Simulation of Controlled Motion of a Person When Walking in an Exoskeleton

Purpose of reseach. Robot exoskeletons open up new possibilities in the rehabilitation of patients with lower limb injuries. Despite the growing number of publications on this topic, many issues related to the development of design tools based on the simulation of human movement in an exoskeleton using the theoretical basis of stable movement in the upright position have not been studied well enough. Therefore, the purpose of this paper is to develop methods for improving the efficiency of the lower extremity exoskeleton control system for biped gait. 

Methods. The key feature of the paper is the application of modeling techniques determining the laws of the exoskeleton motion. Methods of mathematical modeling of the motion of sections are used, taking into account their subsequent possible use in modeling the motion of exoskeleton sections; trajectory equations are composed using the vector-matrix method. The trajectories of the exoskeleton's foot, lower leg, and hip movement during steady walking are studied.

Results. To simulate the operation of a robotic complex - a prototype of an exoskeleton of the lower extremities with ten active degrees of freedom, kinematic definition the trajectory of the sections is used. To find the vector of generalized coordinates, the inverse kinematics problem is solved applying the vector-matrix method using the Jacobian matrix. The results of numerical simulation show high convergence and eficacy of the proposed method. The proposed method allows defining the trajectory of the operator in the exoskeleton in real devices.

Conclusion. In the paper, the study of walking is performed from the standpoint of modeling a quasi-static gait using kinematic approaches. The developed method for determining the defining angles of rotation of the exoskeleton sections for different foot positions taking into account the position of the mass center projections, is used in the development of algorithms for controlling human motion in the exoskeleton. 

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