Research On Control Method Of Lower Extremity Exoskeleton Based On Energy Recycling

Lower extremity exoskeleton is a kind of wearable devices that provide assistance to the wearer’s lower extremity and improve their movement function.In order to reduce the mechanism weight of exoskeleton and improve its power-assisting effect,an energy recycling device is assigned to collect the kinetic energy of the lower limbs of human body.The energy recycled by exoskeleton will be released to assist the wearer’s target joint movement under the control of a brushless motor.In order to reduce the disturbance caused by the mechanism,the control method of the extremity exoskeleton was studied,along with the influence of the main parameters of the exoskeleton on its working effect.main tasks as follows:(1)Design a lower extremity exoskeleton based on the dynamics analysis of human lower extremityA lower limb kinematics model was established to analyze the gait and the biodynamic characteristics of the lower limb during walking at designated gait.According to the dynamic characteristics of the lower limbs,the energy recycling mechanism is studied,of which the working scheme and mechanical structure are designed.Design the structure of the lower extremity exoskeleton based on energy recycling.Establish an exoskeleton system model,and study the human-machine codrive system composed of the exoskeleton and the wearer.(2)Design of the lower extremity exoskeleton control system based on disturbance observerA sensor system is built based on inertial measurement unit to detect lower limb movement data.A sliding mode controller is designed to control the nonlinear strong coupling system composed of exoskeleton and human body,and use disturbance observer to estimate the interference during human-machine interaction,compensate the control process.The stability of the control system is analyzed.Several simulation experiments are carried out to prove that the designed control system can meet the needs of exoskeleton drive and has good anti-interference ability against disturbances from the mechanism itself and the environment.(3)Research on the assist effect of lower exoskeletonAccording to the muscle metabolic cost theory,the metabolic rate of lower extremity muscles is calculated as an index to evaluate the effectiveness of the lower extremity exoskeletons.The design parameters of the lower extremity exoskeleton and their relationship are analyzed,and the parameter design method of the lower extremity exoskeleton based on energy recovery is summarized.Carry out muscle metabolism depletion simulation,analyze the influence of control parameters on exoskeleton boosting effect,and provide reference for parameter design of such exoskeleton control system.