Garmin Lite VR Lidar Construction and Build Video - Page 1
Forum section: electronics / projects

author: DavidCambridge
author_rank: Newbie
timestamp: June 30, 2018, 07:05:09 am
content: Hello AllAs promised, here is the build video for the home made Lidar images I posted a few weeks back. As discussed before it’s built around the Garmin lite V3, a couple of STM32s, and the unity game engine.If you’re watching it, please do go easy on me with the soldering skills. It was my first go at putting down any sort of surface mount component, so I was just chuffed it worked at allAlso, a massive thanks to this forums owner who has produced some great videos that opened my eyes to the fact it was possible to do this sort of stuff at home, and without a lab full of skilled technicians!David

author: Siwastaja
author_rank: Super Contributor
timestamp: June 30, 2018, 08:19:11 am
content: I'm impressed by the mechanical design you went through, especially using a DIY cast aluminum part. I would have used some cardboard and a lot of hot melt glue.Note that the cheapo slip rings have proven problematic, especially for data. Scanse.io needed to stop their production completely due to failing slip ring communication they didn't anticipate. We used their lidars and saw 10% DOA and 50% dead after just one month of light use. OTOH, the remaining few units seem to work quite reliably. The chances are, you have a similar slip ring. This is good for prototyping if you are lucky and get a working one, but be careful if you ever think about commercializing this design! Magnetic power and optical communication shouldn't be too difficult in that case.Have you seen the issue that the Garmin lidar is very noisy at short distances? We were seeing that with the Scanse. This is clearly why its operation is completely unspecified below 40cm, and specified with 25% error at 40cm.

author: cs.dk
author_rank: Unknown
timestamp: June 30, 2018, 09:42:20 am
content: Impressive

author: DavidCambridge
author_rank: Newbie
timestamp: July 01, 2018, 08:38:04 am
content: Siwastaja - You are right about the slip ring. Mine was the cheapest I could find from eBay, with a rated lifetime of about 3 million cycles. That sounds a lot, but if you do the maths, and even if you get one that performs to spec, then it isn’t going to last more than a few months of continuous use. If it was a commercial design I’d look at doing exactly as you’d say, or look at better quality slip rings, and maybe look at keeping the sensor still and mechanically spinning a mirror above it. (In the case of the spinning mirror, the Garmin input and output sensors are a good 5 cm apart, which makes the bearings more expensive and the mechanics more work to machine). Either way, my Lidar now has no purpose other than a shelf assisted dust collector - so 3 million cycles is orders of magnitude better than I need.The sensor is not bad at shorter distances. After reading your response, I’ve tried the Lidar in the foot well of my desk, and that came out just fine. That being said, for scanning large areas like the church or my back garden I’ve been throwing away all data points that are closer than 50 cm. This is because I’m seeing points that are actually at infinity coming out as close up noise. Still, for around the £100 I paid it’s a pretty amazing sensor.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 01, 2018, 10:19:11 am
content: It isn't meaningful to do the lifetime calculation, since those slip rings can't conform to that spec. Worst case, they are DOA, typical case, they are good for about 100 hours. I'm not sure if they are even specified for data. For power, add enough capacitance and a very intermittent connection will be good enough. Maybe you could buffer more data on the sending side, compress it down, then use slower baud rate with a lot of RC filtration, and/or checksumming + multiple send attempts, and/or actual error correction code.