Engineering topics

Warrington, Thomas J.

Publications and source records attributed to Warrington, Thomas J..

4 records

NASA NTRS1992

A study of control approaches for large-angle beam slewing with an adaptive truss

This paper presents an analytical study of large-angle beam slewing with a double-octahedral adaptive truss and documents the performance of different control laws for simultaneous vibration control and beam slewing. A general nonlinear model of an adaptive truss and flexible beam is derived which includes a degree-of-freedom previously considered negligible for a double-octahedral adaptive truss actuated at its mid-plane. Linear and nonlinear, gain-scheduled, control laws are developed and applied to the nonlinear model for various large-angle slewing maneuvers. The nonlinear, gain-scheduled, control law is found to perform better than the linear control laws.

Warrington, Thomas J.↗

NASA NTRS1991

The analysis and large-angle control of a flexible beam using an adaptive truss

This preliminary study of an adaptive truss slewing problem investigates the static positioning of an adaptive truss at slewed orientations and the dynamic vibrations of an attached flexible beam. A nonlinear model of an adaptive truss and flexible beam is derived. Linear control laws are developed and simulated for various truss configurations. Results show the linear control laws developed at a slewed configuration perform best at that configuration.

Warrington, Thomas J.↗

NASA NTRS1990

Flexible beam control using an adaptive truss

To demonstrate the feasibility of adaptive trusses for vibration suppression, a 12-ft-long beam is attached to a single cell of an adaptive truss which has three active battens. With the base of the adaptive truss attached to the laboratory frame, the measured strain of the vibrating beam shows the adaptive truss to be very effective in suppressing vibration when subjected to initial conditions. Control is accomplished by a PC/XT computer that implements an LQR-designed control law.

Warrington, Thomas J.↗

NASA NTRS1989

A planar comparison of actuators for vibration control of flexible structures

The methods and results of an analytical study comparing the effectiveness of four actuators in damping the vibrations of a planar clamped-free beam are presented. The actuators studied are two inertia-type actuators, the proof mass and reaction wheel, and two variable geometry trusses, the planar truss and the planar truss proof mass (a combination variable geometry truss/inertia-type actuator). Actuator parameters used in the models were chosen based on the results of a parametric study. A full-state, LQR optimal feedback control law was used for control in each system. Numerical simulations of each beam/actuator system were performed in response to initial condition inputs. These simulations provided information such as time response of the closed-loop system and damping provided to the beam. This information can be used to determine the 'best' actuator for a given purpose.

Clark, William W.↗