Predictive equation for a circular trajectory period in a cable-driven robot for rehabilitation

Rehabilitation training is the most effective way to reduce motor impairments in stroke patients, and cable-driven robots can be an efficient way to increase the intensity of this training. The motor functions of stroke patients are often related and evaluated using circle drawing/tracing tasks as studies show that these patients produce elliptical instead of circular shapes. Training can increase the hemiparetic arm workspace and the performance of circular design in these patients. Thus, this paper presents a robot actuated by cables that can be used in rehabilitation producing circular trajectories. First, the circular trajectory and mathematical model to keep the cables in tension are presented. Next, a serious game is described that uses the circular trajectory for stroke rehabilitation. The results showed that the predictive equation proposed in the present paper represented the experimental data with an average relative error of only 1%. Finally, an optimization was performed to obtain the shortest period of a circular trajectory.