Optimizing simulation of freestyle arm stroke for swimmers with hemiplegia

Abstract

For the competitive swimmers with physical disability, an ideal stroke to master has not been fully clarified yet. The objectives of this study were to solve computationally the arm stroke of the crawl swimming that maximized the swimming speed for swimmers with hemiplegia, and to investigate the features of the optimized stroke. For this objective optimizing calculations with the random search, PSO (Particle Swarm Optimization) algorithm, and the swimming human simulation model was conducted. In the optimizing calculation the design variable was the upper limb motion of the unaffected side, represented by five degrees-of-freedom (three at the shoulder joint and two at the elbow joint), and the fastest stroke was obtained as the optimum stroke. For the motions of the other body parts, the legs, trunk and the upper limb of the affected side, the motion of the actual swimmer were used. When the stroke cycle was 1.0 s or 1.1 s, the swimming speed became fastest (1.19 m/s). With the short stroke cycles there were the differences at the end of the stroke, and with the long stroke cycles the swimmer pushed the water deeper in the optimum stroke.