I am guessing that the magnetometer / compass can see the electric field generated by your battery system power leads. You are using a switching power supply to convert battery power to a constant load. Fully charged batteries drop Voltage quickly when first used, then are constant for a while, then go off a cliff when almost fully discharged. Your switching power supply is converting this drop in Voltage to an increase in current which is an increase in the interfering magnetic field.
Get the compass/magnetometer sensor as far away from the battery/power system as you can. --- Graham == On Saturday, September 30, 2017 at 7:13:24 AM UTC-5, Jason Kridner wrote: > > > On Fri, Sep 29, 2017 at 5:18 PM <[email protected] <javascript:>> wrote: > >> Hi all, >> >> At my work we use the BeagleBone Blue boards to control somewhat small >> AUVs. >> The board is placed in underwater tubes along with batteries, ESCs for >> thrusters and all other electronics. >> We use the in-build magnometer and gyro to calculate the heading for >> navigating under water. >> Testing the beagleboard alone on the desk shows that the heading is >> fairly stable and correct within reasonable limits. >> The problem arises when we do offshore tests with the AUV. Here the >> heading will start to drift. A controller has been configured for the AUV >> to follow a reference heading for X amount of time. From the data we can >> see that the AUV actually do keep a steady heading, but from inspecting the >> vehicle IRL it becomes obvious that something is wrong as the vehicle will >> follow an arc instead of a straight line. >> >> So to the AUV actually thinks that it keeps the same heading and actually >> does this for the first few meters and then starts to turn following an arc >> while still thinking it is on the same heading. >> >> I know that we introduce quit some noise on the sensors by having the >> batteries, ESCs and wiring going around the board, but could this really be >> the course of this? Can anyone of you think of other possibilities? And can >> anyone suggest a solution to this (other than moving power units and wires >> to another shielded tube - this is not an option at this moment)? >> > > How are you reading the IMU? Are you using any of the filtering of > libroboticscape? > > >> Best, >> Jesper >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/a0e21882-6109-45df-8e35-b3d562098e5d%40googlegroups.com >> >> <https://groups.google.com/d/msgid/beagleboard/a0e21882-6109-45df-8e35-b3d562098e5d%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > -- > https://beagleboard.org/about > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/4cb74e1d-f38a-477f-bba4-3b8d13d1cbb5%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
