Kinematics analysis of lower extremity exoskeleton

The lower extremity exoskeleton is a wearable device that can increase the strength, speed, and endurance of the wearer. In order to let the exoskeleton moving at desired trajectories, an accurate kinematics model of the mechanism is required. As the exoskeleton has many degrees of freedom (DOFs) and has no fixed base, it is difficult to analyze the kinematics by using conventional methods. In this paper, a generalized kinematics model of lower extremity exoskeletons is proposed by employing coordinate transforming matrix. Meanwhile, the formulation of forward kinematics and the inverse kinematics are discussed in detail. Finally, gait planning is realized according to the results of kinematics analysis. The commercialized dynamics analysis software ADAMS was selected for the modeling and simulation of the generalized lower extremity exoskeleton. To verify the theoretical analysis, a virtual low extremity exoskeleton is built. Based on the inversed kinematics of low extremity exoskeleton, the virtual prototype walks stably in ADAMS by controlled by MATLAB SIMULINK for tracking a desired gait data.