Hacking the APM2 Part #5: Flight Testing

This is the payoff video showing the hybrid autopilot system in action in the Resolution 3 airframe. (By the way, this is HD video so watch it full screen if you can!)

I am skipping many details between integrating the hardware and flying, but just as a quick overview:

We first integrated the system into a Senior Telemaster.  After 4 trips to the field over the span of 2 days, numerous flights, and a bunch of work in the evenings, we felt like the system was coming together and working every bit as well as it was supposed to.  There are always more things we could do with the telemaster airframe, but now that we were fairly confident that the system was working end-to-end as designed, we dropped it into our Resolution 3 (blended body, composite flying wing airframe.)  The new hybrid autopilot system needed some gain adjustments versus the old prototype autopilot so we guessed at those based on what changes were needed with the Telemaster configuration.

We enjoyed a flawless bungee launch of the wing, climbed to altitude, flipped over to AP mode, and the aircraft flew off flawlessly and ran through it’s demo routine without a hitch.  The clouds were dramatic and we noticed a rain squall moving in, so we landed and packed up just as the rain set in.

Here are some high points of the new system:

  • 800Mhz ARM processor (with hardware floating point) running a 15 state kalman filter and all the autopilot and navigation code.
  • WGS-84 math used for heading and route following.
  • Accurate yaw estimation when the filter converges.
  • Accurate wind estimation
  • 100hz sensor sampling, 100hz filter updates, 100hz autopilot and navigation updates, 100hz actuator updates with up to 400hz PWM signal generation rate for digital servos.
  • APM2 sensors.
  • Tablet/smart phone/laptop ground station interface.

If you just like airplanes, here’s some nice footage of our Telemaster landing.  This video was taken during our 2 days of Telemaster integration effort …

Landing in psycho winds:

In calmer winds:

Last flight of the day:

2 Replies to “Hacking the APM2 Part #5: Flight Testing”

  1. heyy i just read your review about ardupilot, mm have you ever use rpm sensor to measure the rpm of the prop and put into port sensor as well as airspeed? Thanks

    Regards,
    William

    1. I have not personally done an rpm sensor. I have mostly flown electrics so there may be something a person could get directly from the ESC with a minimal amount of hacking? I’m sure directly measuring prop rpm is possible via a couple different sensor technologies, but I have not done that myself. If the sensor can output an analog signal, or a number through a digital interface (i2c or spi) then I’m sure it could get integrated some how.

      I’m not sure what you mean by “port sensor”? We can do pressure altitude with the APM’s built in barometer and airspeed via an external pressure sensor that outputs an analog signal that is fed into one of the APM’s A2D ports.

      Regards,

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