Model Predictive Trajectory Set Control with Adaptive Input Domain Discretization

From a theoretical point of view, model predictive control (MPC) promises a high control quality since the future system performance is predicted and evaluated in every sampling interval. Additionally, desired optimization objectives can be realized while explicitly adhering to state and control input constraints. This control concept has the potential to set a new standard in industrial applications. In practical terms, functioning and properties of online optimization algorithms must be familiar to the developer to adjust the control performance of a mechatronic system. Moreover, it is challenging to realize a computationally expensive control concept for mechatronic systems with fast dynamics due to the limited computing power. It is worth mentioning that industrial systems usually exhibit hardware with low computing power. This contribution presents the model predictive trajectory set control (MPTSC) that constitutes a sub-optimal MPC with a sparse discretization of the control input domain. The optimal control input is determined without the use of iterative optimization techniques. To mimic quasi-continuous control input values similar to MPC, an adaptive input domain discretization is developed. MPTSC includes most advantages of MPC and is still computationally efficient. The implementation is less complex and error-prone and thus addresses especially industrial applications. The performance and the computation time are evaluated in comparison to MPC with nonlinear benchmark systems. Furthermore, the approach is tested experimentally on an industrial plant emulator with a sample rate of 100 Hz.

[1]  Jan Swevers,et al.  A model predictive control approach for time optimal point-to-point motion control , 2011 .

[2]  Samir Kouro,et al.  Model Predictive Control: MPC's Role in the Evolution of Power Electronics , 2015, IEEE Industrial Electronics Magazine.

[3]  Jay H. Lee,et al.  Model predictive control: past, present and future , 1999 .

[4]  Tore Hägglund,et al.  The future of PID control , 2000 .

[5]  David Q. Mayne,et al.  Correction to "Constrained model predictive control: stability and optimality" , 2001, Autom..

[6]  Lorenz T. Biegler,et al.  On the implementation of an interior-point filter line-search algorithm for large-scale nonlinear programming , 2006, Math. Program..

[7]  Stephen P. Boyd,et al.  Fast Model Predictive Control Using Online Optimization , 2010, IEEE Transactions on Control Systems Technology.

[8]  Emmanuel G. Collins,et al.  Nonlinear Model Predictive Control using sampling and goal-directed optimization , 2010, 2010 IEEE International Conference on Control Applications.

[9]  Haitham Abu-Rub,et al.  Assessing Finite-Control-Set Model Predictive Control: A Comparison with a Linear Current Controller in Two-Level Voltage Source Inverters , 2014, IEEE Industrial Electronics Magazine.

[10]  M. Morari,et al.  Move blocking strategies in receding horizon control , 2004, 2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601).

[11]  Torsten Bertram,et al.  Model predictive trajectory set control for a proportional directional control valve , 2017, 2017 IEEE Conference on Control Technology and Applications (CCTA).

[12]  Hans Joachim Ferreau,et al.  An online active set strategy to overcome the limitations of explicit MPC , 2008 .

[13]  Torsten Bertram,et al.  Sparse shooting at adaptive temporal resolution for time-optimal model predictive control , 2017, 2017 IEEE 56th Annual Conference on Decision and Control (CDC).

[14]  Helfried Peyrl,et al.  First-order methods in embedded nonlinear model predictive control , 2015, 2015 European Control Conference (ECC).

[15]  M. Diehl,et al.  Real-time optimization and nonlinear model predictive control of processes governed by differential-algebraic equations , 2000 .

[16]  Arthur Richards,et al.  Fast model predictive control with soft constraints , 2013, 2013 European Control Conference (ECC).

[17]  Torsten Bertram,et al.  A Model Predictive Approach to Emergency Maneuvers in Critical Traffic Situations , 2015, 2015 IEEE 18th International Conference on Intelligent Transportation Systems.

[18]  Knut Graichen,et al.  A Real-Time Gradient Method for Nonlinear Model Predictive Control , 2012 .

[19]  F. Hoffmann,et al.  Evolutionary hardware-in-the-loop optimization of a controller for cascaded hydraulic valves , 2007, 2007 IEEE/ASME international conference on advanced intelligent mechatronics.

[20]  Stephen J. Wright,et al.  Numerical Optimization (Springer Series in Operations Research and Financial Engineering) , 2000 .

[21]  MORITZ DIEHL,et al.  A Real-Time Iteration Scheme for Nonlinear Optimization in Optimal Feedback Control , 2005, SIAM J. Control. Optim..