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A Method for Compensation of Interactions Between Second-Order Actuators and Control Allocators

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Bibliographic Details
Title: A Method for Compensation of Interactions Between Second-Order Actuators and Control Allocators
Authors: Oppenheimer, Michael W., Doman, David B.
Contributors: AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
Source: DTIC
Publication Year: 2005
Collection: Defense Technical Information Center: DTIC Technical Reports database
Subject Terms: Flight Control and Instrumentation, Numerical Mathematics, Electrical and Electronic Equipment, Air Navigation and Guidance, ALGORITHMS, INTERACTIONS, ACTUATORS, CONTROL SURFACES, LINEAR SYSTEMS, LINEAR PROGRAMMING, ATTENUATION, DYNAMICS, FLIGHT CONTROL SYSTEMS, CONTROL DESIGN, CONTROL ALLOCATION ALGORITHM, CONSTRAINED CONTROL ALLOCATORS, CONTROL EFFECTOR, ACTUATOR DYNAMICS
Description: Typically, actuator dynamics are ignored when designing flight control allocators for aircraft because the bandwidths of actuators are normally much larger than the frequencies of the vehicle's rigid body modes. Unfortunately, this is not always the case, particularly when dealing with non-aerodynamic surface actuators. Ignoring the interactions between constrained control allocators and actuator dynamics can have serious consequences. In this work, a method, which post-processes the output of a control allocation algorithm, is developed to compensate for actuator dynamics. The actuators can have dynamics which are either first-order, second-order with no zeros, or second-order with a single zero. The method developed here solves for a gain, which multiplies the commanded change in control effector setting as computed by the control allocator. This approach is not computationally intensive and thus has the added benefit of being an algorithm which can operate in real-time on a typical flight computer. Likewise, this approach is applicable to both the saturated and unsaturated control effector cases. The basic premise of this method is to post-process the output of the control allocation algorithm to overdrive the actuators so that at the end of a sampling interval, the actual actuator positions are equivalent to the desired actuator positions. ; IEEEAC paper no. 1164. The original document contains color images.
Document Type: text
File Description: text/html
Language: English
Relation: http://www.dtic.mil/docs/citations/ADA445165
Availability: http://www.dtic.mil/docs/citations/ADA445165
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA445165
Rights: Approved for public release; distribution is unlimited.
Accession Number: edsbas.96909E89
Database: BASE
Description
Abstract:Typically, actuator dynamics are ignored when designing flight control allocators for aircraft because the bandwidths of actuators are normally much larger than the frequencies of the vehicle's rigid body modes. Unfortunately, this is not always the case, particularly when dealing with non-aerodynamic surface actuators. Ignoring the interactions between constrained control allocators and actuator dynamics can have serious consequences. In this work, a method, which post-processes the output of a control allocation algorithm, is developed to compensate for actuator dynamics. The actuators can have dynamics which are either first-order, second-order with no zeros, or second-order with a single zero. The method developed here solves for a gain, which multiplies the commanded change in control effector setting as computed by the control allocator. This approach is not computationally intensive and thus has the added benefit of being an algorithm which can operate in real-time on a typical flight computer. Likewise, this approach is applicable to both the saturated and unsaturated control effector cases. The basic premise of this method is to post-process the output of the control allocation algorithm to overdrive the actuators so that at the end of a sampling interval, the actual actuator positions are equivalent to the desired actuator positions. ; IEEEAC paper no. 1164. The original document contains color images.