Integrating a nonlinear dynamic system, a discrete event system and a finite state machine to approach the design of a hybrid control system for use in environmental control of an artificial acclimatization chamber

• Main Authors: Pang-Yen Chang, 張邦彥
• Other Authors: Li-John Jou
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/dd564q

碩士 === 國立宜蘭大學 === 生物機電工程學系碩士班 === 102 === In this paper, based on the modeling scheme of a hybrid control system, a temperature-humidity environmental controller for use in a phytotron is designed by using a LabVIEW software with the virtual instrumentation techniques to implement the simulator of a temperature-humidity environmental control system. By employing a set of nonlinear state-space differential equations based on the principles of energy and mass equilibrium, the dynamics of indoor temperature-humidity environment in a phytotron was described. This study integrates the mixed logical dynamic system (MLDS) and logical analytic methods to simulate this controlled indoor temperature-humidity environmental system under the state of discrete time. Through the use of piecewise linear functions, which could discrete and approach such a nonlinear temperature-humidity dynamic system, this method solved the complex mathematical problem issued from a set of nonlinear state-space differential equations. With the integration of physical laws, logic rules, and operating constrains, the finite state machine, which control temperature-humidity environment in a phytotron, was deduced. By the combination of Boolean algebra algorithms and linear inequalities, the systemic mechanism was built to successfully present the complex logical rules existing in temperature–humidity environmental control procedures. The above mentioned systemic mechanism was systematically transformed to a compiled LabVIEW program to complete the simulator and user’s interface of such a modular temperature-humidity environmental control system. Simulation outcome demonstrates that this simulator could satisfactorily and dynamically modulate the indoor temperature-humidity environment in a phytotron according to expected target ranges under various seasonal conditions (spring (autumn), summer and winter) to provide suitable growth conditions for plants. Through above-mentioned virtual operating conditions, this simulator could accurately estimate power consumption as well as real performance results. This study confirms that the linkage of the above mentioned systemic mechanism, methodology and virtual instrumentation techniques (LabVIEW software) could emulate the temperature–humidity dynamic environment in a phytotron, in order to greatly reducing the costs, developed time and errors in practical implementation.