http://forums.leaflabs.com/topic.php?id=257 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:09:50 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=257&page=2#post-4919 Wed, 01 Jun 2011 14:29:47 +0000 ridgebackred 4919@http://forums.leaflabs.com/ <p>brijesh,<br /> It would be great to be able to use a Maple Mini on the single task of laser range finding and reporting results back over the SPI or i2c bus. Keep us posted! </p> http://forums.leaflabs.com/topic.php?id=257#post-4918 Wed, 01 Jun 2011 12:12:19 +0000 brijesh 4918@http://forums.leaflabs.com/ <p>Hello Guys,</p> <p>I have had same thoughts about low cost laser range finder. I went through the same steps of trying to find a suitable camera and camera interface.</p> <p>Finally ended up trying with Taos Inc's 128*1 linear array sensor.<br /> <a href="http://www.taosinc.com/ProductDetails.aspx?id=3" rel="nofollow">http://www.taosinc.com/ProductDetails.aspx?id=3</a></p> <p>Initially I tried to hack something together on a bread board. That did not work as the laser and image sensor have to be rigidly mounted, small disturbances result in large errors.</p> <p>So ended up designing and building a custom board with lens and laser mounting. I just got the boards fabricated and will be firing them up soon. By the way I am also using STM32 processor on the board, but it is lower end one STM32F100C4.</p> <p>If you guys are still interested in the this project(after 7 months), I will keep you guys posted. If someone wants to work on it, just let me know.</p> <p>Cheers </p> http://forums.leaflabs.com/topic.php?id=257#post-1931 Fri, 22 Oct 2010 16:52:40 +0000 poslathian 1931@http://forums.leaflabs.com/ <p>oh yeah! Will have to check in to those sensors, thanks! </p> http://forums.leaflabs.com/topic.php?id=257#post-1930 Fri, 22 Oct 2010 15:53:30 +0000 gbulmer 1930@http://forums.leaflabs.com/ <p>Anyway, back to the Laser rangefinder. </p> <p>Apitina and Omnivision make sensors at a reasonable price (sub $30 at one off prices), which support windowing.</p> <p>At 48MHz pixel transfer rate (e.g. one of the less capable Aptina's), 3600 frames/second (10 frames at 360 positions) would be a 115 x 115 pixel square, which should be big enough to encompass the laser dot if it is keeping track of where things are going.</p> <p>Some of those image sensors support 96MHz clock rate, so 115x115pixels should be a reasonably conservative estimate.</p> <p>Push the data straight into an FPGA for initial processing, and it should give reasonable distance feedback 360 degrees around, at 10 sweeps/second.</p> <p>Do any of LeafLabs have contacts in an engineering department? They could probably make a reasonable prototype mechanism for you to experiment with.</p> <p>Some of the papers suggest that integrating this sort of 3D distance data with traditiomal image/vision data gives very high quality object recognition and navigation. With a few Oaks, and some low-cost cameras, you might have a pretty good low-speed DARPA-challenge-style sensor system for well under $1000, maybe well under $300.</p> <p>Just a thought ;-) </p> http://forums.leaflabs.com/topic.php?id=257#post-1929 Fri, 22 Oct 2010 15:40:52 +0000 gbulmer 1929@http://forums.leaflabs.com/ <p>Well you folks seem to manage okay, but maybe it's those Border Cafe Fajitas, and Hornitos Margarita's that keep them neuron's poppin' and jivin' !-)</p> <p>(while as I was doing the estimate, I realised I needed to raise the 7000 an extra few powers of 10 to get to yotta-ops, so that's why your visual processing neurons are so fast :-) </p> <p>I was a bit surprised at 5ms/neuron-firing, how (relatively) little processing power was available for 'real-time' vision processing. Still a lot, but not an amazing amount (any more). </p> http://forums.leaflabs.com/topic.php?id=257#post-1923 Fri, 22 Oct 2010 12:08:17 +0000 poslathian 1923@http://forums.leaflabs.com/ <p>I think MIT neurons are actually a bit slower, due to the inevitable burn out effect. </p> http://forums.leaflabs.com/topic.php?id=257#post-1916 Thu, 21 Oct 2010 19:27:17 +0000 gbulmer 1916@http://forums.leaflabs.com/ <p>Okie - </p> <blockquote><p>you meant 10^9 neurons? </p></blockquote> <p>I am really, really sorry about this, ...<br /> no, 10^99 neurons for me, you can speak for yourself (urggh)</p> <p>It's about 100,000,000,000, i.e. 10^11 neurons, so about 10^10 for vision, with a 'fan-out' of 7,000?</p> <p>An average neuron can fire in 5ms, so an MIT neuron, is probably quicker, say about 2ms?<br /> Flicker stops being a big problem arond 50Hz, so 10 sequential neuron events?<br /> In theory one neuron might trigger 7000^9 other neurons in that time, or 4x10^34 triggers, so all 10^10 neurons could get involved, doing 4x10^24 ops = 4 yotta-ops!</p> <p>A friend of a friend has got something like time of flight working<br /> <a href="http://www.photon.org.uk/activity/Programme/page_41480.html">Real time low cost pseudo-random noise continuous wave lidar</a> </p> http://forums.leaflabs.com/topic.php?id=257#post-1906 Thu, 21 Oct 2010 18:52:07 +0000 poslathian 1906@http://forums.leaflabs.com/ <p>These high speed cameras are simply amazing, but nearly as expensive as youd expect (10-200k$). But i think youre right about windowed output on cheaper consumer image sensors. Lets try and find one that does what we want. I wouldnt be too surprised if someone makes an inexpensive sensor that has single-scan-line output mode for just this sort of thing. </p> <p>Of course, you could also try and get time of flight working ;) </p> http://forums.leaflabs.com/topic.php?id=257#post-1905 Thu, 21 Oct 2010 18:50:06 +0000 okie 1905@http://forums.leaflabs.com/ <p>you meant 10^9 neurons? </p> http://forums.leaflabs.com/topic.php?id=257#post-1900 Thu, 21 Oct 2010 17:15:29 +0000 gbulmer 1900@http://forums.leaflabs.com/ <blockquote><p>I usually take laser rangefinders as evidence that were all still "doing it wrong" - I get around just fine with just a couple well placed image sensors in my face. </p></blockquote> <p>I see your point, but how many yotta-ops are you applying to the problem?-)<br /> IIRC, about 10% of the brain is associated with vision, so about 10^99 neurons?<br /> A lot more than one yotta-ops.</p> <p>I have no problem using man-made physical phenomina, like coherent light from a LASER.<br /> We didn't have the chance to evolve the capabilty :-)<br /> (but then, I believe evolution is the best explanation we've got, unlike most of the folks on your side of 'the pond' :-)<br /> (I should not start this, but I'm in a playful mood :-)</p> <p>Anyway, the reason I posted is to stimulate folks to consider the power of FPGA+high-volume sensors, and image sensors are a great example. If the FPGA can be tied directly to the image sensor, we're cooking!</p> <p>Many modern camera sensors can return subimages (window) much more quickly than an entire image. A friend has a video camera which, I think, but I might be muddled, can do over 800 frames/second for about 10% of the image.</p> <p>An extreme example is <a>http://www.laboratorytalk.com/news/phj/phj108.html</a> which can do 5,000 one megapixel images/second, but a jaw dropping 150,000 sub-images/second. This isn't something like STEAM, but an image sensor.</p> <p>So, I strongly agree, FPGA+Camera = Awesome!<br /> So when will Oak be ready?-) </p> http://forums.leaflabs.com/topic.php?id=257#post-1889 Thu, 21 Oct 2010 15:24:16 +0000 poslathian 1889@http://forums.leaflabs.com/ <p>I usually take laser rangefinders as evidence that were all still "doing it wrong" - I get around just fine with just a couple well placed image sensors in my face. </p> <p>BUT - neat project idea. Im not sure I fully understand the "low cost" image sensor part, being that - as was pointed out - a 3.6fps refresh rate doesnt come standard on most CMOS sensors. I suppose you really only need to grab a single horizontal line, not the whole frame - perhaps someone can find a sensor that supports this type of configuration. </p> <p>Other than that, FPGA's+Cameras = awesome! </p> http://forums.leaflabs.com/topic.php?id=257#post-1880 Thu, 21 Oct 2010 13:49:25 +0000 gbulmer 1880@http://forums.leaflabs.com/ <p>Okie - Any ideas about how we could get hold of, or make something like that Laser Rangefinder sensor?</p> <p>Being able to scan 360 degrees of the environment at 10Hz would be a fabulous sensor for any sort of mobile robot. It won't win a DARPA challenge, but it might be able to dodge a rampaging VW Touareg!-) </p> http://forums.leaflabs.com/topic.php?id=257#post-1877 Thu, 21 Oct 2010 13:41:16 +0000 okie 1877@http://forums.leaflabs.com/ <p>awesome project idea! </p> http://forums.leaflabs.com/topic.php?id=257#post-1875 Thu, 21 Oct 2010 13:27:09 +0000 gbulmer 1875@http://forums.leaflabs.com/ <p>I think the makerbot cyclops is one of the family of low-cost 3D scanners which work upto a couple of feet away, and take upto several minutes to scan an object. AFAIK, it doesn't really measure absolute distance, but gets a displacement relative to the surface it is scanning from each scan line, and builds up a 'cloud' of data from many scan lines. A piece of post-processing stitches together the neighbouring points in the cloud to yield a 3D 'mesh'.</p> <p>The Neato Laser Rangefinder measures absolute distance (relative to the robot, of course). It claims to scan 360degrees, at 10Hz and examines the scene at approximatly one degree increments, and so reads a subframe from the camera at 3.6k frames/second (they say almost 4k frames/secobd). </p> <p>It triangulates the single laser dot reflected back onto the camera sensor to calciulate distance. Extracting the appropriate subimage (so that it can scan at 4k frames/second) and doing the subpixel iterpolation looks a bit beyond a Cortex-M3, but maybe 'easy' with Oak's FPGA.</p> <p>So they would both be great to have, and an LDR would be great for a mobile/roving robot. </p> http://forums.leaflabs.com/topic.php?id=257#post-1868 Thu, 21 Oct 2010 06:44:13 +0000 josheeg 1868@http://forums.leaflabs.com/ <p>I agree a smarter camera that does the difference of every pixcel or detects distances by a projector sending out lines like in the makerbot cyclopse is a good aplication then the robot can avoid obsticles and maby identify ones it can work with. </p>