Bilateral Teleoperation of a Hydraulic Robotic Manipulator in Contact With Physical and Virtual Constraints

Abstract

Teleoperated robotic manipulators can be used to remotely operate within hazardous, hard to reach or dangerous environments. In tasks requiring handling of heavy objects with high forces, hydraulic manipulators have remained the most practical solution. Contrary to the previous research on teleoperation of hydraulic manipulators based on linearization and linear control theory, the present study proposes a full-dynamics-based bilateral force-reflected teleoperation, designed between a multiple degrees-of-freedom (n-DOF) electrical master manipulator and an n-DOF hydraulic slave manipulator. The used teleoperation method allows arbitrary motion and force scaling between the n-DOF manipulators, effectively enabling the use of two greatly dissimilar manipulators. The proposed teleoperation system is demonstrated with a full-scale two-DOF hydraulic slave manipulator (having 475 kg payload attached to the tip) in a free-space motion task, and in a constrained motion task including both real and virtual constraints in the environment. Despite the inherent highly nonlinear dynamic behaviour of hydraulic systems and challenges in realizing a bilateral teleoperation, the experimental results demonstrate that the proposed controller for full-dynamics-based teleoperation 1) can rigorously address the system nonlinearities, 2) can realize a high-performance bilateral teleoperation with hydraulic slave manipulators, and 3) is capable to operate in constrained motion with the environment having both real and virtual (i.e., artificially rendered) constraints.

Learning from Demonstration for Hydraulic Manipulators

“…The method to connected the separately controlled master and slave plants for the force-reflected bilateral teleoperation is discussed in Section III-C. The detailed control designs for the hydraulic slave manipulator and electric master manipulator can be found in [8] and [18], [19].…”

“…The designed force-reflected bilateral teleoperation system is identical with the system presented in [18], [19]. Individual NMB controllers are designed for both master and slave manipulator according to VDC design principles defined in section III-A.1.…”

Force-Sensor-Less Bilateral Teleoperation Control of Dissimilar Master–Slave System With Arbitrary Scaling

“…In this study, the results of [22] and [23] are used as the foundation for designing a theoretically sound high-precision bilateral teleoperation control for significantly asymmetric systems. In [23], preliminary attempts for full-dynamics-based bilateral teleoperation for an asymmetric hydraulic/electric system were demonstrated, while in [24], artificial constraints in the task space were implemented. However, in-depth stability analysis and theoretical discussions were not included in [23] nor in [24].…”

“…In [23], preliminary attempts for full-dynamics-based bilateral teleoperation for an asymmetric hydraulic/electric system were demonstrated, while in [24], artificial constraints in the task space were implemented. However, in-depth stability analysis and theoretical discussions were not included in [23] nor in [24].…”

“…In modern control systems engineering, modularity is considered as a key aspect to address the ever-growing complexity of target applications [25]. To design the intended high-precision teleoperation for complex asymmetric system, the study takes advantage of a novel virtual decomposition control (VDC) approach (see [26], [27]). The method is developed especially for controlling complex robotic systems, with a number of significant state-of-the-art control performance improvements with robotic systems (see [5], [6], [11], [12], [22], [23], [28]).…”