What Is an AGV? Automated Guided Vehicles Explained (2026)
Automated guided vehicles (AGVs) explained — types, navigation methods (wire, magnetic, laser, vision), how they're controlled and dispatched, and AGV vs AMR.
An automated guided vehicle (AGV) is a driverless, motorized vehicle that moves materials through a facility along a predefined path. The vehicle follows a fixed route defined by embedded wires, magnetic tape, reflective targets, or digital maps, and it stops, picks up, deposits, or transfers loads at designated stations without human intervention.
AGVs are a cornerstone of modern intralogistics. Automotive plants, distribution centers, pharmaceutical warehouses, and food processing facilities all rely on them to move raw materials, work-in-progress pallets, and finished goods reliably, repeatably, and safely around the clock.
What an AGV Is
An automated guided vehicle is not a single product — it is a category. The defining characteristic is guided, autonomous travel along a structured route within a facility. Unlike a conventional forklift or tugger operated by a person, an AGV executes its mission from a dispatch command issued by a fleet management system (FMS) or a higher-level warehouse management system (WMS). The vehicle navigates, manages its own path conflicts, and reports its status back to the control layer without requiring a driver.
Three core subsystems define every AGV:
- Navigation system — sensors and software that determine the vehicle's position and steer it along the route
- Onboard controller — the embedded PLC or industrial computer that executes the local control logic (drive, lift, stop, communicate)
- Fleet management system — the server-side software that assigns jobs, tracks vehicle locations, and resolves traffic conflicts across an entire fleet
All three must work together cleanly. A vehicle with excellent navigation but a poorly configured FMS will still deadlock at intersections or leave transfer stations idle.
For the broader context of how AGVs fit into a facility's automation stack, see our material handling PLC programming guide.
Types of AGVs
AGVs are classified primarily by the load they carry and the transfer mechanism they use. Choosing the wrong type for the application is one of the most common early-project mistakes.
Tow Vehicles (Tuggers)
Tow vehicles pull a train of non-powered carts behind them. They follow a fixed route — typically a loop — and stop at stations where operators load or unload the carts manually or with a small lift assist. Tugger AGVs are well-suited to mixed-load line-side delivery in assembly plants, where a single vehicle can supply multiple work cells on a single circuit.
Typical payload: 500 kg – 10,000 kg (across all carts in the train)
Unit-Load Carriers
Unit-load AGVs carry a single discrete load — usually a pallet, tote, or flat-bed carrier — directly on a platform or roller deck. They are the most common type in warehouse and distribution applications. Load transfer is handled by onboard conveyors, rollers, or lift forks that interface with stationary conveyor systems or rack structures at load/unload stations.
Typical payload: 500 kg – 5,000 kg
AGV Forklifts
AGV forklifts replicate the function of a counterbalanced or reach truck. They pick loads from floor level or from racking at height. Because of the complexity of load-height sensing, rack alignment, and fork insertion accuracy, these vehicles demand the most sophisticated navigation and sensor packages. They are common in pallet storage systems and automated high-bay warehouses.
Typical payload: 1,000 kg – 2,500 kg (floor-level to several metres of lift height)
Underride (Automated Under-Cart) Vehicles
Underride AGVs slide beneath a cart or shelf unit, lift it slightly off the floor, and carry it to a new location. Popularized in e-commerce fulfillment, this design eliminates fixed conveyor infrastructure in the storage zone. The vehicle itself is small; the load is the entire storage unit above it.
Typical payload: 500 kg – 1,500 kg (shelf or cart unit)
Navigation Methods
How an AGV knows where it is and where to go is the most technically varied aspect of the technology. Different navigation methods carry different infrastructure costs, flexibility trade-offs, and tolerance to environmental change.
Wire Guidance
The original AGV technology, dating to the 1950s. A wire is embedded in the floor and energized at a low-frequency AC signal. A sensor on the vehicle detects the electromagnetic field and steers toward the wire centerline. Wire guidance is highly reliable and immune to dust, poor lighting, and reflective surfaces, but rerouting requires physical floor work.
Still used in heavy industry (steel, automotive stamping) where routes rarely change and environments are hostile.
Magnetic Tape
A strip of flexible magnetic tape bonded to the floor surface replaces the embedded wire. Sensors on the vehicle detect the tape. Tape can be laid without cutting the floor, making it faster to install and reconfigure than wire — though it is vulnerable to damage from traffic and cleaning equipment.
Color-coded tape markers or RFID tags embedded at intervals provide positional reference points and trigger station events (stop, lift, lower, handshake with conveyor).
Laser Navigation (Natural Feature and Reflector-Based)
A scanning laser rangefinder mounted on the vehicle emits a rotating beam. In reflector-based laser navigation, passive reflective targets are fixed to walls and columns at known coordinates. The vehicle triangulates its position from the angles and distances to multiple reflectors in a map stored onboard. Accuracy is typically ±5–10 mm.
In natural feature laser navigation (sometimes called contour or feature navigation), the laser maps raw environmental geometry — walls, racks, machinery — without any installed reflectors. This requires a stable environment but eliminates the cost of reflector installation.
Laser navigation is the dominant technology for indoor distribution and manufacturing AGVs today.
SLAM (Simultaneous Localization and Mapping)
SLAM-based systems build and maintain a map of the environment in real time while simultaneously tracking the vehicle's position within that map. Input comes from laser rangefinders, cameras, or a combination. SLAM allows the vehicle to operate without any pre-installed infrastructure and to handle environments that change incrementally over time.
SLAM is more commonly associated with AMRs than traditional AGVs, but the boundary is narrowing as AGV vendors add SLAM capabilities to route-following vehicles.
Vision and QR Code Navigation
Downward-facing cameras read QR codes, DataMatrix codes, or colored pattern tiles fixed to the floor at grid intervals. The vehicle knows its exact position by reading the code beneath it. This approach is highly accurate at code locations and is used extensively in grid-based fulfillment systems (underride vehicles in e-commerce warehouses).
Between codes, dead-reckoning from wheel encoders bridges the gaps. The floor grid must be kept clean and undamaged for reliable reads.
How AGVs Are Controlled
The controls architecture of an AGV system is layered. Understanding each layer is essential for integrating AGVs into an existing automation infrastructure.
Onboard Vehicle Controller
Every AGV carries an embedded controller — often an industrial PC running a real-time OS, or in simpler vehicles, a dedicated motion controller or PLC. This controller handles:
- Steering and drive — executing motion commands (move forward, turn, stop) from speed and heading setpoints
- Load handling — controlling onboard conveyors, roller beds, lift masts, or clamp mechanisms
- Safety I/O — reading safety scanner zones, bumper contacts, and E-stop circuits; initiating safe stops
- Station handshaking — communicating with stationary conveyor PLCs at load/unload points to synchronize load transfers
- FMS communication — maintaining a wireless link (typically Wi-Fi 802.11 or private 5G) to the fleet management system
The onboard controller is where the PLC programming knowledge directly applies. Load transfer sequences at stations are implemented as interlocked ladder logic or structured text routines. The AGV requests permission from the station PLC, the station confirms clear and ready, and both sides execute a synchronized transfer. A failed handshake must stop both the vehicle and the station conveyor safely.
For a deeper look at how conveyor and station logic is structured, see our material handling PLC programming guide.
Fleet Management System (FMS)
The FMS is the traffic brain of the AGV system. It runs on a server (on-premises or edge-hosted) and communicates with every vehicle and with the facility's WMS or ERP. Its core functions are:
- Job dispatch — receiving move requests from the WMS and assigning them to available vehicles based on proximity, battery state, and priority
- Traffic management — enforcing zone blocking, segment locking, and intersection rules to prevent collisions and deadlocks
- Path calculation — computing optimal routes through the facility map for each assigned job
- Fleet monitoring — providing real-time visibility of vehicle positions, battery levels, active jobs, and fault states
- Error handling — managing vehicle blockages, failed handshakes, and communication timeouts
Most FMS platforms expose a REST or OPC UA interface that the WMS uses to submit move requests and receive completion confirmations. This northbound interface is the integration point that warehouse and automation engineers must configure carefully.
Traffic Control and Zone Management
Within the FMS, traffic control prevents vehicles from occupying the same physical space. The two primary approaches are:
| Method | Description | Typical Use |
|---|---|---|
| Zone blocking | The facility map is divided into exclusive zones; only one vehicle may occupy a zone at a time | Simple layouts, wire-guided systems |
| Segment locking | Path segments (edges in a graph) are locked to a single vehicle as it advances | Complex multi-route facilities |
| Deadlock detection | FMS monitors for circular wait conditions and pre-empts one vehicle to break the cycle | High-density fleets |
Zone configuration is a commissioning task that significantly affects throughput. Zones that are too large create unnecessary waiting; zones that are too small increase the computational overhead of lock/release cycles.
AGV Safety
Safety is non-negotiable for any moving machine operating around people. AGVs must comply with relevant machinery safety standards (ISO 3691-4 for industrial trucks, EN ISO 13849 for safety-related control functions) and satisfy the site's own risk assessment.
Safety Laser Scanners
The primary protective device on most AGVs is a safety-rated laser scanner (e.g., SICK S300, Keyence SZ series, Pilz PSENscan). The scanner monitors a configurable protective field in front of and around the vehicle. When a person or obstacle enters the protective field, the scanner triggers a safe stop via a safety relay or safety PLC output. A secondary, larger warning field triggers a speed reduction before the stop.
Many vehicles carry multiple scanners to provide 360-degree coverage, particularly on vehicles that travel in both directions.
Bumpers and Contact Detection
Mechanical bumpers or tactile edge sensors provide a last-resort physical detection layer. Contact with the bumper triggers an immediate stop. Bumpers are not a substitute for scanners — they are a redundant final layer.
Safety Architecture
The safety circuits on an AGV must be designed to Safety Integrity Level (SIL) 2 or Performance Level d/e depending on the risk assessment. This means:
- Safety scanner outputs are read by a dedicated safety controller (not the standard motion controller)
- E-stop circuits use dual-channel wired logic with cross-monitoring
- Safe Torque Off (STO) functions on the drive axes are engaged by the safety controller, not by software alone
For engineers coming from manufacturing automation backgrounds, the safety architecture of an AGV is closely analogous to the safety zones around a robot cell — the same standards and design patterns apply.
AGV Applications
AGVs are deployed across a wide range of industries. The common thread is repetitive, high-volume material movement over fixed or semi-fixed routes.
Automotive Manufacturing
AGVs deliver body panels, engines, and sub-assemblies to assembly line stations. Unit-load carriers and custom flat-bed vehicles follow precise routes timed to the line's takt time. Station handshakes with assembly cell PLCs confirm delivery and trigger the next process step.
Distribution and Fulfillment
Unit-load AGVs move pallets between receiving docks, buffer storage, and outbound staging. Tugger AGVs supply pick lines with replenishment totes. Underride AGVs carry mobile shelf units to stationary pickers in goods-to-person fulfillment systems.
Pharmaceutical and Food Processing
AGVs handle materials in clean-room and hygienic environments where human traffic must be minimized. Stainless steel construction, smooth surfaces, and HEPA filtration are common requirements. The controlled, repeatable nature of AGV movement also supports traceability requirements in regulated environments.
Airports and Hospitals
Baggage handling systems use AGV-like guided vehicles to route bags between check-in, sorting, and gates. Hospitals deploy AGVs for linen, medication, and waste transport through service corridors.
Integration with Industrial Automation
In all of these applications, AGVs are not standalone systems. They are nodes in a wider automation network that includes PLCs controlling conveyor stations, SCADA systems monitoring OEE, WMS platforms managing inventory, and ERP systems driving order fulfillment. The FMS acts as the middleware translating WMS move requests into vehicle commands and reporting completions back upstream.
The PLC/WMS Handshake at Load and Unload Stations
This is the controls detail most explanations skip, but it is where most integration effort lives.
A typical station handshake between an AGV and a fixed conveyor PLC works as follows:
- FMS assigns job — the FMS sends the vehicle a destination station ID and load/unload command.
- Vehicle approaches station — the AGV navigates to the station approach point and requests a dock clearance signal via the FMS, which relays it to the station PLC over the facility network (OPC UA, Ethernet/IP, or Modbus TCP depending on the installation).
- Station PLC confirms ready — the station PLC checks that the conveyor is clear, the load is present (for unload) or the landing zone is clear (for load), and asserts a "ready" signal back to the FMS/AGV.
- Vehicle docks — the AGV advances to the final docked position, confirmed by a precision stop sensor or inductive position marker.
- Transfer executes — the AGV onboard controller and the station PLC coordinate the conveyor and roller motion to transfer the load. Both sides monitor the transfer with load sensors. The transfer is interlocked: neither side advances until the other is confirmed ready.
- Completion handshake — both sides confirm the load has transferred. The station PLC releases the dock. The AGV notifies the FMS of task completion and waits for the next assignment.
Failure modes to handle in the ladder logic:
- Load sensor disagrees (load detected on both sides simultaneously, or neither side after commanded transfer)
- Station PLC communication timeout
- AGV misalignment at dock (position sensor not confirmed within timeout)
- E-stop triggered during transfer (both sides must hold and wait for operator clearance, not resume automatically)
Handling these failure modes cleanly — with appropriate alarm states, operator prompts, and safe recovery logic — is the difference between a system that runs reliably and one that requires constant operator intervention.
AGV vs AMR
Automated mobile robots (AMRs) are often discussed alongside AGVs, and the distinction matters when specifying a system.
| Feature | AGV | AMR |
|---|---|---|
| Path type | Fixed or semi-fixed route | Dynamic, computed in real time |
| Obstacle response | Stop and wait (or call for help) | Replan route around obstacle |
| Infrastructure | Tape, wire, reflectors, or floor codes | None (SLAM-based) |
| Flexibility | Low-to-medium (rerouting requires map/config change) | High (adapts to layout changes) |
| Typical environment | Structured, controlled, high-throughput | Semi-structured, changing, lower-throughput |
| Safety standard | ISO 3691-4 (industrial trucks) | ISO 3691-4 + additional AMR guidance |
| Typical cost | Lower per vehicle, higher infrastructure | Higher per vehicle, lower infrastructure |
The core difference: an AGV follows a route; an AMR finds a route. In practice, the boundary is blurring — modern AGVs incorporate SLAM and dynamic replanning, while AMRs are increasingly deployed in structured high-throughput applications.
For a detailed side-by-side comparison including specific use-case guidance, see our dedicated AGV vs AMR comparison.
A related application that often operates alongside AGVs in high-throughput end-of-line operations is automated palletizing. For the controls logic behind those systems, see our palletizer PLC programming guide.
Frequently Asked Questions
What is an AGV?
An automated guided vehicle (AGV) is a battery-powered, driverless industrial vehicle that transports loads within a facility along a predefined route. It receives move commands from a fleet management system, navigates using embedded wires, magnetic tape, laser reflectors, or visual codes, and transfers loads to and from fixed stations through interlocked handshakes with stationary conveyor PLCs.
How do AGVs navigate?
AGVs navigate using one of several methods: wire guidance (following an energized wire embedded in the floor), magnetic tape (following a tape strip on the floor surface), laser navigation (triangulating from reflective targets or natural features), vision and QR codes (reading floor-mounted codes with a downward camera), or SLAM (building and using a real-time map). Laser navigation with reflective targets is the most common method in general manufacturing and distribution applications today.
What is the difference between an AGV and an AMR?
An AGV follows a fixed or configured route and stops when it encounters an obstacle. An AMR computes its own route dynamically and replans around obstacles in real time. AGVs require some level of floor infrastructure (tape, wire, or reflectors) and are suited to high-throughput, structured environments. AMRs require no floor infrastructure and are better suited to environments where layouts change frequently or where obstacle avoidance flexibility is a priority.
How are AGVs controlled?
AGVs are controlled by three layers: the onboard vehicle controller (handles drive, load handling, safety I/O, and station handshaking), the fleet management system (dispatches jobs, manages traffic, tracks the fleet, and communicates with the WMS), and the facility's WMS or ERP (generates move requests based on inventory and order logic). The onboard controller typically runs ladder logic or structured text for load transfer sequences and safety interlocks.
Key Takeaways
- An AGV is a driverless vehicle that moves materials along a fixed or configured route using guidance infrastructure embedded in or on the floor, or laser/vision-based localization.
- Four main types — tow/tugger, unit-load, AGV forklift, and underride — each suited to different load types and transfer mechanisms.
- Navigation methods range from simple magnetic tape to sophisticated SLAM, with laser-reflector navigation the most widely deployed in manufacturing and distribution today.
- Three control layers — onboard controller, fleet management system, and WMS — must be correctly integrated for reliable operation.
- The load/unload station handshake between the AGV's onboard PLC logic and the station conveyor PLC is the critical integration point and the most common source of commissioning issues.
- Safety scanners implementing SIL 2 / PLd protective fields are the primary safety device, backed by bumpers and a dual-channel safety circuit.
- AGVs follow fixed routes and stop at obstacles; AMRs compute dynamic routes and replan around them — choose based on throughput requirements, layout stability, and flexibility needs.
