Controlling fluid in a life support system, eg a flying suit

摘要

A parameter (flow or pressure) in the system 11 is controlled by a valve 14 driven by actuator 15. The desired position of the valve is compared at 26 with a representation of the actual position derived from valve model 25 and the difference converted to a command signal by calculating means 30 for driving the actuator in incremental movements. The input to the actuator is also used to update the model. This results in a faster and more precise response in the valve. Also included in the control system may be a parameter feed back signal 21 from sensor 24, which is compared with desired value 16 at 17 and the error compensated for gain and phase at 19 and limited to an achievable range at 29. If the incremental movements from calculating means 30 are below a meaningful level then controller 31 issues no command signal to the actuator.