Detecting Instrument Malfunctions in Control Systems

TLDR

The paper proposes an automatic scheme to detect early failures in control system feedback sensors. The scheme is tested on a simplified fourth‑order hydrofoil flight‑control model using a single inertial instrument set, with redundancy simulated by multiple Luenberger observers and logic circuits. Experiments show that scale‑factor, threshold, and bias errors are detected in real time, and highlight the need for further analysis of the scheme’s limits.

Abstract

A scheme for automatically detecting incipient failures in the feedback sensors (or instruments) of control systems is described. The feasibility of the scheme is investigated by applying it to a simplified version (fourth order) of the flight control system for a hydrofoil boat. A single set of inertial instruments is used to provide the feedback signals; the redundancy which is normally obtained by multiple instrument sets is obtained here, artificially, by a subsystem of multiple Luenberger observers and logic circuits. Tests indicate that scale factor errors, errors due to threshold effects, and bias errors in the instruments are detected as they occur. The tests also indicate further analytical work which should be done to explore the limitations of the basic scheme.