For the past two years, I've been working on and off on a basic, open source scientific computing library in C (basic linear algebra on embedded devices, etc.),

For the past two years, I've been working on and off on a basic, open source scientific computing library in C (basic linear algebra on embedded devices, etc.), and hired a student this summer to work on adding some orientation algorithms. It's still a work in progress, but we did dig up a couple other filter options to try out beyond the usual Extended Kalman (contributors very much welcome!) [1]. As another poster mentioned, finding the right parameters for the filters is essential, and involves a fair amount of testing and some trial and error to narrow them down to the right range for your application. There isn't a lot of info out there on that, either. [1]: https://github.com/zephyrproject-rtos/zscilib/tree/master/src/orientation/fusion https://github.com/zephyrproject-rtos/zscilib/tree/master/sr...