Using the Robotiq Gripper as a Hand Tool Holder

Samuel_Bouchard

I was asked by a customer to find examples of Robotiq grippers used as gripper and tool holders. I found these by @matthewd92

https://www.youtube.com/watch?v=a_g3WrgOEHA

https://www.youtube.com/watch?v=-bFgAvCDFqI

And this one with the 3-Finger Gripper on a Yaskawa:

https://www.youtube.com/watch?v=3Vm-c65DA6I 

Do you have more examples?

Samuel_Bouchard

@matthewd92 this seems to become one of your specialty!

https://www.youtube.com/watch?v=4jlFzKuYUDw

matthewd92

We definitely try to use tools that a person could always step in and run if needed. We will be showcasing some of this with our demo robot at IMTS working with Biax out of Germany. They make deburring type pneumatic tools that are both hand operated and some that are designed for mounting on a robot. We will have a UR5 interacting with both rotary and linear motion deburring tools, it will be picking some of them up to use while others it will manipulate the part to use a fix mount tool. 

matthewd92

Heres another example of using the two finger gripper with a standard hand tool.  We actually would not do this like this in production but we wanted to showcase the robot actually preparing itself for the DreamForce event next week that the robot will be on display at.  We used a path node to do the sanding, then copied the path node and reversed it for the return path, we then just looped the program so that the part was polished over and over until the mill finish was removed.

https://www.youtube.com/watch?v=1ZftRSsSSU0

Hope you enjoy,
Matt

Samuel_Bouchard

Thanks Matt for sharing! Are you using the force information from the FT sensor to do the polishing or just the compliance of the tool?

matthewd92

We put the paths inside of a force node, but we were just using the built-in feedback of the robot.  Since this is just a demo, I didn't want to go make the changes to let the FT sensor drive the forces for the force mode.

MIKELCINZA

Hello matthewd92, In case of using the force sensor to control the pressure, how would the program be done?

matthewd92

@MIKELCINZA what are you attempting to do as it will vary based on task?

MIKELCINZA

I need to polish an irregular surface, like a door of  car.

matthewd92

The way that I would do it, using the built-in force control, is to use the force wizard.  Placing the path that was taught under a force wizard node.  You can then choose frame, and choose the amount of force that you want to apply in the direction.  You will also want to limit the speed of compliant axes and work up until you get the motion that you want.

A more complex method would be to slice the path up into tiny segments, and then to measure the force being applied and make adjustments in the Z direction to either lift or lower the tool slightly at each slice of the motion.  So if I want to move from point A to point B that is 200mm away, I could basically loop something like this:

loop until you reach where you want to go&nbsp;<br>&nbsp; if Fz <10<br>&nbsp; &nbsp; z=.001 (move TCP closer to the part by 1mm)<br>&nbsp; else&nbsp;<br>&nbsp; &nbsp; z=-.001 (move the TCP 1 mm away from the part)]<br>&nbsp; newposition = pose_trans(TOOL, p[.001, 0,z,0,0,0]) (This would move the robot 1mm in the tool frame direction)<br>&nbsp; move(newPosition)

I Think there is a way to incorporate the force sensor into the built-in force wizard but I couldn't quickly find something on the UR website or the Robotiq website, @Tyler_Berryman or @Etienne_Samson do you guys have any information on how to do that?

Tyler_Berryman

@matthewd92 You cannot inject the sensor's data into the robot's built-in force wizard. We are aware that this would be a nice feature to have and it's in our idea list. 

You can use the path recording feature within the robot's force mode to give the robot compliance. I have used this method for a few insertion applications, but I have never tried it in a polishing application. I'll try it out, and I'll get back to with some results. 

matthewd92

@Tyler_Berryman that would be an awesome addition to the robot if you could do that.

We used the path node inside of the force wizard for a sanding application, same basic principle as polishing, and it worked reasonably well.  If I had taken more time to more accurately create the path it probably would have worked better, it was done as a "joke" for a video and so we did it in like 10 minutes.  Its the video that is in the post further up.

MIKELCINZA

Thank you, we will move forward with the project.

matthewd92

@Tyler_BerrymanThere is a guide in the universal forum for developers on how to integrate the force from the FT sensor into the robot.  It requires the user to use the RTDE interface which may be beyond a lot of users but its not possible since the release of software 3.3.  I do look forward to you guys releasing a URCap though to make this an option for the masses.

Tyler_Berryman

@matthewd92 Thanks for this information! As Marc-Antoine mentioned in this post: http://dof.robotiq.com/discussion/comment/1763#Comment_1763, it is possible to integrate the Force sensor's data into the UR's force control. However, it did not improve the UR's force mode. I'm guessing that the control loops weren't designed with our's sensor's signal in mind