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It looks like the acceleration limits for the robots in this repository do not match the values from here. I'm not positive these are the correct limits to use, but the values in this repository come from this commit. The justification of the values was
As MoveIt! does not support jerk limits, the acceleration limits provided here are the highest values that guarantee
that no jerk limits will be violated. More precisely, applying Euler differentiation in the worst case (from min accel
to max accel in 1 ms) the acceleration limits are the ones that satisfy
max_jerk = (max_acceleration - min_acceleration) / 0.001
I am also not positive that switching between the minimum and maximum accelerations in 1 ms is the best estimate of jerk. There is a parameter called resample_dt in TOTG that creates waypoints every 100 ms by default. It seems that the jerk estimate would be (max_acceleration - min_acceleration) / 0.1 in the worst case. Of course, JTC interpolation also has the potential to significantly impact this. Regardless, since this commit added a parameter to enable/disable jerk limits, I believe the max_acceleration values can be updated. There are at least two options that are worth considering: 1) update the acceleration values joint_limits.yaml or 2) add another configuration joint_limits_jerk.yaml or something like that with new values. Option 1) is concerning because it's not opt-in.
I think this is something worth discussing. I'll create a PR with this issue.
The text was updated successfully, but these errors were encountered:
To me, keeping separate configurations is an okay fix, though no suffix vs. _jerk suffix doesn't seem like the clearest option we can provide.
Some options would be:
joint_limits.yaml - original file / joint_limits_servo.yaml - new file
joint_limits_jerk_limited.yaml - original file / joint_limits.yaml - new file
or something like that.
Also while I think the jerk limits parsing was added for Ruckig, I suspect that TOTG doesn't use them at all so this proxy first-order Euler jerk limit is what would be needed there. Although I guess the right answer would be, if you want jerk limits, use a trajectory timing scheme that supports them?
pac48
changed the title
Update acceleration limits in for robot configs
Update acceleration limits for robot configs
Dec 28, 2023
It looks like the acceleration limits for the robots in this repository do not match the values from here. I'm not positive these are the correct limits to use, but the values in this repository come from this commit. The justification of the values was
I am also not positive that switching between the minimum and maximum accelerations in
1 ms
is the best estimate of jerk. There is a parameter calledresample_dt
in TOTG that creates waypoints every100 ms
by default. It seems that the jerk estimate would be(max_acceleration - min_acceleration) / 0.1
in the worst case. Of course, JTC interpolation also has the potential to significantly impact this. Regardless, since this commit added a parameter to enable/disable jerk limits, I believe themax_acceleration
values can be updated. There are at least two options that are worth considering: 1) update the acceleration valuesjoint_limits.yaml
or 2) add another configurationjoint_limits_jerk.yaml
or something like that with new values. Option 1) is concerning because it's not opt-in.I think this is something worth discussing. I'll create a PR with this issue.
The text was updated successfully, but these errors were encountered: