Novel Water Hydraulic On/Off Valves and Tracking Control Method for Equal Coded Valve System
Research output: Book/Report › Doctoral thesis › Monograph
|Publisher||Tampere University of Technology|
|Number of pages||85|
|Publication status||Published - 2 Nov 2018|
|Publication type||G4 Doctoral dissertation (monograph)|
|Name||Tampere University of Technology. Publication|
This equal coding method suﬀers from a lack of suitable valves. Thus, a fast-acting and low-power-consuming miniature valve is developed. The valve development is based on previous experience with oil hydraulic miniature valves and is carried out mainly with heuristic methods, by using simpliﬁed electromagnetic equations and scaling. However, the prototypes show good properties for the intended purpose. As another challenge, a high number of these valves are needed in order to achieve suﬃcient resolution for demanding control. To decrease this requirement, the circulating switching control method is proposed, which can increase the eﬀective ﬂow resolution of the valve system using the existing valves. The method divides the switching duty equally among the valves and can diminish the drawbacks that exist in typical non-circulating switching control.
As the main goal, a water hydraulic servo axis was implemented using the developed miniature valves and the control method. The control system comprises a simple model based valve controller as the lower level part and a ﬁltered P-controller as the upper level motion controller. Excellent tracking and positioning accuracy was achieved with a valve system having 16 miniature valves in total and using this relatively simple controller structure. This veriﬁes that high-performance water hydraulic motion control can be realized with a reasonable eﬀort using on/oﬀ seat valves. This gives hope for increasing the applicability of water hydraulics.