Functional electrical stimulation fused ankle joint mixed exoskeleton system and assisting torque distribution method

Abstract

The invention discloses an ankle joint mixed exoskeleton system fused with functional electrical stimulation. The ankle joint mixed exoskeleton system comprises a leg support used for being fixed to a shank, a foot fixing plate hinged to the bottom of the leg support, a driving mechanism arranged on the leg support and used for driving the foot fixing plate to swing and a system module matched with the driving mechanism. The invention further provides an assisting torque distribution method. The system provided by the invention can effectively assist the patient in keeping the correct position of the foot in the walking process, so that the foot drop is effectively prevented, and the walking safety and efficiency are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of rehabilitation training equipment, and in particular relates to an ankle joint hybrid exoskeleton system integrating functional electrical stimulation and an assist torque distribution method. Background Art

[0002] As people age, their body functions deteriorate, and their muscles and bones are increasingly unable to support their daily walking and exercise needs, which seriously affects their healthy lives. In terms of bones, from the age of 40 to 80, people lose a lot of bone mass, their bones become less porous, and the incidence of osteoporosis increases, which easily leads to the risk of fractures. Among them, the elderly are more likely to have symptoms in their ankle joints. As a very important joint in the body, the ankle joint is responsible for supporting the body's weight, maintaining balance and motor control. Sports injuries, such as sprains, ligament strains or fractures, as well as chronic diseases, may lead to loss or damage of ankle joint function, affecting an individual's walking ability and quality of life. In the process of human activities, ankle injuries caused by various reasons are everywhere, and the demand for ankle exoskeletons is increasing.

[0003] The lower limb wearable exoskeleton is an intelligent mechanical device that refers to the movement form of human joints and can provide auxiliary torque to the wearer. In the medical field, the lower limb exoskeleton can be used as a medical rehabilitation device to assist patients in rehabilitation training, and gradually developed into the current medical mechanical exoskeleton. The medical mechanical exoskeleton is an advanced technology that integrates engineering, medicine and biomechanics. This technology is designed to improve human physical performance and provide support for individuals with movement disorders, rehabilitation needs or disabilities. The ankle exoskeleton is a mechanical assistive device that is specially designed to support and enhance the function of the ankle joint. It is used for patients with ankle injuries and motor dysfunction. On the one hand, it is used as a medical rehabilitation device to assist them in rehabilitation training. On the other hand, it assists the elderly who cannot carry out daily activities due to ankle problems to walk, meet their life needs, and reduce the investment resources of hospitals in treating ankle-related symptoms. Therefore, research on ankle exoskeletons is becoming more and more important.

[0004] Patent document CN103655122A discloses a knee joint exoskeleton system integrating functional electrical stimulation. In the field of lower limb rehabilitation, especially knee joint rehabilitation, traditional rehabilitation training methods often rely on manual operation of physical therapists, which is inefficient and difficult to achieve personalized treatment. In order to improve the efficiency and effect of rehabilitation, the prior art proposes a knee joint exoskeleton system integrating functional electrical stimulation. This system is connected to the knee joint exoskeleton through a DC servo motor driver, and the controller controls the motor driver and the multi-channel functional electrical stimulator at the same time to achieve the coordinated work of the knee joint exoskeleton and the functional electrical stimulation. This system can give play to the autonomous power of the patient's muscles, and the rehabilitation robot provides auxiliary functions, which work together on paralyzed patients and provide optimal knee joint rehabilitation training. However, the prior art mainly focuses on the rehabilitation of the knee joint, and pays insufficient attention to the rehabilitation training of other lower limb joints such as the ankle joint, which limits the comprehensiveness and effect of the rehabilitation training.

[0005] Patent document CN111408042A discloses a functional electrical stimulation and lower limb exoskeleton intelligent allocation method, device, storage medium and system, which obtains the user's bone dynamic characteristic parameters and the motion parameters of the lower limb joints, and inputs them into the inverse dynamics model of the exoskeleton robot to determine the torque relationship of each joint. This method is applicable to the field of rehabilitation training and improves the intelligent level of rehabilitation training. Nevertheless, the prior art still has certain limitations in the intelligent allocation method, especially in real-time monitoring and dynamic adjustment, and lacks more accurate and personalized control strategies to adapt to the specific needs and rehabilitation progress of different patients. Summary of the invention

[0006] The purpose of the present invention is to provide an ankle joint hybrid exoskeleton system integrating functional electrical stimulation and a method for distributing assisting torque, which can effectively assist patients in maintaining the correct position of their feet during walking, thereby effectively preventing foot drop and improving the safety and efficiency of walking.

[0007] In order to achieve the first object of the present invention, the following technical scheme is provided: a hybrid exoskeleton system of ankle joint integrating functional electrical stimulation, comprising a leg support for fixing on the calf, a foot fixing plate hinged to the bottom of the leg support, a driving mechanism for driving the foot fixing plate to swing and a system module matched with the driving mechanism, which is arranged on the leg support; The system module includes FES electrodes for stimulating leg muscles, a pressure sensor on a foot fixing plate for collecting gait information, an ankle joint encoder at the hinge between a leg support and the foot fixing plate for collecting rotation angles, and a controller for generating control instructions based on the gait information and the rotation angle. The controller sends the control instructions to a drive mechanism to complete the assisted walking task, wherein the gait information includes heel-to-ground and toe-off.

[0008] The system provided by the present invention collects the patient's gait information in real time to adjust the driving force of the exoskeleton on the patient's legs, and at the same time cooperates with FES electrodes to electrically stimulate the leg muscles during walking, thereby correcting the patient's abnormal gait and promoting his or her rehabilitation process.

[0009] Specifically, the FES electrodes are set on the tibialis anterior and soleus muscles of the human body, and during the rehabilitation process, both active muscle-driven rehabilitation of physiological electrical stimulation and passive rehabilitation of exoskeleton physical interaction force stimulation are played, thereby accelerating the rehabilitation process and reducing dependence on traditional single physical therapy.

[0010] Specifically, the leg support includes support rods arranged on both sides of the calf, and a first fixing ring located below the knee for connecting the support rods on both sides.

[0011] Specifically, the foot fixing plate includes a foot bracket hinged to the bottom of the leg bracket and a second fixing ring, as well as a rear foot rest and a forefoot foot rest arranged on the foot bracket, and pressure sensors are provided on the rear foot rest and the forefoot foot rest to obtain more accurate gait information.

[0012] In order to achieve the second object of the present invention, the following technical solution is provided: a method for distributing assist torque, which is implemented by the above-mentioned ankle joint hybrid exoskeleton system integrating functional electrical stimulation, comprising the following steps: The ankle joint encoder is used to collect the swing angle changes of the foot fixing plate under the preset number of steps, and the corresponding angle feedback is generated according to multiple sets of swing angle changes; Based on the angle feedback and the preset normal ankle angle change data, a segmented calculation method is used to obtain the gait deviation matrix; Constructing a corresponding cost function according to the gait deviation matrix and the preset weight parameters, and optimizing the power-assist torque parameters based on the cost function to output a corresponding power-assist parameter matrix; The gait phase of each gait cycle is estimated according to the gait information collected by the pressure sensor, and the corresponding parameterized assist torque is constructed based on the estimated gait phase and assist parameter matrix; Generate a swing angle change caused by calf muscle fatigue according to the angle feedback, and compare and calculate the swing angle change with a normal ankle joint angle to construct a corresponding muscle fatigue trajectory deviation index, wherein the calf muscles include a gastrocnemius muscle and a tibialis anterior muscle; Based on the parameterized assist torque and muscle fatigue trajectory deviation index, the control instructions corresponding to the drive mechanism are generated through the torque collaborative control strategy.

[0013] The method provided by the present invention introduces a torque coordination control strategy based on the design of an over-fatigue protection mechanism in the optimization process of conventional parameterized assisting force, thereby avoiding the risk of secondary injury to patients due to excessive muscle fatigue during long-term recovery training.

[0014] Specifically, the assist torque parameters include the start time, peak time, torque magnitude and stop time of the motor plantar flexion torque curve, and the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve.

[0015] Specifically, the expression of the parameterized assist torque is as follows: ; ;in, Represents the assist torque output by the exoskeleton, represents the plantar flexion assist torque, represents the dorsiflexion assist torque, represents the normalized gait phase, where , , and They correspond to the starting time, peak time, torque magnitude and stopping time of the motor plantar flexion torque curve respectively; , , and They correspond to the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve respectively.

[0016] Specifically, the calculation formula of the muscle fatigue trajectory deviation index is as follows: in, and They are the normal angle and actual angle when stimulating the gastrocnemius muscle. and They are the normal angle and actual angle when stimulating the tibialis anterior muscle. Represents the number of steps walked.

[0017] Specifically, the torque coordination control strategy adjusts the distribution coefficient of the parameterized assist torque according to the muscle fatigue trajectory deviation index to generate corresponding control instructions, and the process is as follows: ; ;in, and are the fatigue indexes of the gastrocnemius and tibialis anterior muscles, represents the symbolic function, Indicates the corresponding i +1 step gastrocnemius muscle fatigue trajectory deviation index, Indicates the corresponding i The muscle fatigue trajectory deviation index of the gastrocnemius muscle at the step, Indicates the corresponding i +1 step of tibialis anterior muscle fatigue trajectory deviation index, Indicates the corresponding i Muscle fatigue trajectory deviation index of the tibialis anterior muscle during walking; The expression of the distribution coefficient is as follows: ;in, and The distribution coefficients corresponding to the gastrocnemius muscle and the tibialis anterior muscle respectively; the expression of the control instruction is as follows: ; ;in, represents the torque generated by electrically stimulating the muscle, Represents the motor assist torque, and They correspond to the torque generated by electrical stimulation of the gastrocnemius and tibialis anterior muscles, represents the plantar flexion assist torque, Represents the dorsiflexion assisting moment.

[0018] Specifically, the gait phase estimation process is as follows: By detecting heel strike and toe lift events, the gait cycle is divided into multiple sub-intervals; In each subinterval, the gait phase is estimated by linear interpolation, and the linear interpolation is expressed as follows: ;in, Indicates the current time. and Respectively represent the start and end time of the sub-interval.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The structure is designed for the human ankle joint, which can achieve electrical stimulation and exoskeleton assistance, correct abnormal gait, prevent foot drop, and promote neuromuscular rehabilitation; At the same time, based on the muscle fatigue mechanism, an algorithm is provided to detect muscle fatigue and adjust the intensity of electrical stimulation, which helps to provide patients with efficient and safe rehabilitation effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the design of the ankle joint hybrid exoskeleton system integrating functional electrical stimulation provided in this embodiment; Figure 2 A schematic diagram of the mechanical structure of the ankle hybrid exoskeleton system provided in this embodiment; Figure 3 A schematic diagram of the bending change of the front end of the foot fixing plate provided in this embodiment; Figure 4A schematic diagram of the assist torque distribution method provided in this embodiment; Figure 5 A schematic diagram of a gait deviation assessment process provided in this embodiment; Figure 6 A schematic diagram of the conversion of gait phase estimation provided in this embodiment; Figure 7 A schematic diagram of the use of the subject provided for this embodiment; Figure 8 A schematic diagram of the ankle joint angle of a subject during use provided in this embodiment; In the figure, 101, controller; 102, battery; 103, bandage; 104, FES electrode; 105, pressure sensor; 2, mechanical part; 201, crank; 202, crank housing; 203, crank connecting rod; 204, ankle joint encoder; 205, foot fixing plate; 206, second fixing ring; 207, heel parallel rod; 208, rear foot rest; 209, motor; 210, forefoot foot rest; 211, first fixing ring; 212, support rod. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] like Figure 1 and Figure 2 As shown, a hybrid ankle exoskeleton system integrating functional electrical stimulation is provided in this embodiment, wherein the mechanical part 2 includes a leg support for fixing on the calf, a foot fixing plate hinged to the bottom of the leg support, and other parts include a driving mechanism arranged on the leg support for driving the foot fixing plate to swing, and a system module matching the driving mechanism.

[0023] The leg support includes support rods 212 arranged on both sides of the calf, and a first fixing ring 211 located below the knee for connecting the support rods on both sides.

[0024] The foot fixing plate includes a foot support 205 hinged to the bottom of the leg support and a second fixing ring 206, as well as a rear foot support 208 and a forefoot foot support 207 arranged on the foot support, wherein the rear foot support 208 and the forefoot foot support 210 are both provided with pressure sensors 105.

[0025] The system module includes an FES electrode sheet 104 for stimulating leg muscles, a pressure sensor 105 arranged on a foot fixing plate for collecting gait information, an ankle joint encoder 204 arranged at the hinge between the leg support and the foot fixing plate for collecting the rotation angle, and a controller 1 for generating control instructions based on the gait information and the rotation angle. The controller 1 sends the control instructions to the drive mechanism to complete the assisted walking task. The gait information includes heel landing and toe leaving the ground. In this example, the controller 1 and the matching battery 102 are fixed to the patient's waist, and its data cable is fixed to the position below the patient's knee through a strap 103.

[0026] In this embodiment, the driving mechanism includes a motor 209 fixed on a support rod 212, the output end of the motor 209 is connected to a crank 201, and the other end of the crank 201 is connected to a crank connecting rod 203, the crank connecting rod 203 is connected to a heel parallel rod 207 at the rear end of the foot support 205 to drive the foot support 205 to complete the swing, and a crank housing 202 is arranged outside the motor 209.

[0027] In addition, Figure 3 As shown, in this embodiment, the foot support 205 at the forefoot foot support 210 is made of a relatively thin material with a certain toughness, so that the forefoot of the wearer's shoe can be effectively clamped by tightening the strap to bend, thereby achieving adaptation to individuals of different sizes. Figure 3 (a) shows the forefoot support is not clamped. Figure 3 (b) shows the state after the forefoot support is clamped.

[0028] This embodiment also provides a method for distributing assist torque, which is implemented by the ankle joint hybrid exoskeleton system provided by the above embodiment. Figure 4 As shown, the following steps are included: The ankle joint encoder is used to collect the swing angle changes of the foot fixing plate under the preset number of steps, and the corresponding angle feedback is generated according to multiple sets of swing angle changes; Based on the angle feedback and the preset normal ankle angle change data, a segmented calculation method is used to obtain the gait deviation matrix; Constructing a corresponding cost function according to the gait deviation matrix and the preset weight parameters, and optimizing the power-assist torque parameters based on the cost function to output a corresponding power-assist parameter matrix; The gait phase of each gait cycle is estimated according to the gait information collected by the pressure sensor, and the corresponding parameterized assist torque is constructed based on the estimated gait phase and assist parameter matrix; Generate a swing angle change caused by calf muscle fatigue according to the angle feedback, and compare and calculate the swing angle change with a normal ankle joint angle to construct a corresponding muscle fatigue trajectory deviation index, wherein the calf muscles include a gastrocnemius muscle and a tibialis anterior muscle; Based on the parameterized assist torque and muscle fatigue trajectory deviation index, the control instructions corresponding to the drive mechanism are generated through the torque collaborative control strategy.

[0029] in, Figure 4 (a) is a schematic diagram of the ankle hybrid exoskeleton system.

[0030] More specifically, if Figure 4 (b) is the gait evaluation process provided by this embodiment, in which the gait deviation matrix E calculation process requires the controller to obtain angle feedback through the ankle joint encoder , the gait data is used to evaluate the current gait and the target ankle joint angle The error is as follows: Each iteration corresponds to wearing walking Step, where The average ankle encoder angle data for multiple steps is as follows: , by calculating the root mean square error between the ankle joint encoder data and the preset normal ankle joint angle data, E is obtained. When calculating the root mean square error of the ankle joint angle, a segmented calculation method is used to obtain the six elements of the error matrix E. The basis for segmentation comes from the experience summarized in the previous test on user preferences.

[0031] These experiences also play a role in the parameter space of the optimization parameters. Specifically, they are shown in the following formula: ; ; ; ;like Figure 4 As shown in (c), it is the process of parameterized assist torque optimization, which includes the calculation of cost function and the selection of optimization algorithm for assist torque.

[0032] The cost function is calculated based on the error between the plantar flexion / dorsiflexion angle collected by the exoskeleton ankle encoder and the normal ankle angle data and a series of weights. The input is the gait deviation matrix E， The cost function cost is calculated by manually setting the weight matrix W， The final cost function cost is calculated. The formula is: The purpose of setting the weight matrix is ​​to pay more attention to the errors of toe flexion / dorsiflexion during the iterative optimization process and speed up the iteration.

[0033] The controller in this embodiment uses a black box optimization algorithm to optimize the power torque parameters. The input is the cost function cost, and the output is the power parameter matrix M The parameters of the assist torque include 8 parameters, which correspond to the torque magnitude, start time, peak time and stop time of the positive and negative peaks respectively. The assist parameter matrix M The expression is as follows: ;in, , , and They correspond to the starting time, peak time, torque magnitude and stopping time of the motor plantar flexion torque curve respectively; , , and They correspond to the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve respectively.

[0034] When choosing an optimization algorithm, the parameter matrix M Any one of them will have an impact on the overall evaluation index, so global optimization capability is required; the human-exoskeleton system tends to be regarded as a black box; the cost function has no way to calculate the gradient, and the calculation takes a certain amount of time, so the black box optimization algorithm described in this embodiment specifically adopts Bayesian optimization.

[0035] like Figure 4 (f) in the figure is the process of generating the exoskeleton assist torque, and its formula is as follows: The expression of the parameterized assist torque is as follows: ; ;in, Represents the assist torque output by the exoskeleton, represents the plantar flexion assist torque, represents the dorsiflexion assist torque, represents the normalized gait phase, where , , and They correspond to the starting time, peak time, torque magnitude and stopping time of the motor plantar flexion torque curve respectively; , , and They correspond to the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve respectively.

[0036] like Figure 4As shown in (d), it is the over-fatigue protection mechanism provided in this embodiment. The principle is to define the degree to which the actual trajectory deviates from the ideal trajectory under the same electrical stimulation intensity and motor assistance intensity as the "Muscle Fatigue Trajectory Deviation Index" (MFTDI). MFTDI is used to measure the degree of deviation between the actual motion trajectory and the expected ideal trajectory due to muscle fatigue under fixed electrical stimulation and motor assistance conditions. MFTDI takes into account the impact of muscle fatigue on motion control, and evaluates the fatigue state of the muscle by analyzing the deviation between the actual trajectory and the ideal trajectory. Since the objects of FES are the gastrocnemius and tibialis anterior muscles, they need to be calculated separately.

[0037] Therefore, the MFTDI in this study is set as the vector , the calculation formula of muscle fatigue trajectory deviation index is as follows: ;in, and They are the normal angle and actual angle when stimulating the gastrocnemius muscle. and They are the normal angle and actual angle when stimulating the tibialis anterior muscle. Represents the number of steps walked.

[0038] like Figure 4 As shown in (e) in the figure, the torque coordination control strategy based on the motor and FES proposed in this embodiment is as follows: the controller outputs the fatigue index according to the over-fatigue protection mechanism. Adjust the torque distribution coefficient between FES and motor The torque distribution coefficient output by the over-fatigue protection mechanism decreases accordingly when the fatigue index increases, preventing excessive muscle fatigue due to continuous high-intensity FES. The over-fatigue protection mechanism is shown in the following formula: ; .

[0039] in, and are the fatigue indexes of the gastrocnemius and tibialis anterior muscles, ranging from -1 to 1, Function represents a symbolic function, Indicates the corresponding i +1 step gastrocnemius muscle fatigue trajectory deviation index, Indicates the corresponding i The muscle fatigue trajectory deviation index of the gastrocnemius muscle at the step, Indicates the corresponding i +1 step of tibialis anterior muscle fatigue trajectory deviation index, Indicates the corresponding iMuscle fatigue trajectory deviation index of the tibialis anterior muscle during walking.

[0040] Among them, when all hour, When it reaches 1, it means that MFTDI is decreasing and muscle fatigue is recovering. hour, A value of -1 indicates that MFTDI continues to increase and muscle fatigue becomes more severe.

[0041] The expression of the distribution coefficient is as follows: ;in, and Corresponding to the distribution coefficients of the gastrocnemius and tibialis anterior muscles respectively.

[0042] like Figure 4 As shown in (g) in the figure, the expression of its control instruction is as follows: ;in, represents the torque generated by electrically stimulating the muscle, Represents the motor assist torque, and They correspond to the torque generated by electrical stimulation of the gastrocnemius and tibialis anterior muscles, represents the plantar flexion assist torque, Represents the dorsiflexion assisting moment.

[0043] like Figure 5 As shown in the figure, during the gait evaluation process, the deviation matrix E and muscle fatigue trajectory deviation index required for power assistance parameter optimization and over-fatigue protection mechanism are output simultaneously in one iteration. . The input data of the power-assistance parameter optimization and the over-fatigue protection mechanism are essentially the error between the real-time data of the ankle encoder and the normal gait. The input muscle fatigue trajectory deviation index of the over-fatigue protection mechanism is meaningful only when the electrical stimulation intensity and motor power-assistance intensity are the same. And each iteration of the power-assistance parameter optimization corresponds to the same electrical stimulation intensity and motor power-assistance intensity when walking. The walking data of each step can be calculated and recorded at each step of the process. At the end of the iteration process, the corresponding Output to fatigue protection mechanism and adjust torque distribution coefficient At the same time, the deviation matrix E of the multi-step average angle in the iterative process is output to the hybrid exoskeleton power-assistance parameter optimization process to calculate the cost of power-assistance parameter optimization.

[0044] like Figure 6As shown in (a) in FIG. 1 , in this embodiment, gait information detection is achieved by identifying key events in the gait cycle, including heel strike (HS) and toe off (TO). These events can be detected by the pressure change of FSR. FSR sensors are placed at the heel and toe positions respectively to detect pressure changes.

[0045] Continuous gait phase estimation estimates the gait phase by monitoring gait events in real time. The gait phase is usually expressed as a value between 0 and 100%, where 0 represents a HS event and 100% represents the next HS event.

[0046] Time-based gait phase Estimation method: In each gait cycle, the gait phase is estimated by time interpolation, and the process is as follows: The specific steps are as follows: Gait cycle division: The gait cycle is divided into multiple sub-intervals by detecting HS and TO events.

[0047] Gait phase interpolation: In each sub-interval, the gait phase is estimated using linear interpolation. The linear interpolation formula is as follows: ;in, Indicates the current time. and Respectively represent the start and end time of the sub-interval.

[0048] According to the results of gait event detection and time-based gait phase estimation (linearized interpolation), a continuous and stable gait phase can be obtained, and the obtained gait phase is shown in (b) of Figure 6.

[0049] In order to better illustrate the technical effects of the system and the assist torque distribution method provided in this embodiment, patients from a rehabilitation hospital were asked to perform a wearing experience test. Figure 7 shown.

[0050] As shown in (a) of Figure 7, a patient wearing experience test was conducted in a rehabilitation hospital, and the wearing experience was good. The experimental subjects were three hemiplegic patients, and the experimental walking distance was 30 m. To ensure safety in the experiment, the peak value of the power-assistance curve was adjusted to 18 Nm. As shown in (b) of Figure 7, the three hemiplegic patients all performed 30 m walking tests without wearing an exoskeleton and wearing an exoskeleton to assist, and compared the walking speeds of independent walking and assisted walking. Among them, "P1 N" represents patient 1 walking independently, and "P1 A" represents patient 1 assisted walking. Compared with independent walking, the walking speed of two patients decreased during assisted walking, and the speed of one patient increased. The result of the decrease in walking speed of the two patients may be caused by a variety of factors, such as the exoskeleton's power-assistance strength is too small or the patient fails to adapt to the power-assistance after wearing the exoskeleton.

[0051] like Figure 8 As shown in Figure 8, the result of active leg force under FES is shown by the ankle joint movement angle. A total of 3 subjects without walking impairment participated in this experiment, corresponding to (a), (b) and (c) in Figure 8. Figure 8 (b) and Figure 8 (c) in the figure. EFN refers to the walking test with exoskeleton assistance but without FES, the serial number is group number, and there are 3 groups in total; EFY refers to the walking test with FES under the assistance of exoskeleton, the serial number is group number, and there are 2 groups in total.

[0052] It can be seen that the ankle flexion angles of the three subjects under FES were greater than those of the group without stimulation, and the increasing trend of the flexion angles was similar, indicating that the FES unit had good consistency in the stimulation output for different individuals. Compared with the other two subjects, subject 1 showed a larger muscle response, with a maximum difference of more than 15°. At the same time, the ankle angle range was -15°~10° without stimulation. The foot drop simulated in the experiment was consistent with the actual patient condition.

[0053] In addition, the terms "upper", "lower", "inner", "outer", "front", "rear" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps described in these embodiments do not limit the scope of the present invention.

[0054] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes or modifications made according to the structure, characteristics and principles described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

[0055] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A hybrid exoskeleton system for ankle joints integrating functional electrical stimulation, characterized in that: It includes a leg bracket for fixing on the calf, a foot fixing plate hinged to the bottom of the leg bracket, a driving mechanism arranged on the leg bracket for driving the foot fixing plate to swing, and a system module matched with the driving mechanism; The system module includes FES electrodes for stimulating leg muscles, a pressure sensor on a foot fixing plate for collecting gait information, an ankle joint encoder at the hinge between a leg support and the foot fixing plate for collecting rotation angles, and a controller for generating control instructions based on the gait information and the rotation angle. The controller sends the control instructions to a drive mechanism to complete the assisted walking task, wherein the gait information includes heel-to-ground and toe-off.

2. The ankle joint hybrid exoskeleton system integrating functional electrical stimulation according to claim 1, characterized in that: The FES electrode sheets are arranged on the tibialis anterior muscle and the soleus muscle of the human body.

3. The ankle joint hybrid exoskeleton system integrating functional electrical stimulation according to claim 1, characterized in that: The leg support comprises support rods arranged on both sides of the calf, and a first fixing ring located below the knee for connecting the support rods on both sides.

4. The ankle joint hybrid exoskeleton system integrating functional electrical stimulation according to claim 1, characterized in that: The foot fixing plate comprises a foot bracket hinged to the bottom of the leg bracket and a second fixing ring, as well as a rear sole footrest and a forefoot footrest arranged on the foot bracket, wherein the rear sole footrest and the forefoot footrest are both provided with pressure sensors.

5. A method for distributing boost torque, characterized in that: The ankle joint hybrid exoskeleton system integrating functional electrical stimulation according to any one of claims 1 to 4 is implemented, comprising the following steps: The ankle joint encoder is used to collect the swing angle changes of the foot fixing plate under the preset number of steps, and the corresponding angle feedback is generated according to multiple sets of swing angle changes; Based on the angle feedback and the preset normal ankle angle change data, a segmented calculation method is used to obtain the gait deviation matrix; Constructing a corresponding cost function according to the gait deviation matrix and the preset weight parameters, and optimizing the power-assist torque parameters based on the cost function to output a corresponding power-assist parameter matrix; The gait phase of each gait cycle is estimated according to the gait information collected by the pressure sensor, and the corresponding parameterized assist torque is constructed based on the estimated gait phase and assist parameter matrix; Generate a swing angle change caused by calf muscle fatigue according to the angle feedback, and compare and calculate the swing angle change with a normal ankle joint angle to construct a corresponding muscle fatigue trajectory deviation index, wherein the calf muscles include a gastrocnemius muscle and a tibialis anterior muscle; Based on the parameterized assist torque and muscle fatigue trajectory deviation index, the control instructions corresponding to the drive mechanism are generated through the torque collaborative control strategy.

6. The assist torque distribution method according to claim 5, characterized in that: The assist torque parameters include the start time, peak time, torque magnitude and stop time of the motor plantar flexion torque curve, and the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve.

7. The assist torque distribution method according to claim 5, characterized in that: The expression of the parameterized assist torque is as follows: ; ;in, Represents the assist torque output by the exoskeleton, represents the plantar flexion assist torque, represents the dorsiflexion assist torque, represents the normalized gait phase, where , , and They correspond to the starting time, peak time, torque magnitude and stopping time of the motor plantar flexion torque curve respectively; , , and They correspond to the start time, peak time, torque magnitude and stop time of the motor dorsiflexion torque curve respectively.

8. The method for distributing the assist torque according to claim 5, characterized in that: The calculation formula of the muscle fatigue trajectory deviation index is as follows: in, and They are the normal angle and actual angle when stimulating the gastrocnemius muscle. and They are the normal angle and actual angle when stimulating the tibialis anterior muscle. Represents the number of steps walked.

9. The assist torque distribution method according to claim 6, characterized in that: The torque coordination control strategy is to adjust the distribution coefficient of the parameterized assist torque according to the muscle fatigue trajectory deviation index to generate the corresponding control instruction, and the process is as follows: ; ;in, and are the fatigue indexes of the gastrocnemius and tibialis anterior muscles, represents the symbolic function, Indicates the corresponding i +1 step gastrocnemius muscle fatigue trajectory deviation index, Indicates the corresponding i The muscle fatigue trajectory deviation index of the gastrocnemius muscle at the step, Indicates the corresponding i +1 step of tibialis anterior muscle fatigue trajectory deviation index, Indicates the corresponding i Muscle fatigue trajectory deviation index of the tibialis anterior muscle during walking; The expression of the distribution coefficient is as follows: ;in, and The distribution coefficients corresponding to the gastrocnemius muscle and the tibialis anterior muscle respectively; the expression of the control instruction is as follows: ; ;in, represents the torque generated by electrically stimulating the muscle, Represents the motor assist torque, and They correspond to the torque generated by electrical stimulation of the gastrocnemius and tibialis anterior muscles, represents the plantar flexion assist torque, Represents the dorsiflexion assisting moment.

10. The assist torque distribution method according to claim 6, characterized in that: The estimation process of the gait phase is as follows: By detecting heel strike and toe lift events, the gait cycle is divided into multiple sub-intervals; In each subinterval, the gait phase is estimated by linear interpolation, and the linear interpolation is expressed as follows: ;in, Indicates the current time. and Respectively represent the start and end time of the sub-interval.

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