Adaptive contact-force control and vibration suppression for multi flexible manipulators with unknown control directions and time-varying actuator faults

This article proposes an adaptive control scheme for multi-flexible manipulators to address the challenges of unknown control directions and time-varying actuator faults, then realize contact force control and vibration suppression. Unlike existing methods that require identical control directions, the proposed approach expands application scope to multi-agent systems with nonidentical control directions. By introducing extended Nussbaum functions with saturated amplitudes, the scheme prevents oscillations caused by the unbounded growth of traditional Nussbaum functions. The interdependent design of multiple extended Nussbaum functions enhances the robustness against actuator faults and unknown control dynamics. The controllers achieve consensus in contact force control while suppressing vibrations, ensuring global stability and asymptotic convergence without relying on force sensors, thus avoiding sensor noise. Simulation results demonstrate the effectiveness of the proposed approach in dealing with the unknown control dynamics and realizing control objectives. The theoretical analysis and simulation results demonstrate that the proposed approach is a promising solution for practical multi-agent applications including force control of multi-flexible manipulators.