One of the biggest challenges of our project was accurately weighing a load on the end effector on the cobot. In order to solve this problem a few hardware and software design choices were made. In this article these choices are explained.
First of a way of removing the weight from the end effector was designed. For our project we used a pneumatic gripper that can grab end let go off the part of the end effector that needs to be weighed. Because there are external forces working on the end effector the gripper needs to hold the part tightly while it needs to have enough space to be removable when subtracted. For this reason a T- shaped hole were the gripper will fit in tightly was designed.
Next up a holding station for the removable part of the end effector needs to be designed. The most important part of this design is that the placement is always the same, no matter the change in weight. For this reason a holding station was designed were the end effector can turn in order for the heaviest part of the end effector to always be facing directly down. This way the hole for the pneumatic gripper will always be facing up.
The holding station stands on a scale with 0.1 gram accuracy. The final thing that needs to be done is the communication between the scale and the code.