Mantissa Conveyor Production Tracking
We were called into a large retail catalog fulfillment house who told us they had been looking for someone to do a production tracking system for their Mantissa tilt tray conveyor system; they had been looking for someone to do this system for five years, and no one had been willing to take the job on. Of course we were immediately interested.
There are 10 stations where employees take product from a large bin and place it on the conveyor, barcode up. These items are then scanned by two Accusort QuadX scanners and diverted to the proper packing station.
Their issue was that they couldn't track individual productivity for the employees in this area. They believed they could realize a pay back from a data collection system that tracked employee's individual production.
Our Hardware Solution
We were told that our solution could not impact how the employees were doing their job, so it had to be an automated, hands free system. Fixed scanners at the work stations were not acceptable because it would slow down the employee, and fixed laser scanners at each station was far too costly. In addition, the conveyor travels at 350 feet per minute, which meant that we had about 300 milliseconds to process each tray.
We decided that what we needed was in intelligent camera, and decided to use the Cognex DVT 515 Vision Sensor. These were installed just downstream of each worker, and their job was to detect if a package was present or not. Two additional cameras were installed up stream of the first two stations to detect any packages that had failed to be diverted, and had made the trip all the way around the system.
The Accusort laser was used to confirm that a package was present in the tray, and the barcode was scannable. This also filtered out prevented "false positives" (i.e. barcode facing down, or an employee holding his hand in front of the camera) and the data output from the laser was processed to detect missing items from orders.
We built a custom controller using an Opto22 industrial computer. Each camera was wired back to a relay installed in the controller, and was sampled each time a tray passed a photo eye. We tied our system into the existing conveyor in order to detect a tray 1 pulse, and so we knew the location of each package on the conveyor.
We used Symbol Technology LS2208 laser scanners and Logic Control pole displays at each station to allow the employees to log in and log out of the system
The Laser Scanners:
Software and Controller
A custom program was written in Opto22's Pac Control Basic language to detect the input from the cameras, synchronize to the conveyor speed, the tray one pulse, and to capture the output from the Accusort scanner. The program sends collected data to Switchboard, our data collection software program, which posts it to an SQL data base by employee ID. Indirect time is tracked In addition to employee productivity.
The inside view of the controller
This system has proven to be a very accurate and reliable and has surpassed our customer's expectations. The system processes over 42 transactions per second, 22 hours a day, over 3 million per day; another challenge met by Accurate Data Systems.