Reciprocating Geared Mechanism with Compliant Suspension

We present a novel cycloidal geared mechanism with a continuous rotational input featuring a reciprocating translational output. A statically balanced compliant mechanism suspends an annulus driven by a cycloidal rotor. The freedom and constraint topology design method is used to synthesize the compliant suspension. A fixed transmission ratio of 15 results from the ratio between the cycloidal rotor and the annulus. The static balancing conditions of the suspension are developed analytically, and validated using finite-element modeling and experimental results. Moreover, the estimation of the frictional loss as a function of the stiffness of the compliant members is derived using a force analysis of the system and verified using experimental data. A case study on a mechanical watch yields dimensions for the prototype, which is fabricated in silicon using deep reactive ion etching. Experiments show that energy loss as a function of the stiffness of compliant members is marginal and independent of the position of the compliant suspension.