Rev:
1.00
Date:
11.22.2013
Page:
12 of 40
AIMMS-20
OPERATING MANUAL
Document-P/N:
AIMMS20-OM
© Aventech Research Inc. 2013. All Rights Reserved.
Figure 4: AIMMS-20 GPS Phase Module
2.4 Central Processing Module (CPM)
The CPM is essentially the main computational center for the AIMMS-20 system.
CPM firmware utilizes acceleration and angular-rate information from the IMU and
carrier-phase information from the GPS to compute the precise three-dimensional
orientation of the aircraft using an Extended Kalman Filter (EKF) algorithm. In
parallel, the three-dimensional winds relative to the aircraft are evaluated from air
data provided by the ADP. These data, when combined with aircraft attitude and
velocity, are transformed into the earth reference frame to provide the final three-
dimensional wind output.
The CPM also acts as the main interface between the aircraft spray navigation
system and the rest of the AIMMS-20.
Aircraft power is provided to the AIMMS-20 through the CPM module which steps
the input voltage down +12 VDC and distributes it to power the balance of the
modules through the Controller Area Network (CAN) cables.
The real-time aircraft state (attitude) and meteorological (temperature, humidity,
wind speed, wind direction and turbulence) data provided by the AIMMS-20 is
broadcast on the second serial port of the CPM as two unique aircraft state and
meteorological packets which can be read by a host computing device such as a
GPS navigation system or data acquisition system. Details of the format of these
packets can be found in Appendix A.
