A Real-Time Stability Control Method Through sEMG Interface for Lower Extremity Rehabilitation Exoskeletons

Abstract

Herein, we propose a real-time stable control gait switching method for the exoskeleton rehabilitation robot. Exoskeleton rehabilitation robots have been extensively developed during the past decade and are able to offer valuable motor ability to paraplegics. However, achieving stable states of the human-exoskeleton system while conserving wearer strength remains challenging. The constant switching of gaits during walking may affect the center of gravity, resulting in imbalance of human–exoskeleton system. In this study, it was determined that forming an equilateral triangle with two crutch-supporting points and a supporting leg has a positive impact on walking stability and ergonomic interaction. First, the gaits planning and stability analysis based on human kinematics model and zero moment point method for the lower limb exoskeleton are demonstrated. Second, a neural interface based on surface electromyography (sEMG), which realizes the intention recognition and muscle fatigue estimation, is constructed. Third, the stability of human–exoskeleton system and ergonomic effects are tested through different gaits with planned and unplanned gait switching strategy on the SIAT lower limb rehabilitation exoskeleton. The intention recognition based on long short-term memory (LSTM) model can achieve an accuracy of nearly 99%. The experimental results verified the feasibility and efficiency of the proposed gait switching method for enhancing stability and ergonomic effects of lower limb rehabilitation exoskeleton.

Human Factor Engineering Research for Rehabilitation Robots: A Systematic Review

“…Early studies by Lokomat, ALEX, HAL, and BLEEX [68][69][70][71]: all used impedance control to achieve the fexibility of the rehabilitation motion, as shown in Figure 3. Four studies delved into the fexibility and stability of the rehabilitation motion, of which Chen et al [28] and Wang et al [29] combined impedance control, motion planning trajectory tracking, etc. Te studies were conducted to improve the trajectory tracking accuracy and robustness to achieve the supple stability control of the rehabilitation robot.…”

Design of lower limb rehabilitation exoskeleton with self-adaptive knee optimal force

“…The general medical robot needs accurate movement as it can be able to accomplish intrinsic operation, while medical exoskeleton robot movement as arthrogryposis requires co-operation with human body like fingers or knees. Some rehabilitation exoskeleton robots play an auxiliary role in helping the sick or the elderly recover from disability, and available exoskeleton robots, in disaster or medical rescues, need to be promoted for amplifying strength [3].…”

“…Others like a kind of hybrid exoskeleton with 4-link in bipedal waking system [6] or hybrid FES-exoskeleton with cooperative strategy designed for muscles recovery [7] have mature technologies about collecting electric sign and how to cope with it. In recent years, a type relying on surface on skins through sEMG Interface tech makes a great update to become lighter and more effective with more dexterity and mobility [3], which promotes the Elec-Mech technology in medical therapies. All of the researches make an improvement in exoskeletons for lower limb.…”

Deep reinforcement learning to assess lower extremity movement intention and assist a rehabilitation exoskeleton

“…Central to our approach is the use of sensor fusion, combining sEMG and IMU data to create a detailed real-time profile of muscle activity and limb movement as well as positioning [4]. The LSTM network is pivotal in interpreting these real-time sequential data streams, enabling the prediction of user intentions by analyzing patterns over time [20]. Concurrently, the PPO model fine-tunes the control policy, prioritizing smooth and natural movements that align closely with the user intended actions.…”