LIDAR-Lite Optical Distance Measurement Sensor
Tim-M
Posts: 522
A company or group called Pulsed Light have developed an optical distance measurement technology and are crowd-funding the sensor production... looks unique, interesting and cost effective. This video was posted at SparkFun Electronics yesterday, that's where I came across it.
There has been a long history of laser distance measurement here on the forums, so I thought there might be good evaluation, discussion and interest in this as well.
https://www.youtube.com/watch?v=30Jc0GpYKYI
Tim
There has been a long history of laser distance measurement here on the forums, so I thought there might be good evaluation, discussion and interest in this as well.
https://www.youtube.com/watch?v=30Jc0GpYKYI
Tim
Comments
It appears that it WILL detect. This could be very useful in certain applications. It probably going to be roughly equivalent to ultra sonic (ping or sf04) in that it is short range and requires specific conditions. These would not necessarily be replacements for each other, but light could have advantages over sound and vice versa in particular situations.
Consider: at first, we tend to think of distance measurement as similar to a blind person's cane, when we expect fairly solid measurements. In fact, the measurements can vary greatly. any target will have points closer and points further, anbd the readings reported tend to be anywhere in and around those distances. So instead of a cane, its more like tapping out measurements with a round bolloon, and the further the distance the bigger the balloon. If you tried to tap your way through a room with a weather balloon, it might be a challenge.
Even a very directional sensor like a laser range finder is challenged; the reading can be from any visible point on the target, so a widely varying range of values can be reported depending on conditions such as the angle to a wall, etc. The real trick with any sensor is dealing with the reading in software to interpret them appropriately.
It is possible to get very fast parts these days, the first trick is getting them to respond consistently (the stray capacitance and other variables are quickly compunded). The second trick is interpreting the reading. I don't know what the third trick is yet, I haven't gotten that far.
So the LED sensor CAN work, but more like a YES/NO detector, rather than a distance sensor. It all depends on how much work they put into it. How much do you think we can expect for $65?
I image I would the LED detectors on the sides to prevent bouncing into walls on the sides, and use the laser range finder to see whats out front.
I know the laser will work outside in direct sunlight, to 40 meters. I don't know if I figured right (on the back of this envelope), but I think the LED sensor will only have 1-2 meters in direct sun, (if that) and will have a 20 to 50 % variance in reading, even when stationary. Which would be useful for certain cases.
I know for a fact that there were lazers back in the 60s that were used from miles away. The trick is in using some form of encoding from your transmitter and having a number of detecting receivers and extrapolating a mean. Satellite tracking radar sends a series of pulses with each at slightly different frequency and receivers that give instant readouts. Also the better you can focus your transmitter and your receiver the more detail you can discern.
For most just wanting to get their bot through a maze quicker I believe using lengths of tubing, flat black inside, with transmitter in one and receiver in the other. Oh, and you have to stop all other processing while you use the range finder.
I know well what you mean about stray capacitance and other variables. I have been in design review meetings when engineers would practically come to blows over whose signal was interfering with whose. This was in the 60s also. We were trying to use computers to design and build multiprocessor computers. I was a lowly Engineering Assistant but I was overseeing a handful of worth their weight in gold R&D draftsmen that could fix the computer generated logic layout. I then had to meet with the programmers and see if they could change their software to come up with the same or similar solution the R&D draftsmen had. Things would really get intense once the length of wires became a consideration also.
As far as communications for my project I would like to find something like B8ZES that will work with really small frames in short burst. I sat out initially to build my own but stray capacitance other variables got in the way< ]8-( >.
Google did not tell me about B8ZES. Link?
LOL!
It makes my day to know something that Google does not know or may be filtered to not give away the store.
I could be speaking out of school and the big black SUVs with dark windows are already on their way. I will be glad to hand over my weapon just as soon as I give them all of my ammunition. Today could well be a very good day to die.
Decades ago a large regional telephone and data company was working with a CA university to develop an ultra high(in those days) frequency communications system and the associated hardware. I was a lowly FSE that had to be available to jump in my(company) car on a minutes notice and head to one of the regional data centers to pull the fat out of the fire. To be able to troubleshoot and fix stuff I had to know and understand what the IEEEs had built and how it was being used/programmed. Since they were working of the ragged edge of manufacturing capability at that time, replacement parts were as rare hens teeth and I likely had half of the ones available in the trunk of my car.
I worked with it again later for a company that was building T-1/Frac T1 modems and multiplex/demultiplex equipment. That was well before Al Gore invented the internet<VBG>.
I hope that with the above mentioned projects you may be able to exit Google and do a properly focused(filtered) search.
Tim
"And that is all I have to say about that." - Forrest Gump
Nope.
At that time light was not yet a medium in long or short range data communications(excepting optical isolators).
One additional hint I will add that may jog some memories - consider using USB and LSB modulation as components of the same signal - it is all in the timing and what is _not_ there at times.
OK - one more hint - I already had experience with single bit error correction and double bit error detection without using CRC/LRC which waits until the end of the transmission to request a resend and adds timing overhead.
There is also the distinct possibility that what I worked on back then is called something else these days. The stuff we were working with most likely became a part of fiber optic communications.
I was pointing out that using slightly different coded frequencies you could get a more accurate fix on the distance to the target.
Sometimes I get a bit revved and exceed orbit velocity. Sorry about that.
I think that what they talk about in the kickstarter. Fast parts (comparitor?) to detect the signal, then characterize thesignal by comparing to stored data. I don't understand it all, maybe you could talk us through the specifics?