Thursday, April 15, 2010

Wireless, PID Controls, new Props, and First Motor Spin-up

We have completed and started several things since the last post. First of all, we have fairly robust RF communication between two MaEvArMs. This allows us to send motor commands to a Wyvern unit and to receive telemetry data back from the unit. As we continue to tweak our PID controls, this will also allow us to change our gains without reprogramming the unit. We have finished writing the majority of the PID control code, but the road to a stable, hovering quadrotor will undoubtedly present us with more challenges than we foresee.

After all of our soldering and wiring we re-massed our unit at about 695 grams. After landing gear we expect to be just slightly above this. This would give a new flight time of about 12.5 minutes with the tri-blade props that were tested in previous posts. However, since then we have ordered new tri-blade 8x4 props that have characteristics similar to the two-blade props tested earlier. In fact, they seem to match the two-blade props at lower RPMs and even outperform them at higher RPMs.

The first motor spin-up was very successful. We were able to achieve a thrust that we determined to be adequate for hovering (determined by holding the body lightly and seeing if it would lift). Knowing that all of our mechanical parts were in order, we were able to turn our full attention to developing the rest of the code.

Below are some videos of test flights before our PID code was optimized.

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