Control of a Soft Robotic Arm Using a Piecewise Universal Joint Model
This work addresses control problems for soft robotics, but it is incremental as it builds on a previously developed model.
The paper tackled the challenge of controlling soft robotic arms with infinite passive degrees of freedom by designing two closed-loop controllers based on a universal joint model, resulting in superior tracking accuracy and reduced settling time and steady-state error in experiments.
The 'infinite' passive degrees of freedom of soft robotic arms render their control especially challenging. In this paper, we leverage a previously developed model, which drawing equivalence of the soft arm to a series of universal joints, to design two closed-loop controllers: a configuration space controller for trajectory tracking and a task space controller for position control of the end effector. Extensive experiments and simulations on a four-segment soft arm attest to substantial improvement in terms of: a) superior tracking accuracy of the configuration space controller and b) reduced settling time and steady-state error of the task space controller. The task space controller is also verified to be effective in the presence of interactions between the soft arm and the environment.