Parameter identification and evaluation of a proportional directional flow control valve model
CITATION: Van der Merwe, Muller, J. H. & Scheffer, C. 2013. Parameter identification and evaluation of a proportional directional flow control valve model. R&D Journal, 29:18-25.
The original publication is available at https://www.saimeche.org.za
Servo-pneumatic command device selection and control may be greatly aided by adequate mathematical models and identification procedures. This paper reports on theory and experimental procedures applicable to the characterisation of pneumatic proportional directional flow control valves. The model implemented is shown to be well suited to predicting the effects that sharp-edged, concatenated orifices and small openings have on mass flow. An experimental setup and test protocol is presented that is less wasteful in terms of energy and effort than that of the ISO 6358:1989(E) standard. Unknown model parameters are optimised during the identification procedure, characterising the behaviour of the valve for the entire range of control signal inputs. The identified model yields adequate results, with mean absolute error (MAE) values of less than 10 kPa in the presence of 700 kPa supply pressure for quasi-static control signal inputs. Acceptable prediction is also achieved for the transient control input case investigated. The work presented here then not only serves as a thorough introduction to proportional servo valve modelling theory and identification but may also prove suitable for use in a multitude of practical applications.