Einladung zum Vortrag im Kolloquium Technische Kybernetik

  Fast explicit model predictive control

Prof. Dr. Martin Mönnigmann
Regelungstechnik und Systemtheorie
Ruhr-Universität Bochum

Tuesday, 17. January 2012, 4:00 p.m.
IST-Seminar-Room 3.243 - Pfaffenwaldring 9 - Campus Stuttgart-Vaihingen

Abstract

Today model predictive control (MPC) is an established method for the control of constrained multivariable systems. Improved and tailored optimization algorithms, new theoretical insights, and the ever growing performance of today's hardware have helped MPC advance to higher and higher sampling frequencies. At very high sampling frequencies and for linear systems, explicit MPC (EMPC) methods are an interesting alternative. In EMPC it is no longer necessary to solve a receding horizon optimal control problem online. Instead, an analytical expression for the MPC control law can be found by solving a parametric optimization problem offline. While attractive conceptually, EMPC can still only be applied to very simple problems with short horizons for two reasons: For one, it is more difficult and computationally more complex to solve the parametric optimization problem than its receding horizon counterpart. Secondly, the expression for the explicit control law u(x) may grow so large, that a naive online evaluation of u(x) takes as much time as solving the receding horizon optimal control problem online. The talk summarizes recent progress with respect to both obstacles, the offline calculation of explicit control laws, and their fast online evaluation. Specifically, a simple new approaches to the fast evaluation of EMPC control laws results in online evaluation times on the order of 10ns. This approach does not require a CPU, but it can be implemented on low-cost, compact hardware with low power consumption such as programmable gate arrays. Progress in the fast evaluation of EMPC control laws has triggered the development of new approaches to solving the offline optimization problem. To this end, a new approach is suggested that avoids the state space exploration common to most existing methods. Finally, the talk gives an outlook on extensions to nonlinear EMPC, which result in control laws that are suboptimal, but can be evaluated as fast as in the linear-quadratic case.

Biographical Information

Martin Mönnigmann received a Ph.D. degree from RWTH Aachen University in 2003. He was a DFG postdoctoral scholar at Princeton University from 2004 to 2005, postdoc at RWTH Aachen from 2005 to 2007, deputy director of the Aachen Institute for Advanced Study on Computational Engineering in 2007, and assistant professor at TU Braunschweig from 2007 to 2009. In 2009 he was offered a full professor and institute leader position at TU Braunschweig. Since 2009 he is full professor and head of the Automatic Control and Systems Theory group in the Department of Mechanical Engineering of Ruhr-University Bochum.