Trajectory Planning of an Underactuated Cable-Driven Planar Device for the Trunk

In this study, an innovative combination of an underactuated cable-driven planar device for the trunk (CAPT) and an omni gait trainer is proposed to provide certain trunk motion restraints in gait rehabilitation activities for individuals with lower limb dysfunction. This style of integration presents several possible benefits over modern gait rehabilitation devices, including a trunk postural control function, body weight support, considerable range of motion, and economic benefits. Based on the system kinematic, dynamic mathematical models, and nonholonomic constraints, a numerical optimization trajectory planning strategy based on the Radau pseudospectral method is proposed. Simulation results prove that the strategy can be employed to achieve trajectory planning for the CAPT. The selected cost function, considering the fluctuation of the cable tension, can effectively smoothen the variation of the cable force in the CAPT.