Controller design for a real-time air handling unit

A real-time HVAC system is proposed which implements real-time control of thermal environment for virtual reality. It consists of a pair of hot and cold air loops that serve as thermal reservoirs, and a mixing box to mix the hot and cold air streams supplied from the loops. Their flow rates are controlled to meet the set temperature and flow rate. Cascade control algorithm and gain scheduling was applied to the system. Test results showed that the controller approaches a set temperature and flow rate within 2 or 3 s, thereby satisfying the requirement of implementing real-time thermal environment.