Automatic Guided Vehicles
Automatic Guided Vehicles (AGVs) are basically vehicles that operate on factory floors or on paved outdoor areas without onboard drivers or operators. They are designed to perform their operations without direct human contact. AGVs are used in numerous industrial applications and processes. These vehicles can be either laser, inertially or Cartesian-guided.
An automatic guided vehicle system consists of one or more computer-controlled wheel-based load carriers which are generally powered by battery. Instructions are programmed to move AGVs from point A to point B, wait for a fixed duration or until a signal is given and then move on to the next point. In addition, the AGV may perform tasks like lifting loads and placing them at predetermined spots, etc.
AGVs have defined paths and areas within which they can navigate in or over and there are several ways to navigate AGVs. They can move by following a path which is defined by inductive wires that are buried or embedded into the ground. They can also steer themselves with surface mounted magnetic or optical strips and they can navigate by way of inertial or laser guidance systems.
A fixed or designed path is an actual physical guide path for the vehicle. This could be anything from wire to tape or paint on the floor. A free-ranging AGV has no physical guide path, making it easier to change the vehicle’s path in the computer software. However, absolute position estimates from such things as lasers are needed to correct any dead-reckoning error.
Automatic guided vehicles that are navigated by embedded or buried wire in the floor follow a wire that has a specific frequency of current running through it. The AGV has an antenna built onto it which enables it to follow the frequency that is transmitted.
Inertially guided AGVs are fitted with an onboard gyroscope that keeps the vehicles on their programmed route. Like most other vehicles, AGVs also have an onboard odometer which counts the rotations of the wheels to calculate how far they have traveled. Many AGV systems use a combination of gyroscopic data and odometry as they can achieve high precision in-vehicle location by using an under-vehicle sensor to detect magnets or transponders that are embedded into the floor. AGVs that are guided by laser systems use a laser scanner and highly reflective targets to guide the vehicles along.
There are basically three main types of automatic guided vehicles. These are the unit load, the forklift and the tugger. Unit load AGVs are powered, wheel based transport vehicles that are designed to carry discrete loads, such as an individual item like a large roll of paper, coil of steel or an automobile engine. They are also made to carry items that are contained on or inside of single carrying or storage units such as pallets, crates, chests and boxes etc.
Forklift AGVs are generally used to transport pallets. These vehicles include counterbalanced, narrow-aisle straddle, and side loading versions. Many forklift AGVs have infrared sensors built onto their forks for pallet interfacing.
Like unit load AGVs, tuggers are also powered, wheel-based transport vehicles. However, tuggers are capable of pulling one or more non-powered, loaded vehicles behind them much like a train does.
AGVs have definitely become an asset to the industrial world as they are designed to work without depending on constant human contact and they can operate and maneuver themselves in dangerous and hazardous areas.