Systematic analysis of transparency in the gait rehabilitation device the FLOAT

Increasing the transparency of robotic systems used for gait rehabilitation can improve training of various daily activities such as walking or balancing. However, until today, there has been very little effort invested in a systematic analysis of occurring unwanted interaction forces between the patient and the robot. In this paper, we have developed such a setup for systematic analysis and quantification of interaction forces between the gait rehabilitation device the FLOAT and the patient. The results of our analysis show that our setup is capable of quantifying small interaction forces and movement effects under different, precisely controllable experimental conditions. Measured interaction forces of the FLOAT were found to be small and in the range of 3.3 N at low body weight support (52 N) to 17.6 N at high body weight support (376 N) when moving with constant velocity. In addition, deviations of the measured forces in the FLOAT ranged from 2 to 5 N. In combination with additional measurements that investigate other robot workspace locations and movement directions these results will help to understand the influence of unwanted interaction forces on patient recovery.