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Study fundamental issues associated with the control of electro-hydraulic systems.
Develop accurate but tractable nonlinear models of hydraulic components.
Design nonlinear physical model based intelligent and high performance adaptive robust controllers.
Design energy-saving motion and pressure control algorithms and switching strategies for electro-hydraulic systems using novel programmable valves. Implement and test the strategies on the control of a scaled down version of industrial excavator arm driven by hydraulic cylinders.
Coordinated motion and/or pressure control of multiple link systems such as the boom, stick, and bucket of hydraulic excavators.
Develop intelligent control strategies for autonomous vehicles.
Motivations and Control Issues:
Hydraulic
systems have been used in industry in a wide number of applications by virtue of
their small size-to-power ratios and the ability to apply very large forces and
torque; examples like electro-hydraulic positioning systems, active suspension
control, hydraulic robot manipulators, industrial testing, drive systems of
large vehicles, injection molding machine, and flight simulator. However,
hydraulic systems also have a number of characteristics which complicate the
development of high performance closed-loop controllers. Control of electro-hydraulic systems not only includes all the issues in the control of electro-magnetic motor driven
mechanical systems, but also involves the following additional difficulties: (i) the highly nonlinear dynamics of
hydraulic systems, (ii) the appearance of non-smooth and discontinuous nonlinearities due to directional
change of valve opening and valve overlap, (iii) the large variations of hydraulic parameters (e.g., bulk modulus) due to the change of temperature and
component wear, (iv) significant amount of modelling errors due to factors such as the flow leakages and seal frictions, (v) quite noisy pressure, position, and velocity measurements, (vi) very high-order system dynamics of hydraulic systems, as evident by the fact that even its physical control element (i.e., the valves) is itself an electro-magnetic actuator driven complex mechanical system, and subsequently (vii) effect of severe unmatched model uncertainties and (viii) large extent of neglected high-frequency dynamics when lower-order hydraulic dynamic models are used in the controller design.
These nasty characteristics make the precision control of hydraulic systems
rather difficult, and there has been a significant lack of advanced controls
that deal with all these issues well and systematically.
Another emphasis of the project is on the energy-saving control of electro-hydraulic systems using the novel programmable valves developed in the PI's laboratory. Hydraulic systems are mainly used for large-scale applications and tend to consume significant amount of energy. In today's world that energy shortage is always a significant threat, it becomes imperative to investigate new and effective ways of controlling hydraulic systems using novel control hardware. Such an objective can be met by the novel programmable valves developed by the PI at the IPCL Laboratory.
Click Here to Download the Presentation at WCICA'02
The laboratory facilities for the electro-hydraulic control research are located at the Ray W. Herrick Laboratories of the School of Mechanical Engineering. The main test-stand is a three-link robot arm driven by hydraulic cylinders and regulated by different kinds of valves. The details of each part of the overall system are given below:
Mechanical Linkages: Descriptions Photos Pump: Descriptions Photos EH Valves: Descriptions Photos Instrumentation: Descriptions Photos Control and Data Acquisition Hardware and Software:
Descriptions Photos
Experimental Demonstrations and Results:
Videos of Experimental Demonstrations:
| Fast Trajectory with Load: | Video | Results |
| Fast Trajectory without Load: | Video | Results |
| Slow Trajectory with Load: | Video | Results |
| Slow Trajectory without Load: | Video | Results |
Car Crash Testing System, the Insurance Institute of Highway Safety (IIHS)
