Force Control Object Tracking

Zaal3595 Boulder, CO

I think I want to use force control on an IRB 4600 arm. My work case is this:
1. I want the arm to engage with an object
2. I want to activate Force Control to maintain a certain force against the object.
3. If the object moves while engaged, I want the arm to move with the object to maintain that force.
4. After a certain amount of time, I want to turn off Force Control.
5. Then, I want to disengage from the object.

I have read the manual and I've seen the three main examples detailed there: assembly, pressure control, and speed control.

Those examples seemed to require some sort of movement by the arm relative to the part. My example doesn't require a move while engaged with the part. It only requires movement by the arm if the object moves from the engagement position. 

Does anyone have experience using Force Control and if my example above would be supported by one of the three methods? I was leaning toward the pressure control functionality but, I don't want to buy an expensive sensor if the built-in functionality doesn't work for my case.



  • I have worked with a Force/Torque sensor made by ATI for a couple of years now for a polishing application, and to be honest with you it is really difficult have precise control of the position based on the forces received by the sensor. If I were you, I would pursue something like this:

    It is pneumatic so there is much more compliance and thus much more precise control, as opposed to a F/T sensor mounted on the flange of the 6th axis of the robot. The problem is that the signals generated by a traditional F/T sensor change too quickly and dramatically, you can filter them with a low pass/high pass type of filter but then you must reconfigure everything when switching to a different application or a different area you wish to work on.