3D Robotics

Updates from the DIY Drones dev teams

Here's the latest from some of the Dev Team leaders: First, the core ArduPilot team is close to a beta release of ArduPilot 2.5, which is a huge clean-up of the code, with top to bottom improvements. As always, you can get a preview by watching the activity on the Google Code development repository. This team is also creating the code architecture foundations for ArduPilot Mega. The IMU code team is working from this repository. Other projects: ArduIMU thermopile replacement (This is the version of ArduIMU that is intended to be a plug replacement for any thermopile sensor, on ArduPilot, AttoPilot, Paparazzi or FMA. It has no GPS, so it will add a 3-axis magnetometer to get a full attitude solution) Mike Zaffuto: "Magnetometer selected is the HMC5843, it's a good price $20 (qtys of 1), 3-axis, available at digikey and sparkfun, I2C interface and small QFN package like the chips on ArduIMU. The Dual DAC I selected is the LTC2627, I2c interface, 12bits and small 12pin DFN package. The magnetometer will most likely need to be mounted as far back on the tail, underneath, on the sides, inside, as possible to keep it away from the electric motor and wiring. This will be to avoid as much as possible a motor rpm dependency on H field calibration. ArduIMU is very small and can be made even smaller to make the module less obtrusive in this proposed mounting location. I have arduino code to communicate with this magnetometer. It is someone else's code, but good to communicate with just the magnetometer, it needs modification to handle multiple i2c devices on the bus. Nonetheless it is a good guiding framework for a rewrite so that it is original code. " Turn-rate limiter shield (This is the project to make a turn-rate limiter shield for ArduPilot, which will consist of a single yaw gyro. Combine with the GPS, this can be a very simple and inexpensive full autopilot for stable aircraft, eliminating the need for thermopiles or an IMU for that sort of application. This is meant to create an "entry-level" full autopilot solution) Jeff Taylor reports that the first custom PCBs had the wrong footprint for the gyro, so he's using a Sparkfun breakout board for testing while we wait for new PCBs. Lego Mindstorms Universal RC Interface (This is the project to modify the ArduPilot board to be a universal RC interface for Lego Mindstorms NXT: Read RC and GPS data and drive servos vis the NXT's I2C bus) Christopher Barnes: "I've got some robust and generic code running on the Arduino to allow the NXT to communicate with the board so that it can read an/or write any variables that we want to share. This includes Remote Control channel inputs (& PWM outputs), analogue inputs, logic inputs (MUX, Failsafe) as well as any GPS parameters extracted from the GPS messages. (I've been testing with uBlox 5 in binary mode). I would intend to release this software with a general purpose configuration but with clear, commented code so that anyone interested can customise the parameters that are exchanged with the NXT." ArduIMU documentation This is already in good shape, as Andy Geppert reports: "The majority of the sections are roughed in. I'd like to add much more detail (block diagram of the hardware, and one of the software, high level description of the schematic, start-up details, gain suggestions...)." ArduStation Mega (ArduPilot Mega ground station) hardware: Sarel Wagner reports: "I am in the process of doing a version of the schematics. The block diagrams are complete. As you know the case mock up was done. Also working on the data sheets for all components to get the mechanical info for the board layout. Still awaiting some info on the new switches suggested by Scott. Tthe schematic is about 60% done, not in Eagle though, don't have any Eagle skills :/ so need to build a few things first :) I would say we may have the schematic done by late December "
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  • 3D Robotics
    Yes, the idea is that this is a universal thermopile replacement, requiring no modification of the underlying platform. As such, we are limited to the one-way analog communications that a thermopile would provide. Although we could have added a GPS, for most of these systems that would mean two GPS modules, which is wasteful. Instead, we're hoping that the magnetometer, with declination set at the factory or in a setup procedure at home, will lead to a sufficient attitude solution.
  • A question for with regards to thermopile replacement, The magnetometer is required because there is no GPS ? But 3 of the 4 systems that this is looking already have one on board. Was this decision not to have gps info fed through the imu based on the idea of gps compatibility over the range of autopilots being too difficult ?
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