Kinetostatic Analysis and Actuation Strategy of a Planar Tensegrity 2-X Manipulator

A planar tensegrity manipulator made of two X-mechanisms in series is studied in this paper. Contrary to a classical 2-R linkage, the proposed architecture does not contain elements subject to bending and it can be driven with remote actuation and cables in an antagonistic way. Accordingly, it is an interesting candidate for the design of lightweight manipulators with variable stiffness suitable for safe interactions. On the other hand, its kinematics is more challenging because of a variable instantaneous center of rotation of the X-mechanisms. First, the inverse kinematic problem is solved using an adequate methodology, the singularities are determined, and the workspace shape is analyzed as a function of the design parameters. Then, two actuation schemes are studied and the wrench feasible workspace is analyzed for each of them. The second actuation scheme provides a larger wrench feasible workspace and allows for stiffness control.