Data-Driven Design of a Six-Bar Lower-Limb Rehabilitation Mechanism Based on Gait Trajectory Prediction

Abstract

For patients who need lower-limb kinetism rehabilitation training, this paper proposes an effective datadriven approach seeking the design of 1-degree-of-freedom (DOF) six-bar rehab mechanism through gait prediction by body parameters. First, gait trajectories from 79 healthy volunteers are collected along with their body parameters. Then, the normalized gait samples are clustered and regressed into a limited number of representative trajectories with K-means algorithm, and the cluster index is recorded as the label for each trajectory. Next, a genetic-algorithmoptimized support vector machine method is adopted to establish a classifier for the trajectories, obtaining the correspondence between body parameters and cluster labels of gait trajectories. As a result, once a group of body parameters are input into the classifier, the suitable gait trajectory can be predicted for the specific patient. A GA-BFGS algorithm is developed for 1-DOF six-bar mechanism synthesis and a GUI design software is presented that shows how the data-driven design process is realized. The novelty of this paper is using clustering and prediction technique to accomplish the patient-mechanism matching, so that simple, low-priced 1-DOF mechanisms could be adopted for large number of various patients without expensive customized design for each individual. In the end, a gait rehab device design example is provided, and a prototype device driven by a constant speed motor is presented, which illustrates the feasibility of the proposed method.

Computer aided design of a single degree-of-freedom six-bar mechanism via Monte Carlo layered optimization method

“…Single degree of freedom (DOF) mechanisms offer the advantages of simple control and high stiffness, making them prevalent in the design of diverse robotic systems. Considering the diversity of tasks and the complexity of constraints, developing an efficient design for a single DOF mechanism that satisfies multiple constraints remains a challenging task [ [1] , [2] , [3] , [4] ].…”