I am trying to build an application in which a camera detects the position of a marking in order to perform a drilling task at that point and I am using an F/T sensor in order to control the pushing force applied at the surface by the drilling tool. The problem I am facing is regarding to the performing of the drilling motion (down through the plate and back up). Turns up that, using the F/T Control Command together with the F/T Move and F/T Waypoint does not give me a translational motion on the Z axis as intended. I have selected the Z axis as a compliant axis under the F/T Control command and set the treshhold value to 10N but when I simulated the movement using a piece of paper I noticed that the robot is not performing a translational motion on the Z axis as expected but downward pointed translational movement in the XY plane. I think this may be due to the construcion of F/T Functions themselves as they are not intended to be position controlled (like inbuild UR commands) but force controlled (using the F/T Sensor exclusively). D

If you use the force control node of copilot with force applied on tool z axis and no compliance for x and y, you should not have any deviation on x and y axis.

Do you use copilot or ur embedded force functions ?

I have used compliance on Z axis (just Force, no torque) and I used the URCap functions F/T Control, F/T Move, F/T Waypoint. The motion performed is indeed pointed downward but it is not performed only on the z axis but on the y axis as well.

If you use copilote urcap functions, please send video of the deviation behaviour with picture of the force control node settings to support@robotiq.com. We will advise you.

You should not have deviation on x and y axis.

We did this several years ago by simply having an if loop, when force dropped below a threshold we stepped down, when it exceeded we sat still for one cycle. Very simple to implement using standard UR functionality. 

We do do the same basic control for tapping as well as screw driving and it works well for all of those situations where we want the robot to follow the tool and allow the tool to do the work.