A Synergistic Rehabilitation System and Method Integrating Functional Electrical Stimulation and Lower Limb Exoskeletons

Abstract

The present invention discloses a collaborative rehabilitation system integrating functional electrical stimulation and lower limb exoskeleton, comprising: a multi-channel functional electrical stimulation generator for performing periodic and regular functional electrical stimulation on corresponding muscles of a patient; a lower limb exoskeleton, with one side including a hip joint link, a hip joint motor, a thigh link, a knee joint motor, a calf link, a mechanical ankle joint and a foot plate connected in sequence; an attitude sensor for inputting the detected hip flexion / extension angle θ and angular velocity ω values to a host computer; and a host computer for responsible for processing human-computer interaction instructions, generating gait trajectories, and distributing the combined torque of functional electrical stimulation and exoskeleton by receiving the data from the attitude sensor; the present invention also discloses a collaborative rehabilitation method. By combining functional electrical stimulation (FES) with the lower limb exoskeleton (EXO), the present invention provides scientific and regular functional electrical stimulation to target muscles, enabling patients to participate more actively in the process of active rehabilitation.

Description

Technical Field

[0001] The present invention relates to the technical field of rehabilitation equipment, and particularly relates to a collaborative rehabilitation system and method integrating functional electrical stimulation and lower limb exoskeletons. Background Art

[0002] As of 2017, there were as many as 13 million stroke patients living with illness in China. Among them, 80% - 90% of stroke patients have sequelae of walking disorders after the illness, which seriously affects the quality of life of patients and brings a heavy economic burden to the families of patients and society. Traditional rehabilitation methods usually involve clinicians cooperating with instruments to guide patients to perform passive repetitive functional movement training, so that they can recover some or all of their motor functions after long-term rehabilitation training. However, only about 40% - 50% of patients can benefit from this intensive treatment, and only a few hemiplegic patients can recover to the normal walking level.

[0003] Functional electrical stimulation (FES) applies a stimulating current to human muscles to activate muscle contraction, enabling patients to autonomously complete corresponding actions. While realizing functional movement assistance, FES can enhance muscle strength and promote neural plasticity, thereby improving the effect of motor rehabilitation. Although FES has practical applications and commercial products for the rehabilitation of patients' motor functions, there are still obvious limitations, such as: the torque of the electric stimulation driving the muscle is limited, it is difficult to precisely control the muscle as a non-linear element, and continuous electric stimulation for a long time is likely to cause muscle fatigue, etc. These problems seriously limit the actual clinical application of the FES-based motion rehabilitation system.

[0004] In recent years, researchers have proposed a hybrid control method integrating FES and lower limb rehabilitation robots: on the one hand, using the high-efficiency torque driving advantage of the exoskeleton robot to make up for the deficiency of FES in driving patients' muscles, and at the same time effectively delaying the occurrence of muscle fatigue caused by electric stimulation; on the other hand, by activating the autonomous contraction of muscles through FES, the maximum degree of active rehabilitation training for patients can be achieved.

[0005] The patent specification with the publication number CN213552679U discloses an ankle-foot orthosis carrying a functional electrical stimulation device, which includes two parts: an ankle-foot orthosis (AFO) and a functional electrical stimulation device (FES). The ankle-foot orthosis (AFO) cannot provide an active assistive torque, and the control system only targets functional electrical stimulation.

[0006] The patent specification with the publication number CN103655122B discloses a knee exoskeleton system integrating functional electrical stimulation. A DC servo motor driver is connected to the knee exoskeleton, and a controller is connected to the DC servo motor driver and a multi-channel functional electrical stimulator. The controller controls the knee exoskeleton through the DC servo motor driver, controls the multi-channel functional electrical stimulator, and the knee exoskeleton and the multi-channel functional electrical stimulator work together, and the synchronism between the two is controlled by the controller. The device in this solution is only a simple superposition of functional electrical stimulation and the knee exoskeleton in terms of function, and does not achieve the integration and complementarity of the two in the control system. Secondly, the device only targets a single joint, and the patient needs to lie on a rehabilitation chair for treatment, which cannot simulate normal gait and is difficult to achieve the overall muscle coordination rehabilitation treatment for the patient. Summary of the Invention

[0007] An object of the present invention is to provide a collaborative rehabilitation system integrating functional electrical stimulation and lower limb exoskeleton. By cooperating functional electrical stimulation (FES) with the lower limb exoskeleton (EXO), scientific and regular functional electrical stimulation is given to the target muscles, enabling the patient to participate more actively in the process of active rehabilitation.

[0008] A collaborative rehabilitation system integrating functional electrical stimulation and lower limb exoskeleton includes:

[0009] A multi-channel functional electrical stimulation generator for performing periodic and regular functional electrical stimulation on the corresponding muscles of the patient;

[0010] A lower limb exoskeleton, one side of which includes a hip joint link, a hip joint motor for providing assistance for hip joint extension and flexion of the patient, a thigh link, a knee joint motor for providing assistance for calf gait movement, a calf link, a mechanical ankle joint, and a foot plate connected in sequence;

[0011] An attitude sensor for inputting the detected hip joint flexion / extension angle θ and angular velocity ω values to the upper computer;

[0012] An upper computer for responsible for processing human-computer interaction instructions, generating gait trajectories, and distributing the integrated torque of functional electrical stimulation and exoskeleton by receiving the data of the attitude sensor.

[0013] Preferably, the lower limb exoskeleton further includes an integrated control back bin and a fixing component for fixing the integrated control back bin to the patient's waist. The hip joint links are respectively fixed on both sides of the fixing component, and the upper computer is placed in the integrated control back bin.

[0014] Preferably, the multi-channel functional electrical stimulation generator includes a quadriceps femoris functional electrical stimulation channel, a gastrocnemius functional electrical stimulation channel, a soleus functional electrical stimulation channel, and a tibialis anterior functional electrical stimulation channel for performing periodic and regular functional electrical stimulation on the patient's quadriceps femoris, gastrocnemius, soleus, and tibialis anterior muscles.

[0015] In this solution, an 8-channel functional electrical stimulator is configured for each unilateral leg. According to the controller signal, periodic and regular functional electrical stimulation is performed on the patient's quadriceps femoris, gastrocnemius, soleus, and tibialis anterior muscles. The specific working process is as follows: During the standing phase, the quadriceps femoris is electrically stimulated to stabilize the knee joint. During the swing phase, the gastrocnemius and soleus are electrically stimulated to drive ankle plantar flexion, and then the tibialis anterior is electrically stimulated to assist ankle flexion to complete the stepping motion. Such a cycle is carried out to achieve the goal of active muscle rehabilitation for the patient.

[0016] Another object of the present invention is to provide a collaborative rehabilitation method integrating functional electrical stimulation and a lower limb exoskeleton, specifically including the generation step of the lower limb exoskeleton assistance torque and the collaborative step of the lower limb exoskeleton and functional electrical stimulation;

[0017] The generation step of the lower limb exoskeleton assistance torque includes parameterization of the lower limb exoskeleton assistance torque curve and offline optimization of the assistance torque curve;

[0018] The collaborative step of the lower limb exoskeleton and functional electrical stimulation is specifically as follows:

[0019] Input the hip flexion / extension angle θ and angular velocity ω values detected by the attitude sensor at the patient's thigh to the upper computer, and use a phase angle oscillator to generate the gait phase as follows:

[0020]

[0021] where, is the gait phase;

[0022] During each gait cycle, the hip joint torque required for walking is:

[0023]

[0024] are respectively:

[0025]

[0026] and satisfy:

[0027] f(I F ) = K·g(I E )

[0028] where, I FThe current value I input to the multi-channel functional electrical stimulation generator E is the current input to the lower limb exoskeleton motor; is the functional electrical stimulation and lower limb exoskeleton assistance distribution factor within each gait cycle, which is a function of the gait phase ; K F , K E are respectively the torque equivalent coefficients of the functional electrical stimulation and the lower limb exoskeleton; K is the assistance weight ratio between the functional electrical stimulation and the lower limb exoskeleton, representing the proportion of the two under the current assistance rehabilitation strategy.

[0029] Preferably, the assistance torque curve is parameterized by smoothly connecting the assistance torque values provided by the assistance curve at certain gait phases to form a curve.

[0030] Preferably, the offline optimization of the assistance torque curve is to perform offline optimization on the assistance torque curve by means of an algorithm with the help of the feedback physiological signal.

[0031] More preferably, the physiological signal is the electromyogram signal of the patient.

[0032] More preferably, the algorithm is the Bayesian optimization algorithm.

[0033] Advantages of the present invention:

[0034] (1) FES and the active lower limb rehabilitation exoskeleton cooperate to provide rehabilitation assistance torque for the patient. Generally, the active rehabilitation exoskeleton can provide an assistance torque of 60 - 100 Nm for the assisted joint, which is sufficient to meet the torque requirements during the rehabilitation process.

[0035] (2) FES and the exoskeleton cooperate to jointly provide assistance torque for the patient. Therefore, during the rehabilitation assistance process, the current stimulation intensity of FES can be appropriately reduced. Secondly, combined with the torque fusion distribution control model, regular intermittent electrical stimulation that conforms to the rehabilitation process can be provided, that is, when approaching the set threshold of muscle fatigue, the electrical stimulation of the target muscle can be temporarily stopped. After a "rest" for a specified time, the functional electrical stimulation is reapplied to the target muscle, so as to avoid the patient's muscles being over-fatigued by long-term continuous electrical stimulation as much as possible, which is beneficial to the patient's rehabilitation treatment process to a certain extent.

[0036] (3) Through the torque fusion distribution model, combined with the clinical diagnosis and treatment plan, personalized parameters for the patient are set, and scientific and regular functional electrical stimulation is given to the target muscle, enabling the patient to participate more actively in the active rehabilitation process, and allowing the limb to be rehabilitated to receive more active and effective rehabilitation treatment. Description of the drawings

[0037] Figure 1Schematic diagram of wearing an external limb exoskeleton and a multi-channel functional electrical stimulation generator for a patient;

[0038] Figure 2 Schematic diagram of the connection between the multi-channel functional electrical stimulation generator and the host computer;

[0039] Figure 3 Control block diagram of the system; Specific implementation manner

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] As Figure 1 and 2 shown, a collaborative rehabilitation system integrating functional electrical stimulation and lower limb exoskeleton includes a lower limb exoskeleton 1, a multi-channel functional electrical stimulation generator 2, an attitude sensor, and a host computer 3.

[0042] The lower limb exoskeleton 1 includes a fusion control back bin 11, a fixing component for fixing the fusion control back bin 11 to the patient's waist, and a hip joint link 12, a hip joint motor 13, a thigh link 14, a knee joint motor 15, a calf link 16, a mechanical ankle joint 17, and a foot plate 18 that are arranged on both sides of the fixing component and connected in sequence; when worn, the hip joint link 12, the thigh link 1, the calf link 16, the mechanical ankle joint 17, and the foot plate 18 respectively correspond to the patient's hip joint, thigh, calf, ankle joint, and foot sole; the hip joint motor 13 is used to provide assistance for the patient's hip joint extension and flexion, and the knee joint motor 15 is used to provide assistance for the patient's calf gait movement.

[0043] The multi-channel functional electrical stimulation generator 2 specifically adopts an 8-channel functional electrical stimulation generator, wherein the 8 channels are respectively a left leg gastrocnemius functional electrical stimulation channel 21, a left leg soleus functional electrical stimulation channel 22, a left leg tibialis anterior functional electrical stimulation channel 23, a left leg quadriceps femoris functional electrical stimulation channel 24, a right leg gastrocnemius functional electrical stimulation channel 25, a right leg soleus functional electrical stimulation channel 26, a right leg tibialis anterior functional electrical stimulation channel 27 and a right leg quadriceps femoris functional electrical stimulation channel 28, respectively. The patient's left gastrocnemius, left soleus, left tibialis anterior, left quadriceps, right gastrocnemius, right soleus, right tibialis anterior and right quadriceps were subjected to periodic functional electrical stimulation. The specific working process is: in the standing phase, the quadriceps are electrically stimulated to stabilize the knee joint, in the swing phase, the gastrocnemius and soleus are electrically stimulated to drive ankle flexion, and then the tibialis anterior is electrically stimulated to help ankle flexion to complete the stepping action. This cycle is repeated to achieve the goal of active muscle rehabilitation for patients.

[0044] The posture sensor is specifically arranged at the patient's thigh to detect the patient's hip flexion / extension angle θ and angular velocity ω; the upper computer 3 is placed in the fusion control back chamber 11, and performs functional electrical stimulation and exoskeleton fusion torque distribution by receiving the patient's hip flexion / extension angle θ and angular velocity ω input by the posture sensor.

[0045] A collaborative rehabilitation method integrating functional electrical stimulation and lower limb exoskeleton includes a step of generating a lower limb exoskeleton assist torque and a step of coordinating the lower limb exoskeleton and the functional electrical stimulation.

[0046] Steps for generating the lower limb exoskeleton assist torque:

[0047] First, a lower limb exoskeleton assistance torque curve that can coordinate with FES is designed. While meeting the basic torque requirements for rehabilitation, it mainly enables patients to carry out intermittent regular electrical stimulation programs, thereby improving the treatment effect while avoiding muscle fatigue as much as possible.

[0048] The assistive torque curve of the lower limb exoskeleton needs to be continuously optimized according to the patient's muscle state. First, the parameterization of the assistive torque curve needs to be realized to achieve the most compliant assistive torque planning and the assist of coordinated FES through parameter adjustment. The parameterization of the assistive torque curve needs to smoothly connect the assistive torque values provided by the assistive curve at certain gait phases (i.e., the percentage of each time stage in a walking cycle or a handling cycle in the whole cycle time) to form a curve, such as the gait phase corresponding to the peak of the assistive torque curve, the gait phase interval of the curve rise, the peak of the assistive torque, etc. Second, the offline optimization of the assistive torque curve needs to be carried out through the feedback of physiological signals. After the above parameterization of the assistive torque curve, the adjustment of the assistive torque curve through a set of parameters is realized, and the optimization of this set of parameters is obtained through iterative optimization with the help of the Bayesian optimization algorithm based on the feedback of physiological signals.

[0049] During the rehabilitation process, through the surface electromyogram sensors pasted on the rectus femoris, vastus medialis, and vastus lateralis muscles, the weak electrical signals of the muscles can be obtained to characterize the muscle force of the human body. The signals are transmitted to the upper computer PC for preprocessing of the electromyogram signals and calculation of the activation degree characterization. When the muscle force value gradually reaches the specified electrical stimulation muscle fatigue threshold (under continuous functional electrical stimulation, as the patient's muscles fatigue, at the same intensity of electrical stimulation, the degree of muscle contraction becomes smaller and the generated force gradually becomes smaller), the parameters of the assistive torque curve are optimized with the help of the Bayesian optimization algorithm, so that the torque provided by the exoskeleton becomes larger accordingly to make up for the torque loss caused by the muscle fatigue of FES. Similarly, when the patient's muscles have "rested" for a period of time, the exoskeleton torque is gradually reduced according to the feedback physiological data, and the electrical stimulation intensity is appropriately increased. Such a strategy continuously adjusts and optimizes the assistive curve of the exoskeleton to meet the basic requirements of the assistive torque and avoid the muscle fatigue problem caused by functional electrical stimulation as much as possible.

[0050] The cooperation steps of the lower limb exoskeleton and functional electrical stimulation:

[0051] Input the hip flexion / extension angle θ and angular velocity ω values detected by the attitude sensor at the human thigh to the upper computer, and realize the gait phase generation with the help of the phase angle oscillator, as follows:

[0052]

[0053] Among them, is the gait phase;

[0054] During each gait cycle, the hip joint torque required for walking is:

[0055]

[0056] are respectively:

[0057]

[0058] And it satisfies:

[0059] f(I F ) = K·g(I E )

[0060] wherein, I F is the current value input to the multi-channel functional electrical stimulation generator, and I E is the current input to the lower limb exoskeleton motor; is the functional electrical stimulation FES and lower limb exoskeleton EXO assistance distribution factor within each gait cycle, which is a function of the gait phase ; K F , K E are respectively the torque equivalent coefficients of the functional electrical stimulation FES and the lower limb exoskeleton FES and EXO (the proportionality coefficient from current to joint torque); K is the assistance weight ratio of the functional electrical stimulation FES and the lower limb exoskeleton EXO, representing the proportions of the two under the current assistance rehabilitation strategy. The control block diagram is as Figure 1 shown.

[0061] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A collaborative rehabilitation system integrating functional electrical stimulation and lower limb exoskeletons, characterized in that, Comprising: A multi-channel functional electrical stimulation generator for performing periodic and regular functional electrical stimulation on the corresponding muscles of a patient; A lower limb exoskeleton, one side of the lower limb exoskeleton includes a hip joint link connected in sequence, a hip joint motor for providing assistance for hip joint extension and flexion of the patient, a thigh link, a knee joint motor for providing assistance for calf gait movement, a calf link, a mechanical ankle joint, and a foot plate; An attitude sensor for inputting the detected hip joint flexion / extension angle θ and angular velocity ω values to a host computer; A host computer for responsible for human-computer interaction instruction processing, gait trajectory generation, and distributing the functional electrical stimulation and exoskeleton fusion torque by receiving the data of the attitude sensor; The collaborative rehabilitation system further includes a generation step of the lower limb exoskeleton assistance torque and a collaborative step of the lower limb exoskeleton and functional electrical stimulation, and the specific steps are as follows: The generation step of the lower limb exoskeleton assistance torque includes parameterization of the lower limb exoskeleton assistance torque curve and offline optimization of the assistance torque curve; The offline optimization of the assistance torque curve is to perform offline optimization of the assistance torque curve by means of an algorithm with the aid of the feedback physiological signal, and the physiological signal is the electromyogram signal of the patient; The collaborative step of the lower limb exoskeleton and functional electrical stimulation is specifically: Input the hip joint flexion / extension angle θ and angular velocity ω values detected by the attitude sensor at the thigh of the human body to the host computer, and realize gait phase generation by means of a phase oscillator, as follows: wherein, is the gait phase; Within each gait cycle, the hip joint torque required for walking is: Respectively: And satisfy: f(I F ) = K·g(I E ) Among them, I F is the current value input to the multi-channel functional electrical stimulation generator, and I E is the current input to the lower limb exoskeleton motor; is the functional electrical stimulation and lower limb exoskeleton assistance distribution factor within each gait cycle, and is a function of the gait phase ; K F， K E are respectively the torque equivalent coefficients of the functional electrical stimulation and the lower limb exoskeleton; K is the assistance weight ratio of the functional electrical stimulation and the lower limb exoskeleton.

2. The collaborative rehabilitation system according to claim 1, wherein The lower limb exoskeleton further includes a fusion control back box and a fixing component for fixing the fusion control back box to the waist of the patient, the hip joint links are respectively fixed on both sides of the fixing component, and the host computer is placed in the fusion control back box.

3. The collaborative rehabilitation system according to claim 1, wherein The multi-channel functional electrical stimulation generator includes a quadriceps femoris functional electrical stimulation channel, a gastrocnemius functional electrical stimulation channel, a soleus muscle functional electrical stimulation channel, and a tibialis anterior muscle functional electrical stimulation channel for performing periodic and regular functional electrical stimulation on the quadriceps femoris, gastrocnemius, soleus muscle, and tibialis anterior muscle of the patient.

4. The collaborative rehabilitation system according to claim 1, wherein The parameterization of the assistance torque curve is to smoothly connect and form a curve according to the assistance torque values provided by the assistance curve at certain gait phases.

5. The collaborative rehabilitation system according to claim 1, characterized in that The algorithm is a Bayesian optimization algorithm.

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