We invite fans of our Low Orbit Helium Assisted Navigator (LOHAN) project to raise a glass or two today to UAV specialist 3D Robotics, which has very kindly agreed to offer our Vulture 2 spaceplane a brain transplant in the form of the mighty Pixhawk autopilot.
As LOHAN regulars know, our aircraft is already temporarily fitted out with the company’s ArduPilot Mega (APM) 2.6:
This impressive piece of kit recently guided Texan Larry Grater’s North Texas Near Space 4 (NTNS 4) aircraft to the ground from a dizzying 30,780m, proving 3D Robotics’ autopilots have the Right Stuff for our audacious stratospheric mission.
The APM also triumphed in the 2011 UAV Challenge down in Oz. A member of the winning team was ArduPilot (the fixed-wing APM flavour) lead developer Andrew Tridgell, who’s a bit of a celeb in the coding world for his work on Samba.
Andrew got word of LOHAN, and dropped us a line offering his support. He also had a chat with 3D Robotics suggesting we might benefit from the hot-off-the-press Pixhawk, and the company marvellously agreed to send a couple over just as soon as it’s beta tested.
Good news indeed. The Pixhawk has a few new bells and whistles which Andrew says will benefit the mission, including a new digital airspeed sensor and enhanced data recording capability.
At the autopilot’s heart is a 32-bit ARM Cortex M4 processor running NuttX RTOS. Andrew suggests we connect the unit to the Vulture 2‘s Raspberry Pi – principally on board to control a nose-mounted Picam.
He asked: “Do you want to run MAVProxy* on the Pi as a connector to the autopilot telemetry? I run embedded Linux boxes on my planes and actually compile the autopilot firmare on the Linux boxes, and upload, etc, all within the aircraft.”
Well, if that isn’t enough to get LOHAN team member and Pi guru Dave Akerman licking his lips in anticipation, we don’t know what is.
As soon as the Pixhawk flies in (the traditional tip of the hat to 3D Robotics’ Craig Elder for sorting), we’ll bring you details on the beast, and just how we’re going to integrate all the onboard systems. In the meantime, we can continue working with the APM 2.6, which runs the same basic software.
Larry Grater‘s North Texas Near Space 4 (NTNS 4) aircraft hit around 790km/h in an “extended dive” before levelling out at roughly 16,460m, after which it “hit all waypoints and loitered down over the landing location”. Larry then took control and landed the plane manually via First Person View (FPV), as the insert later in this video shows:
UAV3 development board/autopilot has a new lower price – just $79.95 and could be ordered at ARSOVTECH.COM for EU and at AUAV.CO for US. The project becomes open hardware – all the schematics and pcb layouts will be supplied to the customers. The firmware is almost ready….not many bugs left and will be fixed soon. You could download it from here . You could try both Mark Whitehorn and Robert Dickenson branches as there are slight differences.
Let’s recall some AUAV3 specifications:
- MCU – dsPIC33EP512MU810
- Onboard 32Mb Flash AT45DB321
- Onboard IMU – MPU6000
- Onboard compass – HMC5883
- Onboard absolute pressure sensor – BMP180
- Onboard CAN – MAX3051
- Two opto-isolated UARTs – for OSD and Telemetry
- One non-isolated UART
- One I2C and one SPI user interfaces
- 8xRC inputs, 8 servo outputs
- RSSI input
- 4 x Analog inputs
- 3 x Digital I/Os
- Universal GPS 4pin 2.54 connector
- ICSP 5pin connector
- 4 x LEDs red, blue, green and yellow
- Main power – external 5V
- Onboard 3.3V 1A LDO regulator
- Optional BackUp power – 1xLi-Po or 4xNiMH or other 5V
- ESC powering capability
- Preferable power supply – ACSP1 ( Current/Voltage sensor board + 5V3A DC-DC Buck )
- Dimensions – 45 x 35mm
- Two types of connectors – 2 x 3row x 14pin 2.54mm right angled or separate straight color coded connectors
- USB port for programming, etc.
- CAN interface with driver MAX3051
- ESD protection on I2C, USB and SPI
- Reverse power polarity protection by power MOSFET
Pixhawk is an advanced autopilot system designed by the PX4 open-hardware project and manufactured by 3D Robotics. It features advanced processor and sensor technology from ST Microelectronics® and a NuttX real-time operating system, delivering incredible performance, flexibility, and reliability for controlling any autonomous vehicle.
The benefits of the Pixhawk system include integrated multithreading, a Unix/Linux-like programming environment, completely new autopilot functions such as Lua scripting of missions and flight behavior, and a custom PX4 driver layer ensuring tight timing across all processes. These advanced capabilities ensure that there are no limitations to your autonomous vehicle. Pixhawk allows existing APM and PX4 operators to seamlessly transition to this system and lowers the barriers to entry for new users to participate in the exciting world of autonomous vehicles.
The flagship Pixhawk module will be accompanied by new peripheral options, including a digital airspeed sensor, support for an external multi-color LED indicator and an external magnetometer. All peripherals are automatically detected and configured.
Pixhawk orders will begin shipping in late October 2013.