Rapid Design of Mechanical Logic Based on Quasi-Static Electromechanical Modeling

Abstract

Mechanical logic is a class of dynamic electromechanical mechanisms which leverages carefully designed mechanical structures to generate programmed control actions from a constant electrical power supply; thus, it can be employed as a control method for fully printable autonomous robots. Composed of a bistable buckled beam driven by conductive super-coiled polymer (CSCP) actuators, this type of electromechanical system features non-trivial relationships between its design parameters and resulting behavioral characteristics. In this paper we present an efficient method to rapidly design mechanical logic structures from desired behavioral specifications. We describe this dynamic system with a simplified, quasi-static model, whose validity is verified by time constant comparison. An analytical formula of the mechanical logic's behavioral characteristics, i.e. its oscillation period, is then derived as a simplified expression of the design parameters. Based on this expression, we formulate the design of mechanical logic from behavioral specifications into an optimization problem that maximizes the robustness to manufacturing tolerances, as demonstrated by an example case study.