Hi Charles! On 12/08/2013 06:21 PM, Charles Steinkuehler wrote: > ... > > Yes, that's how I'll do it if there's nothing in existing gcode to > support tilting, but I'd still rather run a 3D rotation in a user-space > thread vs. tying up cycles in a real-time thread. Also, the math only > needs to happen on the endpoints, not every mS as the machine is moving > along the commanded path. The BeagleBone has hard floating point, but > does not directly support complex trig functions. Even on an x86, doing > a tilt in kinematics is needlessly increasing the computation overhead > and pushing stuff into the realtime threads that doesn't need to be there.
I've done something similar for accounting for a non-rectangular coordinate system as well. The trick is to use a transform matrix for the calculations, so you can get away without any trig functions in the realtime thread. You would only need them to fill the 4x4 matrix once (if you need all this flexiblity) and everything else just needs floating-point multiplications and additions. > > Note that probekins *DOES* need to do it's job in the realtime thread, > since it's not doing a simple transform but compensating for errors > along the path of the move. I have no problem with that, it's just > overkill for what I'm trying to do, and I'm simply surprised a simple 3D > transform is apparently beyond was provided for in the gcode language. :-/ A few weeks ago, I asked for something similar. But the G-Code seems to be rather limited when it comes to real 3D work (not just stacked planes). Regards, Philipp
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