Impact-Resilient Orchestrated Robust Controller for Heavy-Duty Hydraulic Manipulators

Abstract

Heavy-duty operations, typically performed using heavy-duty hydraulic manipulators (HHMs), are susceptible to environmental contact due to tracking errors or sudden environmental changes. Therefore, in addition to precise control, it is essential for the manipulator to maintain stability and reduce the risk of damage to both itself and the environment during contact, without relying on contact-force sensors, which are typically impractical for these applications. This article proposes a novel force-sensorless robust impact-resilient controller for a generic 6-degree-of-freedom (DoF) HHM constituting from anthropomorphic arm and spherical wrist mechanisms. The scheme consists of a neuroadaptive subsystem-based impedance controller, which is designed to ensure both accurate tracking of position and orientation with stabilization of HHMs upon contact, along with a novel generalized momentum observer, which is for the first time introduced in Plücker coordinate, to estimate the impact force. Finally, by leveraging the concepts of virtual stability and virtual power flow, the semiglobal uniformly ultimately boundedness of the entire system is assured. Extensive experiments and simulation comparisons conducted on a generic 6-DoF industrial HHM validate the method's exceptional performance in achieving subcentimeter accuracy for desired trajectory tracking. Furthermore, the results demonstrate that equipping the controller with impact-resiliency features reduces the impact force from unintended contacts by 80%.