Collocated control stabilizes shape regulation in soft robots
Collocated Shape Regulation for Soft Robots
Robotics
Summary
Controlling the exact shape of flexible soft robots is usually complicated and needs precise models and controlling every part. The authors show that by controlling only the parts directly moved by motors or actuators, it’s possible to reliably shape the whole robot under certain conditions. They developed a general approach with several control methods that ensure stable and predictable robot shapes without knowing the full robot dynamics. Their tests confirm this method works well with different robot setups and control settings. This simplifies designing shape control for soft robots while keeping stability.
What this means in practice
- •For soft robot engineers: Design controllers for soft robots that ensure stable shape control using only actuated joints without full dynamic models.
- •For robotic automation teams: Implement robust control methods for flexible robotic arms in tasks requiring stable shaping despite complex dynamics.
- •For medical device developers: Improve design of soft robotic surgical tools by controlling key actuators to reliably shape instruments inside the body.$Commercial implications: Enables marketable soft surgical robots with stable and predictable shaping without complex full-model control designs.
Authors
Pietro Pustina, Ebrahim Shahabi, Daniel Feliu-Talegon, Alessandro De Luca, Cosimo Della Santina
Abstract
Controlling the shape of a continuum soft robot typically requires an accurate dynamic model and actuation of all degrees of freedom. We show that regulating only the actuated coordinates, through collocated shape control, achieves provably stable convergence of those coordinates and, under an explicit compatibility condition, of the entire robot shape. While collocated control is a cornerstone of high-performance motion control in rigid robotics, extending this formulation to continuum soft robots has remained challenging due to the complexity of their dynamics. We present the first general framework for collocated control of continuum soft robots and derive a unified family of controllers, including PD, PID, PsatID, and their counterparts with compensation and cancellation components. The framework unifies existing approaches while introducing new controller designs. In particular, we develop three classes of PD and PID like regulators with local, semi-global, and global stability guarantees, and provide rigorous convergence analyses for each. Extensive experimental validation demonstrates the effectiveness of the proposed methods across different model discretizations and controller parameters. The resulting framework provides practical design guidelines for selecting and implementing controllers with known stability guarantees, without requiring a complete dynamic model of the robot