Can I lock the robot in a specific orientation to do hand's on teaching?

Tim_Smith

Hi Everyone,

I was wondering if it's possible to lock the robot's wrist in a specific plane to teach the waypoints to the robot? I am a big fan of using the UR's Freedrive mode to move the robot from one waypoint to another. But it is difficult to get the tool flat against the table without having to program the angles in the coordinates system.

matthewd92

@Tim_Smith not with anything built into the robot.  If you have a Robotiq FT150 or FT300 on it you can do that by using their add-on free-drive mode.  It allows you to put the robot into several different modes (planar, scara, etc) and restrict the degrees of freedom that are allowed to move when you are guiding the robot by hand.  Once you teach the robot the program you could remove the FT sensor and adjust the TCP so that the robot will run without it installed.  This would allow you to use one FT sensor to program more than one robot.

I wish this was a built-in feature.  Like other manufacturers where you can choose which axes you want to unlock to move by hand.

Tyler_Berryman

@matthewd92 thanks for replying! Yes, you can use the FT300 or FT150 sensor with the UR to limit the wrist's movements. As Matthew mentioned, you can even modify the robot's behaviour by selecting the planar, scara and translation modes. 
Here is a video showing the different functionalities linked to the ActiveDrive: 
https://www.youtube.com/watch?v=hCNVi4jTQ1w

P.S. Thanks for mentioning that you can program the robot using the sensor and then removing it to be able to program several robots using the sensor. I had not thought of this! As you said, just remember to adjust the TCP, otherwise you will have a Z offset.

Tim_Smith

@matthewd92 Thank you for answering my question! Do you use this feature often? Does it help you with the programming of the UR?

matthewd92

@Tim_Smith unfortunately we do not have a FT sensor that is ours, I have used one for some proof of concept work for a customer application but I got to spend about a month playing with it.  I can definitely see where it would benefit programming, the thing that I actually found most useful was this feature where you can get the wrist to go back to vertical so after you move the arm by hand you can click that button and it "trues" back up the TCP.  I have no data on how accurate this feature is, maybe @Tyler_Berryman does.  

For us the only reason we aren't using the sensor more comes down to simple economics, as a young, start-up we have not felt that we could spare the purchase cost of the sensor at this time.  We do a lot already with calculated waypoints and so there is a lot of our programs where it would not help as we are moving the robot on some calculated path.

I'd be curious to hear from you though if you decide to get one and use it to see how much time you feel it saved you in programming an application as that might help us decide on a path forward ourselves.