Abstract: Double pendulum with unilateral constraints is a complex system, which has many dynamic behaviors. The dynamics of a double pendulum contacting with constraints in initial conditions is studied, and it is found that only very small excitation is needed to separate the pendulum and the constraint when the excitation frequency is appropriate, then the system enters vibro-impact state. In this state, the probability distribution of tangential impulse generated by every impact is invariable. The impact force shows the ability of driving robot to move. Based on this principle, by simulating the characteristic of double pendulum, resonant legs and a prototype robot are developed. Experiment results show that the impact force between resonant leg and ground do have driving effect, and a velocity of 172 mm/s can be got with 10 V driving voltage. The resonant locomotion principle can fit the micro and miniature mobile robots well for it is simple, easy to implement and fast.

Key words: Locomotion principle, Micro and miniature robot, Resonant