Chain Tension Control Of Scraper Conveyor Based On PID Sliding Mode Control

The comprehensive mechanized coal mining is a progressing sign of coal technology. It is a necessary means to increase production, raise labor efficiency and improve economic benefits. Scraper conveyor is an important component of full mechanization of long wall face, and it determines production capacity of coal mining. The chain of scraper conveyor is a main component of scraper conveyor, and it is an elastic body. When transporting coals, the chain would be affected by the traction force. Consequently, the chain form elastic elongation to produce too loose or too tight phenomenon. If the chain is too loose, it will damage the mesh of sprocket and chain, causing impact, vibration or offing of chain; if the chain is too tight, it will increase running resistance of scrape conveyor, resulting in power consumption and making excessive wear of components. In order to avoid these two kinds of phenomena, scraper conveyor must have an adjusting device for chain tension to ensure the automatic adjustment for chain tension in real time. Therefore, this paper utilizes the sliding mode control technique to realize the real-time and effective chain tension control of scraper conveyor.Firstly, establish mathematical model of conveyor chain tension control, according to the basic principle of engineering design of scraper conveyor and referring to scraper conveyor running parameters, select and determine parameters in the control model.Then, use sliding mode control method of reaching law to implement automatic control of scraper conveyor chain tension, in which choosing three different reaching laws, namely exponential reaching law, variable rate reaching law and combined reaching law. In the design of each sliding mode control method of different reaching law for control chain tension, we need to design sliding surface function and sliding mode control law. Through computer simulation for reaching law sliding mode control method of chain tension, find out that combined reaching law sliding mode control method is the best one in three methods for control effects. At the same time, compare the chosen method with the conventional PID control method and fuzzy adaptive PID control method. The simulation results show that the sliding mode control method has more advantages in the chain tension control of scraper conveyor.Finally, in order to solve the chattering problem in sliding mode control, combine PID control law with sliding mode control technique to design PID sliding mode control for realizing automatic chain tension control of scraper conveyor, and make computer simulation experiments that prove the PID sliding mode control is not only has small chattering, but also has better effects for chain tension control.