P&G's Iowa City, IA, plant, which produces shampoo, conditioner and mouthwash, operates 24 hours a day, seven days a week. "We have a total of nine packaging lines and six supply conveyors," says Rebecca Burton, Automated Guide Vehicle (AGV) Area Leader for the Iowa City plant. "During the first shift everything is running at maximum capacity. During second and third shifts most lines are running, a few are shut down for scheduled maintenance checks and other performance functions."
In the early '80s, P&G initiated a company-wide program to automate processing operations, says Dale Hanson, an engineer in P&G's central engineering department in Cincinnati, OH. One of the chosen methods was to use automated guided vehicles (AGVs) and robotics to handle various simple and repetitive tasks. However, within 10 years, "Most of the AGV systems were out of service," says Hanson, "because of difficulties in keeping them running."
P&G's Iowa City, IA, plant, which manufactures shampoo, conditioner and mouthwash, was able to maintain operation of its AGV systems due to the dedication of a few on-site technicians. By the late '90s, however, the Iowa City system was having more problems. The lack of spare parts made it more expensive and eventually impossible to keep the vehicles and the system running. At that time, the company decided to retrofit the plant's AGV system with a user-friendly control system that reduced costs and improved the functionality of the system.
The original AGVs delivered to the Iowa plant in 1987, however, were determined to be beyond retrofit. As a result, AGV Products, Inc., Charlotte, NC, was contracted to supply eight new vehicles designed to utilize the system's existing guide path. This allowed P&G to take advantage of new advancements in AGV technology, such as the ability to travel "off-wire."
"AGV Products, Inc., convinced us that its TRACE (Traffic Routing AGV Command Executive) 2000 control system was flexible enough to meet the Iowa City plant's needs," says Hanson. TRACE is a user-friendly traffic-control software package that runs on any PC computer under the Windows NT operating system. The software is tied into a PLC network that provides engineers "point and click" control commands.
"The primary function of the AGVs is to keep the packaging lines supplied with packaging materials," says Burton, the AGV Area Leader. "They are constantly moving, either delivering packaging materials, such as bottles and caps, to the line, or removing returns." She says the plant produces batches of a specific product and fills a wide variety of container sizes. Operators will enter product information into the PLC and the AGVs are then directed to retrieve the desired shampoo bottles and caps from the warehouse.
"The main reason we wanted to keep our AGV system," says Burton, "was the travel distance between the packaging lines and the warehouse. They have a 2,000-ft. guide path and it makes sense for an unmanned vehicle to make that trip rather than tying up a forklift operator."
Burton says the TRACE system is programmed to do the following: *request an available AGV to move a pallet *command the AGV to perform the proper sequences of movement to carry out the request *monitor the status of the AGV throughout the process of handling the request *and prevent vehicles from colliding.
As part of the system's original design, there were areas along the guide path where the vehicle was forced to take long trips to make a U-turn. Conventional AGV systems solved this problem by cutting the floor and installing a new guide wire. Today's AGVs, however, have the ability to travel "off-wire," executing what is called a programmed turn. The vehicle is able to travel a short distance off the guide wire and return to another path, using the vehicle's on-board programming and odometry for guidance. This feature has significantly increased the system's overall efficiency. Other improvements in the vehicles include ease of maintenance, improved safety devices and rugged vehicle design. Another unique feature is that these vehicles can travel up a 7% grade.
The AGVs used at the P&G facility are unit load type vehicles, capable of handling two pallets at a time. They are fitted with two conveyor decks that can operate independently to load or unload pallets from either side of the vehicle. Each AGV is powered by a 48-volt battery and has a total load capacity of 5200 lbs.
The vehicles have microprocessor-based control boards that monitor all AGV functions. The controller incorporates digital and analog inputs and outputs for load handling, safety features, and steer and drive functions that permit bi-directional travel and automatic load handling. The control board incorporates functions such as low battery detection, low power mode (sleep mode) and navigation.
AGV Products, Inc., 8012 Tower Point Drive, Charlotte, NC 28227; 704-845-1110.