Adjusting Max Increment and ParameterExtraction library information

[emielkemmm]

I'm implementing a slightly modified version of this driver. During certain motions, I am getting "Excessive Segment" warnings, even though I am moving at slow speeds. I have checked the commanded increments, and they are not large (<1000 per cycle) when this occurs. My initial thought is to increase the increment tolerances after this line, but this seems like a superficial value utilized by the motoros layer, rather than what the controller actually believes is the increment limits.

I can see that the driver is utilizing the GP_getMaxIncPerIpCycle function to acquire this value.

My question, then, is there any information on how this library was generated? What is this function doing to acquire the max increment? Is there a way to adjust the max increment from my end?

Any help is greatly appreciated!

[EricMarcil]

The value you are getting from the GP_getMaxIncPerIpCycle function is the value set by the controller. So changing it on the Ros Driver side won't change that the controller will alarm out if exceeded. It cannot be changed.

It is the maximum value for that joint, an it is limited by the motor, gear and inertia of that motor.

However, you could be getting excessive segment alarm for other reasons.
What is you robot model?
Are you moving the robot in the joint space (that was MotoRos does) or did you modify the driver to use the cartesian space (which is available in the incremental motion function but not used by MotoRos)?

[emielkemmm]

I have both a gp88 and a gp8, and I see issues on both.

I am moving in cartesian space.

What I am seeing in my debugging is that limits from GP_getMaxIncPerIpCycle are about 5x less than the amount that triggers an excessive segment. Is this simply a byproduct of using cartesian coordinates, rather than joint? If so, that kind of leads me to the second part of my question above, what exactly is going on in GP_getMaxIncPerIpCycle and the other ParameterExtraction library functions, and is it possible to dive deeper into these?

I'm able to stop triggering by having less aggressive acceleration on my commanded paths, but Ideally I would like to know what these limits are beforehand so that as I send the path, I can have some error messaging that indicates such a thing. The current returned limits, as stated, aren't near the actual limits.

[EricMarcil]

There is nothing going on in the GP_getMaxIncPerIpCycle, it is just getting that axis motor maximum speed.

When moving in the cartesian space, I mean that the mpExRcsIncrementMove function is being passed increments that are not in pulses but in base frame or robot frame.

If that is the case, the excessive segment alarm usually occurs when the robot get close to singularity (usually the R-axis is inline with the T-axis). When converting from cartesian space to the joint space, it causes a motor to exceed its maximum speed.

[emielkemmm]

Ok.

Perhaps what I need to do is use the kinematics api to do some checking that my cartesian increments are not violating the increments obtained from GP_getMaxIncPerIpCycle.

I'm finding the issue mostly happens at sharp corners, rather than at singularities, but thank you for the suggestions! Helpful to have someone to bounce ideas off of.