Overconstrained coaxial design of robotic legs with omni-directional locomotion. (October 2022) - Gu, Yuping
Abstract: While being extensively researched in literature, overconstrained linkages' engineering potential is yet to be explored. This study investigates the design of overconstrained linkages as robotic legs with coaxial actuation starting with the simplest case, Bennett linkage, to establish the theoretical foundations and engineering advantages of a class of overconstrained robots. We proposed a parametric design of the spatial links and joints in alternative forms so that one can fabricate these overconstrained limbs via 3D printing and then attach the linkage coaxially to a pair of servo actuators as a reconfigurable leg module. We adopted multi-objective optimization to refine the design parameters by analyzing its manipulability metric and force transmission, enabling omni-directional ground locomotion projected from a three-dimensional surface workspace. The proposed prototype quadruped was capable of omni-directional locomotion and had a minimal turning radius (0.2 Body Length) using the fewest actuators. We further explored the kinematics and design potentials to generalize the proposed method for all overconstrained 5 R and 6 R linkages, paving the path for a future direction in overconstrained robotics. Graphical abstract: Highlights: Overconstrained co-axial design of robotic legs enables coupled spatial locomotion. Present the 1st design of a quadruped using Bennett legs with omni-directional locomotion. Propose a design optimization method using manipulability and force transmission. Outperform state-of-the-art turning with a radius of 0.2 body length and fewest actuators. Towards a new class of overconstrained robots for advanced robotic engineering.