User-Programmable Flow Controllers
North Star designed and manufactures the
Model 400186 Programmable Flow Controller (PFC) exclusively for Aero Union Corporation. The PFC has been integrated into 7 different air tankers to control
the door mechanisms which control the flow of retardant and water from tanks on these aircraft. Aero Union owns, operates, and maintains aircraft for firefighting along the west coast of the United States.
The PFC
contains multiple analog and digital input signals, a digital signal processor (DSP)
and multiple analog and digital outputs. It is user-configurable via a
serial communications port using a standard PC and terminal emulator such as
Windows HyperTerminal application.
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| User configurable tables of flow
characteristics, servo tuning parameters, and system set-up parameters,
indicators, switches, etc., are all save internally using non-volatile
EEPROM. These tables and parameters can be re-configured at any
time using the serial communications port. Once configured the PC
is no longer needed and the PFC controls the flow of water or retardant
dropped from the aircraft during flight. The pilot
has very simple controls. He selects the drop type using a drop selector
switch (multi-tap rotary switch), then presses a single
drop button.
The PFC does the rest. It calculates all the drop parameters,
configures the servo gain settings, monitors the volume and flow rate of
liquid in the tank, opens and regulates the servo valve that
opens/closes the main doors on the tank to create flow. |
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The
heart of the PFC is a Texas Instruments TMS320F2812 DSP. The DSP and other
circuits are contained on a single printed wiring board. Hardware is fully
environmentally qualified. Software was developed and is maintained by
North Star.
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