Hi Alex,
I've pulled the joints_axes3 branch, built and tried it.
In this branch, the *getStraightVelocity()* and *getStraightAcceleration()*
on emccanon.cc are not suitable for non-trivial kinematics yet.
I will file a feature request on SourceForge later.
Regards,
Yishin
On Thu, Nov 5, 2009 at 2:22 AM, Alex Joni <[email protected]> wrote:
> Hi Yi-Shin,
>
> unfortunately you are correct.
> 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.
>
> Regards,
> Alex
>
>
> *From:* Yi-Shin Li <[email protected]>
> *Sent:* Wednesday, November 04, 2009 6:13 PM
> *To:* emc-developers <[email protected]>
> *Subject:* [Emc-developers] the trajectory planner might not be suitable
> forany machines with non-trivial kinematics
>
> Hello emc-developers,
>
> I was digging into an issue for SCARA Robot controlled by EMC2. That is,
> the angular acceleration for the first 2 joints is way too larger than the
> one
> set by its configuration file. After carefully analyzing the dumped trace,
> I found it might be caused by misleading trajectory planning results.
>
> I then found an interesting issue for the trajectory planner, i.e. it might
> not
> be 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.
>
> Is my understanding for above statement correct?
>
> Yishin
>
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