Design And Development Of The Algorithm Software Of Operational Feedback Control In A Wireless Network Environment

Industrial process operational control consists of operational layer setpoint control and loop layer process control,and aims to keep the operational index in the range of target value.In the current industrial process operational control,the input and output of process are transmitted via the Device net,while the setpoint control information is transmitted via industrial Ethernet.However,since industrial devices are always in motion,or in severe environment,it is hard to connect to the cable network,which makes difficult to implement operational index closed-loop control.Traditional operational control manually set the loop control layer setpoint value by workers,also called open-loop control,but it couldn't adjust the value timely and precisely according to the real time working condition,hence the target operational index cannot be tracked,even some malfunctions are generated.With the development of emerging technology especially Internet of Things,the industrial wireless network can be used to transfer the operational index feedback value to the control system,thus makes it possible to implement operational feedback control for industrial process that unable to be wired.But it should be mentioned that the wireless transmission packet dropout and noise will negatively affect operational control performance and even lead to system unstable.The industrial process operational closed-loop control system that combining Device net,Ethernet and wireless network challenges the current operational control strategy.And the stability and convergence of the system also put forward a huge challenge to the closed-loop control system performance analysis methods in modern control theory.This paper studies operational control design in a class of industrial processes when the operational index is transmitted back via wireless networks,and a stochastic process model of operational index is established with the input and output of process control as its input and the operational index as its output,respectively.In order to track the target operational index,a dual-layer model combining process control and set-point feedback control are presented with different sampling rates and the stochastic stability is guaranteed.And then,a simulation experiment on the operational feedback control in an industrial flotation process is employed to demonstrate the effectiveness of the proposed method.Besides,a wireless network based operational feedback control algorithm is designed and developed to further verify the effectiveness of the proposed strategy by physical experiment.The main work and contribution in this paper are as follows.Firstly,the operational feedback control problem under wireless network environment is described.And the wireless network transmission model with packet dropout and noise of operational index feedback value is established.Secondly,a wireless network-based operational feedback control strategy combining process control and set-point feedback control are presented with different sampling rates and a lifting method between multirate systems are adopted to design a process PI controller and a set-point feedback controller.Besides,the stochastic stability analysis is given.Thirdly,a lot simulation experiments based on flotation process are made to verify the effectiveness of the control strategy proposed in the paper and the proposed algorithm is proved to have better performs than existing algorithms.Finally,the algorithm software of operational feedback control under wireless network environment which can simulate the network packet dropout and noise and implement the algorithm is developed using the multifunction process control experimental platform,and a lot of physical experiments based on level control process of single-tank are made and the experimental results show that the algorithm software can realize the operational feedback control in a wireless network environment.