Digital Control System for An On-Borad Oxygen Generator

摘要

A prototype on-board oxygen generation system (OBOGS) is being tested by the USAF School of Aerospace Medicine (SAM). The OBOGS is a candidate to replace present liquid oxygen systems for aircrew consumption on manned aircraft. The OBOGS passes outside air through a molecular sieve to produce an oxygen enriched breathing product. Oxygen concentration of the OBOGS's output is controlled by a purge orifice valve. The SAM envisions using a digital system to control the OBOGS. A digital contro system for the OBOGS was developed and consists of a stepper motor, microprocessor, system sensor, support circuitry, and software. The control system software is a collection of instructions which allow the MPU to read data from sensors, to interpret that data, and to issue system hardware control signals. System software was fairly complex as methods were employed to compensate for the OBOGS's lengthy response time. This was accomplished by using a segmented table. If motor drive is anticipated to be time-consuming, a software routine is used to preposition the motor to a predetermined location within the segmented table. This position is updated when more accurate information is available. A prototype system was constructed and tested in the laboratory. The control system successfully controlled the stepper motor. (Author)