Ap. Narayan et Wf. Ramirez, 3-DIMENSIONAL MODELING, ESTIMATION, AND FAULT-DIAGNOSIS OF SPACECRAFTAIR CONTAMINANTS, Journal of spacecraft and rockets, 35(4), 1998, pp. 565-574
A description is given of the design and implementation of a method to
track the presence of air contaminants aboard a spacecraft using an a
ccurate physical model and of a procedure that would raise alarms when
certain tolerance levels are exceeded. Because our objective is to mo
nitor the contaminants in real time, we make use of a state estimation
procedure that filters measurements from a sensor system and arrives
at an optimal estimate of the state of the system. The model essential
ly consists of a convection-diffusion equation in three dimensions, so
lved implicitly using the principle of operator splitting, and uses a
flowfield obtained by the solution of the Navier-Stokes equations for
the cabin geometry, assuming steady-state conditions. A novel implicit
Kalman filter has been used for fault detection, a procedure that is
an efficient way to track the state of the system and that uses the sp
arse nature of the state transition matrices.