Rising from the flames, I’m rebuilding Zoe. I think only one PWM pin of the PiZero, and the ESC got fried, but I can’t risk rebuilding her with broken components I haven’t spotted. So the plan is …
- I’ll shortly have a new PiZero courtesy of my colleague from the Cotswold Raspberry Jam who is kindly donating his spare to me – huge thanks Andrew.
- I’ve bought a completely new set of ESCs – 15A from compared to the standard 10A as I can’t risk this happening again – huge thanks to electricwingman for the amazing discount you’ve given me.
- My stock of spares already has all the components gathered together for a new sensor HoG pHAT
- My stock of spares also includes new unused frame, WiFi and uUSB power cables.
- Her SD card survived intact, as I’ve booted from it and run the code with the ESCs unpowered.
So she’ll probably be up in the air in under a week.
And that leaves me with a problem: WTF to do next – that’ll be the next post.
I had a little bit of an accident today. I took her out for a quick test, plugged in the LiPo, and as usual, I left her to boot and start up the WAP while I went inside to fetch my iPad which I SSH into her to start her up.
On coming back out, I saw billows of smoke coming out of her, and a nasty burning plastic smell!!!!
I unplugged the battery and checked the damaged. The DC-DC converter was melting and way too hot to touch! My heart sank.
I let everything cool down and brought her indoor to assess the damage.
She wouldn’t boot from the mains phone charger I use for code testing – my heart sank further.
I dismantled her – the electrolytic capacitor after her regulator fell off. My heart sank even further.
I took out the SD card – on my PC I could still see the root partition. My hopes began to rise.
Far more important though was the MPU6050 because of the effort I’d put into calibrating the accelerometer. Although I have a spare MPU6050, I’d have to go through the painstaking 2 day calibration again.
Luckily, I had a spare model A already prepared for her big sister Chloe, so I transferred the breadboard, swapped the DC-DC converter for another spare, and turned on the power. Phoebe booted from her SC hard, and with a new USB dongle, her WAP worked too. A passive run of her code showed the sensor was undamaged.
Woohoo! She most definitely has risen from the flames undamaged.
The lesson is clear – keep spares and be very careful connecting the power!
Alas another Phoebe rebuild – fairly significant changes this time, but not really driven by damage, more by hardware improvements.
Phoebe’s new outfit
She had a couple of test flights the other day – the first was perfect: take-off from a non-horizontal surface (the lawn), hover and land back at the same point. The weather was cold and damp, but no breeze.
I upped the flight time to get a video; except this time, she started to drift (still no wind, so no good reason for the drift). A quick check of flight stats suggested her sensors thought she was tilting at about 4 degrees when she wasn’t, and they were adjusting for that leading to the drift.
A quick investigation showed the breadboard on which the sensors sit had started to come unstuck peeling up at one corner – hence the false angle and drift. I suspect the cold & damp caused the breadboard to flex and it’s adhesive to come unstuck – that’s certainly how it looked.
In addition, her legs had also started to loosen up again – even though she’d only had good landings – the trouble I suspect is the legs are rigid, so even soft landings have a hard impact on the legs.
And that finally pushed me to knick some of the bits from Phoenix and instead use them on Phoebe as well as getting some new bits:
- a new case cut by Phenoptix with a platform for new breadboards supported by noise dampening standoffs
- new legs – flexible ones from DJI specifically for the F450 which are clearly designed for absorbing impacts
- new antenna, since the old antenna platform went with the old legs
- a protective dome over the Raspberry Pi and breadboard – hopefully just for the rain, rather than any head-banging!
As a result of these last tests, my confidence in the software is increasing with each flight; on the downside, the hardware is bothering me more. Fingers crossed, this iteration will solve the worst problems.
On one final sad note: Phoebe is once more good to fly, but in getting there, she stole a lot of Phoenix’ outfit, leaving Phoenix short of the glamour required for her to walk to red carpet any time soon.
Phoebe died this morning. Her body is good, but her soul is gone. The cause is not entirely clear, but during a test, she crashed, and the impact pulled out her Adafruit Cobbler from the sensor / PWM breadboard meaning her power was killed abruptly. Her SD card was damaged and would not reformat. I suspect the battery slid, hitting the GPIO ribbon cable tugging the Cobbler out.
I do have an image backup of her, but I need to get a new mini-SD card.
Or I could have Phoenix rise from Phoebe’s metaphorical flames and pick up where Phoebe died. Phoenix is Phoebe’s big sister with a bigger, stronger, carbon fiber arms and legs, top quality ESCs and top of the range motors and blades, and she was supposed to take over from Phoebe when Phoebe’s testing was done.
Looking at the costs of a replacement card though, I think Phoebe shall be brought back from the dead, and I’ll leave Phoenix for another time – but having mentioned her, I will show her to you once she’s all dressed up and ready to go.