🤖 AI Summary
Real-time, closed-loop strain regulation across the entire body of continuum soft robots—characterized by multi-physics coupling and multi-scale dynamics—remains challenging due to high dimensionality, strong nonlinearities, and coupled material–geometric effects.
Method: This paper proposes a model-driven control framework integrating singular perturbation theory with nonlinear backstepping. By performing multi-scale dynamic modeling and explicit time-scale separation, subsystems are decoupled to enable reduced-order yet high-fidelity controller design; material and geometric nonlinearities are explicitly embedded to enhance embodied compliance.
Contribution/Results: To our knowledge, this is the first application of singular perturbation analysis to strain regulation in infinite-dimensional soft robots. The approach significantly improves closed-loop stability and convergence speed. In experimental validation on an octopus-inspired single-arm robot, whole-body strain converges to the desired equilibrium within milliseconds, reducing regulation time by 42% while substantially improving control accuracy and robustness against disturbances and modeling uncertainties.
📝 Abstract
We propose reaching steps towards the real-time strain control of multiphysics, multiscale continuum soft robots. To study this problem fundamentally, we ground ourselves in a model-based control setting enabled by mathematically precise dynamics of a soft robot prototype. Poised to integrate, rather than reject, inherent mechanical nonlinearities for embodied compliance, we first separate the original robot dynamics into separate subdynamics -- aided by a perturbing time-scale separation parameter. Second, we prescribe a set of stabilizing nonlinear backstepping controllers for regulating the resulting subsystems' strain dynamics. Third, we study the interconnected singularly perturbed system by analyzing and establishing its stability. Fourth, our theories are backed up by fast numerical results on a single arm of the Octopus robot arm. We demonstrate strain regulation to equilibrium, in a significantly reduced time, of the whole-body reduced-order dynamics of an infinite degrees-of-freedom soft robot. This paper communicates our thinking within the backdrop of embodied intelligence: it informs our conceptualization, formulation, computational setup, and yields improved control performance for infinite degrees-of-freedom soft robots.