Unmanned transportation improves production of glass and steel

Automatic Guided Vehicles, AGVs were introduced in Sweden at ABB and Volvo in the seventies. The technology is typically used in traditional industry sectors like automotive, steel, pulp and paper but nowadays unmanned transportation of food and laundry also is found in a growing number of hospitals.

The company AGV Electronics in Gothenburg, Sweden has developed AGV technology since 1985. The smallest AGV in the product range is used by Orrefors Kosta Boda AB for transportation of hot glass products to cooling ovens. The largest one weighs 22 tons, loads 65 tons of steel and runs on four-wheel drive at Posco, one of the worlds biggest steel producers in Korea. Around 80% of AGV Electronics’s products go for export.

– I believe that no more than 5% of the companies that could benefit from AGVs have introduced the technology, so there is room for growth for us, says Bengt Jarl, one of the founders of the company.

Only the on-board control systems where developed at AGV Electronics at first. The products were integrated in third party AGVs. The biggest selling product group today is complete AGVs that are sold to system integrators to be included in on-site transportation systems. The end users are found world-wide.

– They are large companies like GM and LG, says Bengt Jarl.

Minimizing damage

Samsung uses AGVs for transportation of the glass used in production of LCD screens. Unmanned forklifts tailor-made for cautious handling carry plate glass up to 2.3 meters wide, 2.8 meters high but only 0.7 millimeters thick. Most AGVs are developed specifically to meet the customers material handling requirements.

– We use a design concept that allows us to adapt the vehicle almost completely. Over the years we have developed some 150 different AGVs.

One of the reasons for the customers to choose AGVs in their production line is to minimize damage in transportation of fragile goods. Another benefit is the uninterrupted operation. There is no need for coffee breaks and sick leaves as is the case when manual forklifts and trucks are used.
– When working two-, three- or even five-shifts AGVs are very profitable.

Increasing flexibility

In other cases flexibility is the reason. Assembly line production using mechanical chain transporters in the ceiling or roll conveyors requires workers to keep a steady pace. When problems occur in one place the whole production line is influenced. AGVs are used to keep the flow of products and material in the assembly line at a steady but flexible pace.

Early generation AGVs used wires in the floor for navigation. An AC current in the wire induces a voltage in two coils mounted in the underbody of the vehicle. The differential voltage between the two coils decide if the vehicle need a right or a left turn to stay on its path.

Wire navigation is a simple and cheap technique for navigation. It’s easy to cut the floor and place the wire and people instinctively understand and react to the situation when seeing the vehicle move along the marked path on the floor. Thus accidents are prevented.
– It’s quite flexible. The vehicle can make occasional turns outside path if needed, says Bengt Jarl.

1028_a6d456e6 — Inductive guidance uses a two coil antenna on the vehicle and the magnetic field from an electrical wire in the floor for controlled navigation along paths in production facilities.

Safety

The most commonly used navigational technique today involves a laser scanner mounted in an elevated position on the vehicle. The position of the AGV is calculated from angles and distances to reflex tapes in the surrounding environment. The laser is mounted high to avoid contact with bystanders even though this specific kind of laser is regarded not harmful to eyesight.

Work orders are distributed to the AGV from a fixed control system through radio modem or WLAN with information about what material to transport, where it is and where it should go. The fixed control system in the factory keeps track of all AGVs to prevent collisions.
– There are less accidents when using AGVs compared to manual forklifts for instance, says Bengt Jarl.

Vehicle features further increase safety. Bumpers prevent collisions with obstacles, such as objects or people. The bumpers are mounted much like on a car and are connected to electric switches that cut engine power supply and brake releasing power. The normal state of the brakes in an AGV is engaged. Power on releases the brakes. This is a safety measure.

Laser guidance in corridors and elevators

Right now AGV Electronics is delivering 30 AGVs to a hospital in Bergamo, Italy. These vehicles use yet another technique, called contour navigation. A SICK safety scanner monitors wall contours when dirty bed linen is transported through long corridors to the laundry in the basement. The journey even involves using hospital elevators.

Contour navigation suits low vehicles. An advantage compared to laser guidance is that there is no need for reflex tapes on the walls. On the other hand the vehicle needs to be close to the walls for the navigation to work. Contour navigation is preferred for transportation in corridors, elevators and at Automatic Truck Loading.

1033_a6d456e6 — AGVs for use in hospitals are designed to be easily cleaned and disinfected to avoid spreading of disease among patients and personnel. This vehicle will carry wagons with food, laundry and medicines at a hospital in Bergamo, Italy.

AGV Electronics use a computer platform developed by Hectronic for the application software. The system is used for navigation and other functionalities such as motor control and wireless communication. The computer platform has been in production for five years.

The evermore advanced techniques to navigate unmanned vehicles from AGV Electronics demanded more processing power. The engineers at AGV Electronics communicated the need for a new generation computer platform.
– We needed a small, low-power and fanless computer board. Since solid polyurethane wheels without suspension are used on uneven floors the ride is rather rough. A light-weight computer hardware is an advantage.

Introducing a new computer platform

The specification for the existing computer platform was used as a starting point. Backwards compatibility was an explicit requirement. Hectronic engineers outlined a successor, a semi-custom design using the Hectronic H6049 COM module with the Intel® Atom™. During a one-day meeting the specification was discussed and decided.
– It worked really well. We contributed with our experience to the discussions through our skilled engineers and Hectronic has some professional guys that really know their field of work. We were faced with well-founded arguments which made it easy to take instant and correct decisions, says Bengt Jarl. The meeting was very constructive in that way.

Case - unmanned transportation — The new generation computer platform developed by Hectronic for AGV Electronics is a semi-custom design based on the Hectronic H6049 COM module with Intel® Atom™. Additional functionality such as CAN, HD audio, DVI and 4 USB ports are placed on the carrier board. 6 UARTs and access to a dual port RAM is realized in an FPGA.

The module and carrier board are mounted on an interface board developed by AGV Electronics. The three boards together are labeled CB80 by AGV Electronics. CB80 is fully compatible with the predecessor CB40 and older AGVs are thereby easily updated to the latest platform.

The new computer platform is in place in the unmanned vehicles and AGV Electronics now has the means to develop functionality and add that extra competitive edge to the products to address the requirements from the many potential customers.

Perhaps healthcare and hospitals will grow to be the next big sector along with the traditional industry users. Swedish hospitals haven’t been in the forefront but Bengt Jarl says that a new hospital is planned in Stockholm and the plans include unmanned transportation.