Multivariable adaptive surface control
First Claim
1. A system controlling disturbances and instabilities in a sheet structure having a surface contacting a surrounding fluid and dynamically interacting therewith, such system comprisinga plurality of m actuators attached to the sheet structure, each actuator being located to couple energy into a control segment consisting of a region of said sheet structure about such actuator,a multi-channel amplifier having a plurality of n power outputs for separately driving ones of the m actuators,a plurality of s sensors located with respect to said sheet structure for sensing physical parameters associated with dynamics of the sheet structure and for producing sensing signals indicative thereof, m, n and s being positive integers,estimator means for receiving said sensing signals and determining therefrom estimated state variables descriptive of behavior of said sheet structure, andcontrol means operative on ones of said sensing signals and on at least some of said estimated state variables for producing control outputs, said control outputs controlling the multi-channel amplifier to drive selected ones of the actuators with an amplitude to control a dynamic physical condition of said sheet structure.
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Abstract
An adaptive sheet structure with distributed strain actuators is controlled by a dynamic compensator that implements multiple input, multiple output control laws derived by model-based, e.g., Linear Quadratic Gaussian (LQG) control methodologies. An adaptive lifting surface is controlled for maneuver enhancement, flutter and vibration suppression and gust and load alleviation with piezoceramic elements located within, or enclosed by sheets of composite material at a particular height above the structure'"'"'s neutral axis. Sensors detect the amplitudes of lower order structural modes, and distributed actuators drive or damp these and other modes. The controller is constructed from an experimental and theoretical model using conventional control software, with a number of event recognition patterns and control algorithms programmed for regulating the surface to avoid instabilities. The number of control states of the compensator is then reduced by removing states having negligible effects on the plant, and a smaller set of control laws are optimized and then adjusted based on analytical models bench and wind-tunnel testing.
84 Citations
15 Claims
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1. A system controlling disturbances and instabilities in a sheet structure having a surface contacting a surrounding fluid and dynamically interacting therewith, such system comprising
a plurality of m actuators attached to the sheet structure, each actuator being located to couple energy into a control segment consisting of a region of said sheet structure about such actuator, a multi-channel amplifier having a plurality of n power outputs for separately driving ones of the m actuators, a plurality of s sensors located with respect to said sheet structure for sensing physical parameters associated with dynamics of the sheet structure and for producing sensing signals indicative thereof, m, n and s being positive integers, estimator means for receiving said sensing signals and determining therefrom estimated state variables descriptive of behavior of said sheet structure, and control means operative on ones of said sensing signals and on at least some of said estimated state variables for producing control outputs, said control outputs controlling the multi-channel amplifier to drive selected ones of the actuators with an amplitude to control a dynamic physical condition of said sheet structure.
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15. A controllable sheet structure comprising a skin of a first material having a surface in contact with a surrounding fluid and in dynamic interaction therewith, and at least one actuator of a second material attached to said structure for coupling strain energy over a region into said structure, wherein mechanical impedance of each said actuator is matched to stiffness of said structure over the region to optimize coupling of strain energy thereto, and a dynamic compensator operative on sensed physical parameters of said structure for determining state variables and producing control outputs, said control outputs controlling outputs of a multi-channel amplifier in accordance with the determined state variables to drive selected ones of the actuators with an amplitude to control a dynamic physical condition of said sheet structure.
Specification