Sorry, yes that is certainly possible. I would expect the devices to be cabled to the device unit, so while the devices may not be smart enough they will be in constant contact with the base unit. I am happy with the base unit performing large portions of the processing. My only desire is that a single base unit can handle a moderately variable number of devices, hence I'd rather not have too much base circuitry devoted to individual devices. I would expect to use some form of time slicing for noise elimination (e.g. switch off object 'transmitter', take background noise reading, switch on device, take positional reading). Hence multiple objects could use time slicing. I'd probably slightly prefer non-time based discrimination as it would increase sampling rate. e.g. If I could sample once and seperate devices by frequency, only one set of readings would be needed for 5 devices (or 10 devices) instead of 5 in a time based system. And in systems such as capacitative ranging I would prob. use some from of bandpass filtering for noise elimination, hence a single Fourier transform could be used to ascertain readings for a solely bandwidth\computation limited number of devices. Tom. -----Original Message----- From: Bob Ammerman [mailto:RAMMERMAN@PRODIGY.NET] Sent: Tuesday, January 16, 2001 10:38 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Positioning Can your objects be smart enough that they could be polled so that only one at a time would be actively responding to the base? ----- Original Message ----- From: Brandon, Tom To: Sent: Monday, January 15, 2001 6:33 PM Subject: Re: [EE]: Positioning > Sorry should have given an idea of object size\use. Would ideally like to be > able to track an object less then 1cm cube (this could\will be connected to > a larger device with most of the circuitry so could just be an 'antenna'). > This object should be able to be attached to the hand (or other objects > ideally irrelevant of object (may have to be fairly non-conductive say) > hence a CCD system would prob. make it hard to isolate the target from the > hand (esp. as the object may be visually concealed by the hand or another > object. Maybe a couple of CCD's but then it gets harder, also, I'd like to > avoid having a structure around the area. Ideally only a base would be > required. > > Thanks anyway, > Tom. > > -----Original Message----- > From: Roman Black [mailto:fastvid@EZY.NET.AU] > Sent: Monday, January 15, 2001 6:13 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]: Positioning > > > Brandon, Tom wrote: > > > > I am looking at an application requiring multiple objects (say up to 10 > max) > > to be positioned in about a 40cmx40cmx40cm area. I would be looking at > > achieving a usable accuracy of 7bit minimum but would quite like to have > > 9-10bits of usable range. Hence I'd probably be looking at obtaining rough > > 8-12bit input which can then be filtered. Ideally the sample rate would be > > moderately high, say at least 1kHz per object. However such specs are not > > final. > > > > The main method I've come up with is capacitative ranging from multiple > > points fixed on a base unit, then mapping the various capacitances > > (distances) to cartesian coordinates. However I'm not sure: > > 1) About the effectiveness of such a unit with multiple objects to track. > > 2) The distances this will be effective over. I'm yet to calculate the > level > > of capacitance you would need to measure in such a situation. > > 3) The speed achievable with such a method. > > > > Other possible methods I thought of were: > > 1) Angular determination. If the angle from fixed base points could be > > determined triangulaion could be used. > > 2) Some other form of distance measurment via signal intensity. I'm not > sure > > what signals would be effective. Maybe by using RF transmission techniques > > and power measurement the sensitivity required could be reduced. > > > > I would imagine there would be a moderate amount of DSP involved in > > converting sensor readings to cartesian coordinates and hence would like > to > > use DSP to improve resolution as much as possible (e.g. Digital background > > noise removal, multiple object handling via frequency division). > > > > TIA, > > Tom. > > There is a lot of good stuff on the net re using > a cheap CCD camera for object detection. Your > requirements may suit this via top down camera > and/or side camera? Search some of the uni > sites, and even the robot soccer, there are > algorythms and hardware designs and stuff. > -Roman > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body