Passive Teleoperation of a Multi Degree of Freedom Hydraulic Backhoe Using Dynamic Passive Valve

Passive systems possess the beneficial properties of ease of human control, and stable interaction with arbitrary passive systems. Motivated by these properties, our research has been directed towards developing passive hydraulic systems. A novel hydraulic element called the passive valve was first developed. The passive valve was used in single degree of freedom passive bilateral teleoperation of a hydraulic actuator. The teleoperation control ensured a) passive 2-port behavior of the teleoperator and b) bilateral energy transfer between the human and the work enviroment with a power scaling factor. Although passivity, coordination between the master and slave systems was ensured only when the teleoperator (and hence the passive valve) was manipulated at sufficiently low frequency. In this paper, we extend the previously proposed teleoperation control to multi-degree of freedom control of a hydraulic backhoe, and rectifies the previously imposed bandwidth limitation by accounting for the dynamics of the passive valve. The passivity property of the hydraulic backhoe ensures interaction stability with any human operator and the work environment that could be modelled passive. The intrinsically passive control ensures two-port, rigid coordinated behavior of the passive valve driven teleoperated backhoe.