Bond Graph Based Approach to Passive Teleoperation of a Hydraulic Backhoe

Abstract

Human operated, hydraulic actuated machines are widely used in many high-power applications. Improving productivity, safety and task quality (eg. haptic feedback in a teleoperated scenario) has been the focus of past research. For robotic systems that interact with the physical environments, passivity is a useful property for ensuring safety and interaction stability. While passivity is a well utilized concept in electromechanical robotic systems, investigation of electrohydraulic control systems that enforce this passivity property are rare. This paper proposes and experimentally demonstrates a teleoperation control algorithm that renders a hydraulic backhoe / force feedback joystick system as a two-port, coordinated, passive machine. By fully accounting for the fluid compressibility, inertia dynamics and nonlinearity, coordination performance is much improved over a previous scheme in which the coordination control approximates the hydraulic system by its kinematic behavior. This is accomplished by a novel bond graph based three step design methodology: 1) energetically invariant transformation of the system into a pair of "shape" and "locked" subsystems; 2) inversion of the "shape" system bond graph to derive the coordination control law; 3) use of the "locked" system bond graph to derive an appropriate control law to achieve a target "locked" system dynamics while ensuring the passivity property of the coordinated system. The proposed passive control law has been experimentally verified for its bilateral energy transfer ability and performance enhancements.

Operational Fault Diagnosis in Industrial Hydraulic Systems Through Modeling the Internal Leakage of Its Components

“…A comparison of the Bond Graph method with object oriented modeling is done by Borutzky (2002), where it was found that both methods can be equally reliable, if they are used in appropriate applications and effectively implemented. The basics of bond graph based control and substructuring are analyzed by Gawthorp et al (2009), while Krishnaswamy and Li (2006) used the Bond Graph method in the passive teleoperation of a hydraulic backhoe. Additional work in the field of bond graph modeling of nonlinear hydro-mechanical systems has been conducted by Margolis and Shim (2005), while Li and Ngwempo (2005) have used bond graph modeling in electro-hydraulic valves.…”

Video game device haptic interface for robotic arc welding

“…Recent work has also focused on stability of a remote haptic feedback system, as evidenced by literature [6][7][8][9][10][11][12][13], much of which has focused on passivity control. Significant amount of work has also focused on making the teleoperation system transparent to the user, including, as described by the work of Flemmer, Lawrence, and Zhu in [12,14,15].…”

A nonlinear spring model of hydraulic actuator for passive controller design in bilateral tele-operation

“…Suitable controllers are defined to achieve passivity with respect to a desired supply rate. A bond graph based controller for bilateral tele-operation is presented in [4]. In both [4] and [8], the actuator energy is defined based on linear models and the compressibility of actuator is not modeled.…”

“…A bond graph based controller for bilateral tele-operation is presented in [4]. In both [4] and [8], the actuator energy is defined based on linear models and the compressibility of actuator is not modeled. In [7], an energy function based on the nonlinear dynamics of the actuator is presented.…”