Variable Constraint Mechanism and Its Application for Design of Mobile Robots

This paper describes the existence of one of the most useful mechanisms for robotic systems, coined the “variable constraint mechanism.” The variable constraint mechanism is a system that actively changes constraint conditions by itself, in response to the working purpose or the required motion sequence to acquire varied functionality. The paper discusses some of the generalized design principles for the mechanism and shows some example robotic systems, including an adjustable leg-length walking robot, a legged and wheeled hybrid vehicle, an autonomous multisection robot, and a planetary rover with collapsible frame and compressible wheels. KEY WORDS—variable constraint mechanism, Nagi timing, roller walker, Gunryu, Tri-Star II