7th February 2008, 11:24
| #16 | |
| Senior - BHPian  | Quote:
| |
|
| |
|
7th February 2008, 11:30
| #17 | |
| Distinguished - BHPian   Join Date: Dec 2006 Location: Mumbai
Posts: 10,327
Thanked: 12,914 Times
| Quote:
| |
|
|
|
7th February 2008, 11:40
| #18 |
| Team-BHP Support   | |
|
|
|
7th February 2008, 11:41
| #19 |
| BHPian  Join Date: Nov 2007 Location: Bangalore
Posts: 91
Thanked: 2 Times
| |
|
|
|
7th February 2008, 11:52
| #20 | |
| Distinguished - BHPian Join Date: Dec 2006 Location: Mumbai
Posts: 10,327
Thanked: 12,914 Times
| Quote:
| |
|
|
|
7th February 2008, 12:10
| #21 |
 | |
|
|
|
7th February 2008, 12:17
| #22 | |
| Team-BHP Support | Quote:
| |
|
|
|
7th February 2008, 14:26
| #23 |
| Senior - BHPian  | so this is a REALLY high end Sextant! with realtime information!  ... nice find! |
|
|
|
7th February 2008, 14:52
| #24 | |
| Senior - BHPian  | Quote:
But an inclinometer should give more or less the same reading going up or down the same slope. Maybe you should try placing it in some other place, or change the direction ??? . | |
|
|
|
7th February 2008, 15:08
| #25 | |
| | Quote:
 have fun offroading buddy.. | |
|
|
|
8th February 2008, 05:30
| #26 | |
| Team-BHP Support  Join Date: Feb 2004 Location: Bombay
Posts: 24,203
Thanked: 36,087 Times
| Quote:
I wouldnt say the suspension has a large part to do with this (however, i have always wondered how the Gtech changes its behavior depending on soft/hard suspension and its acceleration readings...anyways thats a whole different story). Let me give this a shot...hopefully i will be on the right track, but beware that i might be totally wrong  I think the reason for your difference in readings (if it isnt a problem with the device) is due to how it works. My guess is that if it is a low end device, it is nothing more than a 2-axis accelerometer. However, if it is better designed than that it will ALSO have a gyro (probably 1-axis to detect pitch only...or for more $$ 2-axis gyro for pitch and roll.) (vikram_d i stand corrected - after thinking about it for a while, in an application where you can set the device's neutral position a 2axis gyro would probably be the way it works, unless there is a huge price advantage to putting an accelerometer in? )Basically the accelerometer can detect gravity(9.8m/s^2), and hence can figure out its orientation based on the pull of gravity. Think of it somewhat like a marble in a bowl placed on your car's dashboard. If you are parked facing downhill on a slope, the marble will be further forwards in the bowl than its dead center/neutral position...and so on. However, this now illustrates the flaw of using (only) an accelorometer to measure inclination.... why?... Think about what would happen (if you were on flat land) and slammed the gas pedal. The marble would move to the rear of the bowl, because it is responding to acceleration (being a faux accelerometer n all). Hence the "inclinometer" would be telling you that you are going uphill at this point of time! Now, my guess is that if you have an inclinometer that does use only accelerometers, the acceleration/deceleration while going up/down the slope is affecting the readings. How to test this > park on the slope facing upwards (stay parked long enough to ensure the readings are refreshed and no smoothing / averaging messes up the reading) and then do the same facing downwards. So... where do gyros come in? Basically, they come in to work in tandem w/ the accelorometer to provide more accurate readings. Gyros can detect rotation on their axis very very well, butttt.. everything is relative. ie. they know they have rotated 15*/sec for 0.1 second, so doing the math they can tell they have rotated 1.5* more than they were at 0.1second ago, but they have no sure sign of what their absolute reading is (they can only figure it out by calculating a.k.a heading gyros). The problem with calculating is that cumulative error builds up, and the readings keep getting more and more offset. When gyros and accelerometers work together, they keep each other in check. A gyro can help the accelerometer know that it is experiencing acceleration and not rotation, and an accelerometer at rest can help the gyro re-adjust its readings to eliminate that cumulative error, and so on... You could figure out what your device has by the instructions given to set it up. For example, the Gtech (cheapest model) requires you to stick it on your windscreen, with the car at rest on flat ground, and then move it up and down till the display tells you it is level. This is a clear indication of an accelerometer at work. If your device has a "set" button which you have to press to tell it that it is on level ground or something like that, i would guess that it is a gyro. This would tell the gyro that "this is 0*". However culumative error would build up the longer the device hasnt been re-calibrated for (if it doesnt have an accelerometer). Anyway...im rambling on.... so i will stop. Let me know : how are you instructed to set up the device and how your stopping on the slope test went. cya R Last edited by Rehaan : 8th February 2008 at 05:35. | |
|
|
| |
|
8th February 2008, 08:49
| #27 |
| BANNED | |
|
|
|
8th February 2008, 16:17
| #28 | |
| Senior - BHPian  | Pictures would be appreciated.. Quote:
| |
|
|
|
8th February 2008, 16:22
| #29 |
| Team-BHP Support | |
|
|
|
8th February 2008, 16:27
| #30 | |
| Senior - BHPian | I too have an analog type sitting on the dash of my Scorpio for the last 2 years..!!  Quote:
| |
|
|
 |
Most Viewed