【正文】 3rd Edition. Addison Wesley, USA, pp. 118137, pp. 505514. [12] SKOCESTED, S. and POSTLETHWAITE ,I.: Multivariable Feedback ControlAnalysis and Design: John Wiley amp。 , pp. 573577. [8] HARRISON, A.: Simulation of conveyor dynamics: in. solids handling Vol. 16 (1996) No. 1, pp. 3336. [9] LOOEWLIKS,G .: On the application of beam elements in the finite element models of belt conveyors part I。 bulk solids handling Vol. 16(1996) No. 4, pp. 543549. [7] KIM, ., PARK, . and LEE, : Transient dynamics analysis of belt conveyor system using the lumped parameter method。 bulk solids handling No. 6 (1986) No. 3, pp. 11631168. [5] SCHULZ, G.: Analysis of the belt dynamics in horizontal curves of the long belt conveyers。 IEEE Press, US 1997. [3] NORDELL, . and CIOZDA, .: Transient belt stress during starting and stopping: elastic response simulated by finite element methods。 A number of techniques on setting the controller gains have to be emphasized. The main aim of the controller is to achieve an optimum control on the system, which produces fast response on velocity changes and, low steady state and transient stresses. The use of proportional controller is to speed up the response of the system. However, large control efforts are needed to produce high proportional gains. In addition, due to the control method used, reducedstate feedback would cause the high proportional gains to produce high overshoot’s response, and results in high transient stresses, The integral controller gives a zero steady state error response to the system. A small integral gain slows down the system response, where it takes a long period of time to reach zero steady state error. However, a huge integral gain could result in an unstable system. Therefore, choosing a set of proper controller gains would always help to produce a system with better performance. A minimum transient stress can be achieved, as the sum of the proportional gains for the drives are equal. By setting the same integral gain for all the drives, a minimum steady state stress can be reached. This is due to the equal sharing of the loads among drives. Also, the controller output power has been limited such that it would not require an unreasonably high power from the drives, and to prevent the drives from overloading in practice. If there is a plete power failure, all the electronic controllers and motors will be shut down and result in an uncontrolled stopping of the conveyor belt. A method to overe this problem is to have some form of energy storage, such as DC bus rectifier capacitors. To regenerate and supply power for both controllers and motors. This will then achieve a controlled stopping of the belt without using too much energy been shifted directly to the left pared to open loop pole. This implies that closed loop control produces a more stable and better performance system. Energy is needed to shift a pole. The large poles are welldamped and of fast response. . low overshoot and short rise time. Therefore, shifting large poles will only be a waste of energy. Shifting small poles, however, can produce better performance, as the frequency and the damping ratio of the ponents have increased. The closed loop system produces a smooth velocity response whereas the open loop system oscillates as it approaches the set point. The result also shows that the open loop system has a slightly shorter rise time pared to the low gain closed loop system. A way to shorten the rise time of a closed loop system is to increase the proportional gain. This results in the small poles being shiften further to the left. The high gain system increases the proportional gain by four times, but not the integral gain. Too much integral gain results in a system with high overshoot or can even be unstable. The main aim of having integration in the system is to achieve zero steady state error. Therefore, a good system should not be affected too much by the integration during transient state, but still be able to achieve zero steady state errors. The small plex poles start to dominate, resulting in an oscillatory response. However, fast response would be expected since the system is dominated by the high frequencies ponents. These are the relationships between poles’ locations and the response [11]. The open loop system produces much higher transient stress pared to the low gain closed loop system. Also, the high gain closed loop system produces the highest transient stress. This is many caused by the high rate of change of velocity. Therefore, this concludes that there is always a trade off between the velocity rise time and the transient stress produced. The open loop system has a higher steady stress pared to both closed loop system. This is the result of having load equally shared between both drives in the closed loop system. It produces a minimum steady state stress difference throughout the whole belt. An important issue in this research is the controllability of the system when feedback control is applied. An uncontrollable system has one or more states that are unaffected by the controller, in other words, the system cannot influence all the poles of the model. This results in the system not being able to fully control the resp