Inertial navigation systems

[Greg Needel]

Originally Posted by shsdragon

wut are yaw switches

yaw rate sensors are also called gyros they can measure the degree of lean in a direction. think of them as a virtual cup of coffie the coffie stays level to the ground but the cup changes. from this your can have it do corrections on directions and lean and a whole bunch of other functions. take last year for instance. if a team knows what the angel your robot is in when it is going striaght up the ramp some teams would write code that would auto correct the direction for autonomus code so that they could go straight up the ramp....there are alot of other uses take the segway for example

for specifics on how to program them i'm sure someone else in this fourm is more qualified to let you know how to do it


hope that helps

[generalbrando]

I'm wondering - for those who have used these sensors (mainly the accelerometers), did you shield the system (as in shielded cables)? I'm not really saying this as a suggestion - my team is planning out a design for position tracking and I was wondering if that would help fix the noise problem.

Thanks

[KevinB]

Originally Posted by generalbrando

I'm wondering - for those who have used these sensors (mainly the accelerometers), did you shield the system (as in shielded cables)? I'm not really saying this as a suggestion - my team is planning out a design for position tracking and I was wondering if that would help fix the noise problem.

Thanks

I toyed with the idea of an accelerometer-based system around the beginning of the year. I bought some, hooked them up to the EDUcontroller, and played with them for a while. I tried everything I could think of to reduce the noise, but it was still far too great to be worth anything for positioning. Some things I tried: different capacitors between the +5v and GND, different wire lengths, different types of filters on the output.

The reason for that (as I now finally have proven to myself) is because the acceleration would have to be integrated twice to achieve position information. The noise from the accelerometer would cause your velocity calculation to drift -- as the noise built up, your system would think you're going faster and faster (in one direction or the other). This is enough to totally throw off the position calculation.

[blindguyinanorg]

this noise we are talking about, what couses it. to me it seems that if the yaw sensor is reset every so often that would eliminate the errors.

[ahecht]

Originally Posted by Greg Needel

yaw rate sensors are also called gyros they can measure the degree of lean in a direction. think of them as a virtual cup of coffie the coffie stays level to the ground but the cup changes.

Not quite. The yaw rate sensor doesn't measure degree of lean, it measures how fast you are leaning. Imagine if someone put a spedometer on the surface of the coffee that measured the speed between that surface and the mug.

The name Yaw Rate sensor come from the naming conventions for the 6 degrees of motion, heave (sliding up and down), surge (sliding forward and backward), sway (sliding side to side), roll (rotating side to side), pitch (rotating forward and backward) and yaw (rotating side to side). Since yaw referrs to side to side turning, so a Yaw Rate sensor measures the rate of side to side turning.