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Quadcopter drone packs first all-Linux APM autopilot

Dec 22, 2014 — by Eric Brown 14,092 views

Erle Robotics launched a ROS-enabled, open source “Erle-brain” autopilot that runs APM directly on Linux. The device also powers an “Erle-copter” drone.

Over the last year, Spanish firm Erle Robotics S.L. has been working with 3DRobotics to develop an open source BeaglePilot autopilot for drones that can run Linux on 3DR’s popular, Arduino-based APM (ArduPilot Mega) platform. The APM Linux port was developed by both companies, as well as several academic institutions. The BeagleBone-based “Erle-brain” autopilot is built into the $490-and-up Erle-copter quadcopter.

Left to right: Erle-brain, Erle-copter, Erle-plane, and Erle-rover

In addition to providing autopilot functionality for the new “Erle-copter” quadcopter, the BeagleBone-based Erle-brain also being designed into a two-winged “Erle-plane” UAV and a four-wheeled “Erle-rover” robotic vehicle based on the Erle-brain. All four products are detailed below.



Like the proof-of-concept BeaglePilot, the new Erle-brain autopilot computer runs Debian Linux on a BeagleBone Black single board computer. It also incorporates the open source APM MultiPlatform Autopilot software and APM-compatible Pixhawk hardware. The latter is implemented with Erle’s Pixhawk Fire Cape.

Erle-brain (left) and an exploded view of its innards
(click images to enlarge)

In a first for APM-based drones, Linux runs the autopilot directly, treating the Pixhawk as a daughter card, rather than running the Nuttx real-time OS, which is APM’s default operating system. The Erle-brain also runs the open source Robot Operating System (ROS) Hydro Medusa software, enabling application development for both Unmanned Aerial Vehicles (UAVs) and terrestrial robots.

The Erle-brain combines the BeagleBone Black Rev C with the Pixhawk Fire Cape daughtercard to create a versatile Linux-based autopilot computer. The system ships with the BB Black’s 1GHz Sitara processor, 512MB DDR3L RAM, and 4GB of eMMC flash. A microSD slot handles data expansion, while peripheral expansion primarily depends on a USB 2.0 host port.

Pixhawk Fire Cape alone (left), and installed on a BeagleBone Black
(click images to enlarge)

The Erle-brain features a micro-HDMI port, 10/100 Ethernet port, and the optional WiFi. You also get four UART interfaces, ADC and CAN interfaces, three I2Cs, a dozen PWM outputs, and PPM/S.Bus I/O. The computer also supports the full range of the BB Black’s I/O via the expansion connector.

The 110-gram box has a 5V power supply, and offers a variety of power input options, including the aforementioned battery and a micro-USB port. The device is further equipped with 29 sensors, via four modules that includes various mixtures of accelerometers, magnetometers, gyroscopes, and temperature sensors.

Specifications listed for the Erle-brain (many of them based on the module’s integrated BeagleBone Black SBC) include:

  • Processor — TI Sitara AM3358BZCZ100 (1x Cortex-A8 core @ 1GHz ); Imagination Power VR SGX530 GPU
  • Memory:
    • 512MB DDR3L RAM @ 800MHz
    • 4GB, 8-bit eMMC flash
    • MicroSD slot
    • 32GB microSD card (on WiFi+MicroSD model only)
  • Autopilot — Pixhawk Fire Cape
  • Sensors (29x total via 4x modules):
    • MPU6000 — 3x accelerometers, 3x gyroscopes, temperature sensor
    • MPU9250 — 3x accelerometers, 3x magnetometers, 3x gyroscopes, temp.
    • LSM9DS0 — 3x accelerometers, 3x magnetometers, 3x gyroscopes, temp.
    • MS5611-01BA — digital pressure (barometer), temp.
  • Wireless — 82.11ac WiFi (2.4GHz/5GHz) only on WiFi and WiFi+MicroSD models
  • Networking — 10/100 Ethernet port
  • Other I/O:
    • Micro-HDMI out port at up to 1920×1080 with stereo audio support
    • USB 2.0 host port
    • Mini-USB 2.0 client port (can be used for power)
    • 4x UARTs
    • ADC connector
    • CAN
    • 3x I2C
    • 12x PWM output
    • PPM/S.Bus in and out for RC
    • Spektrum interface
    • Optional 20-pin debug interface (20-pin CTI JTAG, serial header)
    • Expansion connectors — McASP0, 2x SPI, up to 69x GPIO, LCD, GPMC, 2x MMC, 7AIN (1.8V max.), 4x timers, 4x serial, CAN, EHRPWM(0,2), XDMA interrupt, power button, expansion ID for up to 4x stacking; 5V, 3.3V, VDD_ADC (1.8V) 3.3V I/O on all signals
  • Other features — reset, boot, and power buttons; LEDs including 4x user; buzzer out; safety switch
  • Power — 5V supply via mini-USB, DC jack, or 5VDC expansion header; TPS65217C PMIC regulator and 1x additional LDO; battery backup (LiPo)
  • Weight — 110 g
  • Dimensions — 95.6 x 75.27 x 36.2mm
  • Operating system — Debian 7.5 “Wheezy” Linux; APM 3.2-rc14; ROS Hydro Medusa

The Linux port of APM involved compiling the Linux kernel with some options that make it “pseudo-real time,” according to an email from Víctor Mayoral Vilches, CTO and co-founder of Erle Robotics. “It responds nicely to the higher priority threads that APM launches,” he continued. “The fact that the APM autopilot runs in Linux means that we can now have flying computers with a state-of-the-art software autopilot that are easier than ever to use. The big community of Linux experts can now jump into creating practical applications with their flying computers easier, without the need of interacting with a highly complicated system such as NuttX-based autopilots.”

The Erle-brain will first ship as a standalone autopilot product in February. Like the Erle-copter quadcopter, which integrates it, the Erle-brain is now available for pre-sale. Both products will be available with full specs offered under an open source Creative Commons license.

“We are really excited and surprised to see how versatile the autopilot has ended up being,” added Mayoral Vilches. “Expect even more new vehicles to come as well.”


The Erle-copter will ship in kit form starting at 399 euros ($490). A more workable system with WiFi, a power module, and a 3000mAh battery, costs 494 euros ($606), and a version that adds GPS and a 433MHz RF telemetry radio goes for 589 euros ($722). Other options should be available by the ship date in January, according to Mayoral Vilches. These include an RC controller, legs, a gripper, a gimbal, and several cameras, including a GoPro .

Erle-copter quadcopter
(click image to enlarge)

The 85 x 55 x30cm Erle-copter can be programmed to run for 15 minutes in full autonomous mode using the 3000mAh battery. No speed figures were supplied, but the company says the 500-gram quadcopter can carry up to 2 kilograms of payload. You can connect Spektrum controllers for direct control, and a RC controller option should be ready in early 2015. There was no mention of mobile app controls.

The Erle-copter builds upon the features of the Erle-brain by adding four brushless motors, four propellers, and four electronic speed control (ESC) circuits, all built by Erle. The ESC devices help vary the servo-motor’s speed and direction, and can “possibly also act as a dynamic brake,” says the company.

Specifications listed for the Erle-copter include:

  • Processor/memory, etc. — Erle-brain, based on BeagleBone Black
  • Wireless:
      Optional 802.11ac WiFi
      Optional GPS
      Optional Telemetry 433MHz radio
  • I/O (same as Erle-brain)
  • Other features:
    • 4x Erle Robotics brushless motors — 22 x 12mm, 920 rpm/V
    • 4x Erle Robotics compatible ESC circuits
    • 2x 10 (tall) × 4.5-inch (wide). Erle Robotics propellers CCW
    • 2x 9.4 × 4.3-in. Erle Robotics propellers CW
    • XT-60 to 4x ESC connectors with 30Hz to 450Hz range
  • Future options — cameras; gimbal, RC controller, legs, gripper; Electro Permanent Magnet (EPM); pre-assembled configuratons
  • Power — 5V supply; power module connector (6x DF-13 pins) with ESC signal cables; Optional Li-Po 3000mAh battery
  • Weight — 500 g (depends on options)
  • Payload weight — up to 2 k takeoff weight (payload is inversely proportional to flight time)
  • Dimensions — 85 x 55 x30cm; 45cm diagonal wheelbase

The Erle-copter pricing and capabilities place in the same general category as two other non-APM, autonomous Linux quadcopters: Parrot’s BeBop Drone and the Pleiades Spiri. Both products are now available for pre-order.

Erle-plane and Erle-rover coming soon

Erle Robotics is also prepping two more Erle-brain based devices for a March release: an autonomous fixed-wing, long-range Erle-plane UAV starting at 1,300 Euros ($1,595) and a four-wheeled terrestrial robot called the Erle-rover starting at 350 Euros ($429). Erle Robotics has posted specs for both, but both the specs and pricing are preliminary.

Erle-plane and Erle-rover
(click images to enlarge)

Further information

The Erle-brain is available for pre-order at 269 euros ($300), or 304 euros ($373) with 802.11ac WiFi, or 319 euros ($391) with WiFi and a 32GB microSD card. It will ship in February.

The Erle-copter is available for pre-order at 399 euros ($490), or 494 euros ($606) with WiFi, a power module, and a 3000mAh battery. A version that also adds GPS and a 433MHz RF telemetry radio goes for 589 euros ($722).

More information may be found at the Erle-brain and Erle-copter product pages.

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One response to “Quadcopter drone packs first all-Linux APM autopilot”

  1. M. Tolivi says:

    Last Christmas I bought an Erle drone that comes powered with the Erlebrain2 and I’ve had all kinds of problems getting it to work, no GPS lock and camera never worked, the response from the tech service at Erle was that they had a problem with the master made by DIY Drones and they would fix it and send me a new firmware to install, that was Feb 18th and when I got in touch with them just today, to ask for a solution to this matter, they blew me off sending me to their forum to wait for their engineers to find time off to post a response to me (those were Victors exact words printed on the email).
    I recomend to stay away from any Erle made material since they do not stand behind their product.

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