A Boolean algebra algorithm suitable for use in temperature–humidity control of a grafted seedling acclimatization chamber

The objective of this paper was to link a psychometric chart and Boolean algebra algorithms on deducing the procedural and logical issues of temperature–humidity environmental control for a grafted seedling acclimatization chamber. We developed a condition-sequence control circuit based on Boolean algebra algorithms to solve the complex logical problem existing in temperature–humidity environmental control procedures. A Matlab program was used to deduce and simplify the Boolean relations between input and output logical variables of the controller, whereas the correctness of Boolean function was verified by an Excel program. The Boolean functions were firstly transformed to switching (logical) circuits and subsequently transformed to a programmable logical controller (PLC) program systematically. We implemented the developed industrial wiring devices and PLC in designing a temperature–humidity environmental controller of an acclimatization chamber for grafted seedlings in that we adopted the nonlinear control technique associated with the conditionsequence control methodology as the main control scheme. On the other hand, we adopted the compound control action, two-position set point action, the time-delay control and the conditional action of free cooling as the main control operations for the controller. Our results demonstrate that the overall seasonal survival rate was 97% by using the Boolean algebra-based controlled ∗ Corresponding author. Tel.: +886 2 2363 4512; fax: +886 2 2362 6433. E-mail address: [email protected] (C.-M. Liao). 0168-1699/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.compag.2004.12.008 2 L.-J. Jou et al. / Computers and Electronics in Agriculture 48 (2005) 1–18 chamber grafting, which was higher than that of 90% by employing the field grafted seedling operations. © 2005 Elsevier B.V. All rights reserved.