- Sat Jul 09, 2011 9:15 am
#129873
If you do a Google search on "DARPA Grand Challenge" you'll find a lot of relevant papers on this exact subject. Check it out.
janmartin wrote:Skye,I do not have any direct experience at the hobby level. My experience has mostly been done with expensive top of the line devices. Quarter million dollars ring laser gyros and large processors running algorithms developed by PhD's that can't tie their own shoes. If you fall in that arena, I am your man!
you have very interesting experience with dead reckoning and GPS!
But for a hobby, those types of items are off the plate. The types of items that you likely can afford (and be allowed to buy) are the gyro/accelerometer type devices like you mentioned.
There are several issues that make any IMU a problem.
1) Having to sample and integrate at the faster possible rate to minimize errors. If the device has an analog output, this may mean fast ADCs and the horsepower to integrate. 1024Hz is not uncommon. If a serial device, you need to take the data from it as fast as it allows. The faster and more accurately you integrate the slower your answer will drift away.
2) The environment the unit is in. Vibration and shock will cause jitter on the output that you will then integrate once (for gyros) or twice (for accelerometers). Each time you do, the errors increase.
3) Accuracy of the sensor. Speaks for itself. There is a reason people cough up serious money for serious sensors.
4) No IMU (as of today that I am aware of, if you know better, please let me know as I am in the market) will be accurate (to a few degrees) in a body held device for more than 15 minutes that might fit in a Dixie cup and run of something other than a nuclear power plant. If you can live with those types of numbers (15 minutes +- 5 degrees) than there are solutions. Not sure if the products you pointed to fit that range. My guess is not. These types are likely good to +-10 degrees over ten minutes but I could be wrong. You need to look at drift rate, integration speed, and such to make that calculation.