Production Floor Part 4: First Production Grippers Complete

Part 1: Building a New Lab
Part 2: Stockroom Ready for Raw Materials
Part 3: Gripper Production Underway

PR2 fabrication is progressing nicely, and the production team has built the first set of grippers. As the grippers are assembled, they undergo various tests to ensure high quality. For example, the initial qualification of a motor/encoder assembly tests motor speed and verifies the gear box's gear ratio. After assembly is complete, the grippers undergo a series of controlled drop tests to ensure that all hardware and electrical connections are secure. Next, the grippers are exercised, "burned-in", for 48 hours. During the burn-in, the gripper squeezes a hard rubber ball, and we monitor the amount of current drawn by the motor, as well as the relative positioning of the gripper fingers. The purpose of the burn-in is to weed out potentially defective components, and to verify that the screws holding the assembly together do not work loose. Only after completing all of these tests satisfactorily are the grippers allowed into the stockroom, where they wait to be issued to the next higher assembly of the PR2.

Kevin Watts talks about drop-testing and the burn-in process:

Caster assembly training commenced last week, and the first set of sub-assembly kits are now on the floor. The engineering team is doing Engineering Fit Verification (EFV) tests of the next assemblies to ensure that the parts meet specification. Once the kits are complete and the assembly documentation is ready, base/body/spine assembly training will begin.

The stockroom is a busy place now as we continue to receive parts and issue kits to the production floor. We have 75% of the PR2 parts in the stockroom now, with final parts anticipated within the next 3 weeks.

-- John Blazek