Project 10: Scalable Optimization for Control Systems

Leader: A. Hansson, LiU
Participants at LiU: S. Gunnarsson
Participants at LU: A. Robertsson, A. Rantzer

Project description: Modern control systems put new demands on control theory. Many of the modelling, analysis and design methods available do not scale well with increasing complexity. Applications and/or industrial practice often relies on distributed control structures, and there is a strong need for more systematic approaches to design and analysis of such structures and the corresponding information interfaces, especially with the development of “internet of things” and the so-called “smart society”.

An important challenge for control and optimization is industrial robots where the task is to plan and carry out
an operation as fast as possible given a number of constraints in terms of accelerations, loads on the mechanical
structure, energy consumption, etc. The constraints in combination with dynamical models of very high complexity imply a strong need for efficient optimization methods. There are several challenges. One is that the dynamics is nonlinear making the optimization problem highly non-convex. Another is that re-planning of operations in real time due to obstacles makes the need for efficient optimization methods much more relevant than before. Current industrial standard does not allow for re-planning. Optimization for industrial robots has not been considered in previous ELLIIT projects. The vision is to within 5 years have online optimization routines performing planning and re-planning of optimal robot trajectories in real time.

Another important challenge for control and optimization is robustness analysis of large-scale interconnected systems such as power grids. The introduction of renewables in the power grid requires high-fidelity models, which also imply a strong need for more efficient optimization methods. In this project we will investigate and develop new optimization methods and software for modelling, analysis and design of large-scale control systems that scale well with problem size. Within ELLIIT we have previously developed scalable robustness analysis methods assuming that suitable models where available. For systems like power grids, this is not the case. A major challenge is to in a distributed manner obtain linearized models for power grids, and to in a distributed manner build so-called LPV models which capture the uncertainties of the power grid. The vision for 5 years is to have efficient tools for modelling power-grids based on the Modelica modelling language which admits efficient analysis of robustness of the grid. This work will be carried out in collaboration with ABB Corporate Research in Switzerland.