Sensor-Space Based Robust Kinematic Control of Redundant Soft Manipulator by Learning

TL;DR

This paper introduces a sensor-space imitation learning framework for robust kinematic control of redundant soft manipulators, effectively handling external loads and environmental constraints through simulation training and sim-to-real transfer.

Contribution

It presents a dual-learning strategy combining reinforcement learning and imitation learning, along with a sim-to-real transfer mechanism for deploying soft manipulator control in real-world scenarios.

Findings

Effective path-following and object manipulation in confined spaces.

Robust control under unknown external loads.

Successful sim-to-real transfer for soft manipulator control.

Abstract

The intrinsic compliance and high degree of freedom (DoF) of redundant soft manipulators facilitate safe interaction and flexible task execution. However, effective kinematic control remains highly challenging, as it must handle deformations caused by unknown external loads and avoid actuator saturation due to improper null-space regulation - particularly in confined environments. In this paper, we propose a Sensor-Space Imitation Learning Kinematic Control (SS-ILKC) framework to enable robust kinematic control under actuator saturation and restrictive environmental constraints. We employ a dual-learning strategy: a multi-goal sensor-space control framework based on reinforcement learning principle is trained in simulation to develop robust control policies for open spaces, while a generative adversarial imitation learning approach enables effective policy learning from sparse expert demonstrations for confined spaces. To enable zero-shot real-world deployment, a pre-processed sim-to-real transfer mechanism is proposed to mitigate the simulation-to-reality gap and accurately characterize actuator saturation limits. Experimental results demonstrate that our method can effectively control a pneumatically actuated soft manipulator, achieving precise path-following and object manipulation in confined environments under unknown loading conditions.