This is my situation:
A circle with a diameter of approximately 6m with 6 monitor speakers on the ceiling. It’s not a surround system, but i will be used for spatial sound positioning, that part’s working fine.
This is my problem:
I want to be able to detect the exact location of the people entering the circle. I know this can quite easily be done using motion tracking / camera’s. I even considered LIDAR (laser tracking system). But i wanna solve this using piezo sensors. As i not only want the location of the people, but also wanna use the ‘rhythm’ of the footsteps of the people.
Can somebody help me on my way? Maybe a example patch?
I’m aware that this can be done (http://tangible.media.mit.edu/projects/pingpongplus/) which is more or less the same thing. But I can’t seem to figure out HOW to program this in Max/Msp as I’m quite new to programming.
Any help or suggestion would be much appreciated!
At first glance I think this would be very tricky if you want to track more than one person—how would you be able to distinguish between them? To ensure that your three distances are referring to the same person? Not sure that could be done.
If it’s just one person, you might be able to do it with triangulation. Each distance is a radius of an imaginary circle around the piezo, where they intersect is your person. Or something like that… :)
..and would force-sensing resistors be a better application? You could easily cobble together an [expr] with preset conditions, maybe using [split] as well, to determine proximity to sensor X, Y or Z. Three incoming values, if X > Y+Z; if Y > X+Z; if Z > X+Y. I’m not in front of Max right now, so this is just off the top of my head.
I’m also making some research about this, I found a interesting project dealing with the arduino directly and check position in the space.
I start making some sketchs in Max, but already got stuck in how to calculate the delay value between 2 mics. I know from the amount of amplitude in which side the source is coming but could not figure how the system can work exactly.
Depending on the accuracy you need you may need to use Gen~. As I understand it you need to calculate the time it takes for the sound to get to each piezo and then do some maths! Depending on your audio setup Max receives the audio data in packets equal to your buffer size.
So if your sampling rate is 44,100 and your buffer size is 256 you get approx 172 packets a second. So your time resolution is about 6ms.
This might sound quite fine but the speed of sound is quite fast. 3,500 m/s through wood or 343 m/s through the air.
So depending on if your piezos are surface mounted or not in 6ms sound can travel 18m through wood or 1.8m through the air.
Clearly in a 6m space this isn’t accurate enough. So you need to work at a sub buffer rate.
Gen allows you to do this, allows you to work with the individual samples within the buffer so you can theoretically make the above 256 times more accurate. A sampling rate of 44,100 could give you accuracy to within 8cm through wood or about 0.8cm through the air!
All this could well be wrong but I look forward to being corrected!
I’m sorry to say I never followed this up (not yet anyway) but maybe these will help:
I did some quick preliminary experiments using gen~ to measure position between 2 mics in air, it looked quite promising and was fairly accurate.
Leafcutter, got any code worth sharing at this point? Given the significant difference in sound transmission speed between gases and solids, this may not be a good indicator for the original poster, unfortunately. I’ll be interested to see what comes of this, hoewver…it could be very useful.
On the other hand, perhaps the OP can divide the original problem into two solutions: one for position tracking and one for getting the walking rhythms.
Here follows a patch that calculates the time difference between two received signals coming from an identical source. I’ve used it with a stereo microphone setup (AB not XY!) but it could be extended to a setup with three or four microphones to calculate the exact xyz position of a sound source in space.
The patch calculates the correlation function between two signals and looks for the peak in the function.
The patch only works when the direct signal is louder then the reverb.
I’ve originally made the patch in max 4 and did the peak detection in max. Nowadays it makes more sense to do this with gen~.
-- Pasted Max Patch, click to expand. --Copy all of the following text. Then, in Max, select New From Clipboard.----------begin_max5_patcher---------- 3236.3oc6cs0jhhjE9YqeED9XO10PdiLYeXiX+QrO0wDUfZpESofKfU2SOw3 u8EHAEUtbRJLazt6NhRED3vW9ctlGR+6mlLcd32jwSs9WVewZxj+9oISx2T1 FlT74IS258sEa7hy+ZSCjeMb9eNclZWIxukju4MgdK2JiisX11OWt2W8WtTF jseTwV14kr3U+f0uDIWjntrTL5Y6YVH6r+53l+d9y1V+QwgDreqevFYRb0yi +x7qZpj7YjMp75sJLHIvaqLee+mHeuMSOcRB2mb4YQsoj+ZmTIJSmd7plcph 8+d9NRkorM9OO8T1elMP.ERKTBUfL4nDi2CTx9dBk9sSvScTFV18uaNugfel 0FVfuFKbcGLnvOHwjbFa8zrxgIJomTFWwnjwreqLXemjCGgRcwV+aaV22167 hR2dhL5EYf27M4eC6ZgDRaLmYoHyrVPmRgKQtsvF8z3zKpLL6n15uH6kXYx9 cYuYV1eBB8ikYu4q9Iul85R4Fu+J+64uc+FuD+vTVyezCXeQ31TfO4Jt4oyq U3Jq7KmU1E2ZmevaV4xikWrUb39nExVF1HjbFJUMfIDvF2VEsddN3eBrpLRh 0k.aOXrzFgq7wOqzAOK+fc6Sl1oIeEh3RFB.w9GGfzfosLVxgtoEJ04Ta85p MKnClQrX+0AoGz.ZJa0lvzq8Qa5YfxhvMgQpKn8yBtMSHlU66PU.g4qO+vbR +GeVsuq5g0bvXEvMSe3dPMdhaZnHE37xMeN2KXcWlOSh7iW3Ubcd1c33t4F6 Nj4jwNKr2tYwHamrW3c3KtlPVDN+hFqAMlwpjMQenw7eQiqy5.29CRiEiXZb CvSrbSJ.DFcvB2Bzf4EYtlS1XcP4H0.MjGUnAwPePnAe+AMWmleMHSporOTR 8b2QYFZiO+Atz7HGY37nnoNZizjeh7GD6scWbR3131hKW3nfRWU345inZGWN tCc5Yk32Ppbue6bYzXhIWh67bD2QeaFlI.8hpa7ikG++hRNzpeIaU3g7dFk3 uhIWGlKWQYYt18zF7OSwj+ozSGgNsazTYAf1iPwGLx6fa0c7wcEpnVKQa84t t+J9g54uTTOie.YeWD.QyYGjOF0RHqDkcx7.WoB8wmgaVQakM0CPIKuHu0xq Pk1RUxUfqTFbEcgog4NDdTlpTiPgMl1M4PUNFBUezfbOMYvdKiS7R1Gak38l L78SAjWGxXqXHnbPQ3pseQzvkXRlEEyLAwGQnTSYuG2ZZa4dvTwfwI5iNrwL 5jDtd8FY2Eb4jFSa5M0XTspRITu0cz6.CGIHUbhBsX1ce+qx3gg0d3GyFsNU FgI7fUAMh6aBOXmGxnFGc0ToLVT0.UOpoBl+SSQU9b2wzScy48X8yIEKtyZL qOY0QfZb2hJNqZkCp9Px8Vup8usXHL.DQ0lVDGsQDh8nEQFqV1nHQOsrQPOd V1FsQJTLL0momB+HFoPSIGepAyqKDW2bSs3SjcMyMlbWkabh07r+CYRlq1ek ZQtzNiXRqA8O6hWGPPZ99jjvftACApmI.RX8KMmAsmKZumBTEJifQP5Xx53+ NCVJ9kCyFQOXk0ptgErpdy3d3IjOXvxQynlpbyIV9V9cCNEccce.GwfANEgB XlfUKFI5xwLQUuLBRekI2w6zr0X.7s6esPQx0omI4QsuyxnwOHo6jdKnH8AO POV3gJ+thtpnO3A9NCO5zHhJf9x9LQeiHTxcmQjEg6CRS0vxN8+HaLAfyGGF jYrgUC7nc7oTHOTVFyIz9u62UYjJwHUz6La8oPraVL7lAj1IkucvZ99U.h8E ibUcZj1cZL04tSS6ys1haeTiwr6vtR+SPZ5OBpuHB89CQV3EkDtKbygte.FH p4Omo+TCyX2fFxwXPjevR42NX80zWC+ZavTQbupoPlyzGlbtC4OYdyOnbkSs PsV+gR.Bkqf4p+Ldv3OXlbJzrvr9NsXr6vmZpUqRNTPWx9iM.7gWYUcPO7wc vBt4JKOlzFTpE5jvTa0P7eIX8zLsi8csYZM3UEPEU83U0CKQN36Ld03alsHt EObE3dNAjN+L8jW8oCV31p8FgqpsuvFxSrRcL5wbvqwKB2IOZ6KEfWjG2Q0D 1ufXxvtTDdVsuqKhoBJoEsKZwylpqNX4w3ciREykxkMS6Lbn7k9Hrw80GgyO CgxWTwILgzyP4c3O1gxWBP82Ap3wr5AXFsmgx639PGJeI9vo8LTdt8CRn7YX iLxZq2axW5zRTQW4WT2RDpi56VyJ6DGMPqrSUERYTwMdwcd5W1ei7cYTb9pH 1Qt4jod61UYySpbHYv0ep7X6L63l7CTax93lhju6Wd7B0FSGDdpbmmptP9TT qlnZp54.hvq31NKFgMgKd6L2woricx.+fcQxXYPRwpfVkcuTtxa+ljWpBFH7 y0t+UdKjMdv0h7SltNxeYXPlPb1Qls4xK2WpocTJ9FAd6p4fUOwGy8hx.thn dwk6LILby4653XUJe1KveqWhLwWIrX6imT+s6h7UwbcbapfpeMdQT3lMmcpT 648Z1yxzgyExu5uL40yVMxx1S5W2eW4PvziXzR+0x3jy2Vh253y2xYqWoU4Y UUTOa6sovV2bLbl1Zi0rPjspShUYgyupIaZbxFt54oo50oYBTitEfL2CMYoa Ro0tBksgGP+sr3w6.IKpJVwjiR5FIw0ij3GZj7SVeFLTplZChaugRxCMTtHL FFNpZXRL.JIpdbj9fSIIOinHlKADbhTU485E1SvzR1CNbdrzOc.jpD5uN4Cv .oyCMP964oo.DKwMrfN.FK42+X4YMMc63EqgGbVvlDE8DPpzF02dFzEqNCsC IpNr1g0auDt2DFzY0w9Gmx3+87dapcnrnHrndqLdbMAQarjzIV1PGO8iLNlZ awtNL3YipuK6ZrS6ZbcEQaLl1FF2Rm2ADhOkz7F+flxQLGXx1e8XewpTtRjJ uasNGjRSfMwO3XMD9xwD4t36cZI52txV25ubWX5cWg74Py+0KPEjIQEaT1GN +J5Gmkm8xiSkPmjKcuMcAdWJ.dWd6kXAzwE6QiHWinzfLiFOxLT9OezHxbfR rynQhc.JwrQiDy.JwzQiDSAJwjQiDS.Jw3QiDi0vWIZ.j3h7AJmmfowduKW9 R5UHMnmW7RRh7SSsQEIP0Iw3iVL+tmr.MpvcsBQKW7ltnq2DN2aSwz1b7Xqo P5OcBDGlo5Z99UqjQk0MOeYju6o5B4ppYts9q5pb7v+fXNzOGxxu6sbwgt+s co32YCR4egCBjOdeXLjMt3axNe3LJ+4rQsVk1iGNCNcz8qWSI2O6V2B0AwWT o5cB8WPG4rwOu2nsvUY+cJJdQ0Q9Bc51.G3svUo3ueUIDgYNCGS52Ozw5lCA KpzIkT8apK9XtakZ5mKqron1ZoelVlLXgzxOvJuSOacMNTgTEKzzHLa.9kyh KFdaO4hy4EqPAUWF2UAfccdCmk1dSIlcVVmWGo00QYc0PGT44hKUCoc4XL44 hKUCIUQMl7bwkBPZo2V3AhzXN1iCH1C1bxCFh1kAGtDPvGt4jGND4wsZtd2V sKFTsczHh+PMq0YDDqyHyYctK4gQLm0YBT6gFj+fgveLn9EnwKj47Wff3uvP 3CD6yLWywmgDc3EFMuoxCD+ELy4OkAJ5Pg43OtPzuXl09bm9uLW7FbPwaXN+ oNfhl2b5WNDn3iY3OXH3C1b3CFR7gDyIODPxi43yDJ.6OTygOTH3C0b3CEBe lHL23Ej3MnlyeJEh+Bh47WPf3ufZt5aPgTeChiY026J+BRW4ecY+L4xUMzjq 5WHZUi0d1mvNX0ucQr7GglrOcRHFNzl.czGA+tiyxkYhZ4ClqVttO+SXUq0k sJTyJ9zM3tiLH2cCLWpStsqlboT9B63RcBmPO9oaAhBIaIh4p9HAR0ivFzZA Dq6TssVfxGSUSIbo1Ek+iyh.wb0qL2+DBBhNhzgonOjNrfcK0guP3ZXDFYNc FHxC1bQLhgDwH1bQnggDgFxbQngfTQQgdJ.BUScyX2FiZPFQ4iLmD3OhSBgM 9l5j.C0HHZ7XBgXNUDBjjXvlqH2XWnlXQlKobDDM.jNZ.pjITqKHhzWJ+zMP C.jQPCNKFPzGMmGBHpiHyMmkHHwzhL2bF.oDhjQ1nk4xoCAw4BxbUnmCx3oA 6PAHrYg4lQWNAR7flKCMAFZG2XlwKAA5LnZF4wERzvtMMCFngWdf37x0biWt tP0uFSxiA8WXCI5VNwXDHgCzALrYT3gThHg4JJofAUdLjAZATB8XZ7xbFnEb nxCxPJ7PhPTXNOF.EHdOEH0SbvEKViYxxEKRiWr.Md4hyX5Y6ed5+CHjoJyH -----------end_max5_patcher-----------
Forums > MaxMSP