A Computer Controlled Teaching Experiment

Abstract The paper describes a laboratory experiment relying for measurement and control on a small dedicated microprocessor. The process consists of a copper pipe fitted with four temperature transducers and two heating coils, one at each end. Using any two temperatures a range of multivariable experiments are possible with varying degrees of interaction. A novel feature is that the dynamics of the rig can be drastically changed by mounting the pipe vertically instead of horizontally. This is because heat transfer then involves natural convection. The system is truly distributed and introduces time delays, non-linearities, random load constraints and distributed limits on maximum heating and cooling rates. A number of approaches to design are included in the paper. The computer control relies on a mixed language approach so that the user only needs BASIC. It also provides a useful case study in interfacing.