Hello,
I am trying to do tension control on a cable with UR10 but have been running into some issues that are causing path deviation and eventually triggering protective stop. I’m using a proportional controller to achieve a certain lateral force setpoint. However, it appears that after a certain point, the force stops increasing and the position stalls despite nonzero controls being sent. This is a bit strange as I expected the force to at least increase even in the event of the position stalling. I have tried decreasing the setpoint magnitude but the same behavior appears albeit stalling at a lower force (e.g. setpoint at 20N results in force stopping at 15N while setpoint at 10N results in force stopping at 8N). The only factor that appears to avoid this behavior is if I decrease the length of the cable between the end-effector and the stationary point. I wonder if anyone would have an idea about what could be causing this behavior and if there are ways to resolve this without changing the cable length. We are using ROS melodic and the twist controller from UR controllers cartesian to send the velocity command.
Thanks in advance.