Natural entrainment of mechanical systems with tensegrity structure

Tensegrity structures, which consist of struts and cables, have high strength to mass ratio and high energetic efficiency in deforming its shapes. This structure is sometimes observed in biological systems, which consists of muscles and skeletons, and this structure is adopted to a simplified model of animal body dynamics. From the aspect of engineering, applications of this structure to robotics are an interesting topic of research. On the other hand, for moving a mechanical system with the minimum input energy, to exploit a natural mode of the system is important because of a resonance effect. To exploit a natural mode of a system, a controller consisting of biological oscillators called a central pattern generator (CPG) was studied. In this paper, we use the CPG controller to exploit natural entrainment of tensegrity systems, and evaluate its applicability through numerical experiments. To design the CPG controller, we use the multivariable harmonic balance method, and the tensegrity system is linearized at an equilibrium point.