Automated Guided Vehicles (AGVs) Different types and how they are used in factories By David Holden October 27, 2010

1. Automated Guided Vehicles (AGVs) • Different types and how they are used in factories By David Holden October 27, 2010

2. What are AGVs? • An AGV, or automated guided vehicle, is a mobile robot that moves around by either following markers or wires in the floor, or by using vision sensors combined with motion algorithms in order to handle, store, or retrieve materials.

3. History • First AGV developed in 1954 by A.M.Barrett,Jr. • Using a overhead wire to guide a modified towing truck pulling a trailer in a grocery warehouse. • Subsequently, commercial AGV were introduced by Barrett. • 1973, Volvo developed automated guided vehicles to serve assembly platforms for moving car bodies through its final assembly plants. • Later, Volvo marketed their unit load AGVs to other car companies.

4. Why Use AGVs • AGVs reduce labor costs • Increase efficiency • Reduce long-term costs • They remove many “human errors”, and other concerns inherent of using humans in production or material handling: • AGVs avoid/ prevent Injuries that normally occur during material handling due to a human driver’s lack of attention. • AGVs have visual and pressure sensors integrated within them in order to safely avoid/ prevent Injuries that normally occur during material handling due to other personal not paying attention. (An AGV will stop before running over an idiot) • AGVs don’t get impatient and drive too fast, causing injuries to the drivers, those around them, or possibly losing/ damaging their load • AGVs don’t require Medicare • If an AGV gets damaged/broken down while on the job, it won’t try to sue the company • AGVs don’t go on strike

5. Why use AGVs • Improved Response Time • AGVs can improve the material delivery response time required to a manufacturing cell or shipping dock. AGVs remove and supply loads precisely upon demand [fork trucks are undesirable for precise timing]. • Safe Vehicle Movement • AGVs move slower than manually operated industrial vehicles, operate on a fixed path, and have safety features built in for pedestrian interaction. In applications where "fork truck madness" and pedestrian safety are problems, an Automated Guided Vehicle System can be a good solution. AGVs efficiently share aisles with people and fork truck traffic. • Reduction in Labor • Once set up and configured AGVs can deliver material automatically, 24 / 7, with minimal operator involvement. Therefore, material handling labor costs can be drastically reduced. • Elimination of Conveyor Walls • AGV Systems allow open aisle ways. Since AGVs are operator less industrial vehicles, no fixed obstructions are required. AGVs are a good solution in contrast to a conveyor when a fixed obstruction is in the proposed material path. • Service From Palletizers • AGVs are adaptable to an interface with palletizers. Since palletizers generate consistent unitized loads at a steady rate, AGVs are well suited. AGVs make an excellent bridge between the out feed conveyor of a palletizer and a storage system or shipping dock. • Eliminate Single Point Failures • AGVS are continuous flow devices. However, AGVs are almost immune to single point failures, which could occur on conveyors or monorail systems. One AGV may malfunction but other vehicles will continue to deliver material during its repair. If a vehicle fails on a main guide path, it can be easily moved, allowing for material flow to continue unabated. • Adaptable to Manual Backup Methods • An AGV system allows open aisles and open accessibility to pickup and delivery points. If the AGV system is inoperative, loads can still be delivered by a manual method, such as forklift truck. • Reusable Asset • An AGV System is an reusable asset to any facility. An entire AGV System can be moved to another location or another plant with minimal downtime. Vehicles, Batteries, Chargers, and Fixed Controls can also be moved easily. The only system elements than cannot be reused are any in-floor guide wires. • Reduced Product Damage • AGVs move slower and are in general more careful than manually operated fork trucks. Therefore, AGVs allow little or no product damage in comparison to fork trucks. • Better Tracking of Materials • AGV control systems allow tracking of materials while loads are in the AGV system. Each pallet can be uniquely identified and tracked throughout the material transport process. In addition, load pickup and drop off times can be monitored. • Improved Logistics • Production machinery has already reached a high level of productivity. Further increases in overall manufacturing efficiency must come from logistics. For example, in many manufacturing facilities, about 75% of each work piece cycle time consists of transportation and waiting. An AGV System can link information about material flow and supply the workstation as demand arises. In general, AGV Systems improve the organization and execution of materials transportation. • Improved Image / Better Housekeeping • An AGV System improves plant organization by maintaining clear aisles and organized workstations. Since pickup and drop off stations are fixed and dedicated, operators are able to keep their workstations more organized. This improves the workplace environment for employees and creates a positive image for plant visitors and prospective customers. • Better Discipline • An AGV System forces discipline in plant operations. Material flow in and out are scheduled by the AGV System controls. Unnecessary raw, finished or packing materials do not clog aisles and workstations.

6. When would you consider AGVs • Low to Medium Throughput • In applications where the throughput relative to the distances traveled are in the low to medium range and do not warrant fixed path conveyor [25-100 loads per hour], an AGV system should be considered. Very low throughput can be best served with a manual delivery method such as fork lift trucks, while high throughput requirements are better suited for conveyor or towline. • Zone Containment of Manual Forklifts • Lifting stacking, and loading are functions best accommodated by manual forklift trucks. Manual forklift trucks should not be used for horizontal transportation; AGVs are better suited for horizontal transportation. In a properly designed system, forklift trucks are contained to specific areas of a facility [i.e. shipping dock or staging areas]. An orderly systemized facility will not allow random disbursement of manual fork lift trucks over long distances. • Consistent and Stable Loads • Applications where the load profile is relatively consistent are well suited for an AGV system. A common load footprint, which allows repeat interface by an AGV is a fundamental requirement. • Long Distances • The distance between load pickup and delivery points will influence the material delivery system solution. AGV Systems are typically favored in applications where distances between stations are approximately 200 feet or more. However, shorter distances can be justified if the vehicles are used in a sortation function, or as a bridge between two points. • Steady and Continuous Throughput • In applications where material delivery requirements are steady, continuous, and repetitive shift after shift, AGVs can be the best solution. AGVs can respond well to steady, continuous flow because AGVs operate at fixed speeds and fixed operating cycles. • Electronic Dispatching of Loads • Efficient scheduling and movement of loads can be accomplished with AGVs. Load movement scheduling can be queued in an efficient pre established manner [FIFO or prioritization]. AGVs can respond to calls for pickup and delivery; this improves material handling efficiency. • Process Automation • AGVs can be the best solution when scheduled material flow is required in to and out of manufacturing cells. Automated manufacturing and production systems operate most efficiently when tied together by an Automated Guided Vehicles. • Sortation • AGVs provide an excellent horizontal transportation medium when many pickup and delivery points are required. AGVs have an advantage over a conveyor solution in these situations due to the complexity and cost of the latter solution. • Need For Flexibility • If system expansion and system changes are anticipated, an AGV system may be the best solution. AGVs are more adaptable to change compared to other horizontal transportation methods such as towline, monorail or conveyor. • AS/RS Interface • AGVs offer an excellent transportation method when load movement in to and out of an AS/RS is required. AGVs scan or can interface at multiple storage aisle P/D points while keeping the interface points free of a fixed obstruction. AGVs also blend well with AS/RS because both are automated computer controlled systems. A manufacturing cell can request a load to be delivered out of storage to a station. The partnership between the AS/RS and the AGV allows for combined automated storage and horizontal transportation.

7. Industries that use AGVs

8. How they’re used in industries:

11. Types of AGVs • Towing vehicles • Unit load carriers • AGV pallet trucks • AGV forklift trucks • Light-load transporters • Assembly-line vehicles • Custom AGVs

12. Types of AGVs Towing Vehicles • First type of AGV introduced(1953) • Towing vehicle is called an automated guided tractor • Flatbed trailers, pallet trucks, custom trailers can be used. • Generally, used for large volumes (>1000 lb) and long moving distances (>1000 feet). Unit load Carriers • To transport individual unit load onboard the vehicle. • Equipped with powered or non-powered roller, chain or belt deck, or custom deck. • Loads can be moved by Pallet truck, forklift truck, automatic loading/unloading equipment, etc.

13. Types of AGVs Pallet Trucks • No special device is needed for loading except the loads should be on pallet • Limited to floor level loading and unloading with palletized load • Widely used in distribution functions • Capacity 1000-2000 lb • Speed > 200ft/min • Pallet truck can be loaded either manually or automatically Forklift Trucks • Ability to pickup and drop palletized load both at floor level and on stands. • Pickup and drop off heights can be different • Vehicle can position its fork according to load stands with different heights • Very expensive • Selected where complete automation is necessary/required.

14. Types of AGVs http://tube.lankaeuro.com/video/wis9Wq_ndbY/Packmobile%C2%AE-AGV-Automated-Guided-Vehicle.html Light Load Transporters • Capacity < 500lb • To handle light and small loads/parts over moderate distances • Distribute between storage and number of workstations • Speed 100ft/min, turning radius 2ft • For areas with restricted space Assembly-Line Vehicles • Variation of an light load transporter • For serial assembly processes • As the vehicle moves from one station to another, succeeding assembly operations are performed • This kind provides flexibility for the manufacturing processes • Lower expenses and ease of installation • Complex computer control and extensive planning is required to integrate the system.

15. Costs

16. Costs (continued) • Rule of Thumb System Pricing Ranges (The costs shown are per vehicle)

17. Costs of public AGVs • The AIBO robot pet - $1000 • Several small robot vacuum cleaners like the iRobotRoomba, $129 - $599.99 Video: http://www.youtube.com/watch?v=NKAeihiy5Ck

18. Supporting technologies: • Windows- based control systems • AGV solutions are available with Eagle III technology or with laser navigation. • These wireless guidance systems provide more options and greater flexibility to solutions for a client’s ever changing AGV and business needs. • Laser, Inertial (magnet), natural target, optical, and wire AGV navigationsystems • Sick® laser bumper safety system • Electric steer/drive assembly • Industrial lead-acid batteries • PC onboard running Windows XP® • RF Ethernet (802.11)

19. AGV System Glossary Below is a list of terms commonly used when describing automatic guided vehicle systems. • I/O (Input/Output) – External devices that interface with the AGV System to provide safe, automated material movement. Input devices direct the AGV system to perform certain actions, such as load detection photo eye sensors on a conveyor to indicate when a load is ready for pick up by an AGV. The output devices allow the AGV system to command certain actions, such as running the actuator to open an automatic door to allow the AGV to pass through it. • Higher Level Software – Software which typically controls processes in the entire facility and can interface with and provide direction to lower level systems that control individual pieces of equipment. Examples of higher level software include enterprise resource planning (ERP), press control systems (PCS), and warehouse management systems (WMS). • SGV Manager Server – host control software for the AGV system. Communicates with I/O, higher level software and the vehicles to coordinate movements and provide efficient material movement. Optimizes assignment of tasks to vehicles, controls vehicle traffic and tracks all material movement. • SGV System Client - Used by personnel to interact with the system (can be PC based, handheld, etc). Provides quick, easy access to monitor system operation and optimize performance. Real time 3D graphics allows intuitive interaction with unmatched flexibility and scaleability. • Layout Wizard – software tool used to configure the guide path (road system) for the vehicles and optimize reflector target positions to achieve the desired level of vehicle positional accuracy. A user-friendly toolbar provides quick, easy initial system design as well as modification of existing systems. Provides flexibility to respond quickly to facility changes which are wirelessly downloaded to the vehicles. • Laser Triangulation – the most common form of guidance for AGVs. On each vehicle a rotating laser, complete with a sender (source) and receiver (detector), strobes the plant and receives feedback from reflectors that are mounted on walls, columns and adjacent equipment. This feedback is used to calculate the exact vehicle position in the facility. • Batteries – Used to power most AGVs. Lead acid, sealed lead acid, and nickel cadmium (NiCad) batteries are most common. Other battery types such as Lithium Ion, Hydrogen Fuel Cells are also available. • Battery Charging – All AGV batteries require periodic charging for continued AGV operation. The primary battery charging methods include Swap Out where the discharged battery is exchanged for a fully charged battery, and Opportunity Charging where the AGV automatically reports to a charger during short intervals that are available when the AGV is not busy making material deliveries. With opportunity charging the vehicle makes an electrical connection with a fixed mounted plate (charge shoe) connected to the charger and the battery is charged on board the vehicle. • Wireless Network – a network using RF to provide communication between AGVs, SGV Manager, and/or other remote I/O. The system typically meets the standard IEEE 802.11 a, b or g. Often customers already have a wireless network installed in their facility and the AGV system can utilize available bandwidth within that existing network. • Wired Network – A local area network typically using CAT 5/Ethernet cabling to provide from communication between SGV Manager, Higher Level Software and I/O. • Virtual Private Network (VPN) - a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger networks, such as the Internet, as opposed to running across a single private network.

20. Primary Vendors • HK Systems® • Packmobile® • Transbotics Corporation • Material Handling Industry of America • JBD Corporation • AGV Products, Inc. • Cattron-Theimeg International Ltd. • Control Engineering Company • Egemin Automation Inc. • FMC Technologies • Frog Navigation Systems • Mentor AGVS, Formtek Cleveland, Inc. • Siemens Dematic Material Handling Automation Division • Transbotics Corporation

21. an example of a company that has found AGV success in a distribution center environment http://www.scdigest.com/assets/On_Target/10-05-13-1.php?cid=3458 • Kellogg’s has implemented some 64 AGVs across four plant warehouses which deal entirely in full pallet movement. • Even small back-ups can cause major problems. • (If AGV issues cause the takeaway from palletizing stations at the end of manufacturing lines to stop for as little as five minutes, it can cause a production line to shut down, at tremendous cost. • AGVs simply do not move as fast as a human-driven fork truck, and even rated speeds are difficult to achieve if the warehouse floor is not really smooth or corners are tough to turn. • When the AGVs are being piloted, fork drivers will speed past the AGVs and tell management “look how much better I can do.” • Fork truck drivers do move faster, but they don’t work 24 by 7, and they don’t need breaks.” • Another challenge AGV users must face is that “AGVs are very polite,” meaning that obstacles, including other AGVs, will cause the AGVs to simply stop until the issue is resolved. That could include something as simple as stretch wrap hanging down below the bottom of the load. • That means that companies must plan for “chasers,” – associates who observe both electronically and through observation that an AGV has stopped and needs to be re-activated because of an obstacle or an inventory error (e.g., a pallet expected in a storage location is not there). Planning for that daily operational maintenance from a staffing and ROI perspective is key. • AGVs work best when their paths are really spaced out to avoid AGV congestion. • That may mean rethinking product putaway zones. Companies often use their WMS to drive putaway from production as close as possible to staging lanes and shipping doors. But that can lead to too many AGVs in the same aisles, causing bottlenecks. • He added that AGVs force more discipline about where pallets are placed. If a unit load is placed outside of the AGVs understood movement and storage paths, the vehicles cannot pick up and move a load, and/or can be stopped in their tracks by the unexpected obstacle. As also shown in the figure above, that means you also need to define “induction points” where pallets that are moved elsewhere in the DC can be retrieved to a drop point that can be understood by the AGVs to take the loads back to storage or staging. Kellogg’s has found benefits in three areas from the AGVs:  • Reduce product damage  • Improved overall DC productivity/operational costs  • More efficient trailer loading 

22. Videos • http://www.youtube.com/watch?v=jXodd32NrJQ • http://www.jbtc-agv.com/knowledge/videos_of_agvs_in_action/increasing_productivity_with_agvs.aspx

23. State of the art • Modern AGVs are computer-controlled vehicles with onboard microprocessors. • Position feedback system to correct path • Communication between vehicles via system controller • RF communication • Electric signals • System management computers • Optimising the AGV utilisation • Laser Guided Systems • Tracking the material in transfer and directing the AGV traffic. Laser Guided Unitload Automated Guided Vehicle – Packmobile®

25. Standards • ANSI B56.5 Safety Standard for Guided Industrial Vehicles and Automated Functions of Manned Industrial VehiclesANSI B56.5 defines safety requirements for powered, unmanned automatic guided industrial vehicles. The standard requires that the users are responsible for all factors affecting the operation and maintenance. This responsibility includes load stability and marking the travel path on the floor, including turning and maneuvering clearances. There are also requirements for manufacturers. Deviation from the travel path of more than 3 inches for an external reference (e.g. guide wire), or, more than 6 inches for inertial guidance system shall, require an emergency stop. A loss of speed control also requires an emergency stop. Vehicle warning indicators, audible and/or visual, shall operate when the vehicle is in motion. Emergency controls are required which would stop the vehicle if there is a loss of speed control, loss of guidepath reference, or an object is detected in the direction of travel. Accessible emergency stop switches are required on the vehicle itself.

26. Safety

27. Safety Optical Safety Sensors • The laser scanner offers a greater protection range than bumpers and, therefore, permits higher speeds. • Reliable detection of persons and objects approaching the vehicle.

28. Safety

29. Safety

30. Safety

31. iRobotRoomba

32. iRobotRoomba Shows how the Roomba moves around to clean the floor (Blue represents the area vacuumed) http://resources.irobot.com/index.php/howitworksplayer/gwY2RuOqsZWMd3JU2WB20zX-UqCtB_im/#ooid=gwY2RuOqsZWMd3JU2WB20zX-UqCtB_im …yeah, not too efficient.

33. iRobotRoomba • This video shows an example of how AGVs slow down when objects come within their protective field in order to avoid harm to people and the machine itself, and then if the emergency bumper makes contact with an object, the machine will stop, and then change direction. • http://resources.irobot.com/index.php/howitworksplayer/BvdXVqOozXdaS83QX1MYTasB2Krl80Dg/#ooid=BvdXVqOozXdaS83QX1MYTasB2Krl80Dg • (then show battery charging)

34. Question What type of navigation does the Roomba use? • Wired Navigation • The wired sensor is placed on the bottom of the robot and is placed facing the ground. A slot is cut in the ground and a wire is placed approximately 1 inch below the ground. The sensor detects the radio frequency being transmitted from the wire and follows it. • Guide Tape • Many light duty AGVs (some known as automated guided carts or AGCs) use tape for the guide path. The tapes can be one of two styles: magnetic or colored. The AGC is fitted with the appropriate guide sensor to follow the path of the tape. A flexible magnetic bar can also be embedded in the floor like wire but works under the same provision as magnetic tape and so remains unpowered or passive. • Laser Target Navigation • The wirelessnavigation is done by mounting retro-reflective tape on walls, poles or machines. The AGV carries a lasertransmitter and receiver on a rotating turret. The laser is sent off then received again the angle and (sometimes) distance are automatically calculated and stored into the AGV’s memory. The AGV has reflector map stored in memory and can correct its position based on errors between the expected and received measurements. It can then navigate to a destination target using the constantly updating position. • Gyroscopic Navigation • Another form of an AGV guidance is inertial navigation. With inertial guidance, a computer control system directs and assigns tasks to the vehicles. Transponders are embedded in the floor of the work place. The AGV uses these transponders to verify that the vehicle is on course. A gyroscope is able to detect the slightest change in the direction of the vehicle and corrects it in order to keep the AGV on its path. • Self-guided vehicles • Self-guided vehicles operate without continuously defined pathways. Instead of following physical pathways such as in wired navigation and guide tape, the SGV’s pathways are defined in software. Using one or more range-finding sensors, such as a laser range-finder, as well as gyroscopes, inertial measurement units, or on-board vehicle sensing like bumpers, these vehicles are quickly able to make major changes to their original pathways.

35. Question What type of navigation does the Roomba use? • Wired Navigation • The wired sensor is placed on the bottom of the robot and is placed facing the ground. A slot is cut in the ground and a wire is placed approximately 1 inch below the ground. The sensor detects the radio frequency being transmitted from the wire and follows it. • Guide Tape • Many light duty AGVs (some known as automated guided carts or AGCs) use tape for the guide path. The tapes can be one of two styles: magnetic or colored. The AGC is fitted with the appropriate guide sensor to follow the path of the tape. A flexible magnetic bar can also be embedded in the floor like wire but works under the same provision as magnetic tape and so remains unpowered or passive. • Laser Target Navigation • The wirelessnavigation is done by mounting retro-reflective tape on walls, poles or machines. The AGV carries a lasertransmitter and receiver on a rotating turret. The laser is sent off then received again the angle and (sometimes) distance are automatically calculated and stored into the AGV’s memory. The AGV has reflector map stored in memory and can correct its position based on errors between the expected and received measurements. It can then navigate to a destination target using the constantly updating position. • Gyroscopic Navigation • Another form of an AGV guidance is inertial navigation. With inertial guidance, a computer control system directs and assigns tasks to the vehicles. Transponders are embedded in the floor of the work place. The AGV uses these transponders to verify that the vehicle is on course. A gyroscope is able to detect the slightest change in the direction of the vehicle and corrects it in order to keep the AGV on its path. • Self-guided vehicles • Self-guided vehicles operate without continuously defined pathways. Instead of following physical pathways such as in wired navigation and guide tape, the SGV’s pathways are defined in software. Using one or more range-finding sensors, such as a laser range-finder, as well as gyroscopes, inertial measurement units, or on-board vehicle sensing like bumpers, these vehicles are quickly able to make major changes to their original pathways.

36. References • http://www.hksystems.com/agv/index.cfm • http://en.wikipedia.org/wiki/Automated_guided_vehicle • http://www.egeminusa.com/ • http://www.jbtc-agv.com/knowledge/videos_of_agvs_in_action.aspx • http://www.mhia.org/industrygroups/agvs/costestimating • The Industrial Electronics Handbook By J. David Irwin • http://www.ued.co.uk/categories/product/?product=196&category=165 • www.meche.net/MAE%20464/Notes/AGV-latest.ppt • http://www.hksystems.com/agv/why-agv.cfm • http://www.scdigest.com/assets/On_Target/10-05-13-1.php?cid=3458