ergoCub 1.1 S/N:001 – Fingers cannot reach the upper limits and have jerky motions

[PasMarra]

Robot Name 🤖

ergoCub 1.1 S/N:001

Request/Failure description

While testing the aperture and closure of the fingers, I've noticed the following:

• Jerky movements when there is a zero position reference.
• thumb_add maximum reachable value is 90 deg, but for the documentation is 100 deg.
• several fingers cannot reach maximum value.

Detailed context

I'll provide some plots, each one shows the desired trajectory vs the joint actual trajectory for both the hands, the joints values are in radian.

Additional context

thumb_add

thumb_add

thumb_oc

thumb_oc

index_add

index_add

index_oc

index_oc

middle_oc

middle_oc

ring_pinky_oc

ring_pinky_oc

How does it affect you?

No response

[AntonioConsilvio]

Hi @PasMarra, thanks for the feedback.
We are already aware of the problems present on the fingers and have an internal issue where we are planning how to take corrective action.

[maggia80]

Thanks, @PasMarra for the detailed analysis. it's interesting to see also the motor position, the PWM output and the current while performing the movements.

[lornat75]

@maggia80 it is not a problem for us to run the experiments again - but it seems the problem is already known and under investigation from iCub Tech. are you sure you need additional data?

[maggia80]

@lornat75 yes, as @AntonioConsilvio mentioned we know that there are some problems in the fingers and we are working on it. In the experiments above I see different issues and some more data could help iCub Tech and @PasMarra too to have more awareness of the system.
But of course, those are data we can collect and report here in this issue.

[sgiraz]

Hi guys,

just an update to say that team-dev w/ the support of @PasMarra is working on finding a solution to fix this issue.

cc @AntonioConsilvio @Fabrizio69 @fbiggi @fiorisi