CAD.5:1 - Problem frame

Use this when an engineered controller has to act before a complete, accurate observation is available. A rapid channel may reveal only part of the situation; a more complete channel may describe an earlier state. You need to choose the channels and their timing, determine what the controller must remember or predict, and establish what control those arrangements can support.

For example, an inspection result can arrive after two control updates while a simpler sensor reports one critical quantity immediately. Adding both sensors is not yet a solution: the controller must relate their observations to the same evolving system, account for actions already performed, and retain uncertainty about unobserved disturbances.

This is a specialized method for sampled linear control with bounded uncertainty. It constructs a sufficient information arrangement for a specified control task and a given state-feedback law or a finite set of such laws. It also supplies a stronger negative result when indistinguishable situations require incompatible actions. It does not synthesize arbitrary nonlinear controllers, identify an unknown plant, or infer biological mechanisms from a control analogy.

The intended practitioner can use state-space models, bounded sets and feedback laws. Start with the required controlled quantities, admissible state and input sets, operating horizon, a usable plant model, and realizable sensor and execution alternatives. The first useful result is a comparison that connects available information → one executable action → the required continuation, with the internal state and update needed to maintain that connection.

Retain a simpler qualified arrangement when it already works. A current complete observation can remove the need to reconstruct a delayed state. An unobserved but sufficiently bounded component can remove the need for a sensor. If the only question is whether a diagram represents an already constructed control structure adequately, use C.30.LCA.