Task Driven Skill Learning in a Soft-Robotic Arm

In this paper we introduce a novel technique that aims to dynamically control a two-module bio-inspired soft-robotic arm in order to qualitatively reproduce a path defined by sparse way-points. The main idea behind this work is based on the assumption that a complex trajectory may be derived as a combination of a discrete set of parameterizable simple movements, as suggested by Movement Primitive (MP) theory. Capitalising on recent advances in this field, the proposed controller uses a Probabilistic MP (ProMP) model which initially creates an abstract mapping in the primitive-level between the task and the actuation space, and subsequently guides the movement’s composition by exploiting its unique properties - conditioning and blending. At the same time, a learning-based adaptive controller updates the composition parameters by estimating the inverse kinematics of the robot, while an auxiliary process through replanning ensures that the trajectory complies with the new estimation. The learning architecture is evaluated on both a simulation model, and a real soft-robotic arm. The research findings show that the proposed methodology constitutes a novel approach that successfully manages to simplify the trajectory control task for robots of complex dynamics when high-precision is not required.