title: Three-dimensional modeling, estimation, and fault diagnosis of spacecraft air contaminants.
abstract: A description is given of the design and implementation of a method to track the presence of air contaminants aboard a spacecraft using an accurate physical model and of a procedure that would raise alarms when certain tolerance levels are exceeded. Because our objective is to monitor 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 essentially consists of a convection-diffusion equation in three dimensions, solved 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 sparse nature of the state transition matrices.
authors.affiliation: University of Colorado, Boulder 80309-0424, USA.
authors.forename: A P
authors.initials: AP
authors.lastname: Narayan
authors.forename: W F
authors.initials: WF
authors.lastname: Ramirez
mesh_terms: D000389:Air Conditioning / Q000295:instrumentation; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000517:prevention & control*; D000465:Algorithms; D002245:Carbon Dioxide / Q000032:analysis*; D003198:Computer Simulation; D004784:Environmental Monitoring; D008433:Mathematics; D008452:Maximum Allowable Concentration; D008956:Models, Chemical; D018531:Spacecraft / Q000295:instrumentation*; D014691:Ventilation
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide