Design of a Cam-Actuated Robotic Leg

This paper presents a concept for a single-degree-of-freedom robotic leg, where the lower and upper leg are each controlled by a cam. The two cams are mounted on a common shaft, and are rotating at the same speed. The relevant equations for the mechanism’s kinematics are first developed, to express the position of the foot in terms of the cam’s angular displacement and various design parameters such as link lengths. Next, the design problem is formulated as an optimization, where the objective is to minimize an error metric that compares the foot position to the desired trajectory of the foot. The constraints in the optimization problem include important parameters such as the pressure angle of the cams, as well as a set of constraints to ensure that the leg will fit on an appropriately sized legged robot. Finally, the results are discussed, with a focus on what the advantages and disadvantages of this leg design might be as compared to other types of robotic leg designs.