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This paper reviews the philosophy of large-data-acquisition-system design as it has evolved over the past 20 years and discusses recent developments in applicable hardware and software tools. PIRANHA, a 320-channel system that embodies many of the features discussed and takes advantage of the new technologies, is described.

Satisfactory performance of some recent and near-future spacecraft requires precise pointing and a stationary structural configuration. Elements of modern control theory and structural-dynamics technology are being combined to help achieve these objectives. This paper reviews some analytical and experimental research undertaken to develop methods for actively controlling flexible space structures.

A design for a three-axis shaker system and its control system are described. Emphasis is placed on the digital-control techniques planned to implement realtime control of multiaxis sinewave and random vibration with cross-axis compensation. The microprocessor-based hardware system is designed to perform closed-loop control algorithms using a low-cost array processor.

This paper reports on the evaluation of several modal-testing procedures as applied on a modern data-acquisition and -analysis system. These methods include two forms of specimen excitation (sine and multifrequency) and several methods of modal characterization (analytical curvefitting, multishaker modal tuning, and hybrid techniques). The methods are compared, using examples, and a modal testing procedure is suggested.