Instability and Passivity Concepts for Fast and Safe Electrohydraulic Systems

Perry Y. Li, University of Minnesota

Proposal number: CMS-0088964

Instability and Passivity Concepts for Fast and Safe Electrohydraulic Systems

Electrohydraulics play an important role in many industries, such as construction, material testing, robotics, aerospace. The market place for electrohydraulics is demanding 1) higher bandwidth, lower cost and better reliability, and 2) safer and better human friendliness, especially for applications that require interaction with the environment and direct operation by a human.

This project addresses these two needs by introducing the concepts of instability and passivity to the design of electrohydraulic valves. Firstly, a new class single stage valves (which are inherently cheaper and more reliable than multistage valves) with improved performance will be developed - by making the spool unstable, so as to exploit the agility afforded by the unstable flow forces. Secondly, a new class of electrohydraulic valves that possess a passivity property will be developed. Although passivity is well recognized to improve safety and to enhance human friendliness, it has not been previously exploited in electrohydraulic systems.

Theory for the design and control of the new unstable valves and passive valves will be developed. The new valves will be prototyped. The unstable valves will be demonstrated in typical force and position tracking tasks. The usefulness of the passive valves in safety critical, human operated applications will be demonstrated in the context of a hydraulically actuated teleoperated surgical tool.

This research will enable hydraulic systems to be more cost effective, more reliable, have better performance, and to be safer and more user friendly. These advances will expand hydraulics into a larger segment of industry and to new applications.