Initial In-flight Testing of autopilot SUCCESS!

Depicts a traditional PID controller. (Photo credit: Wikipedia)

I'm such an exciting right now. It's been over a year of putting this UAV glider with custom autopilot and electronics together and now we're at the pivotal stage. In-flight testing of autopilot and GPS waypoint tracking!!

Decided to go for a flight test on Sunday morning before church (around 7am) eventhough I was performing the church band that morning (crazy I know). It was bitter cold but decided to push through. I must say that I realised that I need a small collapse table/stool to setup the instruments instead of the wet/moist ground.

I was great to see that the transmitter code works as expected. There was no lag in the transmission of signals from transmitter -> autopilot -> servos. The turning of aircraft with rudder and elevator control was smooth and consistent. It was refreshing to see that the filtering algorithm worked well.

Decided to test the roll autopilot first, this was a very nervy time as this could potentially lead to a uncontrollable airframe. But the safety switch algorithm was tested before hand it worked as expected on the day. This roll autopilot is a simple P of a PID controller which was not suitable. Although the PID architecture is coded, only the P gain factor is non-zero.

During flight (abeit short), the error gain was too aggressive which caused the glider to violently bank from left to right leading me to quickly switch back to full transmitter control mode.

The biggest headache of all this is not being able to have enough flight time at the park. Since these are soccer fields, I always have to look over my shoulder to see if people are about to invade the pitch. Very frustrating If you ask me.

Nonetheless, the autopilot in-flight testing has started and this is really exciting. It's now a matter of tuning the controller such that it enhances the stability margin of the airframe and not deteriorates it.

Exciting times ahead...

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