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#89 calculate ACC and VEL for non-trivial kins (emccanon.cc)

open
nobody
5
2009-11-08
2009-11-08
Yishin Li
No

Current trajectory planner is not suitable for any machines with non-trivial kinematics. Please take a look for the following code at getStraightAcceleration() on emccanon.cc:

tx = dx? (dx / FROM_EXT_LEN(AXIS_MAX_ACCELERATION[0])): 0.0;

For non-trivial kinematic machines, such as SCARA, the dx is contributed by several joints other than AXIS_0. However, the above code assume that it only depends on AXIS_0, which is not true for those machines. Therefore, the calculated accel/velocity for trajectory planner may be incorrect.

This is the comment from Alex Joni:
There are some problems in the current version of emc2, that joints (motors) and axes (carthesian directions) are mixed in a couple of places. There is ongoing work (on the joints_axes3 branch) to fix this. But it's a lot of work (in a lot of layers and places), so there is no fixed timeline when it will be useable.

Discussion

  • pkm
    pkm
    2011-05-12

    There's also an issue probably connected to this: angular velocity and acceleration settings seems to be ignored for non-trivial kins.