Adaptive Control of Soft Robots Based on an Enhanced 3D Augmented Rigid Robot Matching

Abstract

Despite having proven successful in generating precise motions under dynamic conditions in highly deformable soft-bodied robots, model based techniques are also prone to robustness issues connected to the intrinsic uncertain nature of the dynamics of these systems. This letter aims at tackling this challenge, by extending the augmented rigid robot formulation to a stable representation of three dimensional motions of soft robots, under Piecewise Constant Curvature hypothesis. In turn, the equivalence between soft-bodied and rigid robots permits to derive effective adaptive controllers for soft-bodied robots, achieving perfect posture regulation under considerable errors in the knowledge of system parameters. The effectiveness of the proposed control design is demonstrated through extensive simulations.

Adaptive Dynamic Sliding Mode Control of Soft Continuum Manipulators

“…It is noted that for α = 1, eq. ( 37) reduces to the conventional linear sliding surface ėq = −Λe q used in [17], [21]. By direct integration of eq.…”

“…Remark 3. Compared to adaptive controller in [17], the control law presented here has an additional term bsign(s), which, as shown in the stability proof, can reject the bounded input disturbances. Moreover, thanks to the adaptation law in eq.…”

“…As such, traditional state-feedback controllers may be unsatisfactory, particularly for delivering dynamic tasks. To tackle this problem, a popular adaptive control scheme introduced by Li and Slotine [16] was implemented in curvature-space for a simulated continuum soft arm [17]. Moreover, a non-singular representation of the PCC-based model is employed [18], resolving the discontinuities embedded in the previous parameterizations.…”

“…Thus, previous control methods did not consider the system uncertainties or were built based on oversimplified models, affecting the performance and robustness of the control system. Additionally, the previous adaptive control scheme presented in [17] was not validated on a physical system.…”

Energy Shaping Control of Hydraulic Soft Continuum Planar Manipulators

“…However, research has shown that classical high-gain controllers can increase the closed-loop stiffness of the system, potentially reducing the benefits of soft manipulators [7]. As a result, recent approaches have been combining feedback actions that employ low gains with feed-forward actions [8] or with adaptive algorithms [9]. Nevertheless, most of the controllers in the literature do not account for the pressure dynamics of the fluid and treat the system as fully actuated.…”