An approach to the dynamics and control of a planar tensegrity structure with application in locomotion systems

The use of mechanically compliant tensegrity structures in vibration-driven mobile robots is an attractive research topic, due to the principal possibility to adjust their dynamic properties reversibly during locomotion. In this paper vibration driven planar locomotion of mobile robots, based on a simple tensegrity structure, consisting of two rigid disconnected compressed members connected to a continuous net of four prestressed tensional members with pronounced elasticity, is discussed. The dynamic behaviour of the considered system is nonlinear, due to large vibration amplitudes and friction between robot and environment, and is mainly influenced by the magnitude of prestress. Therefore, the movement performance of the robot can be essentially influenced by the actuation parameters, e.g. by modifying the frequency or the magnitude of actuation the locomotion direction of the system varies. To study the system behaviour, the nonlinear equations of motion are derived and transient dynamic analyses are performed, including the consideration of chaotic system behaviour near to the primary and secondary eigenfrequencies. The dependency of the movement behaviour on the actuation parameters and on the prestress are discussed focused on single-actuated systems with minimal control effort.