Michael G. Skarpetis

Robust triangular decoupling with application to 4WS cars

The necessary and sufficient conditions for the problem of robust triangular decoupling are established for the case of a linear time-invariant system with a nonlinear uncertain structure. The general analytic expressions of the feedback matrices and the robust triangularly decoupled closed-loop system are derived. For the solution of the problem of robust triangular decoupling with simultaneous Hurwitz invariability, sufficient conditions are established. Finally, all of the above results are successfully applied to control four-wheel steering (4WS) cars.

Robust control of pneumatic clutch actuators using Simulated Annealing Techniques

The position control problem of an electro pneumatic clutch actuator is formulated as a robust asymptotic tracking control problem. To solve the problem the Internal Model Principle is appropriately modified to a Hurwitz invariability problem solved through a constructive robust stability algorithm which is numerically integrated via a Simulated Annealing Algorithm. The problem is proven to be always solvable and the controller parameters providing a suboptimal solution are computed. Simulation results for the nonlinear model of the actuator and for all the expected range of model and load uncertainties illustrate the satisfactory control.

Robust PI Controllers for Command Following with Application to an Electropneumatic Actuator

The problem of command following is studied for the case of linear systems with nonlinear uncertain structure and unknown disturbances. The problem is solved using an independent from the uncertainties PI controller. Sufficient conditions for the problem to have a solution are established. The application of a robust PI controller for an electropneumatic actuator is presented. The effectiveness of the controller over a wide range of the system uncertainty is illustrated through simulation

Robust Tracking and Disturbance Attenuation Controllers for Automatic Steering

The problem of asymptotic robust output command tracking with simultaneous disturbance attenuation is studied for the case of linear systems with nonlinear uncertain structure. The problem is solved using a compensator with static state feedback, unity output feedback and integral action. The controller is restricted to be independent from the uncertainties. The output of the closed loop system tracks polynomial type reference signals independently from polynomial type disturbance signals. Sufficient conditions for the problem to have a solution are established. The results are applied to the automating steering of a city bus with large speed and mass uncertainties. An analytic algorithm for the computation of the vehicle tracking controller is presented. The effectiveness of the controller is illustrated through simulation for various manoeuvres

Robust disturbance rejection with simultaneous robust input-output decoupling

Abstract The problem of robust disturbance rejection with simultaneous robust input-output decoupling of linear systems with nonlinear uncertain structure is solved. The controller is static and independent of the uncertainties. The necessary and sufficient conditions for the problem to have a solution via state feedback are established. The general analytical expressions of the feedback matrices and the decoupled closed-loop system are derived. The closed-loop system structural properties of pole assignment and stabilizability are studied.

Robust Exact Model Matching for SISO systems via Finite Precision Dynamic Output Feedback

The problem of robust exact model matching is studied for the case of SISO discrete-time linear systems with nonlinear uncertain structure. The problem is solved using finite precision dynamic output feedback controllers. The controller is restricted to be independent from the uncertainties. Necessary and sufficient conditions for the problem to have a solution are established. The general solution for the controller parameters is derived. Moreover, sufficient conditions for robust exact model matching with simultaneous robust asymptotic stability are derived

Robust PID Controller Design with Application to a Flight Actuator

A PID controller is proposed for robust command following of linear systems with nonlinear uncertain structure and unknown disturbances. The realizability of the controller is guaranteed by requiring the controller to be independent from the uncertainties. Sufficient conditions for the problem to have a solution are established. The application of a robust PID controller for a flight actuator is also presented. Simulation results are used to illustrate the controllers performance.

Longitudinal flight multi condition control using robust PID controllers

A multi flight condition aircraft control autopilot system is proposed to control the horizontal flight of an aircraft involving atmospheric gusts. The control system involves a robust PID controller that stabilizes the closed loop system for various flight conditions. Considering the stability derivatives of the aircraft and the velocity of the aircraft to be uncertain parameters the robust stabilizing and disturbance attenuation controller is designed to cover full envelop pitch control. The robust PID controller parameters are computed using a finite step algorithm based on a Hurwitz invariability technique. Solvability conditions are derived. Simulation results for four different flight conditions are presented indicating the satisfactory performance of the robust controller in the presence of atmospheric gusts.

On the control of the liquid pouring process using cooperative manipulators

A robotic system for a liquid pouring application is presented. The robotic system comprises two cooperative manipulators. A simplified model of the robotically controlled pouring process is derived, considering that the liquids motion is approximated by a pendulum type model. A control scheme is proposed, which achieves positioning of the tank, force control and liquid sloshing suppression. The forces space is decomposed into the moving forces, which are responsible for the motion of the tank and the controllable forces, which may be controlled through the proposed control law. The control scheme comprises a nonlinear inverse dynamic controller, which is designed ignoring liquid sloshing, and a multivariable PID controller, which is used to improve the closed-loop performance with respect to steady state positioning errors and sloshing suppression.

Finite Precision Controllers for Robust Pole Assignment of Linear Systems with Nonlinear Uncertain Structure

Finite precision dynamic output feedback controllers are proposed for robust pole assignment of SISO linear systems with nonlinear uncertain structure. The realizability of the controller is guaranteed by designing an independent from the uncertainties controller. Necessary and sufficient conditions for the problem to have a solution, as well as the general solution for the controller parameters are derived.