Design of a Digital Controller for a Large Flexible Space Structure.
Abstract
Modern optimal control techniques are used to design a digital controller for a large flexible space structure. The structure is modeled as a tetrahedron formed by four lumped masses connected by massless truss members. A NASTRAN analysis is used to generate the twelve mode shapes and frequencies of oscillation. The controller is designed in discrete-time using linear optimal regulator theory. An observer is used to estimate the states. Active control is achieved using six collocated sensor actuator pairs. The effectiveness of the controller is determined using pointing accuracy as a figure of merit. Three controller designs are compared. The first demonstrates the effects of 'control' and 'observation spillover.' The second uses a singular value decomposition to eliminate the spillover terms. The third design uses a more accurate optimal performance index than the first two. The first design proved inadequate to achieve the desired performance. The second and third designs were able to achieve the desired performance for small sampling times. For small sampling times the simplified performance index used in Design II proved to provide a very accurate approximation to the optimal. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1981
- Accession Number
- ADA111170
Entities
People
- David B. Leggett
Organizations
- Air Force Institute of Technology