need doc on frame conventions

[tridge]

The docs really need a section on frame conventions. Here is what I've discovered:

• robot.position is NWU in meters
• robot.orientation is [q1, q2, q3, w]
• robot.linear_velocity is NWU earth frame, in m/s
• eulers are have roll +ve right, pitch +ve down, yaw +ve counter-clockwise from above (in radians)
• robot.angular_velocity is in earth frame (this one is really non-obvious!). Needs to be rotated by multiplying by a rotation matrix for orientation to get to body frame for gyro equivalent. angular_velocity is +ve right for roll, +ve down for pitch, +ve counter-clockwise (from above) for yaw
• acceleration seems to not be available (always gives zero) so needs to be calculated by differentiating velocity in earth frame, adding gravity and rotating to body frame
• when world axes are shown, red is north, green is west, blue is up

I think it would be really nice to have to_earth_frame and to_body_frame helper functions

[lrozo]

Hi @tridge ,

We have this documentation thing as a pending task in our endless ToDo list. As every user may discover new issues, missing stuff, or develop new features, we really encourage people to contribute to Pyrobolearn. So, it would be really cool if you can contribute, for example, by providing some short documentation about the frame conventions you mentioned in this issue.

We would be glad to review this through a pull request!

Leonel

[tridge]

So, it would be really cool if you can contribute, for example, by providing some short documentation about the frame conventions you mentioned in this issue.

sure! I'll do a PR