Built in force sensor

tonyatanya 2021-07-20

Do you guys know of a way to do a part insertion type program using the UR5 built in force sensor? For instance, I have a part that gets placed over a post with the post insterted ino it. The part is located on the post by lowering it down until it fits over some small nubs that fit within the part fixture. I am rotating the post base as the part is lowered, but am unsure of how to tell when the part is actually located down on the nubs or sitting on top of them.

bcastets 2021-07-20

@tonyatanya
Have you ever try the insertion node of our force control software "Force Copilot" ?

MarcAntoine_Gauthier 2021-07-20

Hello @tonyatanya ,

At Robotiq, we do have a software product called Force Copilot that have Insertion nodes already built in.
You can have a look at this eLearning video, it shows exactly how to use them in a real example.

Here is also the product page on our website.

Thanks and let me know if you have further quesitons.

matthewd92 2021-07-20

Before you attempt to seat the part zero out the force sensor. Then while you are rotating look for the forces to drop after you make contact. You can access the forces through script functions. One will return all 6 forces (Fx, Fy, Fz, Tx, Ty, Tz) as a list, remember the frame of reference for UR is the base of the robot, not the TCP. The other function returns the vector of the forces as a single number.

The functions you will need are

zero_ftsensor()

get_tcp_force() # Returns a pose representing the 6 forces
force() #Returns the normal vector value of the forces

tonyatanya 2021-07-21

Thanks Everyone. I will look into the force copilot software and try the script functions.

tonyatanya 2021-09-15

Hi, so how would i evaluate the force value? Can I use an if statement like "If force() = 0 Then do something of a Do until function?

tonyatanya 2021-09-15

i guess im not sure how to slowly lower the part while rotating the base, wait until the force reads 0, and then lower it the rest of the way. any advice would be awesome.