Discrete Time Sliding Mode Temperature Control of an On-Off Heating System
| Autor: | Ming-Feng Lai, 賴明鋒 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In this thesis, the single chip (AT89S51) is the core of the temperature control platform. By using the method of discrete-time on-off sliding mode control, the system temperature output can be maintained within a small variance about the command value. The controlled process is a hair dryer heater actuated by a solid state relay (SSR). The mathematical model of the plant is obtained by using the MATLAB System Identification Toolbox to process the open-loop experimental data, yielding a transfer function for the system. Since the SSR actuator can only issue on-off commands, a direct implementation of on-off control law simply with the temperature error information will result in a zigzag type of temperature output behavior called the chattering phenomenon. We propose the discrete-time on-off sliding mode control method for the system to attenuate the amount of chattering as well as to follow the temperature command. The sliding surface variable is a linear combination of the current and the past temperature errors. Thus the on-off command is determined by the sign of the sliding surface variable, rather than the error variable. Mathematically, this sliding surface serves as a digital low-pass filter, which rejects the high frequency chattering of the temperature error. By tuning the free parameter in the sliding surface, we are able to adjust the bandwidth of the low-pass filter, as a means of attenuating the error magnitude. The experimental results show that the temperature error can be reduced substantially by regulating the parameter of the proposed control scheme. They confirm the stability and accuracy accomplished by the proposed discrete-time on-off sliding mode control method. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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