Optimal dual-loop digital control of diesel engines based on gain scheduling matrix strategy
Flygare, Thomas W.
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In this thesis, a gain scheduling matrix strategy is proposed for optimal dual-loop control of engine speed and fuel position. Models of the plant(s) are identified using computer techniques that examine and synthesize the frequency responses of the physical systems. High and low order mathematical models were developed for each of the physical systems. This enables the application of control theory in the design approach and provides a method for comparing theoretical results to experimental test results. Performance requirements of the closed-loop system are given in the design specifications. Analog proportional-integral-derivative (PID) controllers are designed to meet the specifications. Time and frequency domain analysis of the analog control system was performed using computer simulations. A dual-loop digital system was designed using PID controllers. The digital control system was implemented in hardware and software. The analog and digital low order system simulation results were compared to reinforce the design approach. The experimental data exceeded the design specifications. However, the experimental rise time was greater than the simulated rise time. The experimental rise time was very close to the maximum acceleration rate of the engine. The simulation displayed 7% overshoot when a unit step was applied to the digital engine speed control system. The overshoot resulting from a step speed change was 3.8% for the physical-engine speed control system.