This paper presents a mathematical framework for discussion of large space structure (LSS) control theory. Within this framework, current trends in LSS control theory and related topics in general control science are surveyed.

Trends in large space structure control theory: Fondest hopes, wildest dreams

Control of self-adjoint distributed-parameter systems.

An attempt is made to gather data useful to investigators in the fields of large space structure dynamics and control modeling, design and testing. Attention is given to structural dynamics and its relationship to such allied engineering fields as flutter analysis, as well as to problems in the prediction of atmospheric density at orbital altitude. The first challenge posed by large space structure control is the design of control systems with natural frequencies above several major structural frequencies. The establishment of a sufficiently accurate structural model, plant excitation, and shape maintenance, are noted to be additional problems.

Dynamics and control of large space structures

This paper presents a control scheme for distributed gyroscopic systems based on modal synthesis. The control parameters for each controlled mode are chosen independently of those for any other mode, thus resulting in a diagonal gain matrix for the controlled modes. The modal control laws are implemented by means of a reduced-order observer that estimates linear combinations of the modal state vector. The proposed scheme considers uncontrolled modes simultaneously and has the advantage that it minimizes truncation effects and that it exhibits no observation spillover instability due to modeled uncontrolled modes. The paper also includes specification of positions of actual control forces and torques and sensors.

Modal-Space Control of Distributed Gyroscopic Systems

Optimal Modal-Space Control of Flexible Gyroscopic Systems

A unified treatment of modal control of spinning flexible spacecraft is presented. The equations of motion of the spacecraft are hybrid, i.e., they consist of ordinary differential equations for the rotational motion and partial differential equations for the elastic motion. Problems involving control of distributed-p arameter systems are generally discretized and the actual control is implemented on the discrete systems. An efficient method for control of linear gyroscopic systems is via model synthesis. There remains, however, the question as to how modal control of discrete systems is related to the control of the actual distributed-parameter systems. It is the object of this paper to provide the information concerning the spatial distribution of the sensors and actuators and to relate this information to the discrete modal control.

H. Oz

Papers

Distributed Control of Spinning Flexible Spacecraft