Augment H3000 with DIY sensors

[BlackSwan6336]

I'm running an ancient H3000 system with halcyon (fluxgate I think) compass and no heel/pitch sensor and an ancient GPS.

It seems like for little more than beer money I can put together a little box with arduino in the middle and a gps and gyro/position sensor which, once I overcome the calibration issues could do the following:

1. provide heel and pitch to the H3000 for display on my MFDs.
2. probably more accurate GPS (for what it's worth)
3. more accurate heading - this is the big one, particularly for the knock-on effects on calculating TWA,VMG etc.

I assume I'd have to push the data in through some combination of NMEA0183 and possibly the linear inputs (I have them available for use).

Is this realistic?

[dougweibel]

You could put together a DIY box. The hardware cost would be modest - less than $100 even it you make it a bit fancy I'd expect. I would make sure to base your hardware on a newish 9-degree of freedom IMU sensor (integrated gyros, accelerometers, and magnetometer). I have not kept up on chips in this category over the last several years but based on a quick Google the InvenSense ICM-20948 looks like a good candidate.

The software to do a good job may be more complicated than you expect. Unless you are an expert you will want to find some code for the core sensor integration algorithm. You want a Kalman filter that will use all 9 axes data from the IMU as well as the GPS position and velocity as inputs. Some IMU chips will have this functionality built in. Having a filter that uses the gps data will give much better performance than one with just the IMU data.

[BlackSwan6336]

Thanks Doug, "kalman" was the magic word

I have found it implemented in github for the sensor I have on order.

https://github.com/linhongbin-ws/KFMPU

Thanks to all the FPV/quadcopter guys out there there seems to be heaps of this stuff out there to use, and because they're using it for flight, it's all "at least" the sensitivity we need for boating.