Development of lower limb rehabilitation robot based on polar coordinate

Elderly people have some problems about their decrease in lower limb function. So, there is a possibility of falling and causing serious injury when standing or sitting. The purpose of this research is to construct a system that enables elderly people to receive safe and high quality rehabilitation. At the first, analysis of trajectory of standing and sitting motion is performed. Thanks to the analysis, it turns out that lower limbs of the human beings at the time of standing and sitting have many components of rotational motion around the hip joint. Furthermore, measurement of the floor reaction force by the force plate is also performed. The measurement result shows that the human lower limbs are standing and sitting by adjusting the force in the direction of rotation around the hip joint while exerting a constant force in the linear direction connecting the ankle joint and the hip joint to support their weight. Finally, based on the obtained results, Polar-coordinate-based design of rehabilitation robot is indicated.