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 apssive valve was first developed. The passive valve was used in single degree of freedm passive bilateral teleoperation of a hydraulic actuator. The teleoperation control ensured a) passive 2-port behavior of the teleoperator and b) bilateral between the human and the work environment with a power scaling vactor. 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 passivitiy property of the hydraulic backhoe ensures interaction stability with any human opperator and the work environment that could be modelled passive. The intrinically passive control ensures two-port, rigid coordinated behavior of the passive valve driven teleoperated backhoe.
A degree of freedom and metric approach for non-singular Mueller matrices characterizing passive systems
