Adaptive control applications to aerospace vehicles

Abstract

HE word is used to describe the capability of human beings, animals, and plant life to adjust their characteristics in accordance with a changing environment. The adaptive control system thus is a system which will adjust its own characteristics in order to provide a desired control system performance in a changing dynamic environment. There has been considerable literature published on the subject of adaptive automatic control systems which has been concerned with aerospace vehicle control, process control, and machine control, as well as control in other technical areas. Research has included very general investigations which could apply to automatic controls of all types, as well as specific investigations concerned with the development of systems designed to adapt to particular environmental changes and for a particular application. The present survey is of the latter type, and is concerned with adaptive control systems which adapt for changing dynamics of the aerospace vehicle, when the vehicle is considered as a rigid body. Vehicle aerodynamic characteristics are changing due to changes in vehicle configuration, flight speed, Mach number, and altitude. These changes result in changes in the dynamics of the aerospace vehicle. The research approach used in the current survey was to perform search of patents granted in the United States on adaptive control systems. This search located 45 patents which were granted between the years of 1925 and 1967. Of these 45 patients, only 26 were determined to be within the scope of this paper. In addition to the patented systems, four systems of interest were located from a survey of current papers on adaptive flight control systems. The objective of the survey was to investigate the requirements for adaptive control systems, and to determine the means which have been developed to implement these requirements. The techniques discussed are generally applicable for use on all three axes of the aerospace vehicle. However, the examples presented are with reference to the pitch axis.