Rehabilitation robot joint performance evaluation of a zero-spin traction drive with non-Newtonian fluid considered

In this study, a zero-spin cone-roller traction drive (CRTD) is presented for the joints transmission system in rehabilitation robots due to its high transmission performance and characteristics of overload protection. It can achieve safe interactions among humans, rehabilitation robots, and the environment, making it a potential substitute for traditional gear-based transmission systems. The performance of CRTD, especially efficiency, is studied in this paper based on an elastohydrodynamic lubrication (EHL) model with the considerations of the non-Newtonian effect. The results demonstrate that the overall efficiency differs in different stages, reaching a maximum value of 95%. The overload protection activates when there is a sharp drop in efficiency, and the overload threshold can be identified by the efficiency, which may provide guidance for operation and optimization.