Spring assisted modular and reconfigurable robot: Design, analysis and control

This paper presents an innovative spring assisted modular and reconfigurable robot (MRR) design and control framework, which is developed based on a synergetic integration of robot control with a brake and an embedded spring at each modular joint. By activating the brake, static balancing can be established, allowing reinforced delicate operation in the neighborhood of a balanced configuration such as door opening, as well as spring assisted lift of heavy payload. The developed spring assisted MRR can improve the payload to weight ratio of the conventional robot manipulators without introducing sophisticated mechanisms. A distributed control method has been proposed to facilitate control of the spring assisted MRR. The developed control algorithm does not rely on a prior dynamic models and can suppress uncertainties introduced by module reconfigurations as well as uncertainties due to sensor inaccuracies and noises. With the developed controller, control parameters need not to be adjusted when adding modules to or removing modules from an MRR, or changing its configurations. Prototype modules have been developed, and the experimental results have confirmed the effectiveness of the proposed design and control.