Deadband incorrectly implemented in mixed pos/vel controller

Bug #936907 reported by Hugo Elias on 2012-02-20
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
sr ROS interface
High
Ugo

Bug Description

This is a hard bug to explain, and I don't know what the fix is exactly.

When the joint is within the deadband, the output of the torque demand is zeroed. The problem with this is that the small position error is still fed into the position controller, which continues to integrate. This causes a hidden large velocity demand, and consequently a large hidden torque demand. As soon as the joint exits the deadband (for example due to coupling with another joint) the hidden torque demand is exposed, causing the joint to make a sudden large movement.

Toni and Hugo tried implementing some fixes including zeroing the position error (instead of the torque demand) when inside the deadband. This was an improvement, but still needs some work.

Changed in sr-ros-interface:
assignee: nobody → Ugo (ugocupcic)
importance: Undecided → High
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