Gyros and other inertial sensors
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From: Tim Wescott on 5 Jul 2010 00:06 On 07/04/2010 08:26 PM, Muzaffer Kal wrote: > On Sun, 04 Jul 2010 18:34:19 -0700, Tim Wescott<tim(a)seemywebsite.com> > wrote: > >> On 07/04/2010 05:59 PM, Jim Thompson wrote: >>> On Sun, 04 Jul 2010 17:29:05 -0700, Tim Wescott<tim(a)seemywebsite.com> >>> wrote: >>> >>>> I just did a quick survey of Digi-Key and Mouser -- it looks like >>>> silicon gyros are still in the $5 - $10/ea range, unless of course you >>>> want to spend more. Anyone know of less expensive alternatives? Ditto >>>> accelerometers? >>> >>> In the late '80's I was working at Sperry on chips for Fiber Optic >>> Gyros (FOG's) that were supposed to be so cheap that they could be >>> used in cars. In fact, at one point in the development, we had a demo >>> presented to us by Toyota. >>> >>> I've lost touch with that end of business... do FOG's still exist? >> >> Yes they do, but the least expensive ones are probably $500 to $1000, >> with prices going up from there until they intersect with prices for >> ring laser gyros (out of my league -- I suspect $100000, but I could be >> off by almost an order of magnitude). >> >> I suppose you could build a FOG for a few bucks in quantity, but there's >> a whole lot of tweaking and tuning that you wouldn't be able to do, >> never mind the fact that winding the fiber onto a bobbin then >> terminating it is going to have no end of yield issues. When you were >> done, you'd probably have something that cost a whole lot more than a >> similar performance silicon or quartz MEMS. >> >> AFAIK, the gyro biz kind of goes like this: >> >> order of M: | | | | | >> silicon MEMS: *************** >> quartz MEMS: *************** >> mechanical: **************************************** >> FOG: ********************************* >> Ring laser: ****************** >> >> You pays your money and you gets what you pays for. > > Actually ring laser ones are not that expensive. I think this one at 1 > degree/s is only around $15K : > http://www.honeywell.com/sites/servlet/com.merx.npoint.servlets.DocumentServlet?docid=D7B652202-0601-F56B-1B7F-829F1A7109E4 I _did_ say I could be off by a factor of 10! -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: Tim Wescott on 5 Jul 2010 00:06 On 07/04/2010 08:56 PM, Spehro Pefhany wrote: > On Sun, 04 Jul 2010 20:26:52 -0700, the renowned Muzaffer Kal > <kal(a)dspia.com> wrote: > >> On Sun, 04 Jul 2010 18:34:19 -0700, Tim Wescott<tim(a)seemywebsite.com> >> wrote: >> >>> On 07/04/2010 05:59 PM, Jim Thompson wrote: >>>> On Sun, 04 Jul 2010 17:29:05 -0700, Tim Wescott<tim(a)seemywebsite.com> >>>> wrote: >>>> >>>>> I just did a quick survey of Digi-Key and Mouser -- it looks like >>>>> silicon gyros are still in the $5 - $10/ea range, unless of course you >>>>> want to spend more. Anyone know of less expensive alternatives? Ditto >>>>> accelerometers? >>>> >>>> In the late '80's I was working at Sperry on chips for Fiber Optic >>>> Gyros (FOG's) that were supposed to be so cheap that they could be >>>> used in cars. In fact, at one point in the development, we had a demo >>>> presented to us by Toyota. >>>> >>>> I've lost touch with that end of business... do FOG's still exist? >>> >>> Yes they do, but the least expensive ones are probably $500 to $1000, >>> with prices going up from there until they intersect with prices for >>> ring laser gyros (out of my league -- I suspect $100000, but I could be >>> off by almost an order of magnitude). >>> >>> I suppose you could build a FOG for a few bucks in quantity, but there's >>> a whole lot of tweaking and tuning that you wouldn't be able to do, >>> never mind the fact that winding the fiber onto a bobbin then >>> terminating it is going to have no end of yield issues. When you were >>> done, you'd probably have something that cost a whole lot more than a >>> similar performance silicon or quartz MEMS. >>> >>> AFAIK, the gyro biz kind of goes like this: >>> >>> order of M: | | | | | >>> silicon MEMS: *************** >>> quartz MEMS: *************** >>> mechanical: **************************************** >>> FOG: ********************************* >>> Ring laser: ****************** >>> >>> You pays your money and you gets what you pays for. >> >> Actually ring laser ones are not that expensive. I think this one at 1 >> degree/s is only around $15K : >> http://www.honeywell.com/sites/servlet/com.merx.npoint.servlets.DocumentServlet?docid=D7B652202-0601-F56B-1B7F-829F1A7109E4 > > That's an entire 6 DOF IMU- 3 accelerometers and 3 gyros. > > "Export licensing restricts operation to a maximum of 18,288 meters > and 514 meters per second" I.e. don't buy it to put into your best cousin Ahmed's SCUD missile. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: Nunya on 5 Jul 2010 03:02
On Jul 4, 5:29 pm, Tim Wescott <t...(a)seemywebsite.com> wrote: > I just did a quick survey of Digi-Key and Mouser -- it looks like > silicon gyros are still in the $5 - $10/ea range, unless of course you > want to spend more. Anyone know of less expensive alternatives? Ditto > accelerometers? > > -- > > Tim Wescott > Wescott Design Serviceshttp://www.wescottdesign.com > > Do you need to implement control loops in software? > "Applied Control Theory for Embedded Systems" was written for you. > See details athttp://www.wescottdesign.com/actfes/actfes.html The Inertial Reference device that we buy from GE runs about $50k each. It is about an 8 inch cube and the hi-res GPS antenna gets remotely mounted from it. Works great for keeping a dish pointed at its bird in a mobile setting. |