The addition of an integral feedback loop to an existing radiometric process controller

The purpose of this study was to evaluate the desirability of integrating an additional feedback loop into an existing ratiometric process controller to further reduce the errors inherent in the system design. Several design constraints were imposed on the proposed hardware design, including the consideration of maintainability, testability, and physical constraints of the existing system.

One of the primary constraints imposed was the completely designed, unmodifiable nature of the controller. By developing hardware for an unmodified controller, the upgraded capabilities of the system could be utilized in processors installed and operational prior to the new design. As well as basing the design on previously existing equipment, the integration of two systems of incompatible design must be performed into an inexpensive, but highly reliable system.

Since the mathematics of the system must also be modified, ideally in the minimal amount possible, the internal stored program must be changed. This modification should be consistent with the previously existing versions of the control algorithm, and must be compatible with all other versions. Conclusions generated by the research indicate that the proposed modifications are possible and economically feasible.

System design will allow addition of the interface between the separate pieces of machinery without drastic modification of the individual components. Increased system accuracy will pay for the increased capital expenditure, with an increased savings in milk fat inventory. Any increase in system reliability will justify the purchase of the hardware improvement by the lessened probability of selling a product which does not meet the standards imposed by the Federal government on labeling of content.