Study On Pdf Control Based On 2df In Electro-hydraulic Servo System For Hot-pressing Of Wood-based Panel

Hot-pressing is one of the key processes in wood-based panel artificial. The yield of wood-based panel production line is determined by capability of hot-pressing. And the quality of production depends on technology of hot-press. There is much energy lost in hot-pressing system that the panel's thickness is controlled by spacers. Hop-pressing control system with optical censer is a solution to the question. Because there is no spacer to bind the panel's thickness, the thickness must be controlled by the controller completely. If the control system responses slowly, the hot-press will act later than the optimal hot-pressing time. That will influence panel's quality. If there is much overshoot in the control system, the hot-press will move beyond formulary range. It'll result that panel's thickness is lower than it in request. So it's a key step to study and design the controller which could control the hot-press accurately.Firstly, the disadvantage of 1DF PID controller to adjust tracking performance and disturbance rejection performance simultaneously had been analyzed in this thesis.2DF PID control method had been introduced. PDF control theory had been studied which is one type of the most mature incomplete 2DF control. Hot-pressing process had been analyzed which is based on system of a single hydraulic cylinder. And a model of electro-hydraulic servo system had been given which consists of PLC, digital valve, hydraulic cylinder and optical sensor.Secondly, a conventional feedback 2DF PID controller had been designed based on electro-hydraulic servo system model according to zero-placement theory. It had been concluded through analysis and simulation that this controller could adjust the tracking performance and disturbance rejection performance independently and simultaneously in contrast with 1DF PID controller. It eliminated overshoot in disturbance rejection and lower down the energy cost.At last, a PDF controller had been designed based on this model. It had been verified through analysis that this controller is feasible in electro-hydraulic servo system with a single hydraulic cylinder. The results of simulation showed that this controller's performance is more stable and robust in contrast with 2DF PID controller. It eliminated overshoot both in tracking target an rejecting disturbance. Moreover, it improved system's transient performance. This controller enabled the system to track target more accurately and restrain the disturbance more effectively. It realized controlling the system stable, speed and accurately without overshoot.