A Provably Stable Iterative Learning Controller for Continuum Soft Robots

Pierallini, M.; Stella, F.; Angelini, Franco; Deutschmann, Bastian; Hughes, Josie; Bicchi, Antonio; Garabini, Manolo; Della Santina, C.

doi:10.1109/LRA.2023.3307007

A Provably Stable Iterative Learning Controller for Continuum Soft Robots

Title

A Provably Stable Iterative Learning Controller for Continuum Soft Robots

Author

Pierallini, M. (University of Pisa)
Stella, F. (Swiss Federal Institute of Technology)
Angelini, Franco (University of Pisa)
Deutschmann, Bastian (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR))
Hughes, Josie (Swiss Federal Institute of Technology)
Bicchi, Antonio (University of Pisa; Fondazione Istituto Italiano di Tecnologia)
Garabini, Manolo (University of Pisa)
Della Santina, C. (TU Delft Learning & Autonomous Control; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR))

Date

2023

Abstract

Fully exploiting soft robots' capabilities requires devising strategies that can accurately control their movements with the limited amount of control sources available. This task is challenging for reasons including the hard-to-model dynamics, the system's underactuation, and the need of using a prominent feedforward control action to preserve the soft and safe robot behavior. To tackle this challenge, this letter proposes a purely feedforward iterative learning control algorithm that refines the torque action by leveraging both the knowledge of the model and data obtained from past experience. After presenting a 3D polynomial description of soft robots, we study their intrinsic properties, e.g., input-to-state stability, and we prove the convergence of the controller coping with locally Lipschitz nonlinearities. Finally, we validate the proposed approach through simulations and experiments involving multiple systems, trajectories, and in the case of external disturbances and model mismatches.

Subject

Feedforward systems
Kinematics
Modeling, Control, and Learning for Soft Robots
Motion Control
Robots
Soft robotics
Solid modeling
Three-dimensional displays
Trajectory
Underactuated Robots