One Soft Robot: A Complementary Design & Control Strategy for a Pneumatically Powered Soft Robot

Abstract

A pneumatically controlled soft robot with no rigid elements has great promise, for example in minimally invasive surgery, but also great challenges as the lack of rigidity violates rigid body assumptions fundamental to most robotic processes/systems. A soft robot design strategy that is complementary for a linear MIMO state-space control is proposed. Simplifying the overall structure such that it behaves as a linear dynamical system, affords a linearization (i.e., a Jacobian) over a greater span of the control space between the pneumatic inputs and output pose; offering a simple test for repeatability and reliability of the soft robot design. The paper details the mechanical components, electronics, manufacturing process, and a state-space control strategy for this approach. By compensating for mechanical non-linearities through pressure management and control stages, a novel silicone-based soft robot without rigid components separating segments in the robot was designed. This is illustrated and experimentally validated for a 12-input, 2-output (planar position) robot that was able to alter its shape quickly to trace a rectangular path. The results (over 15 trials) show a repeatability and reliability in the robot's movements. While the mean path traveled did not precisely match the set rectangular path, the general shape was followed and deviations were consistent. This suggests the design strategy produced a soft robot with no rigid links that has the capability of being developed to have movement deviations compensated for using probabilistic control approaches. This together could allow for soft robots to have compliance and precision movements.