Transmission angle in compliant four-bar mechanism

Compliant mechanisms have increasing popularity. However, very few studies are available on transmission characteristics of compliant mechanisms in the literature. For conventional rigid-body mechanisms, the transmission angle is used to define motion quality. On contrary, the classic transmission angle formula cannot easily be employed for compliant mechanisms, unlike rigid-body mechanisms. This paper, a generalized equation that defines the transmission angle of all types of compliant four-bar mechanisms is introduced. For all configurations of partially compliant four-bar mechanisms, the formula is altered. Four theorems in some special cases are devised. Deviation of the transmission angle of a fully compliant four-bar mechanism from its rigid-body counterpart is discussed. Finally, a prototype is built and the theoretical approaches are compared with experimental results. To the best of our knowledge, this is the first study on the transmission angle of a compliant four-bar mechanism.