Sensors

Infrared Sensors

Paparazzi x-y IR sensor board

The paparazzi autopilot uses infrared thermopiles for primary attitude sensing. The theory is that at zero bank or pitch angle, the difference in the heat between the two sensors should be zero, and at 90 degrees it should be maximum. From this relationship a linear regression is made and angles are calculated during flight. Each pair of sensors measures one axis, a minimum of 2 pairs must be used to measure pitch and roll but best results are obtained thru the use of a 3^rd pair on the vertical axis. Since the output signal from each sensor pair is proportional to both the attitude and the weather/terrain, systems with only x-y sensors require a ground calibration and may not provide accurate angle calculations as the aircraft travels over terrain with different IR radiation.

Architecture

Dual Axis Board Pinout

Component Side View

Single Axis Board Pinout

Component Side View

Inertial Measurement

Work is underway to create a complete 17 state Kalman filtered inertial navigation solution! Watch the demonstration video of the current 7-state system.

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  Complete IMU head with 3-axis gyro, 3-axis accelerometer, and 3-axis magnetometer

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  video of ahrs driving flightgear

The IMU features the following hardware:

• Analog Devices AXDRS150 5V 150 deg/s gyros (top left)
• MMA7260 3-axis 1.5 - 6g accelerometer (center left)
• 3.3V LDO regulator (lower left)
• Micromag 3-axis SPI magnetometer (right)
• MAX1167 Multichannel, 16-Bit, 200ksps Analog-to-Digital Converter (below Micromag)
• LPC2148 ARM7 microcontroller (below Micromag)