All: Forgive my novice question, I did know where the gyro came up so I don't know if this has been discussed before.
I am planning some work with the new Analog Devices MEMS gyros, as soon as the evaluation boards are available. I have been discussing the part with their chief engineer for several months now. Would anyone be interested in my results? Michael -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, December 17, 2002 12:26 AM To: [EMAIL PROTECTED] Subject: ERPS-list digest, Vol 1 #523 - 11 msgs Send ERPS-list mailing list submissions to [EMAIL PROTECTED] To subscribe or unsubscribe via the World Wide Web, visit http://lists.erps.org/mailman/listinfo/erps-list or, via email, send a message with subject or body 'help' to [EMAIL PROTECTED] You can reach the person managing the list at [EMAIL PROTECTED] When replying, please edit your Subject line so it is more specific than "Re: Contents of ERPS-list digest..." Today's Topics: 1. Next Meeting ... (Michael Wallis) 2. Next Meeting ... NEW LOCATION (Michael Wallis) 3. Re: Next Meeting ... (Adrian Tymes) 4. Re: Next Meeting ... (Michael Wallis) 5. Apollo 17 memory correction. ([EMAIL PROTECTED]) 6. air bearing gyro? (Ian Woollard) 7. Re: air bearing gyro? (Keith Whitwell) 8. Re: air bearing gyro? (Sean Lynch) 9. Re: air bearing gyro? (Ian Woollard) 10. Re: air bearing gyro? (John Carmack) 11. Re: air bearing gyro? (Ian Woollard) --__--__-- Message: 1 From: Michael Wallis <[EMAIL PROTECTED]> Date: Mon, 16 Dec 2002 10:00:01 -0800 (PST) To: [EMAIL PROTECTED] Subject: [ERPS] Next Meeting ... The next meeting of the Experimental Rocket Propulsion Society will be held this THURSDAY evening at the IHOP starting at 8:00pm. Items for meeting #251 (19 Dec 2002): - Admin Teams - CMT - Documentation - IT - Liaisons - Logistics - PAO - Treasurer - Development Teams - Chief Scientist - Flight Controls - Propellants - Regulatory Issues - Safety - Testing - Project Status - Composites - GizmoCopter - KISS - POGO - SmartFlight - Sparger/FF - Spike The address is: International House Of Pancakes 4200 Great America Parkway Santa Clara, CA The IHOP is located at Great America and Mission College. It's on the South West corner if you consider Great America as North/South. Look for the HOLIDAY INN. It's attached to that. Coming from the East Bay, take Hwy 237 to Great America and then south to the entrance south of Mission College. Turn RIGHT and then RIGHT again into the lot at Bennigan's and proceed past Bennigans and the Holiday Inn to the IHOP. Coming along 101, take Great America North to Mission College and do a U Turn to get on to SOUTH bound Great America. Take the RIGHT just past Bennigan's and RIGHT again into the lot, then proceed past Bennigans and the Holiday Inn to the IHOP. Michael ---------------------------------------------------------------------- Michael Wallis KF6SPF (408) 396-9037 [EMAIL PROTECTED] --__--__-- Message: 2 From: Michael Wallis <[EMAIL PROTECTED]> Date: Mon, 16 Dec 2002 12:58:36 -0800 (PST) To: [EMAIL PROTECTED] Subject: [ERPS] Next Meeting ... NEW LOCATION The next meeting of the Experimental Rocket Propulsion Society will be held this THURSDAY evening at the IHOP starting at 8:00pm. Items for meeting #251 (19 Dec 2002): - Admin Teams - CMT - Documentation - IT - Liaisons - Logistics - PAO - Treasurer - Development Teams - Chief Scientist - Flight Controls - Propellants - Regulatory Issues - Safety - Testing - Project Status - Composites - GizmoCopter - KISS - POGO - SmartFlight - Sparger/FF - Spike The address is: Harry's Hofbrau 1909 El Camino Real Redwood City, Ca Take 101 North to Redwood City. Go West on Route 84 (away from the Bay). Harry's is located on the east side of El Camino, just north of Route 84 -- and I do mean "just north". There's a Wendy's directly opposite it. Look for a square yellow sign that says "The Carvery" at the top and "Harry's Hofbrau" at the bottom. >From the East Bay, cross at Route 84 (Dubaurton Bridge) and continue West to El Camino and turn right. See above. Michael ---------------------------------------------------------------------- Michael Wallis KF6SPF (408) 396-9037 [EMAIL PROTECTED] --__--__-- Message: 3 Date: Mon, 16 Dec 2002 13:06:53 -0800 From: Adrian Tymes <[EMAIL PROTECTED]> Subject: Re: [ERPS] Next Meeting ... To: [EMAIL PROTECTED] Michael Wallis wrote: > The next meeting of the Experimental Rocket Propulsion Society will be > held this THURSDAY evening at the IHOP starting at 8:00pm. I thought we agreed to move it to another restaurant last time. --__--__-- Message: 4 From: Michael Wallis <[EMAIL PROTECTED]> Subject: Re: [ERPS] Next Meeting ... To: [EMAIL PROTECTED] (Adrian Tymes) Date: Mon, 16 Dec 2002 13:12:43 -0800 (PST) Cc: [EMAIL PROTECTED] Adrian Tymes wrote: > Michael Wallis wrote: > > > The next meeting of the Experimental Rocket Propulsion Society will be > > held this THURSDAY evening at the IHOP starting at 8:00pm. > > > I thought we agreed to move it to another restaurant last time. We did and I missed one change. Sorry. 8-( If you look at the actual directions you'll see it says: ===== The address is: Harry's Hofbrau 1909 El Camino Real Redwood City, Ca Take 101 North to Redwood City. Go West on Route 84 (away from the Bay). Harry's is located on the east side of El Camino, just north of Route 84 -- and I do mean "just north". There's a Wendy's directly opposite it. Look for a square yellow sign that says "The Carvery" at the top and "Harry's Hofbrau" at the bottom. >From the East Bay, cross at Route 84 (Dubaurton Bridge) and continue West to El Camino and turn right. See above. ===== I've updated the script so the location in the msg is now a variable set run under the "NEW LOCATION" flag so I'll remember to change it next time we move. Again - we're at the HARRY'S HOFBRAU in REDWOOD CITY on Thursday at 8:00 pm. See you all there! Michael ---------------------------------------------------------------------- Michael Wallis KF6SPF (408) 396-9037 [EMAIL PROTECTED] --__--__-- Message: 5 From: [EMAIL PROTECTED] Date: Mon, 16 Dec 2002 16:26:13 EST To: [EMAIL PROTECTED] Subject: [ERPS] Apollo 17 memory correction. Gentlefolk, It is scary how a memory that seemed accurate a couple of days ago, becomes uncertain the next day and seems wrong today. Today, I think the name of the head of the Vela Hotel office in the STC back in the early 70's was something more like "Wyoma" or "Wynona" Klare, not Norma, and that her husband's name may have been "Norman." Anyway, as far as 1Lt Nordley was concerned back then, her first name was "Major." ;-) --Best, Gerald --__--__-- Message: 6 Date: Tue, 17 Dec 2002 01:26:37 +0000 From: Ian Woollard <[EMAIL PROTECTED]> To: ERPS Main List <[EMAIL PROTECTED]> Subject: [ERPS] air bearing gyro? I was wondering whether it might be possible to make an accurate gyroscope out of a ball bearing floating in an air bearing. In principle you just start it spinning before launch, point 3 or 4 optical mice at it, and read off the rotation; it should be quite accurate, fairly light, and reasonably cheap. Comments? -Ian --__--__-- Message: 7 Date: Tue, 17 Dec 2002 01:30:23 +0000 From: Keith Whitwell <[EMAIL PROTECTED]> To: Ian Woollard <[EMAIL PROTECTED]> Cc: ERPS Main List <[EMAIL PROTECTED]> Subject: Re: [ERPS] air bearing gyro? Ian Woollard wrote: > I was wondering whether it might be possible to make an accurate > gyroscope out of a ball bearing floating in an air bearing. > > In principle you just start it spinning before launch, point 3 or 4 > optical mice at it, and read off the rotation; it should be quite > accurate, fairly light, and reasonably cheap. > > Comments? Unless it's bumped. Keith --__--__-- Message: 8 Date: Mon, 16 Dec 2002 17:39:08 -0800 From: Sean Lynch <[EMAIL PROTECTED]> To: ERPS Main List <[EMAIL PROTECTED]> Subject: Re: [ERPS] air bearing gyro? --RnlQjJ0d97Da+TV1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Dec 17, 2002 at 01:26:37AM +0000, Ian Woollard wrote: > I was wondering whether it might be possible to make an accurate=20 > gyroscope out of a ball bearing floating in an air bearing. >=20 > In principle you just start it spinning before launch, point 3 or 4=20 > optical mice at it, and read off the rotation; it should be quite=20 > accurate, fairly light, and reasonably cheap. >=20 > Comments? I would imagine that reading the rotation of the bearing would be significantly more complex than pointing optical mice at it. Optical mice are designed to read textured surfaces, and a ball bearing would need to be quite smooth to avoid being affected by movement of air. I don't really see the problem with FOGs. They're not particularly expensive when you get anywhere above the scale we're working at now, and for our current scale, decent solid state gyros should work fine ($50-$150 range). --RnlQjJ0d97Da+TV1 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQE9/oA7mvPkVW5ztpERAn7BAJ9EvkPApCWWSdu9PG63WeUsZ8tJcACfb73s F8jMqpwOnifzdrpn6XJFySE= =TKjy -----END PGP SIGNATURE----- --RnlQjJ0d97Da+TV1-- --__--__-- Message: 9 Date: Tue, 17 Dec 2002 02:02:30 +0000 From: Ian Woollard <[EMAIL PROTECTED]> Cc: ERPS Main List <[EMAIL PROTECTED]> Subject: Re: [ERPS] air bearing gyro? --------------040609020400080107010706 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sean Lynch wrote: >On Tue, Dec 17, 2002 at 01:26:37AM +0000, Ian Woollard wrote: > > >>I was wondering whether it might be possible to make an accurate >>gyroscope out of a ball bearing floating in an air bearing. >> >>In principle you just start it spinning before launch, point 3 or 4 >>optical mice at it, and read off the rotation; it should be quite >>accurate, fairly light, and reasonably cheap. >> >>Comments? >> >> > >Unless it's bumped. > > Don't think that's a problem physically- you can ensure that the pressure is high enough that the ball won't touch the sides and the electronics can cancel any slight lateral movement easily enough. >I would imagine that reading the rotation of the bearing would be >significantly more complex than pointing optical mice at it. Optical >mice are designed to read textured surfaces, and a ball bearing would >need to be quite smooth to avoid being affected by movement of air. > > Not sure, a few scratches or paint spots wouldn't disturb the air much, and the spinning would help. Well, it could be an issue, but it's soluble. Alternatively, inductive pickups would work, but it's probably messier. >I don't really see the problem with FOGs. They're not particularly >expensive when you get anywhere above the scale we're working at now, > I thought they weighed in at around $20 k; didn't Johns cost that? I think that's fairly expensive. Are there cheaper ones? I was wondering about how to do guidance for an orbital capable vehicle I'm thinking about. Probably need under a degree accuracy over 5 minutes. >and for our current scale, decent solid state gyros should work fine >($50-$150 range). > I believe they have a drift around 1 degree/second, great if you have GPS to compare against, but GPS capable of orbital velocity cost $10k or so? --------------040609020400080107010706 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body> Sean Lynch wrote:<br> <blockquote type="cite" cite="[EMAIL PROTECTED]"> <pre wrap="">On Tue, Dec 17, 2002 at 01:26:37AM +0000, Ian Woollard wrote: </pre> <blockquote type="cite"> <pre wrap="">I was wondering whether it might be possible to make an accurate gyroscope out of a ball bearing floating in an air bearing. In principle you just start it spinning before launch, point 3 or 4 optical mice at it, and read off the rotation; it should be quite accurate, fairly light, and reasonably cheap. Comments? </pre> </blockquote> <pre wrap=""><!----> Unless it's bumped. </pre> </blockquote> Don't think that's a problem physically- you can ensure that the pressure is high enough that the ball won't touch the sides and the electronics can cancel any slight lateral movement easily enough. <blockquote type="cite" cite="[EMAIL PROTECTED]"> <pre wrap="">I would imagine that reading the rotation of the bearing would be significantly more complex than pointing optical mice at it. Optical mice are designed to read textured surfaces, and a ball bearing would need to be quite smooth to avoid being affected by movement of air. </pre> </blockquote> Not sure, a few scratches or paint spots wouldn't disturb the air much, and the spinning would help. Well, it could be an issue, but it's soluble. Alternatively, inductive pickups would work, but it's probably messier.<br> <blockquote type="cite" cite="[EMAIL PROTECTED]"> <pre wrap="">I don't really see the problem with FOGs. They're not particularly expensive when you get anywhere above the scale we're working at now,</pre> </blockquote> I thought they weighed in at around $20 k; didn't Johns cost that? I think that's fairly expensive. Are there cheaper ones? I was wondering about how to do guidance for an orbital capable vehicle I'm thinking about. Probably need under a degree accuracy over 5 minutes.<br> <blockquote type="cite" cite="[EMAIL PROTECTED]"> <pre wrap="">and for our current scale, decent solid state gyros should work fine ($50-$150 range).</pre> </blockquote> I believe they have a drift around 1 degree/second, great if you have GPS to compare against, but GPS capable of orbital velocity cost $10k or so?<br> <br> </body> </html> --------------040609020400080107010706-- --__--__-- Message: 10 Date: Mon, 16 Dec 2002 20:27:42 -0600 To: [EMAIL PROTECTED] From: John Carmack <[EMAIL PROTECTED]> Subject: Re: [ERPS] air bearing gyro? --=====================_358147500==_.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed >> >>I don't really see the problem with FOGs. They're not particularly >>expensive when you get anywhere above the scale we're working at now, >I thought they weighed in at around $20 k; didn't Johns cost that? I think >that's fairly expensive. Are there cheaper ones? I was wondering about how >to do guidance for an orbital capable vehicle I'm thinking about. Probably >need under a degree accuracy over 5 minutes. The cheap KVH FOG gyros were $1.5k per axis. The fully-integrated-and-compensated, digital output, 6DOF Crossbow FOG unit was $9,500, but their new-and-improved model just bumped the price to $11,500. The non-fog crossbow 6DOF IMUs were $3995 for the 400 series, and $2995 for the 300 series. "solid state" gyros should perform much better than the 1 deg/sec that tuning-fork style gyros like the gyration parts get. I am certainly interested in hearing results from work with them. >>and for our current scale, decent solid state gyros should work fine >>($50-$150 range). >I believe they have a drift around 1 degree/second, great if you have GPS >to compare against, but GPS capable of orbital velocity cost $10k or so? When you have a vehicle capable of orbital velocity, $10k won't be a problem. In any case, GPS by itself doesn't let you re-sync your gyros, you need a multi-antenna GPS attitude sensing system, not just a position output GPS. John Carmack --=====================_358147500==_.ALT Content-Type: text/html; charset="us-ascii" <html> <blockquote type=cite cite><blockquote type=cite cite><br> <pre>I don't really see the problem with FOGs. They're not particularly expensive when you get anywhere above the scale we're working at now,</pre><font face="Courier New, Courier"></font></blockquote>I thought they weighed in at around $20 k; didn't Johns cost that? I think that's fairly expensive. Are there cheaper ones? I was wondering about how to do guidance for an orbital capable vehicle I'm thinking about. Probably need under a degree accuracy over 5 minutes.<br> <blockquote type=cite cite></blockquote></blockquote><br> The cheap KVH FOG gyros were $1.5k per axis. The fully-integrated-and-compensated, digital output, 6DOF Crossbow FOG unit was $9,500, but their new-and-improved model just bumped the price to $11,500.<br> <br> The non-fog crossbow 6DOF IMUs were $3995 for the 400 series, and $2995 for the 300 series.<br> <br> "solid state" gyros should perform much better than the 1 deg/sec that tuning-fork style gyros like the gyration parts get. I am certainly interested in hearing results from work with them.<br> <br> <br> <blockquote type=cite cite><blockquote type=cite cite><pre>and for our current scale, decent solid state gyros should work fine ($50-$150 range).</pre><font face="Courier New, Courier"></font></blockquote>I believe they have a drift around 1 degree/second, great if you have GPS to compare against, but GPS capable of orbital velocity cost $10k or so?<br> </blockquote><br> When you have a vehicle capable of orbital velocity, $10k won't be a problem.<br> <br> In any case, GPS by itself doesn't let you re-sync your gyros, you need a multi-antenna GPS attitude sensing system, not just a position output GPS.<br> <br> John Carmack<br> </html> --=====================_358147500==_.ALT-- --__--__-- Message: 11 Date: Tue, 17 Dec 2002 04:13:12 +0000 From: Ian Woollard <[EMAIL PROTECTED]> Cc: [EMAIL PROTECTED] Subject: Re: [ERPS] air bearing gyro? John Carmack wrote: >>> >>>I don't really see the problem with FOGs. They're not particularly >>>expensive when you get anywhere above the scale we're working at >>>now, >>> >> I thought they weighed in at around $20 k; didn't Johns cost that? I >> think that's fairly expensive. Are there cheaper ones? I was >> wondering about how to do guidance for an orbital capable vehicle I'm >> thinking about. Probably need under a degree accuracy over 5 minutes. > > > The cheap KVH FOG gyros were $1.5k per axis. The > fully-integrated-and-compensated, digital output, 6DOF Crossbow FOG > unit was $9,500, but their new-and-improved model just bumped the > price to $11,500. Not quite as bad then. That's the way I would go if I had the money. > The non-fog crossbow 6DOF IMUs were $3995 for the 400 series, and > $2995 for the 300 series. > > "solid state" gyros should perform much better than the 1 deg/sec that > tuning-fork style gyros like the gyration parts get. I am certainly > interested in hearing results from work with them. My limited understanding of them suggests that the accuracy is largely just clever filtering, and that a bit better than 1 degree per second is all they can really achieve currently. The crossbow units appear to be correlating multiple sensors (gravity and magnetic, and the attitude sensors) to zero the drift out, which would work great for aviation, most of the time, although even then, they seem to lack FAA approval, which is suspicious. If I'm right, you'd want to steer clear for your application- since there's no direct way to measure gravity once a rocket has left the ground. >>>and for our >>>current scale, decent solid state gyros should work fine >>>($50-$150 >>>range). >>> >> I believe they have a drift around 1 degree/second, great if you have >> GPS to compare against, but GPS capable of orbital velocity cost $10k >> or so? > > > When you have a vehicle capable of orbital velocity, $10k won't be a > problem. Probably, possibly, maybe. I'm currently looking at how small a vehicle can be made, with a payload and still make orbit and hopefully come back. $10k is actually significant, and I may lose a few... The guidance looks to be the most expensive subsystem at the moment, but that probably just means I haven't understood my problems yet. > In any case, GPS by itself doesn't let you re-sync your gyros, you > need a multi-antenna GPS attitude sensing system, not just a position > output GPS. During a burn the GPS track acceleration is going to be the same as the attitude, pretty much; atleast when outside the atmosphere. Within the atmosphere it's not quite as simple, but it's earlier in the flight, so the error is smaller, and my vehicle may be nose heavy which helps keep the track and the attitude aligned. This trick doesn't get you roll, but a sun sensor can reset the roll gyros. > John Carmack --__--__-- _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list End of ERPS-list Digest _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
