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Automated Guided Vehicles, or AGVs, are computer-guided, wireless, battery-powered vehicles that can perform a variety of functions in a facility. AGV systems are designed based on their intended application, and they are most often used to move materials around a facility.



Automated Guided Vehicles, or AGVs, are computer-guided, wireless, battery-powered vehicles that can perform a variety of functions in a facility. AGV systems are designed based on their intended application, and they are most often used to move materials around a facility.

Pallet Truck

Pallet truck AGVs are used generally in distribution and warehousing applications. They are capable of automatically reversing into pallets on the floor; or operators can manually board the vehicle and back the forks into the pallet.

Fork Truck

Fork truck AGVs are designed to transport loads automatically from floor or stand level where the heights of load transfer vary between pick up and drop off locations. Fork truck AGV systems have the ability to stack materials with exacting precision at great height, such as in a multi-level storage rack.

Figure 1: This is an overhead view of an AGV vehicle

Notice that the section where the forks are located is considered to be the rear of the vehicle. This is because the AGV travels through a facility with its load behind the main body of the vehicle. There are numerous reasons for this transport configuration, but most importantly are the safety considerations that have to be taken into account when transferring a large, heavy load with automated equipment.

Unit Load

Unit load AGVs are equipped with a deck that permits unit load transportation and transfer. The load deck can be designed with a lifting and lowering mechanism, powered or non-powered rollers, chains, belts, or a combination system with multiple load transfer devices.

Light Load - Light load AGVs usually have a capacity limit of around 500 pounds or less and are used to transport items such as small parts, baskets, totes, tubs, cartons, or other materials throughout a facility. They are designed to efficiently operate in confined areas where larger automated or manual vehicles cannot.

Light Load

Light load AGVs usually have a capacity limit of around 500 pounds or less and are used to transport items such as small parts, baskets, totes, tubs, cartons, or other materials throughout a facility. They are designed to efficiently operate in confined areas where larger automated or manual vehicles cannot.


Tow AGVs were the first type of automated guided vehicles introduced and remain in widespread use today. These tow vehicles can pull a variety of trailer types and have a capacity ranging from 8–60 thousand pounds.

Traction/ Steering Components

The drive and steering functions on this particular AGV are accomplished using one individual powered wheel located on the forward centerline of the vehicle. The entire drive/steering assembly consists of a drive wheel assembly and steering unit.

Drive Wheel Assembly

The drive wheel on this AGV consists of several components comprising one complete drive assembly. Drive force is provided by a DC motor coupled to the drive wheel via an integrated gearbox. An electromechanical brake is also integrated into the drive wheel and is normally used only as a parking brake or for emergency stop situations.

Steering Servomotor

Steering is provided by a servomotor coupled to a geared flange on the drive wheel assembly by a single steering gear. The complete drive/steering assembly turns as one complete unit.

Load Handling System

The load handling system on an AGV is almost identical to those found on non-automated fork trucks, the exception being the inclusion of load sensors that communicate the presence of a pallet to the AGV’s onboard computer system to aid in positioning the forks when picking up a load.


The hydraulic system on the AGV provides the lifting power needed to transfer pallets between destinations in a facility. The major components of this system are a fluid reservoir, hydraulic pump, distribution manifold, solenoid valves, and a hydraulic cylinder. The fluid reservoir, pump, manifold, and solenoid valves are located in the housing on top of the AGV and the hydraulic cylinder is directly bolted to the mast framework. The lift capacity for this particular system is 3,000 pounds.


The mast is the vertical framework that provides lateral stability for the carriage. Rollers attached to the carriage travel through a channel in the mast rails as a load is lifted and lowered. There are two inductive proximity sensors attached to the mast that are activated when the carriage reaches either its maximum upper or lower height. They are used to prevent the carriage from travelling too high or too low.


The carriage is the intermediate frame between the forks and mast. The hydraulic cylinder transfers lifting force to the carriage by means of two sprockets riding on a chain that has one end fixed to the mast and one to the carriage itself.

Figure 2: AGV Carriage

Lifting Attachments

Lifting attachments are the components which actually contact the load. This is an automated fork truck, therefore, the attachments consist of two L-shaped forks, but a variety of attachments can be fitted to an AGV to match material handling requirements.

Figure 3: Lifting Attachments

Load Sensors

This AGV has three sensors that are used to communicate load position to the AGV’s computer; all three sensors are photoelectric type sensors. Two of these sensors are designated as "load off-board" sensors. They are located in each fork tip. The "load off-board" sensors are responsible for detecting a load, or lack of a load, at a pick or drop location. The remaining sensor, positioned on the carriage facing rearward, is the "load on-board" sensor. This sensor communicates to the AGV computer that a load is onboard or not.

Controls and Indicators

The controls and indicators on the AGV allow an operator to monitor the AGV for operating condition and to control all aspects of system movement.

Touch Panel Interface

The touch panel interface is a multi-functional display unit that provides an interface between the operator and the AGV’s control system. The functions of this display include: allowing an operator to view or change the AGV’s operation mode or destination, displaying operating information such as battery voltage, speed, position, etc., displaying a visual overview of the AGV’s navigation and calculated position on guide path, and displaying information to aid in troubleshooting and maintenance.

Stop/Run Buttons

When the red STOP button is pressed during normal operation, the AGV will come to a controlled stop. The STOP button will light when the AGV is ready to be restarted. The green RUN button starts or enables the AGV into operation after pressing an E-Stop or STOP button, turning the key switch from the RUN position, or to recover from a fault.

Circuit Breakers

There are two circuit breakers on this vehicle. The primary circuit breaker, located on the left, removes power from the high power electrical circuits. The control system circuit breaker, on the right, protects the AGV’s sensitive electrical components and computer system.

Figure 4: Circuit Breakers

Strobe Beacon

The strobe beacon flashes red whenever the AGV has been stopped using any of the STOP or E-Stop buttons or when the system is in an alarm condition.

Key Switch

The system key switch controls power to the operational circuits of the AGV. During normal operation, the key switch should remain in the RUN position. The START position is used simultaneously with the AGV RUN buttons in order to manually restore system operation from an OFF state.

Manual Control Pendant

The manual control pendant allows an operator to control steering, travel direction, speed, and load positioning of the AGV when the system is in manual guide mode.

Safety Components

Due to the inherent dangers associated with transferring large, heavy loads throughout a facility, AGVs are equipped with several reliable safety devices that enable the vehicle to maintain a high safety standard while operating autonomously.

Warning Lights

There are four amber warning lights on this vehicle. These lights combine to display several different patterns according to the AGV’s operating mode and alarm condition. A steady, alternating left/right flashing indicates normal operation. An intermittent, alternating left/right flashing pattern indicates the AGV has come to some form of a stop. If both sides are flashing simultaneously a system error has occurred.

Figure 5: Warning Lights

Audible Warning Signal

The AGV is equipped with several small speakers that emit an audible warning signal. The audible signal’s tone and pattern change according to the current mode of operation or alarm condition.

E-Stop Buttons

There are four red E-Stop buttons that immediately shut down electrical power to the AGV. When pressed, the AGV comes to an immediate stop, emits an alarm tone, flashes its warning lights, and ceases all transfer operations regardless of manual or automatic operational mode.

Figure 6: E-Stop Buttons

Contact Obstacle Detectors

The four side sensors on this AGV are photoelectric devices that communicate to the AVG’s computer that contact has been made with some type of obstacle. When triggered, the AGV comes to an immediate stop, activates the strobe beacon, flashes a warning light pattern, and emits an audible alarm tone.

Non-Contact Obstacle Detector

The front obstacle detector is a multi-zone laser scanner that has the ability to detect obstacles within a 180-degree field of view. Depending upon which zone an obstacle is detected in, the AGV will react in one of two ways. If an obstacle is detected in the warning zone, within three to five feet and within the AGV’s path of travel, the AGV decelerates in anticipation of a full stop. If the obstacle is still present once the AGV has closed to within a three foot distance, the AGV applies its brake so that it stops before coming into contact with the obstacle.

AGV Sub Systems

The proper and automatic operation of an AGV depends upon the cohesive operation of several different sub-systems.


Two separate computer networks are needed for the proper operation of the AGV. The facility network interprets the inputs and outputs from the various stations throughout the facility and then relays the information to the AGV controller. The AGV controller decides what AGVs will perform which tasks and then uses the AGV network to assign a task to an individual AGV. Each AGV is equipped with a computer that receives a wireless signal from the AGV controller.

Inertial Navigation

An inertial navigation system (INS) is a navigation aid that uses a computer and various sensors to continuously calculate the position, orientation, and velocity of a moving object. The AGV’s inertial navigation system is constantly aware of its current location within the facility and continuously plots the path needed to get to the next desired location. It does this by referencing a map of the facility that is stored in its onboard memory. Some of the components used in the navigation of the AGV are incremental and absolute encoders attached to the AGV’s wheels, a gyroscope, magnets buried in the floor of the facility, control software, and an on-board computer.

Guidance System

Guidance is the process of guiding an object along a defined path. The inertial navigation system can calculate the best path to take to a desired location, but it takes the guidance system to actually get the AGV there. The AGV’s guidance system compares the best estimated current location provided by the navigation system and with a reference "ideal" location from the facility map. The guidance system then provides the appropriate signals needed to operate the drive and steering components and get the vehicle to its destination.

Magnets and Map

Magnets are installed in the floor of the facility. The location of each is entered onto a database map that is stored on the AGV’s computer. This map is used in navigation to help the AGV know where it is currently located, where the next destination is, and the best path to take to get there.

Battery and Charging System

The AGV gets its power from a large battery centrally located on the AGV. The battery is either charged on-board or manually swapped out with a fully charged battery, depending upon the facility’s capability. In an automatic, opportunity charge configuration, when AGV controller detects that the AGV’s battery is below a certain voltage during normal operation, it will send the vehicle to a battery charging station. The charging shoes on the bottom of the AGV make contact with the charge plate located in the floor of the warehouse, activating the battery charger.

Functional Concepts

Two terms that are repeatedly used and often confused when discussing AGV functions are Navigation and Guidance. It is important to differentiate the two processes in order to understand how the AGV system functions.


In general terms, Navigation is the process of monitoring and controlling the movement of a vehicle from one place to another. The word is derived from the Latin command for "sail". This AGV navigates by the process of inertial navigation, or the estimation of present position by projecting its acceleration from a known past position and also the prediction of future position by projecting its acceleration from the known present position. The AGV’s navigation system uses various sensors and computers to accomplish navigation.


If navigation is the process through which the AGV calculates its current position, ideal future position, and how best to get to this position, then guidance is the actual process that will get the vehicle there. In other words, the guidance system is the driver. It controls the AGV’s drive and steering components in order to most efficiently reach its target destination.


To gain a clear perspective of the differences between Navigation and Guidance, imagine you are driving a car in an unfamiliar town. Your car is equipped with a GPS navigation system. You, as the driver, are relying on the commands issued from that system to tell you how to get to your destination. You make decisions based upon what the navigation system is telling you and use the car’s steering, throttle, and brakes to get you where you need to go. The GPS system is navigating and you are guiding.

Inertial Navigation

Inertial navigation systems were originally developed for use on submarines and rockets as a reliable navigation aid. The AGV’s inertial navigation system consists of a computer, encoders, gyroscope, magnet sensor, and a series of magnets embedded into the floor of the facility.


The AGV’s navigation components work together to allow the vehicle to operate autonomously throughout a facility.


The AGV’s computer takes inputs from all navigation components and uses specialized software to calculate where the AGV is in the facility at all times. The computer software tracks the vehicle’s physical properties, such as acceleration, that have an effect on navigation in order to provide a better estimate of the AGV’s location.


Two different types of encoders are used on this AGV. There are two incremental encoders on the front wheel, one on each side, and also one incremental encoder on a single rear wheel. The incremental encoders send a signal to the computer on regular intervals to update the distance travelled since the last signal was sent. The absolute encoder is attached above the front wheel, in-line with the steering axis. This encoder continuously updates the computer with the vehicle’s steering angle.


A gyroscope is a device used for measuring or maintaining orientation. Unlike a conventional gyroscope, which uses a spinning disk suspended in gimbals, the gyroscope on this AGV uses a length of optical fibre coiled multiple times, along which two beams of light travel in opposite directions. If the steering angle of the AGV is zero degrees, both beams contact a light sensor at exactly the same time. When the AGV turns, one of these beams takes a slightly shorter path and therefore is received at the sensor slightly before the other. This difference represents a change of direction and is calculated by the computer for navigation purposes.

Magnet Sensor

The magnet sensor detects the presence of the individual magnets that are installed into the facility floor when the AGV travels directly above them. A detection signal is sent to the computer and the software fixes the AGV’s exact position as a reference point for further navigation.

Embedded Magnets

A series of magnets are installed within the AGV’s normal path of travel into the facility’s floor. This path of travel is designed using CAD software along with the facility’s engineering plans. From this design, points along the path of travel are stored into a database representing a virtual map that the AGV references when navigating through the facility.

AGV's Guidance Systems

As mentioned previously, the AGV’s guidance system is responsible for translating navigation information into physical movement in order to direct the vehicle to its destination. This vehicle’s guidance system consists of the three major sub-sections: inputs, processing, and outputs.


The inputs to the vehicle’s guidance system come from the same sensors that are used for navigation. These sensors provide the AGV’s estimated position, heading, and speed to the guidance processor.


The guidance processor calculates error signals for position, heading, and speed based upon the sensor inputs and the values stored on the virtual map. These error signals are equivalent to the difference between their estimated values minus their ideal values. For example, if the estimated position of the vehicle is 10, yet the ideal position is 15, the difference is five. Therefore, the position error equals five. These error signals are used to drive the vehicle’s traction and steering components.


From the guidance processor, error signals are sent to a pair of power amplifiers. These amplifiers increase the error signals by a factor large enough to operate the traction and steering motors. Feedback loops are also incorporated between each amplifier and its respective encoder to aid in precise motor drive.