Adaptive robust control of programmable valves with manufacturer supplied flow mapping only

The energy-saving programmable valves, a unique combination of five independently controlled poppet type cartridge valves, have been shown to significantly reduce energy usage while maintaining excellent control performance. Due to the fact that the flow characteristics of poppet type cartridge valves are very difficult to model, pressure compensated flow mapping via off-line system identification were used in all previous controller designs. However, individually calibrating each valve in use would prohibit their widespread industrial applications. It is desirable to have a controller requiring only the manufacturer supplied valve flow mappings, which may differ from the true individual valve flow characteristics to certain degrees. This paper presents an adaptive robust controller to control the multi-input valve system with the manufacturer supplied flow mapping only. Robust stability is guaranteed under bounded modelling errors, and the effect of modelling errors is effectively attenuated by the use of nonlinear robust feedback structure that achieves a prescribed transient performance and final tracking accuracy. In addition, real-time adaptation is used to reduce the degree of modelling errors for an improved performance. Experimental results are obtained to validate the proposed scheme.