Dynamic analysis and control of rehabilitation robot manipulator for head-neck orthopedic disorders

Nowadays, robots have been used widely in medical applications for repetitive and sensitive tasks with developing technology. In this regard, the rehabilitation robots are a current subject and have taken their place in the field of health. This study includes a dual-arm robot manipulator design for the treatment of orthopedic neck diseases such as torticollis. Each arm of the manipulator has four degrees of freedom. Therefore, in this system, which is a deficient and kinematically closed loop, the universal joint is used to connect the arms with the head, in rehabilitation motion, in order to make the free orientation movements of the head complete, i.e. to move the robotic system without locking. As a result, each arm is a serial manipulator with a total of six degrees of freedom, four of which are actively actuated and two of which are passive. The head-and-neck model was designed as a four-degree of freedom serial manipulator consistent with the head motions. The link lengths of the dual-arm robot manipulator were determined based on the workspace of the head-neck model. In the study, kinematic analyses were conducted for deficient manipulators to study the motion of the neck-head model and dual-arm robot manipulator in a synchronized manner. In order to see how the system behaves under the effects of force and moment, the decoupled dynamic analyses of the head and the dual-arm robot manipulator were performed. The rehabilitation robotic system was controlled via the computed torque method by taking the external forces as the torque/force inputs to the arms, which make the required basic rehabilitation reference motions for the model defining the head-neck.