Electro-hydraulic active ankle joint artificial limb control method and device

Abstract

The invention provides an electro-hydraulic active ankle joint artificial limb control method and device. The method comprises the steps that a human body mass center height sequence in a first gait cycle of a normal leg of a subject is obtained; determining the human body mass center height of the prosthetic leg of the subject at the current moment of the second gait cycle by using the human body mass center height sequence of the first gait cycle; acquiring a hip joint angle, a knee joint angle and an ankle joint angle of the prosthetic leg of the subject at the current moment of the second gait cycle; based on the human body mass center height, the hip joint angle and the knee joint angle at the current moment, calculating an expected ankle joint angle and an expected ankle joint angular velocity at the next moment by utilizing a human body lower limb motion model; and determining a control law of the ankle joint controller at the next moment based on the ankle joint angle at the current moment and the expected ankle joint angle and the expected ankle joint angular velocity at the next moment. Compared with a traditional finite-state machine method, the method greatly simplifies the whole process of the test, and improves the control precision.

Description

An electrohydraulic active ankle joint prosthesis control method and device Technical Field

[0001] This application relates to the field of prosthetic control technology, and in particular to an electro-hydraulic active ankle joint prosthetic control method and device. Background Technology

[0002] In ankle prostheses, the most widely used control method is the finite state machine (FSM). This method uses impedance parameters fitted from human walking tests and is only applicable to wearers testing at a fixed pace on a treadmill. Because this control method uses many parameters, extensive preliminary tests are required to adjust these parameters for different individuals before prosthesis trials. However, human walking patterns often differ during normal walking, and even within the same walking pattern, speeds vary. This causes the parameters used by the prosthesis to change continuously throughout the walking process, making the overall testing process very complex. Summary of the Invention

[0003] In view of this, this application provides an electro-hydraulic active ankle joint prosthesis control method and device to solve the above-mentioned technical problems.

[0004] In a first aspect, embodiments of this application provide an electro-hydraulic active ankle joint prosthesis control method, comprising: acquiring a sequence of the center of mass height of the subject's normal leg during the first gait cycle; using the sequence of the center of mass height of the subject's prosthetic leg during the first gait cycle to determine the current moment of the center of mass height of the subject's prosthetic leg during the second gait cycle; acquiring the hip joint angle, knee joint angle, and ankle joint angle of the subject's prosthetic leg during the current moment of the second gait cycle; calculating the desired ankle joint angle and desired ankle joint angular velocity at the next moment using a human lower limb motion model based on the current moment's center of mass height, hip joint angle, and knee joint angle; and determining the control law of the ankle joint controller at the next moment based on the current moment's ankle joint angle and the desired ankle joint angle and desired ankle joint angular velocity at the next moment.

[0005] In one possible implementation, the method further includes: placing IMUs at the waist, thigh, calf, and dorsum of the foot above the pelvis of the subject, respectively; collecting quaternions from the four IMUs when the subject is at rest to obtain the initial posture of the four IMUs; calculating the human center of mass height sequence using data collected by the IMU at the waist when the subject walks with his normal leg; and collecting data from the subject's prosthetic leg while walking. The quaternions of the four IMUs at time t are used to obtain the rotation values ​​of the IMUs placed at the waist relative to their initial orientation. The rotation value of the IMU placed on the thigh relative to the initial orientation. The rotation value of the IMU placed on the lower leg relative to the initial orientation. and the rotation value of the IMU placed on the foot relative to the initial posture ; Calculate the relative rotation quaternion of the hip joint The relative rotation quaternion of the knee joint The relative rotation quaternion of the ankle joint ;Will , and Convert each angle to Euler angles to obtain the subject's position at time [time]. The angles of the hip joint, knee joint, and ankle joint.

[0006] In one possible implementation, the second gait cycle and the first gait cycle are continuous; the height of the center of mass of the subject's prosthetic leg at the current moment of the second gait cycle is determined using the height sequence of the center of mass of the first gait cycle; this includes: calculating a sequence of center of mass velocity using the height sequence of the center of mass; and calculating intermediate values. :

[0007] in, This is the first value in the human body's center of mass height sequence. This is the first value in the human body's center-of-mass velocity sequence. This represents the maximum value of the human body's center of mass height sequence. The length of the first state period. Let gravitational acceleration be the vector; calculate the vector using the following formula. :

[0008] in, Let z be the boundary condition vector in the z-direction; Represents the boundary condition matching matrix; , , , ; Calculate the polynomial parameter vector :

[0009] in, It is a matrix basis vectors of the null space:

[0010] in, express The last column, express The matrix with the last column removed; the timing of the second gait cycle of the subject's prosthetic leg calculated. Human center of gravity height Center of mass velocity and center of mass acceleration : .

[0011] In one possible implementation, based on the current height of the human body's center of mass, hip joint angle, and knee joint angle, the expected ankle joint angle and expected ankle joint angular velocity at the next moment are calculated using a human lower limb motion model; this includes: calculating the next moment according to the following formula. Expected ankle angle :

[0012] Calculate the time using the following formula. Expected ankle joint angular velocity :

[0013] in, , , These represent the physiological angles of different positions on the foot; As an intermediate variable; and These represent the angles of the hip and knee joints, respectively. , and These represent the physiological dimensions of different positions on the foot; For a moment The height of the human body's supporting feet on the ground.

[0014] In one possible implementation, the control law for the ankle joint controller at the next moment is determined based on the current ankle joint angle and the desired ankle joint angle and angular velocity at the next moment, including: calculating the time according to the following formula. The control law of the ankle joint controller :

[0015] in, and All parameters were obtained when the subjects walked at their natural walking speed. For a moment Ankle angle, To control the gain, ; Observations representing lumped uncertainty.

[0016] Secondly, embodiments of this application provide an electro-hydraulic active ankle joint prosthesis control device, comprising: a first acquisition unit for acquiring a sequence of human center of mass height during the first gait cycle of a subject's normal leg; a first determination unit for determining the current moment of the human center of mass height of the subject's prosthetic leg in the second gait cycle using the sequence of human center of mass height during the first gait cycle; a second acquisition unit for acquiring the hip joint angle, knee joint angle, and ankle joint angle of the subject's prosthetic leg at the current moment of the second gait cycle; a calculation unit for calculating the desired ankle joint angle and desired ankle joint angular velocity at the next moment using a human lower limb motion model based on the current moment's human center of mass height, hip joint angle, and knee joint angle; and a second determination unit for determining the control law of the ankle joint controller at the next moment based on the current moment's ankle joint angle and the desired ankle joint angle and desired ankle joint angular velocity at the next moment.

[0017] Thirdly, embodiments of this application provide an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method of embodiments of this application.

[0018] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer instructions that, when executed by a processor, implement the methods of embodiments of this application.

[0019] Fifthly, embodiments of this application provide a computer program product, including a computer program / instructions, which, when executed by a processor, implement the method of embodiments of this application.

[0020] Compared with the traditional finite state machine method, the method in this application greatly simplifies the overall experimental process and improves the control accuracy. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 is a simplified kinematic model of the human lower limb provided in the embodiment of this application; Figure 2 is a schematic diagram of the human lower limb foot provided in the embodiment of this application; Figure 3 is a flowchart of the electro-hydraulic active ankle joint prosthesis control method provided in the embodiment of this application; Figure 4 is a diagram of the test results of three subjects wearing prostheses walking on a treadmill provided in the embodiment of this application; Figure 5 is a functional structure diagram of the electro-hydraulic active ankle joint prosthesis control device provided in the embodiment of this application; Figure 6 is a structural diagram of the electronic device provided in the embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] First, a brief introduction to the design concept of the embodiments of this application will be given.

[0026] The ankle joint is the main weight-bearing joint of the lower limb, capable of supporting up to five times the body weight. Furthermore, the muscles in the ankle joint work in conjunction with the muscles of the hip and knee joints to propel the body forward and upward. Therefore, the flexibility and stability of the ankle joint are crucial for smooth movement and balance coordination of the lower limbs. To help amputees regain confidence and reintegrate into society, the most common method is to fit them with ankle prostheses, which reproduce the lost leg functions. With technological advancements, prostheses have evolved from primitive mechanical fixed prostheses to the more advanced stage of intelligent active prostheses based on microcomputer control. An excellent active ankle prosthesis should be able to achieve corresponding movements according to the wearer's true intentions, completely replicating or even surpassing the function of a normal biological ankle joint. Therefore, intelligent and efficient ankle prosthesis control technology is a crucial guarantee for the stable operation of ankle prostheses.

[0027] Therefore, this application proposes an electro-hydraulic active ankle joint prosthesis control method, including: Step 1: deploying sensors on the human body to obtain the trajectory of the human center of mass; Step 2: establishing a human center of mass trajectory prediction model to predict the expected human center of mass trajectory when walking with the prosthesis; the vertical human center of mass trajectory can be fitted using a fourth-order polynomial curve, and the vertical human center of mass trajectory can be represented as:

[0028] In the formula: , and These represent the vertical position of the human body's center of mass, velocity, and acceleration, respectively. Represents the polynomial parameter vector in the vertical direction. , and These are vectors representing time scales.

[0029] For each step of the upcoming gait, the vertical centroid trajectory can be fitted using a fourth-order polynomial curve, which contains five polynomial parameters, thus requiring five boundary conditions for solution. First, we can define the four linear boundary conditions in the vertical direction for each step:

[0030] In the formula: , These represent the boundary condition vector and the boundary condition matching matrix in the vertical direction, respectively. This indicates the duration of a support phase within the gait cycle. In the vector, the first element represents the position of the center of mass at the initial moment, i.e., when the heel touches the ground; the second element represents the velocity of the center of mass at the initial moment; the third element represents the acceleration at the initial moment, when the heel has just touched the ground and the center of mass of the human body is only subject to gravity; and the fourth element represents the acceleration at the end of the support phase, i.e., when the toes leave the ground, when the foot leaves the ground and the center of mass of the human body is only subject to gravity.

[0031] For linear systems The solution can be obtained as follows:

[0032] In the formula, It is a matrix The vector is a basis vector of the null space, therefore it can be written as:

[0033] In the formula, express The last column, express Other columns.

[0034] In order to calculate A fifth boundary condition needs to be given. The previous four boundary conditions were obtained in the support state; the fifth boundary condition will be given by the pendulum dynamics. From the moment the toes leave the ground to the moment the center of mass reaches its highest point, the position and velocity of the center of mass can be written as:

[0035]

[0036] In the formula, and These represent the position and velocity of the human body's center of mass at its highest point, respectively. and These represent the position and velocity of the human body's center of mass when the toes leave the ground. It indicates the time from when the toes leave the ground to when the body's center of mass reaches its highest point.

[0037] Since the vertical velocity of the human body's center of mass is 0 at its highest point, we have:

[0038] The position and velocity of the human body's center of mass in the vertical direction when the toes leave the ground can be expressed as:

[0039]

[0040] From this, we can obtain... A quadratic equation with variables:

[0041] Seek The value is:

[0042] Step 3: Establish a human lower limb motion model to obtain the desired ankle joint prosthesis angle and angular velocity; when the human body walks normally, take the hip joint position as the human body's center of mass position, and use it as the coordinate origin to establish a human lower limb kinematic model as shown in Figure 1. Then the forward kinematic position equation of the human lower limb is:

[0043]

[0044] In the formula, and These represent the link lengths from the hip joint to the knee joint and from the knee joint to the ankle joint, respectively. and These represent the angles of the hip and knee joints, respectively. , , These represent the positions of the body's center of mass, knee joint, and ankle joint, respectively.

[0045] Modeling the human foot, the lower limb foot model is simplified into a triangle. During the standing phase, the heel position remains unchanged. Therefore, with the heel as the origin of the coordinate system, the relationship between the coordinates of the key points of the foot and the angles is as follows:

[0046]

[0047] In the formula, point A represents the heel, point B represents the ankle joint, and point C represents the toe. , , , These represent the physiological dimensions of different positions on the foot; , , These represent the physiological angles of different positions on the foot. The angle of the ankle joint is shown in Figure 2.

[0048] Since point B represents the ankle joint and point A represents the heel, with the heel touching the ground at this moment, therefore:

[0049] Ultimately, the relationship between the ankle joint angle and the human body's center of mass can be obtained as follows:

[0050]

[0051] Step 4: Using the desired joint angle and angular velocity as the reference trajectory, the ankle prosthesis is made to follow the reference trajectory using an active disturbance rejection control method, thereby achieving precise control of the ankle prosthesis.

[0052] For ankle prostheses, the impedance model is as follows:

[0053] In the formula, For the desired torque of the ankle joint, For ankle joint angle, The linear stiffness coefficient is... For nonlinear stiffness coefficients, The damping coefficient is... For the equilibrium angle, the impedance model can be rewritten as:

[0054] In the formula, , This represents the parameters when the subject walks at their natural pace. This indicates aggregate uncertainty.

[0055] The control objective of the system can be expressed as: given a given ankle prosthesis impedance model, given a desired ankle angle... and the expected ankle joint angular velocity Design the ankle joint torque under given constraints. The control law makes:

[0056] In the formula, This represents the desired boundary between the ankle joint angle and the reference command. is an arbitrarily small positive number.

[0057] Constructing a reduced-order linear extended state observer to estimate lumped uncertainties in the impedance model Design the following lumped uncertainty reduced-order linear extended state observer:

[0058] In the formula, Representing aggregate uncertainty The observed values, For observer auxiliary variables, This is the observer gain.

[0059] Design the control law for the system. To ensure the ankle joint angle... Approaching the desired angle The expected dynamic of the ankle joint angle can be expressed as:

[0060] In the formula, To control the gain, From the perspective of expectation.

[0061] Combined with observer observations The control law for the input torque of the ankle joint can be obtained as follows:

[0062] After introducing the application scenarios and design concepts of the embodiments of this application, the technical solutions provided by the embodiments of this application will be described below.

[0063] As shown in Figure 3, this application embodiment provides an electro-hydraulic active ankle joint prosthesis control method, including: Step 101: Obtaining the human center of mass height sequence of the subject's normal leg during the first gait cycle; Step 102: Using the human center of mass height sequence of the first gait cycle, determining the current human center of mass height of the subject's prosthetic leg during the second gait cycle; Step 103: Obtaining the hip joint angle, knee joint angle, and ankle joint angle of the subject's prosthetic leg during the current second gait cycle; Step 104: Based on the current human center of mass height, hip joint angle, and knee joint angle, calculating the expected ankle joint angle and expected ankle joint angular velocity at the next moment using a human lower limb motion model; Step 105: Based on the current ankle joint angle and the expected ankle joint angle and expected ankle joint angular velocity at the next moment, determining the control law of the ankle joint controller at the next moment.

[0064] For example, the prosthesis in this embodiment is an electrohydraulic active ankle prosthesis.

[0065] This embodiment uses the center of mass height of the normal leg to predict the center of mass height of the prosthetic leg, and uses the ankle joint angle of the prosthetic leg as the control target to plan the prosthetic limb's motion trajectory. This transforms the prosthetic limb control problem into a tracking problem of a predetermined trajectory obtained from the healthy limb, thus ensuring that the human center of mass trajectory when walking with an ankle prosthesis is consistent with that of the healthy limb. Compared to the traditional finite state machine method, this greatly simplifies the overall experimental process and improves control accuracy.

[0066] In some embodiments, the method further includes: placing IMUs (Inertial Measurement Units) at the waist, thigh, calf, and dorsum of the foot above the pelvis of the subject, respectively; collecting quaternions from the four IMUs when the subject is at rest to obtain the initial posture of the four IMUs; calculating the human center of mass height sequence using data collected by the IMU at the waist when the subject walks with his normal leg; and collecting data on the subject's walking posture when the subject walks with his prosthetic leg. The quaternions of the four IMUs at time t are used to obtain the rotation values ​​of the IMUs placed at the waist relative to their initial orientation. The rotation value of the IMU placed on the thigh relative to the initial orientation. The rotation value of the IMU placed on the lower leg relative to the initial orientation. and the rotation value of the IMU placed on the foot relative to the initial posture ; Calculate the relative rotation quaternion of the hip joint The relative rotation quaternion of the knee joint The relative rotation quaternion of the ankle joint ;Will , and Convert each angle to Euler angles to obtain the subject's position at time [time]. The angles of the hip joint, knee joint, and ankle joint.

[0067] In some embodiments, the second gait cycle and the first gait cycle are continuous; the timing of the second gait cycle of the subject's prosthetic leg is determined using the human center of mass height sequence of the first gait cycle. The human center of mass height; including: using the human center of mass height sequence to calculate the human center of mass velocity sequence; calculating intermediate values. :

[0068] in, This is the first value in the human body's center of mass height sequence. This is the first value in the human body's center-of-mass velocity sequence. This represents the maximum value of the human body's center of mass height sequence. The length of the first state period. Let gravitational acceleration be the vector; calculate the vector using the following formula. :

[0069] in, Let z be the boundary condition vector in the z-direction; Represents the boundary condition matching matrix; , , , ; Calculate the polynomial parameter vector :

[0070] in, It is a matrix basis vectors of the null space:

[0071] in, express The last column, express The matrix with the last column removed; the timing of the second gait cycle of the subject's prosthetic leg calculated. Human center of gravity height Center of mass velocity and center of mass acceleration : .

[0072] In some embodiments, based on time The human body's center of gravity height, hip joint angle, and knee joint angle are used to calculate the time using a human lower limb motion model. The desired ankle angle and desired ankle angular velocity; including: the time calculated according to the following formula. Expected ankle angle :

[0073] Calculate the time using the following formula. Expected ankle joint angular velocity :

[0074] in, , , These represent the physiological angles of different positions on the foot; As an intermediate variable; and These represent the angles of the hip and knee joints, respectively. , and These represent the physiological dimensions of different positions on the foot; For a moment The height of the human body's supporting feet on the ground.

[0075] In some embodiments, based on time Ankle angle and time Determine the desired ankle angle and desired ankle angular velocity, and the timing. The control law of the ankle joint controller includes: calculating the time according to the following formula. The control law of the ankle joint controller :

[0076] in, and All parameters were obtained when the subjects walked at their natural walking speed. For a moment Ankle angle, To control the gain, ; Observations representing lumped uncertainty.

[0077] This embodiment uses only one controller, enabling the prosthetic ankle joint to mimic the walking of a healthy lower limb, making it more adaptable to the subject's movement at different walking speeds.

[0078] The method of this embodiment will be described below with reference to specific examples.

[0079] Figure 4 shows the ankle joint prosthesis data obtained by three subjects of different weights wearing prostheses on a treadmill at three different walking speeds of 1 m / s, 1.1 m / s, and 1.3 m / s. The average ankle joint angle, torque, and power of the healthy subjects are represented by the black curve, and the gray shading bandwidth represents the average ± one standard deviation. The red curve represents the average ankle joint angle, torque, and power of subject 1, and the light red shading bandwidth represents the average ± one standard deviation. The green curve represents the average ankle joint angle, torque, and power of subject 2, and the light green shading bandwidth represents the average ± one standard deviation. The blue curve represents the average ankle joint angle, torque, and power of subject 3, and the light blue shading bandwidth represents the average ± one standard deviation.

[0080] The results show that the control method of this embodiment can make the characteristics of the ankle prosthesis close to those of a healthy subject, and can meet the needs of the ankle prosthesis.

[0081] Based on the same inventive concept, this application provides an electrohydraulic active ankle joint prosthesis control device. Referring to Figure 5, the electrohydraulic active ankle joint prosthesis control device 200 provided in this application includes at least: a first acquisition unit 201, used to acquire the human center of mass height sequence during the first gait cycle of the subject's normal leg; a first determination unit 202, used to determine the human center of mass height of the subject's prosthetic leg at the current moment of the second gait cycle using the human center of mass height sequence of the first gait cycle; a second acquisition unit 203, used to acquire the hip joint angle, knee joint angle, and ankle joint angle of the subject's prosthetic leg at the current moment of the second gait cycle; a calculation unit 204, used to calculate the expected ankle joint angle and expected ankle joint angular velocity at the next moment using a human lower limb motion model based on the human center of mass height, hip joint angle, and knee joint angle at the current moment; and a second determination unit 205, used to determine the control law of the ankle joint controller at the next moment based on the ankle joint angle at the current moment and the expected ankle joint angle and expected ankle joint angular velocity at the next moment.

[0082] It should be noted that the principle of the electro-hydraulic active ankle joint prosthesis control device 200 provided in this application embodiment to solve the technical problem is similar to the method provided in this application embodiment. Therefore, the implementation of the electro-hydraulic active ankle joint prosthesis control device 200 provided in this application embodiment can refer to the implementation of the method provided in this application embodiment, and the repeated parts will not be described again.

[0083] Based on the same inventive concept, this application also provides an electronic device, as shown in FIG6, including: a memory and a processor, wherein the memory stores an executable program, and the processor executes the executable program to implement the steps of the electro-hydraulic active ankle joint prosthesis control method provided in the above embodiments.

[0084] The aforementioned processor can be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The aforementioned PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0085] Since the electronic device described in this application embodiment is an electronic device equipped with a memory for implementing the electro-hydraulic active ankle joint prosthesis control method disclosed in this application embodiment, those skilled in the art can understand the structure and variations of the electronic device described in this application embodiment based on the electro-hydraulic active ankle joint prosthesis control method described in this application embodiment, and therefore will not be described again here.

[0086] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the electro-hydraulic active ankle joint prosthesis control method provided in the above embodiments.

[0087] The storage medium in this embodiment may be included in an electronic device; or it may exist independently and not be assembled into an electronic device. The storage medium carries one or more computer programs, which, when executed, implement the steps of the electro-hydraulic active ankle prosthesis control method provided in the above embodiment.

[0088] It should be understood that the various solutions in this embodiment have the same technical effects as those in the above method embodiments, and will not be repeated here.

[0089] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. Optionally, specific examples in this embodiment can refer to the examples described in any embodiment of this application, which will not be repeated here. Obviously, those skilled in the art should understand that the various modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular hardware and software combination.

[0090] This application also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the electro-hydraulic active ankle joint prosthesis control method provided in the above embodiments.

[0091] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions targeted in the blocks may occur in a different order than those targeted in the drawings. For example, two consecutively represented blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0092] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. Multitasking and parallel processing may be advantageous in certain environments. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this application. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

Claims

1. A method for controlling an electrohydraulic active ankle prosthesis, characterized in that, include: Obtain the human center of mass height sequence of the subject's normal leg during the first gait cycle; use the human center of mass height sequence of the first gait cycle to determine the current human center of mass height of the subject's prosthetic leg during the second gait cycle; obtain the hip joint angle, knee joint angle, and ankle joint angle of the subject's prosthetic leg at the current moment of the second gait cycle; based on the current human center of mass height, hip joint angle, and knee joint angle, calculate the expected ankle joint angle and expected ankle joint angular velocity at the next moment using a human lower limb motion model; based on the current ankle joint angle and the expected ankle joint angle and expected ankle joint angular velocity at the next moment, determine the control law of the ankle joint controller at the next moment.

2. The method according to claim 1, characterized in that, The method further includes: placing IMUs at the waist, thigh, calf, and dorsum of the foot above the pelvis of the subject; collecting quaternions from the four IMUs when the subject is at rest to obtain the initial posture of the four IMUs; calculating the human center of mass height sequence using data collected by the IMU at the waist when the subject walks with his normal leg; and collecting data on the subject's walking posture when the subject walks with his prosthetic leg. The quaternions of the four IMUs at time t are used to obtain the rotation values ​​of the IMUs placed at the waist relative to their initial orientation. The rotation value of the IMU placed on the thigh relative to the initial orientation. The rotation value of the IMU placed on the lower leg relative to the initial orientation. and the rotation value of the IMU placed on the foot relative to the initial posture ; Calculate the relative rotation quaternion of the hip joint The relative rotation quaternion of the knee joint The relative rotation quaternion of the ankle joint ;Will 、 and Convert each angle to Euler angles to obtain the subject's position at time [time]. The angles of the hip joint, knee joint, and ankle joint.

3. The method according to claim 1, characterized in that, The second gait cycle and the first gait cycle are continuous; using the human center of mass height sequence of the first gait cycle, the current moment of the subject's prosthetic leg's second gait cycle is determined; this includes: using the human center of mass height sequence to calculate the human center of mass velocity sequence; and calculating intermediate values. ： in, This is the first value in the human body's center of mass height sequence. This is the first value in the human body's center-of-mass velocity sequence. This represents the maximum value of the human body's center of mass height sequence. The duration of the first state period. Let gravitational acceleration be the vector; calculate the vector using the following formula. ： in, Let z be the boundary condition vector in the z-direction; Represents the boundary condition matching matrix; , , , ; Calculate the polynomial parameter vector ： in, It is a matrix basis vectors of the null space: in, express The last column, express The matrix with the last column removed; the timing of the second gait cycle of the subject's prosthetic leg calculated. Human center of gravity height Center of mass velocity and center of mass acceleration ： 。 4. The method according to claim 3, characterized in that, Based on the current height of the human body's center of mass, hip joint angle, and knee joint angle, the expected ankle joint angle and expected ankle joint angular velocity at the next moment are calculated using a human lower limb motion model; this includes: calculating the time according to the following formula. Expected ankle angle ： Calculate the time using the following formula. Expected ankle joint angular velocity ： in, ， ， These represent the physiological angles of different positions on the foot; As an intermediate variable; and These represent the angles of the hip and knee joints, respectively. ， and These represent the physiological dimensions of different positions on the foot; For a moment The height of the human body's supporting feet on the ground.

5. The method according to claim 4, characterized in that, Based on the current ankle joint angle and the expected ankle joint angle and angular velocity at the next moment, determine the control law for the ankle joint controller at the next moment, including: calculating the time according to the following formula. The control law of the ankle joint controller ： in, and All parameters were obtained when the subjects walked at their natural walking speed. For a moment Ankle angle, To control the gain, ; Observations representing lumped uncertainty.

6. An electro-hydraulic active ankle joint prosthesis control device, characterized in that, include: The first acquisition unit is used to acquire the human center of mass height sequence of the subject's normal leg during the first step phase cycle; The first determining unit is used to determine the height of the human center of mass of the subject's prosthetic leg at the current moment of the second gait cycle using the human center of mass height sequence of the first gait cycle; the second acquiring unit acquires the hip joint angle, knee joint angle and ankle joint angle of the subject's prosthetic leg at the current moment of the second gait cycle. The calculation unit is used to calculate the expected ankle angle and expected ankle angular velocity at the next moment based on the current height of the human body's center of mass, hip joint angle, and knee joint angle, using a human lower limb motion model. The second determining unit is used to determine the control law of the ankle joint controller at the next moment based on the ankle joint angle at the current moment and the expected ankle joint angle and expected ankle joint angular velocity at the next moment.

7. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method as claimed in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the method as described in any one of claims 1-5.

9. A computer program product, characterized in that, Includes a computer program / instruction that, when executed by a processor, implements the method as described in any one of claims 1-5.

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