The Beginning of "Driverless" Vehicles
In 1954, when Arthur "Mac" Barrett, of Barrett Electronics Corporation, unveiled the first AGV, he named it Guide-o-Matic and described it as a driverless vehicle. Guide-O-Matic was a towing machine that followed a signal given from a wire in the ceiling, which was later replaced by a wire buried in the floor. It had the simple function of pulling trailers in a warehouse.
Arthur Barrett spent his life exploring and investigating different ways of using automation to open doors, move materials, and develop other work saving devices. His radio controlled industrial vehicles were called Radox, which allowed operators to program it to pick up pallets, tow vehicles, or index a pallet truck.
The advancements of Barrett inspired engineers and designers to develop the modern systems of AGVs that use cameras, lasers, electrically charged tape, and other means to maneuver automated vehicles in various environments. The discovery of automatic guided vehicles has revolutionized raw and finished material transport.
What is an AGV?
AGVs are guided computerized vehicles that use computer software to determine their positioning, movement, and location. Powered by a battery or electric motor, they are able to complete manufacturing, warehousing, loading, and other operations without human interference. Self-powered AGVs can do load transfers, move and stack pallets, complete assemblies, and tow heavy loads, functions previously performed by people. They have improved production efficiency, removed humans from unsafe and potentially dangerous conditions and overcome possible human errors.
Though the term AGV, or automatic guided vehicle, may seem to be self defining, in actuality, there are multiple ways that AGVs receive their instructions and programming, which include wires implanted in the floor, cameras, radio waves, lasers, or other forms of technology.
AGVs began as a method of towing trailers to speed up production. At the time, they were considered nice conveniences that saved time. During the latter part of the twentieth century, designers explored other ways to use the technology to improve factory conditions, which has led to a wide array of capabilities, uses, and functions for AGV technology.
Types of AGVs
Three types of AGVs are towing, fork trucks, and heavy load carriers. Each is designed to perform repetitive actions such as delivering raw materials, keep loads stable, and complete simple tasks. Unlike human workers, AGVs operate continuously only needing to stop to be recharged or repaired.
Towing AGVs, or tugs (otherwise known as a warehouse tugger), pull loads of several tons, reducing the hazards associated with using large heavy equipment. They are capable of moving loads of 10,000 to 50,000 pounds. Heavy-duty towing AGVs can pull sub-assemblies, machine components, equipment, and other materials that are unsafe for manual labor.
Fork AGVs are mechanized forklifts that can retrieve stock, place materials, and move and stack pallets. They supply automated machines and take finished products to storage or place them for shipment. Forklift AGVs can prove to be economical and cost savings since they replace lift trucks and Hi-Lo operators that require licensing and training. Heavy-duty forklift AGVs can move large paper rolls, steel coils, engines, and vehicles over any distance depending on their programming
Heavy Load AGV:
Though towing and fork AGVs are capable of handling large loads, certain industries such as aviation, large construction vehicle manufacturers, and shipbuilders require AGVs able to handle huge loads of up to 250,000 pounds. For these processes, AGV producers have created machines with large bases, solid wheels, and wide platforms. In many cases, this form of AGV has to be custom designed to exactly fit the requirements of the customer’s industry.
Unit load AGVs have one specialized function, which is transporting totes, pallets, goods, and racks that are too heavy to be moved by other means. They are designed to move goods and heavy materials in a warehouse or storage facility. Unlike fork and towing AGV’s, unit load, or unit load decks, are flat tables that can carry one or several individual units to and from conveyors, stands, automated storage, and various types of retrieval systems. Very similar to a flatbed, they usually move along one path in two directions, repetitively, and without variations.
Light duty AGVs are usually found outside of production facilities in hospitals, offices, or commercial locations. They are able to move very small loads of under 500 pounds. Small AGVs are especially useful in places requiring cleanliness where human presence may contaminate the environment. For example, in hospitals, they deliver patient charts and daily medications.
AGV robots are automatic guided vehicles equipped with robotic limbs. AGV robots are more adept at picking up and moving items than regular AGVS, which are must less dexterous. In short, they combine the intuitiveness of a human and their ability to adjust to their surroundings, and combine them with the brute force of a lifting machine like a palletizer.
AGV robots offer their users many benefits. First, using AGV robots, manufacturers can save time and money. During auto parts assembly, for example, AGV robots can put together large parts much more efficiently than humans. They can even make tooling switches without assistance. Not only that, but they have no learning curve. Once programmed, they will perform their duties perfectly. Also, their programming tends to make them more precise and eliminates human error. Their operation also takes people out of harm’s way. For loading and unloading applications, AGV robots offer greater mobility and high strength. Plus, once again, they eliminate the need to people in high stress or high risk situations. Another advantage of AGV robots is the fact that they are easier to set up that regular AGVs, as they require fewer physical markers and guides.
The term “AGV systems” refers to automated, or automatic, guided vehicles. AGV systems run on industrial batteries or electricity to perform movement solutions within warehouses and facilities. Solutions include material handling, transportation, assembly, delivery and storage; these solutions have applications within most industries, including: greenhouse, general manufacturing, plastics and metal, newspaper and mail, automotive, aerospace, food and beverage processing and packaging.
To ensure smooth operations, AGV systems usually require monitoring. Especially in large factories or warehouses and/or where multiple AGV systems are in use, a traffic operating systems and controller are very important components. Generally, traffic operating systems consist of locator panels, CRT display and a central logging and report center. With the help of this technology, staff can successfully monitor and track the location and movement of in-house AGV systems and gauge their efficiency, thus avoiding collisions and traffic congestion.
Automated Guided Vehicles
Automated guided vehicles, also known as automatic guided vehicles or AGVs, computer operated, self-powered transportation machines used for applications within the material handling and moving industry. Though they were originally designed to serve only industrial market transportation and lifting, their use is now more widespread. Fields within which they are now used also include: general manufacturing, food and beverage processing, automotive, aerospace, packaging, greenhouse/industrial horticulture, metals and plastics and mail and newspaper.
These systems either operate with fixed guidance systems or free range systems. Fixed guidance makes use of magnetic tape, colored paint or embedded wire to guide vehicles that respond to antennae, signal emissions and frequencies on simple paths. Fixed guidance systems are reliable and they work well, but they are inflexible and limit the capabilities of their AGVs and they simply may not be well suited to some environments and applications. Fortunately, most automated guided vehicles are not limited by fixed guidance systems. Instead, most contemporary AGV systems are free range. Free range systems are computer-controlled, with onboard microprocessors and supervisory control systems.
Guided vehicles are computer-controlled transportation units that perform applications without any sort of human direction or control. They are used for material handling and transportation applications and can be designed for sorting, storage, delivery or product assembly use. Guided vehicles, or automatic guided vehicles, reduce labor costs in manufacturing processes by providing high volumes of repetitive and tedious movements and actions with around the clock capabilities.
Vehicles can be equipped with an infrared detection system, or a bumper system, which helps to reduce the damage potential of collisions. Free range AVG systems which are controlled by computer software and international navigation capabilities are able to adjust a vehicle's route according to flow of traffic and possible obstructions, therefore making the factory floor a safer place to work.
Laser Guided Vehicles
Laser guided vehicles are becoming increasingly popular worldwide in applications that call for repetitive actions over a distance or for transporting extremely heavy loads. There are four main types of laser guided vehicles: high reach lift LGVs, fork LGVs, conveyor-bed LGVS and reel LGVs. High reach lift LGVs can carry up to 1200 kg and are used for heavy pallet handling and pallet stacking up to 9m. Fork LGVs are used for pallet handling of one to four pallets and the regular delivery of stable loads. Conveyor-bed LGVs can carry numerous products simultaneously and are used for high speed sortation, material flow and transport, distribution and raw material handling.
Self Guided Vehicles
Self guided vehicles are computer-controlled transportation units that perform applications without any sort of human direction or control. Used increasingly in place of forklifts, conveyor systems and manual push-carts, automatic guided vehicles provide high volumes of movement, especially for repetitive and continuous processes. Industries such as aerospace, automotive assembly, food and beverage processing, mail service, assembly, newspaper, pharmaceutical, plastic manufacturing and storage use AGVs for sorting, delivering, transporting and assembling operations.
Depending on the specific application for which a vehicle is to be used, self guided vehicles range significantly in construction and shape. They may have a towing mechanism, room for unit or pallet loading, fork lifts, space for light loads or components needed in assembly lines like robotic arms.
Light load vehicles can be used for small parts distribution and assembly, while much larger vehicles such as towing vehicles can be used for moving heavy and cumbersome loads. Other self-guided vehicles are designed for use in specific environments such as those used in clean room processes and operations. These electric battery powered vehicles are useful in indoor applications where no sudden or essential decisions are made that cannot be done by automated machinery.
Self Propelled Vehicles
Self propelled vehicles, also known as automatic guided vehicles, are able to perform applications without any sort of human direction or control, thus allowing operational processes and tasks to be achieved more efficiently and more often. AGV systems provide high volumes of repetitive movement and can be designed with the capacity for far greater loads and weights than manual labor provides. They also reduce the factor of human negligence in the movement of vehicles and loads, thereby reducing the risk of bumping, crashes and collisions on the manufacturing floor. Self propelled vehicles are typically powered by industrial strength batteries or electricity. Required power capacity will depend on the intended application and load of the vehicle, and can be adjusted to fit custom specifications. Automated guided vehicles were originally designed for use in industrial activities, but have become popular alternatives to manual cart transports, conveyors and forklift trucks in many types of applications.
Also referred to as tuggers, towing vehicles are unmanned, computer-controlled transport vehicles that are capable of pulling one or more non-powered, wheel-based vehicles and are one of the most effective types of automatic guided vehicles. The non-powered vehicles, or carts, are attached behind the AGV in a train that is adjustable in terms of length and capacity.
They are often used in conjunction with other AGVs such as transfer cars or material handling robots. Towing vehicles allow workers to maneuver large numbers of carts that would not have been efficiently possible through manual labor. By creating a safer work environment as well as increased productivity, towing vehicles prove advantageous for industries such as metal processing, warehouse, automotive, food processing, agriculture, aerospace, construction, communications and military.
The Benefits of Going Automated
Manufacturers have found that by using automation, they can significantly reduce errors and costs while raising quality and improving machine performance. Implementation of computer driven mechanisms increases production and efficiency approaching the point of perfection. Jobs that seemed to be impossible can be completed with ease in little time.
Initially, investing in an AGV system can be expensive requiring significant adjustments to manufacturing operations as well as the cost of the equipment. Once the system is in full operation, there is a noticeable reduction in labor costs with an increase in efficiency to balance the costs of implementation. Related additional savings can be seen in the reduction of labor.
Production environments have unsafe and hazardous conditions that include dangerous materials and substances. AGVs are perfect for those circumstances, which may endanger workers. The aircraft industry has huge engine components and parts that workers are unable to lift and can be lethal if they fall. AGVs are used to avoid damage to the materials and keep workers safe. In some cases, AGVs are equipped with robotic limbs to perform functions that require superior dexterity and strength, such as tooling changes.
The decision of what AGV system is best for your operation should be based on the needs of your facility. Every industry has their unique and specialized conditions. A close examination of each step of a process assists in determining where to place an AGV unit. As with all business decisions, the cost of a system can be a primary determining factor. AGV manufacturers have data that provides guidance to help in making a purchase choice. They are more than happy to assist with implementation and offer details on their system works.
Common AGV Components
AGVs can be equipped with three types of batteries – gelified electrolyte lead acid (GEL) or absorbed glass mat (AGM), lead, and lithium ion. Which battery is used depends on its charging system and is predetermined by the manufacturer. In most cases, the three types are not interchangeable and how they are charged has to be carefully managed since inappropriate charging can damage the battery. Lithium ion or Li-ion batteries are the most commonly used for their long life and reliability.
Job Control Software
AGV’s communicate with each other through a central command system, the brains of the system, to complete their work. When orders are received, they are placed in a work queue and acted on in the order they were received. Priority can be given to a specific command that can advance it in the queue. An essential part of the central command is traffic control to avoid accidents or repetitions.
An essential part of an AGV is its safety features such as lasers to detect and avoid obstructions. Contact bumpers are a required feature for safety as well as warning lights and signals. Loads and load transfers are present so the machine is not overtaxed beyond its capacity. Common AGVs use sensors to communicate with magnetic tape, QR codes, barcodes, RFID, lasers, inductive wire, spot magnets, remote sensory objects such as LiDAR (light detection and ranging) or SLAM (simultaneous location and mapping).
Traffic Management System
In a facility where multiple AGVs are used, a traffic operating system controller is a necessity. They are equipped with a central logging and report center, locator panels and a CRT display. This technology helps to monitor, track, and locate AGVs observing their operations, avoiding collisions, keep traffic running smoothly, and gauge the system’s efficiency. Advanced fleet controls choose the best path for the AGVs reducing waiting times and travel without a load. The entire fleet can be routed by planning for optimal utilization according to fleet status, available space, storage buffers, and order queue.
Guidance System Software
There are two types of guidance systems for AGVs – fixed path and free range. Fixed path systems are guided by wire, tape on the floor, sensors on the walls, or other form of guidance outside the vehicle. Their path is marked out so that vehicles or people cannot interfere with their operation. Unlike fixed path vehicles, free range systems have a programmed path that does not require any external devices to guide them. Their programming gives them sufficient adjustments to avoid collisions and hazards that may interfere with their programmed task. Installation is easy and does not require any major changes to the work environment.
AMR or AGV robots vs AGV – Robots vs Guided Vehicles
For over fifty years, AGVs have been an important addition to the movement of materials and the improvement of production methods. Their ability to save time and increase efficiency has made them one of the most popular innovations in modern warehousing and production. In the last few years, as robotic technology has advanced, AGVs have had their abilities enhanced with the development of the AMR, autonomous mobile robot.
The biggest difference between AGVs and AMRs is how much faster, smarter, and more efficient AMRs can be. AGVs follow a guided pre-programmed route and can only obey simple instructions. When there is an obstruction in their path, they are unable to adjust and change. Expanding their applications requires time consuming programming.
An AMR has an onboard computer with sensors to evaluate its operating environment. They can navigate a complicated set of restrictions using an uploaded map that allows them to select the most efficient route to their destination. They can react to people, vehicles, and unplanned obstructions while successfully and safely completing their job. The chaos and confusion of the surrounding environment does not interfere with the completion of their tasks.
AMRs do not require any adjustments to their work environment with the exception of adding a map to their programming. There isn’t any need for laser sensors, guiding tape, or installing special pathways. Instead of adapting the working conditions to the AMR, it adapts to fit the situations and can be easily adjusted. These two factors make an AMR less expensive than an AGV.
A properly programmed AMR can quickly and efficiently complete an assembly process, make tooling changes, and finish complex tasks more precisely than humanly possible. Using robotic technology has the advantage of freeing people from dangerous and hazardous tasks since an AMR can enter any environment without a concern for its health or safety.
AGV Guidance and Navigation Systems
One of the main things to consider when shopping for an AGV system is the type of computerized navigation it uses. Every industry and user has a different set of requirements for how to implement AGV’s, which dictates the type of navigation system. In general, the guidance system determines the route and functions of the AGV. The performance of the AGV is very dependent on the quality of the system and the way it is installed.
There are a wide variety of guidance systems that manufacturers use for AGV vehicles. They vary depending on whether they are fixed path or free ranging and include laser guided navigation (LGV), magnetic navigation, LiDAR NAVIGATION, magnetic spot navigation, wired navigation, optical navigation, or vision navigation. Each of the different types has benefits and are designed for specific purposes. Below is a short description of each. A more technical description can be found at the individual manufacturers’ websites.
LGV – laser navigation:
The LGV system uses a laser positioning device mounted on the top of the vehicle. Targets, located in its workspace, guide it. The navigation system sends laser signals to the targets, which sends signals back to the AGV navigation device. Three targets are required for the AGV to find its position. Corrections are made every 30 to 40 seconds. By industry standards, LGV’s are incredibly accurate and easy to install.
Magnetic tape AGVs are equipped with magnetic sensors and follow a clearly defined path that is marked by magnetic tape. The tape induction system can be modified to account for line changes. The sensor measures the distance from the center of the tape and sends the information to the controller to adjust steering and path so that the AGV is always centered on the tape.
LiDAR navigation is also referred to as natural navigation. This system maps the environment with an assortment of sensors such as cameras, lidar, and lasers that are used for safety purposes. All of the data is combined with an internal inertial measurement unit (IMU) to help the AGV define and calculate its position. The array of calculations are made by a complex algorithm called SLAM (simultaneous localization and mapping).
Magnetic spot navigation:
For magnetic spot navigation, magnets are embedded in the floor for the AGV to follow at approximately 15 feet apart. The AGV moves from one spot to the next using sensors and controls such as half effect sensors, encoders, counters, gyros, and other such encoders to steer and guide the vehicle. A CAD drawing of the workspace is loaded in the system to serve as a reference. As with magnetic tape, installation is easy and quick.
When Mr. Barrett invented the first AGV, he hung a wire from the ceiling to guide the tug. As he worked on his device, he changed the position of the wire in the ceiling and embedded it in the floor. Though technology has advanced, his original wire design is still used by some manufacturers. All that is required is burying a wire guide about one inch in the floor. It transmits signals to the AGV giving it its location to regulate steering.
Paint or colored tape is placed on the floor of the workspace. A built in sensor detects the path. There are systems that use ultraviolet light to light up the paint or tape. Highly sensitive cameras are able to recognize the AGVs path and position.
Vision activated systems use cameras that record the main features of the AGVs programmed route. Using vision sensors, the AGV system gets image information regarding its workspace. The system requires a camera, light, and hood to measure the ground texture. When navigating its workspace, the onboard system compares the recorded ground to its map to determine its position. The system is very accurate and has low hardware costs.
Automatic Guided Carts
Automatic guided carts are a flexible and a less expensive alternative to an AGV system. Since they are smaller and more maneuverable, they have more versatility and can be easily adjusted. Their capacity varies depending on the manufacturer and model. Most can carry up to 2000 lbs. and tow loads heavier than they can carry. As with AGV’s, each type has a different form of navigation.
Carts are an excellent alternative to conveyors or forklifts since they are cleaner, quieter, and easier to modify. They provide a fast and safe stream of products to and from selected areas and can be modified for non-production jobs such as warehouse organization.
The immediate benefit of a cart system is its low cost compared to labor costs. Materials flow easily and are quickly and readily available for operators. It only takes a few hours to upgrade a production environment with a cart system. Additional carts can be purchased and easily integrated into the existing system. The number of carts can be adjusted with variances in production. Since material handling removes the human factor, the installation of a cart system results in a significant decrease in accidents and other potential hazards.
AGV Safety and Compliance Standards
The American National Standards Institute (ANSI) has approved the standards proposed by the Material Handling Industry of America (MHIA), which has developed standards and guidelines regarding the implementation and use of Automatic Guided Vehicle Systems. The MHIA standards are safety requirements for system suppliers, manufacturers, users, construction, application, operation, and maintenance.
The Material Handling Industry of America (MHIA), in 2012, set forth the safety standards for driverless, automatic guided industrial vehicles and other automatic industrial vehicles. The standards cover every aspect of AGV equipment from the bumpers to the types of required emergency controls. The requirements also have guidelines regarding manned vehicles that have been converted to unmanned.
To be able to market an AGV vehicle, a manufacturer should be certified by the MHIA in several categories. The first category is a set of general requirements for AGV and other industrial equipment. The other categories are more specific to AGVs such as the type of permitted wireless components and includes a section on types of permitted batteries, chargers, motors, and other electrical components.
When making the choice to purchase an AGV system, it is wise to research manufacturers regarding their compliance with the MHIA regulations. In many ways, it is a protective umbrella to help avoid a bad investment.