It’s been a while since I worked on this project in earnest, but this weekend I tried to fly the helicopter with the LIDAR mounted to the tail to record altitude. I bought the original LIDARLite for $90 like 3 years ago. Since then, Garmin acquired PulsedLight (the original manufacturer) and now sells what looks like the same sensor for $150. The V1 LIDAR had an unfortunate cable – a tiny 6 pin JST where one of the wires is red, and the remaining 5 are all black, so it was very tough to distinguish GND, from SDA, from SCL, and so on. This weekend I realized that two of the wires had snapped off at the connector, and after a futile effort trying to reuse the the JST contacts, I decided to remove the JST connector from the board and solder my own (uniquely colored) leads to it.
My first sensor package is too heavy, and even with the throttle gain at 200%, I was basically at T/W = 1 and barely got off the ground. The plot below shows the LIDAR altitudes and the throttle PWM high period. I characterized the throttle signal before flying using pulseIn() (so take that with a grain of salt), and the command a 337 Hz (T = 2.96 ms) PWM with duty cycle = 37.4% (1108 us) at 0% throttle and 63.2% (1872 us) at 100% throttle. I think the highest altitude is 80 cm (31.5 inches) near the 8100 sample mark.
Here’s what the helicopter looks like now. I’ll trim some weight and try again this week. Expect rubber bands and hot glue.