Mathematical Modeling of Human Gait in a Rehabilitation Exoskeleton Using Gait Video Analysis Method

Abstract

Purpose of research One of the ways to increase effectiveness of rehabilitation systems for patients with musculoskeletal disorders is the use of exoskeletons, which make it possible to ensure lower limbs movement according to the laws close to natural gait set by the rehabilitation therapist. The article considers a method based on construction of ankle joint motion trajectories (AJ) followed by synchronous determination of rotation angles of lower limb links based on numerical solution of inverse kinematics problem. It is known that the use of simplified laws of ancle joint movement and feet without taking into account anthropometric parameters of a patient leads to the formation of an incorrect gait and, as a result, a significant increase in rehabilitation time of a patient. Therefore, when constructing mathematical model of ankle motion patterns, it is proposed to use the method of video capture of marker points selected on AJ and foot, followed by processing and approximation of received signals using polynomials, which provides high accuracy of reproducing motion patterns. Purpose of research is to build motion laws of exoskeleton links along the trajectory of AJ motion based on a numerical solution of inverse kinematics problem.Methods. Experimental walking studies with the construction of AJ motion trajectory based on video fragment, smoothing and approximation of this trajectory and solving reverse kinematics problem are used to achive this goal.Results. Method for construction and processing of foot motion trajectory and finding kinematic characteristics of links motion for creation of exoskeleton motion patterns in gait is introduced.Conclusion. Simulation results shows that proposed methods of constructing motion trajectory and gait modeling of the exoskeleton make it possible to copy the gait of a person with high accuracy in rehabilitation process.