Reconciling distributed compliance with high-performance control in continuum soft robotics
🤖 AI Summary
This work addresses the longstanding trade-off between compliance and high-performance dynamic control in continuum soft robots by proposing a co-designed approach that preserves full intrinsic compliance while achieving unprecedented speed and precision. Through an integrated framework combining direct-drive actuation, a tendon routing scheme enabling coupled bending–torsion deformation, and a structured nonlinear control architecture grounded in a reduced-order strain model of the underactuated system, the study demonstrates—for the first time—the concurrent realization of distributed compliance and high-bandwidth, accurate task-space control without relying on hardware discretization or stiffness constraints. Experimental results show that the system executes Cartesian tasks such as rapid positioning and dynamic interaction at speeds nearly four times faster than existing methods while maintaining sub-millimeter accuracy, establishing a new benchmark for speed in soft robotics.
Application Category
📝 Abstract
High-performance closed-loop control of truly soft continuum manipulators has remained elusive. Experimental demonstrations have largely relied on sufficiently stiff, piecewise architectures in which each actuated segment behaves as a distributed yet effectively rigid element, while deformation modes beyond simple bending are suppressed. This strategy simplifies modeling and control, but sidesteps the intrinsic complexity of a fully compliant body and makes the system behave as a serial kinematic chain, much like a conventional articulated robot. An implicit conclusion has consequently emerged within the community: distributed softness and dynamic precision are incompatible. Here we show this trade-off is not fundamental. We present a highly compliant, fully continuum robotic arm - without hardware discretization or stiffness-based mode suppression - that achieves fast, precise task-space convergence under dynamic conditions. The platform integrates direct-drive actuation, a tendon routing scheme enabling coupled bending and twisting, and a structured nonlinear control architecture grounded in reduced-order strain modeling of underactuated systems. Modeling, actuation, and control are co-designed to preserve essential mechanical complexity while enabling high-bandwidth loop closure. Experiments demonstrate accurate, repeatable execution of dynamic Cartesian tasks, including fast positioning and interaction. The proposed system achieves the fastest reported task-execution speed among soft robots. At millimetric precision, execution speed increases nearly fourfold compared with prior approaches, while operating on a fully compliant continuum body. These results show that distributed compliance and high-performance dynamic control can coexist, opening a path toward truly soft manipulators approaching the operational capabilities of rigid robots without sacrificing morphological richness.
Problem
Research questions and friction points this paper is trying to address.
continuum soft robotics
distributed compliance
high-performance control
dynamic precision
soft manipulators
Innovation
Methods, ideas, or system contributions that make the work stand out.
continuum soft robotics
distributed compliance
high-performance control
underactuated modeling
tendon-driven actuation
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