Modeling and System Identification of a Life-Size Brake-Actuated Manipulator

Safety is a critical factor when designing a robotic rehabilitation environment. Whole-limb or life-size haptic interaction would allow virtual robotic rehabilitation of daily living activities such as sweeping or shelving. However, it has been too dangerous to implement such an environment with conventional active robots that use motor, hydraulic, or pneumatic actuation. To address this issue, a life-size 6-degree-of-freedom (DOF) brake-actuated manipulator (BAM) was designed and constructed. This paper details the BAM's system models including mechanisms, kinematics, and dynamics, as well as detailed input and friction models. In addition, a new system-identification technique that utilizes human input to excite the robot's dynamics with unscented Kalman filtering was employed to identify system parameters. Noise sources are discussed, and the model is validated through force estimation with inverse dynamics. Model parameters and performance are compared with other commercially available haptic devices. The BAM shows a significantly larger workspace, maximum force, and stiffness over other devices exhibiting its promise toward rehabilitative applications.