COMPUTER AIDED ANALYSIS AND DESIGN OF MULTI-ACTUATOR SYSTEMS

Abstract

The actuator systems are used in a variety of load control applications, such as position control of antennas, industrial robots, airframe surfaces, machine tools , etc. where it is required to apply forces to points on a mechanical structures. The system could be single, two or multi-channel depending upon the application.

The thesis is concemed with the computer aided analysis and design of actuator systems from control theory point of view. Several topics such as system modeling and analysis, controller design, pole assignment, decoupling design and sensitivity analysis are handled in this study . In the system modeling and analysis the block diagrams which represent each of single, two and multi-channel system are introduced, and also the equations which describe the system behavior . By the aid of MATLAB computer program the system response specifications are calculated accompanied by plots of the system time and frequency response. Two control strategies are used for system design. Firstly, three classical types of industrial controllers (P, PI, PID) are added individually to the system to improve the perfonnances, it found that the PID controller is more convenient because it achieved a zero steady-state etTor and very small values of rise time ,settling time and percentage of overshoot. Secondly a modem design approach is considered, where two algorithms (Akennann and Bauss-Gura) for single-channel system compansator design using state Feedback are used to shift the poles to a desired location. For the two actuator system a direct algorithm is used where there is no need for • coordinate transformation. In many practical applications it is not possible to access the system states, so a full-order observer and a reduced order one are designed to estimate the system states. A set MATLAB-programs are developed to calculate the compansator Feedback gain matrices the observers gain matrices and plot the compensated system behavior. Interaction is the main problem which arises in such systems , so decoupling design must be considered to avoid the effect of interaction in the system performances. It found through plots of the outputs that the actuator systems are steady-state decoupled. The study has considered the dynamic decoupling, where two methods are used to achieve noninteracting systems. The first is by using state Feedback and the second is by using output Feedback . The two designed decouplers using these two methods have achieved a satisfactory system response, where two MATLAB-programs are developed to plot compensated system outputs . Most of these control systems are subjected to an extemal disturbances, which change the system parameters and as a result the system behavior will be affected. So sensitivity to the variation of the system parameters is considered to show how the output changes with this variation . This is illustrated for the single channel system through 3-D plots which are resulted from running the developed MATLAB programs.