Using the gripper to bin parts

Tyler_Berryman

Hi all,

I curious to see how sensitive the Robotiq camera was to a variation in the dimensions of a part that was taught to the vision system. So I 3D printed two parts that have the same geometry, but the dimensions are slightly different. The first part is 2.25"x2.25", whereas the second part is 2"x2". The following picture illustrates the small difference between these two parts.

As you can see, the parts are very similar. I taught the larger part to the vision system using a yellow background. I tested the difference between the detection scores, the larger object(The object taught to the vision system) I was getting a detection score of about 82%, and I was getting a detection score of roughly 65% for the smaller part. So I could have used the detection threshold to differentiate these parts, but I would've had to use a second camera locate node to find the smaller part. So I decided to work with a detection threshold of 60% to be able to identify both parts using the same camera locate node. I decided to use the gripper's function " rq_current_position" to get feedback from the gripper regarding the position of the fingertips. When gripping the larger part, I was getting a position value of 89, and I was getting a value of 105 for the larger part. Knowing this I simply used two if statements to place these parts into two different bins. 
Here is a video of the demonstration:

Tyler_Berryman

Here is the program I used for the demonstration: 
Program
   Robot Program
     MoveJ
       Waypoint_1
       Gripper Open
     Camera Locate
       MoveL
         Waypoint_6
         Waypoint_5
         Gripper Close
         Waypoint_7
     If rq_current_pos()≥85 and rq_current_pos()≤95
       MoveL
         Waypoint_2
         Waypoint_3
         Gripper Open
         Waypoint_4
     If rq_current_pos()≥100 and rq_current_pos()≤110
       MoveL
         Waypoint_8
         Waypoint_9
         Gripper Open
         Waypoint_10

K_Bing

Interesting application. How precise are the grippers? What does the position value of 105 equate to in Inches?

Annick_Mottard

@K_Bing the gripper will close 0.4mm per count for the 2-Finger 85. It is detailed in this section of the instruction manual. Note that the gripper is fully open at the 0 position and fully closes in encompassin mode at 255.