Design and optimzation of fractional controller in manufacturing system with application of multilink robot and time delay chatter

This research focuses on the design and optimization of fractional order controllers in manufacturing field. The study covers the theoretical design, the optimization methodologies, the modeling and simulation techniques as well as the analysis and evaluation criteria of fractional order controllers. Two typical types of controllers are explored in this work, and they are the fractional order PID controller and the adaptive fractional order integration controller. The study of fractional order PID controller is based on the motion control of Adept 550 robot, and the work starts with dynamic models of this multilink robot, and then focuses on the state space representation of the system function. Later on, based on the system function the stability and the optimization design have been explored. The performance of the optimized fractional order PID controlled robot system has been evaluated based on simulation data. The results showed the methodologies proposed in this study could achieve the desired optimization goal and the fractional order controller yield high precision trajectory control results. The adaptive fractional order integration control is designed to solve the time delay machining chatter issue in the machining process. The study begins with the mechanism of the regenerative time delay chatter, after that based on the analysis of the mechanism the research focuses on using a reference control platform to solve the chatter issue. The orders of the integrator used in this study is fractional orders instead of integer ones. And to better absorb the chatter energy those orders are adaptive to the chatter process. The theoretical analysis, the optimization design framework and the system evaluation has been conducted. Based on simulation results, the adaptive fractional order control method developed in this work could monotonically absorb the chatter energy and suppress the vibration process efficiently without significant changes to the machining condition. In the end of this work, the fractional order PID controller has been used to suppress the machining chatter. The control law, the stability analysis based on energy criteria and the analysis of feasible design areas have been conducted. The work shows that, in this application the PID type controller would provide the highest dissipated energy when the orders of integrator and the differentiator are fractional numbers. The simulation results show that the regenerative chatter could be suppressed efficiently with the optimized controller. Results from this study provide manufacturing industry new approaches to multilink robot motion control and machining chatter suppression issue and the fractional order controller studied here could be easily adapted to industry without expensive updated to the existing systems. The techniques and the metrologies included in this work could also be transferred to similar studies in the fractional order control field. Therefore, this study brings significant original contributions to both the academia world and the manufacturing industry