iCubErzelli01 S/N:032 – Eyelids stuck in closed position after robot power-up

[Ep3896]

Robot Name 🤖

iCubErzelli01 S/N:032

Request/Failure description

The eyelids of the robot remain closed and do not respond to commands after the motors are powered on.

Detailed context

When the robot is powered off, the eyelids can be moved freely , whereas when the robot is on they seem to "lock" in a closed state and they cannot be opened anymore with commands. This followed after the use of standard facial expressions and while investigating the /face/raw ports for possible custom facial expression.

Additional context

We had a similar issue with the same robot here #919

How does it affect you?

Critical: this issue prevents the correct use of facial expressions during and experiments that is in the making.

[edersonferrante]

WIP

On robot 032, the eyelids initially did not open.
At first, the issue was suspected to be related to the motor (code 1837), which was replaced with a known working unit, but the problem persisted.
The investigation then moved to the control board (code 736), which was replaced with a board tested on bench and validated by @Jacopo.
After this replacement, the first positive results were observed: at robot startup, the eyelids close correctly, and they can be reopened via Motorgui.
However, during the initial opening of the eyelids, it is noticeable that the motor is forcing. In my interpretation, this behavior is due to the fact that the eyelid mechanism must be installed in a very specific angular position. If the mechanism is not properly aligned, the motor motion is not correctly transmitted to the eyelids, resulting in excessive load.
In fact, the motor works correctly when the eyelid mechanism is not installed.
When the mechanism is mounted, it is necessary to place it in the correct position relative to the motor gear, otherwise the motor forces significantly and tends to overheat.
At the moment, the movement is not yet fully optimized: in particular, during eyelid closing, some motor forcing can still be perceived. This behavior is mitigated by immediately reopening the eyelids.

[edersonferrante]

Hi @Ep3896, as agreed, I'll be coming in on April 15 with @MSECode to resolve this issue.