Inverse kinematics and workspace analysis of a cable-driven parallel robot with a spring spine

•Kinematics is solved together with bending motion of the spring spine.•Optimal design of cable placement is performed.•Workspace of the bio-inspired parallel robot is analyzed.

We present a cable-driven flexible parallel robot with low motion noise to mimic a human neck in this paper. The fixed base and moving platform of the robot are connected by three cables and a compression spring. The spring serves as the cervical spine to support and facilitate the motion of moving platform corresponding to human head. The cables serve as the muscles around the human neck to drive the robot. Due to the flexible compression spring, we cannot solve the inverse kinematics directly. As shown in this paper, it should be combined with the statics for possible solutions. Based on the inverse kinematics and statics analysis, we optimize the cable placements to minimize the actuation force. Moreover, the workspace of the robot is analyzed with the constraint of positive cable tension. Simulations were performed and demonstrated the correctness and feasibility of the inverse kinematics and workspace analysis of the parallel robot. The approach presented in this paper can be extended to other parallel robots with a flexible compression spring.