Based on some useful frequency domain methods, this paper proposes a systematic procedure to address the limit cycle prediction of a neural vehicle control system with adjustable parameters. A simple neurocontroller can be linearized by using describing function method firstly. According to the classical method of parameter plane, the stability of linearized system with adjustable parameters is then considered. In addition, gain margin and phase margin for limit cycle generation are also analyzed by adding a gainphase margin tester into open loop system. Computer simulations show the efficiency of this approach.

Most of the time people stay in the indoor environment, so Taiwan government established indoor air quality (IAQ) regulations to protect public health and the living environment. This study defined fuzzy sets and fuzzy rules according to the national IAQ and standard ANSI/ASHRAE 55-1992. The fuzzy controller determine the operation time of air conditioner and exhaust fan to meet the national IAQ regulations and accepted thermal comfort. Using relay to switch the power of AC exhaust fan ON during operation time computed by fuzzy controller is cheaper and simpler than using variable frequency technology to control the wind velocity of AC exhaust fan. The study used exhaust fan to draw the outside cool and dried air into inside to help air conditioner to meet the standard thermal comfort quickly, so the air conditioner can decrease the operation time to save power.

In this paper, the PID type single-input fuzzy logic controller (SFLC) is proposed by modified from PD type SFLC. By proposed structure, the steady error from PD type SFLC can be improved. Furthermore, the optimal control performance can be achieved by tuning membership function and gain parameter with genetic algorithm (GA). The simulation results show the proposed structure has better performance by comparing with GA PID and Ziegler-Nichols PID approaches.