The parts for 12 assemblies are loaded onto a parts cart with the correct parts for each assembly roughly located in each slot on the cart. When production begins on a new cart the M-16iB/20 robot will locate the cart using 2D and 3DL iRVision, this will define a user frame for the cart. The motor and reducer are unloaded, their exact position and orientation determined by 2D and 3DL iRVision. The motor and reducer will have their detected heights (relative to cart frame) checked against the KAREL Database to ensure that they are the correct parts for the assembly being build. The pinion gears are located and checked to be the correct type using 2D vision. The retainers are checked for correct style (2 different kinds) and that they are right side up using 2D vision, 3DL vision is used for picking.
The side of the reducer that contains its' access plug and the radial orientation of its' output shaft key are both discovered using 2D vision with the same fixed mounted camera. This information along with the orientation of the input coupling of the motor assembly station is required for loading the reducer into the motor assembly station. For both the motors and reducers their part numbers are confirmed using another fixed mounted camera equipped with a tele-centric lens to give a small but crisp field of view making letters and numbers good candidates for 2D patterns. If an incorrect motor or reducer is found the entire slot is rejected to a dedicated reject station and production continues to the next slot.
The motor is installed into the reducer using two different force control schedules, Hole Search, which locates the hole of the coupling and engages the motor shaft a few mm's then Shaft Insert takes the motor shaft to the correct depth. By using Hole Search the User Tools for all 7 different motors did not have to be exact as any error is compensated for with force control.
A FANUC Intelligent parts feeder is used to feed the M5X16 SHCS (with pre-applied loctite) into the system. The feeder is controlled through an auxiliary axis of the M-16iB/20 and a 2D camera mounted above the robot unload end of the feeders' bowl. If parts are not found the bowls is commanded to shake back and forth to scatter parts and put one part in a spot and orientation suitable for picking. After so many shakes the feeder is rotated for 2 seconds to introduce new parts from the load side of the bowl. The vision not only locates the screws position but also checks each side of the screw using a histogram to ensure the gripper fingers will not crash into another screw resting too close to the found screw. A histogram is a 2D Vision tool where a search area (dynamically linked to a pattern) is examined and various statistics about the gray scale in that search area are reported such as average gray scale, standard deviation, etc. Also the presence of the pre-applied loctite is confirmed using a histogram, and the length of the screw is confirmed to be correct using a caliper. A caliper is a 2D vision tool used to discover the length between two edges, or the X,Y location of a single edge. The search window for a caliper is dynamically linked to a 2D pattern, in this case the screw. If a screw is found to be of incorrect size and/or to not have loctite it is picked up and dropped in a reject box located immediately outside of the feeder bowl. Once a good screw is found and picked it is handed off in space (no hand-off fixture) to the LR Mate 200iC robot.
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