Design and analysis of a three-dimensional bridge-type mechanism based on the stiffness distribution

A 3-D bridge-type mechanism is designed and analyzed in this paper. Compared with the previous design, the mechanism proposed in this paper, among other advantages that the conventional bridge-type mechanisms have e.g., compact size, simple design and symmetric structure etc, features a high amplification ratio. To evaluate the displacement loss of the amplifier, as a new evaluation index, the relative amplification rate, is proposed in this paper. An analytical model for the amplification ratio and the relative amplification rate is established based on the screw theory. Several bridge-type mechanisms combined with four frequently used flexure hinges are analyzed based on the consideration of stiffness distribution, which are compared via the aforementioned analytical model. Based on the comparison, the numerical results show that the proposed bridge-type mechanism reaches the optimal performance in terms of the amplification ratio and the relative amplification rate when the V-shaped hinge and the filleted leaf hinge are employed in bridge 1 and bridge 2 respectively. Finally, the performance of the amplifier with amplification ratio of 41 and relative amplification rate of 0.93 is confirmed by FEA simulation and experiments.