Robust ℋ2 Performance: Guaranteeing Margins for LQG Regulators

This paper shows that ℋ2 (LQG) performance specifications can be combined with structured uncertainty in the system, yielding robustness analysis conditions of the same nature and computational complexity as the corresponding conditions for ℋ∞ performance. These conditions are convex feasibility tests in terms of Linear Matrix Inequalities, and can be proven to be necessary and sufficient under the same conditions as in the ℋ∞ case. With these results, the tools of robust control can be viewed as coming full circle to treat the problem where it all began: guaranteeing margins for LQG regulators

ROBUST STABILITY AND PERFORMANCE VIA FIXED-ORDER DYNAMIC COMPENSATION

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57855/1/RobustStabilitySicon1989.pd

Adaptive Optimal Control The Thinking Man's GPC

Exploring connections between adaptive control theory and practice, this book treats the techniques of linear quadratic optimal control and estimation (Kalman filtering), recursive identification, linear systems theory and robust arguments

Control and structural optimization for maneuvering large spacecraft

Presented here are the results of an advanced control design as well as a discussion of the requirements for automating both the structures and control design efforts for maneuvering a large spacecraft. The advanced control application addresses a general three dimensional slewing problem, and is applied to a large geostationary platform. The platform consists of two flexible antennas attached to the ends of a flexible truss. The control strategy involves an open-loop rigid body control profile which is derived from a nonlinear optimal control problem and provides the main control effort. A perturbation feedback control reduces the response due to the flexibility of the structure. Results are shown which demonstrate the usefulness of the approach. Software issues are considered for developing an integrated structures and control design environment

Optimization and control of feed and transfer pumps

A new low pressure fuel system implementation for Scania’s trucks is being investigated. The main challenge consists in exchanging the mechanical pump with electrical pumps. The electrical pumps must then be controlled to supply exactly the demanded amount of fuel at the required pressure. System redundancy allows a lot of degrees of freedom influencing the final performance. This thesis studies the factors influencing system’s performance to design a controller that enhances its behavior. The physical basis of the elements in the system are investigated and stated with that purpose. The system is analyzed and the output pressure and tank level are controlled by a LQG regulator giving successful results in reference tracking. Integral action is included for disturbance rejection and the states are estimated to overcome quantifications and noise from the signals. The disturbance rejection performance is improved by extending the regulator with a Smith Predictor for time delay compensation and including information about the engine mass-flow demand. The control actions are minimized by the tuning of the controller in order to extend component’s life. The controller includes different modes for when an external action should be input e.g., when a diagnosis test must be run. The optimization of free set-points is discussed and holistic criteria from experience is set. The result is that the system endurance is enhanced by running only two pumps when one does not provide higher efficiency. Results show that different pumps should be chosen in the final design for an improvement of the global efficiency. Future work will consist in implementing the resulting controller in the real system built with actuators selected accordingly to the optimization results