The Effects of a Knee-Joint Energy Harvester on Muscle Activation in the Human Lower Limbs Based on EMG Signal

Knee-joint energy harvesters for the lower limb provide sustainable power for outdoor environments, addressing the limitations of portable devices and the high metabolic costs of batteries. Biomechanical energy is dissipated at the knee joint during the acceleration and deceleration phases of walking. Over the past two decades, researchers have designed numerous knee-joint biomechanical energy harvesters to capture this dissipated energy, generate electrical power, and reduce bioenergy consumption. However, the biomechanical effects of these harvesters on walking remain unclear, hindering further optimization. Therefore, this study aimed to explore the biomechanical effects using electromyography and gait analysis with knee-joint biomechanical energy harvesters. The results indicated that during the first negative work phase (0-20<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup>) of walking with the powered exoskeleton in energy harvesting mode, the ampere torque generated by the closed-loop system reduced the activation of the vastus lateralis (VL) and rectus femoris (RF) muscles in the early stance phase by 12%. Furthermore, during the deceleration phase of the swing stage, the activation levels of these two muscles were significantly lower compared to other muscles.