Engineering topics

Hu, Tsay-Hsin G.

Publications and source records attributed to Hu, Tsay-Hsin G..

2 records

NASA NTRS1993

Impact of suntracking on Space Station controllability

The multibody dynamics of the Space Station is studied as affected by the suntracking motions of the photovotaic arrays. Dynamic responses are simulated for the Station being controlled by control moment gyros (CMGs). Controllability is shown to be a function of flight orientation, stage (inertial properties, CP-CG offset) and the suntracking dynamics. For certain combinations of these parameters, the aerodynamic, inertial disturbances and motor torques from alpha joint(s) arising from near-perfect suntracking are too large for the control moment gyro system to control. However, by imposing slight restrictions on the dynamics of the suntracking, CMGs are able to provide Station attitude stability with excellent pointing performance and an excellent microgravity environment.

Chipman, Richard↗

NASA NTRS1992

Adaptive control applied to Space Station attitude control system

This paper presents an adaptive control approach to enhance the performance of current attitude control system used by the Space Station Freedom. The proposed control law was developed based on the direct adaptive control or model reference adaptive control scheme. Performance comparisons, subject to inertia variation, of the adaptive controller and the fixed-gain linear quadratic regulator currently implemented for the Space Station are conducted. Both the fixed-gain and the adaptive gain controllers are able to maintain the Station stability for inertia variations of up to 35 percent. However, when a 50 percent inertia variation is applied to the Station, only the adaptive controller is able to maintain the Station attitude.

Lam, Quang M.↗