-coupling, 3-bidirectional gear pump, 4-first accumulator, 5-second accumulator, 6-hydraulic cylinder, 7-first pressure sensor, 8-second pressure sensor, 9-receiving chamber interface, 10-piston rod connecting shaft, 11-piston rod connecting end, 12-first connecting frame connecting shaft, 13-second connecting frame connecting shaft, 14-arch, 15-heel, 16-connecting frame, 17-hydraulic valve block, 18-angle conversion block, 19-displacement sensor, 20-external load sample, 21-controller, 22-angle sample. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0033] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection (i.e., non-detachable connection) includes but is not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but is not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and hinge connection is selected for detachable connection.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Embodiment 1, combination Figure 1-Figure 10 The present embodiment is described. A powered ankle-foot prosthesis based on electro-hydraulic direct drive in the present embodiment comprises an electro-hydraulic direct drive actuator, a calf prosthesis and a control module. The control module is connected to the electro-hydraulic direct drive actuator in the form of an electrical signal. The electro-hydraulic direct drive actuator comprises a servo motor 1, a bidirectional gear pump 3, a first accumulator 4, a second accumulator 5, a hydraulic cylinder 6, a first pressure sensor 7, a second pressure sensor 8 and a hydraulic valve block 17. The servo motor 1, the bidirectional gear pump 3, the first accumulator 4, the second accumulator 5, the hydraulic cylinder 6, the first pressure sensor 7 and the second pressure sensor 8 are respectively mounted on the hydraulic valve block 17. The servo motor 1 is connected to the bidirectional gear pump 3 through a coupling 2. Fluid pipelines are distributed in the hydraulic valve block 17. The hydraulic cylinder 6, the first accumulator 4 and the first pressure sensor 7 are connected to one end of the oil port of the bidirectional gear pump 3 in a fluid pipeline. The hydraulic cylinder 6, the second accumulator 5 and the second pressure sensor 8 are connected to the other end of the oil port of the bidirectional gear pump 3 in another fluid pipeline. The calf prosthesis is connected to the hydraulic cylinder 6.

[0036] The calf prosthesis includes an arch 14, a heel 15 and a connecting frame 16. The connecting frame 16 is connected to the hydraulic cylinder 6 through the first connecting frame connecting shaft 12 and the second connecting frame connecting shaft 13, wherein the connecting frame 16 is connected to the piston rod connecting end 11 through the second connecting frame connecting shaft 13, and the piston rod connecting end 11 is connected to the piston rod section of the hydraulic cylinder 6 through the piston rod connecting shaft 10. The connecting frame 16 is connected to the cylinder body of the hydraulic cylinder 6 through the first connecting frame connecting shaft 12. A receiving cavity interface 9 is provided on the sealing cover of the hydraulic cylinder 6, and the hydraulic cylinder 6 is connected to the residual limb of the amputee wearing the receiving cavity through the receiving cavity interface 9. The arch 14 and the heel 15 are sequentially installed at the bottom of the connecting frame 16, and the coordinated work of the electro-hydraulic direct drive actuator and the hydraulic cylinder 6 provides power for the arch 14 and the heel 15.

[0037] The first pressure sensor 7 and the second pressure sensor 8 are connected to the control module through electrical signals to monitor the pressures of the two fluid circuits. The pressures of the fluid circuits can be adjusted in time according to their feedback signals.

[0038] As attached Figure 7 As shown, a simulation model of a power ankle-foot prosthesis function matching drive unit based on electro-hydraulic direct drive is established in the simulation software Simcenter Amesim, including a servo motor 1, a bidirectional gear pump 3, a hydraulic cylinder 6, a first accumulator 4, a second accumulator 5, a controller 21, a displacement sensor 19 and an angle conversion block 18, and the input signals are an angle sample 22 and an external load sample 20.

[0039] As attached Figure 8 As shown in the figure, a simulation study on the output power of a powered ankle-foot prosthesis based on electro-hydraulic direct drive was carried out using angle samples and external load samples. The simulation results show that negative work can be effectively absorbed in the negative power range, and the peak power of the prosthesis drive unit can be effectively reduced in the positive power range, thereby realizing energy recovery and power amplification.

[0040] As attached Fig. 9 As shown in the figure, a simulation study was carried out on the effect of a powered ankle-foot prosthesis based on electro-hydraulic direct drive on eliminating flow pulsation. The simulation results show that when a uniform speed signal is given, the speed pulsation amplitude of the actuator of a powered ankle-foot prosthesis based on electro-hydraulic direct drive is smaller, while the speed pulsation of the actuator of a powered ankle-foot prosthesis without bilateral accumulators is more intense. A powered ankle-foot prosthesis based on electro-hydraulic direct drive has the effect of eliminating flow pulsation.

[0041] As attached Fig.10 As shown, a simulation study was conducted on the stiffness of the first accumulator 4 and the second accumulator 5 provided in a powered ankle-foot prosthesis based on electro-hydraulic direct drive and the stiffness of a traditional mechanical spring. The simulation results show that the bilateral accumulator has a nonlinear stiffness curve, which can better fit the human body impedance characteristic curve and has a better restoration of the impedance of the human ankle and foot.

[0042] Embodiment 2, combined Figure 1-Figure 7 This embodiment is described. This embodiment is a power ankle-foot prosthesis control method based on electro-hydraulic direct drive. First, the residual limb of the amputee is put on the receiving cavity, and the receiving cavity is connected to the receiving cavity interface 9 on the hydraulic cylinder 6. After the wearing, the following stages are included:

[0043] Controlling plantar flexion: the heel 15 touches the ground before the arch 14, and the bidirectional gear pump 3 and the hydraulic cylinder 6 form a closed loop. The piston rod of the hydraulic cylinder 6 will be passively retracted, and the oil will flow through the oil outlet at one end of the bidirectional gear pump 3 and the oil port at one end of the hydraulic cylinder 6 in sequence, and flow back to the oil inlet at the other end of the bidirectional gear pump 3 from the oil port at the other end of the hydraulic cylinder 6. In this process, the first accumulator 4 and the second accumulator 5 can adjust the circuit pressure, and control it through the servo motor 1 to drive the bidirectional gear pump 3 to rotate, thereby providing a certain damping for the hydraulic oil, simulating the damping of controlling the plantar flexion stage during human walking;

[0044] Control dorsiflexion: Driven by the knee, the calf moves forward, the piston rod of the hydraulic cylinder 6 will be passively extended, and the oil flows through the oil outlet at one end of the two-way gear pump 3 and the oil port at one end of the hydraulic cylinder 6 in turn, and flows back to the oil inlet at the other end of the two-way gear pump 3 from the oil port at the other end of the hydraulic cylinder 6. In this process, the first accumulator 4 and the second accumulator 5 adjust the circuit pressure and store energy at the same time. The cooperation of the servo motor 1 and the two-way gear pump 3 simulates the damping of this stage during human walking;

[0045] Power plantar flexion: The power ankle-foot prosthesis actively provides power, the piston rod of the hydraulic cylinder 6 actively retracts, and the oil flows through the oil outlet at one end of the two-way gear pump 3 and the oil port at one end of the hydraulic cylinder 6 in sequence, and flows back to the oil inlet at the other end of the two-way gear pump 3 from the oil port at the other end of the hydraulic cylinder 6. In this process, the first accumulator 4 and the second accumulator 5 adjust the circuit pressure and release the stored energy to assist the two-way gear pump 3 in providing power;

[0046] Swinging stage: the powered ankle-foot prosthesis actively returns to its initial position, and the piston rod of the hydraulic cylinder 6 actively extends, allowing the powered ankle-foot prosthesis to complete the dorsiflexion movement. The oil flows through the oil outlet at one end of the two-way gear pump 3 and the oil port at one end of the hydraulic cylinder 6 in turn, and flows back from the oil port at the other end of the hydraulic cylinder 6 to the oil inlet at the other end of the two-way gear pump 3. During this process, the first accumulator 4 and the second accumulator 5 adjust the circuit pressure.

[0047] This embodiment is only an exemplary description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto. As long as they do not exceed the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A powered ankle-foot prosthesis based on electro-hydraulic direct drive, characterized in that: The invention comprises an electro-hydraulic direct-drive actuator, a calf prosthesis and a control module, wherein the control module is connected to the electro-hydraulic direct-drive actuator in the form of an electrical signal, wherein the electro-hydraulic direct-drive actuator comprises a servo motor (1), a bidirectional gear pump (3), a first accumulator (4), a second accumulator (5), a hydraulic cylinder (6), a first pressure sensor (7), a second pressure sensor (8) and a hydraulic valve block (17), wherein the servo motor (1), the bidirectional gear pump (3), the first accumulator (4), the second accumulator (5), the hydraulic cylinder (6), the first pressure sensor (7) and the second pressure sensor (8) are respectively mounted on the hydraulic valve block (17); the servo motor (1) is connected to the bidirectional gear pump (3); a fluid pipeline is distributed in the hydraulic valve block (17); the hydraulic cylinder (6), the first accumulator (4) and the first pressure sensor (7) are connected to one fluid pipeline with one end oil port of the bidirectional gear pump (3); the hydraulic cylinder (6), the second accumulator (5) and the second pressure sensor (8) are connected to the other end oil port of the bidirectional gear pump (3) with another fluid pipeline; and the lower leg prosthesis is connected to the hydraulic cylinder (6); The calf prosthesis comprises a foot arch (14), a heel (15) and a connecting frame (16); the foot arch (14) and the heel (15) are sequentially mounted on the bottom of the connecting frame (16); the connecting frame (16) is connected to the hydraulic cylinder (6) via a first connecting frame connecting shaft (12) and a second connecting frame connecting shaft (13); the second connecting frame connecting shaft (13) is connected to a piston rod connecting end (11); and the piston rod connecting end (11) is connected to a cylinder body of the hydraulic cylinder (6) via a piston rod connecting shaft (10); Controlling plantar flexion: the heel (15) touches the ground before the arch (14), the bidirectional gear pump (3) and the hydraulic cylinder (6) form a closed circuit, the piston rod of the hydraulic cylinder (6) will be passively retracted, and the oil will flow through the oil outlet at one end of the bidirectional gear pump (3) and the oil port at one end of the hydraulic cylinder (6) in sequence, and flow back from the oil port at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) can adjust the circuit pressure, and control the bidirectional gear pump (3) through the servo motor (1), so as to provide a certain damping for the hydraulic oil, simulating the damping of controlling the plantar flexion stage during human walking; Controlling dorsiflexion: driven by the knee, the lower leg moves forward, the piston rod of the hydraulic cylinder (6) is passively extended, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil outlet at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil outlet at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure and store energy at the same time. The coordinated work of the servo motor (1) and the bidirectional gear pump (3) simulates the damping of this stage during human walking. Power plantar flexion: the power ankle-foot prosthesis actively provides power, the piston rod of the hydraulic cylinder (6) actively retracts, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil outlet at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil outlet at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure and release the stored energy to assist the bidirectional gear pump (3) in providing power; Swinging stage: the powered ankle-foot prosthesis actively returns to the initial position, the piston rod of the hydraulic cylinder (6) actively extends, so that the powered ankle-foot prosthesis completes the dorsiflexion movement, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil port at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil port at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure.

2. The electro-hydraulic direct-drive powered ankle-foot prosthesis according to claim 1, characterized in that: A receiving cavity interface (9) is installed on the upper sealing cover of the hydraulic cylinder (6).

3. The electro-hydraulic direct-drive powered ankle-foot prosthesis according to claim 2, characterized in that: The first pressure sensor (7) and the second pressure sensor (8) are connected to the control module via electrical signals.

4. A control method for a powered ankle-foot prosthesis based on electro-hydraulic direct drive, the method being implemented by the powered ankle-foot prosthesis based on electro-hydraulic direct drive as claimed in claim 3, characterized in that: The following phases are included: Controlling plantar flexion: the heel (15) touches the ground before the arch (14), the bidirectional gear pump (3) and the hydraulic cylinder (6) form a closed circuit, the piston rod of the hydraulic cylinder (6) will be passively retracted, and the oil will flow through the oil outlet at one end of the bidirectional gear pump (3) and the oil port at one end of the hydraulic cylinder (6) in sequence, and flow back from the oil port at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) can adjust the circuit pressure, and control the bidirectional gear pump (3) through the servo motor (1), so as to provide a certain damping for the hydraulic oil, simulating the damping of controlling the plantar flexion stage during human walking; Controlling dorsiflexion: driven by the knee, the lower leg moves forward, the piston rod of the hydraulic cylinder (6) is passively extended, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil outlet at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil outlet at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure and store energy at the same time. The coordinated work of the servo motor (1) and the bidirectional gear pump (3) simulates the damping of this stage during human walking. Power plantar flexion: the power ankle-foot prosthesis actively provides power, the piston rod of the hydraulic cylinder (6) actively retracts, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil outlet at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil outlet at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure and release the stored energy to assist the bidirectional gear pump (3) in providing power; Swinging stage: the powered ankle-foot prosthesis actively returns to the initial position, the piston rod of the hydraulic cylinder (6) actively extends, so that the powered ankle-foot prosthesis completes the dorsiflexion movement, and the oil flows through the oil outlet at one end of the bidirectional gear pump (3) and the oil port at one end of the hydraulic cylinder (6) in sequence, and flows back from the oil port at the other end of the hydraulic cylinder (6) to the oil inlet at the other end of the bidirectional gear pump (3). During this process, the first accumulator (4) and the second accumulator (5) adjust the circuit pressure.

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