Definition
AGV (Automated Guided Vehicle) is an automatically guided transport vehicle, commonly used in warehouse logistics as a handling robot. It receives WMS scheduling commands and reports its location and battery status via a 4G module to achieve intelligent warehousing.
Guidance and Scheduling
AGVs use guidance methods such as magnetic strips, QR codes, laser SLAM, and visual navigation to travel along preset or dynamic paths within the warehouse. WMS or WCS (Warehouse Control System) sends task commands through 4G/5G or Wi-Fi. The AGV executes actions such as picking, transporting, and placing items after receiving them, and simultaneously reports its location, status, battery level, and faults in real-time. In large-scale warehouses, multiple AGVs work collaboratively, relying on stable communication to ensure scheduling timeliness.
Role of communication modules
In scenarios with insufficient Wi-Fi coverage or cross-regional deployment, 4G/LTE Cat.1 modules become the preferred networking option for AGVs. The module is responsible for communicating with cloud-based WMS to receive scheduling tasks and report operational data; it supports offline caching and reconnection after network loss to ensure tasks are not lost in weak network environments. Some AGVs also integrate GNSS positioning for outdoor transportation or cross-park scheduling, and the module needs to support multiple networks and positioning capabilities.
Differences from AMR
AGVs usually travel along fixed paths and rely on ground guidance facilities; AMRs (Autonomous Mobile Robots) have autonomous navigation and obstacle avoidance capabilities, making their paths more flexible. They complement each other in warehouse and manufacturing scenarios: AGVs are suitable for high throughput and fixed processes; AMRs are suitable for flexible production lines and human-machine co-working. The communication requirements are similar, both needing a stable network connection to support cloud-based scheduling and monitoring.
Engineering Practice Supplement
Starting from "AGV," common on-site issues often focus on "performance meets standards in the lab but is difficult to reproduce in the field." In addition to radio frequency and protocols, power grounding, connector contacts, and firmware race conditions should also be checked. On the cellular side, it is recommended to collect RSRP/SINR, cell reselection, and PDP reconstruction records; on the application side, there should be clear strategies for retries, idempotency, and queue persistence. When involving data security and compliance, write the scope of collection, storage location, retention period, and third-party sharing into privacy and contract appendices to avoid high costs of patching after going live.
How dispatch messages and a safe stop divide the work
In the context of a communication module, an AGV is a moving terminal that receives tasks and reports pose and battery. It is not a cart that can finish a warehouse on floor tape alone. A dispatch message may arrive late. A safe stop may not. Path tracking, obstacle avoidance, and the emergency stop close locally on the vehicle. Cellular or Wi-Fi only carries tasks, map versions, and status. If the link is down longer than the set time, the vehicle should stop at the current safe point, not keep driving to the end of the aisle on the last command.
The task number must be idempotent. The same pick instruction arriving twice because of replay must not move the forks twice. Battery, fault codes, and task state should be stored locally during an outage and sent in order after recovery. If the cloud only remembers that the vehicle has left, a power loss in the field cannot tell whether the load is still on the forks.
Cell reselection jitter from rack blockage
Metal racks change the antenna pattern. When the vehicle turns into an aisle, the serving cell changes back and forth, and task delay suddenly grows. Resetting the module does not fix that. Keep the antenna clear of the forks and the battery’s metal face, and check radio quality in both loaded and empty attitudes. If warehouse Wi-Fi coverage is complete, cellular is a better backup for cross-zone or outdoor transfer than a contender for real-time avoidance deep among the racks.
Another mistake is to treat an outdoor fix as an aisle coordinate. Satellites are unavailable inside the warehouse, so dispatch should keep using in-warehouse coordinates. For a transfer outside, hand the position to the 4G link, and let an edge computing node do conflict checks locally so each vehicle does not send avoidance decisions to a remote site.
When the task cache is full, stop or drop
If the aisle loses the network for a stretch, dispatch commands pile up on the vehicle. The cache policy has to be written in advance: keep received tasks that have not run until they are acknowledged, and cancel timed-out tasks with a reason instead of executing an old pick after the signal returns. Position may be reported less often. Fork height and whether a load is present cannot be thinned until it is unclear whether the load is on the forks. Below the return-to-charge threshold, new tasks should be refused locally even if the cloud queue still has orders. After recovery, report the current fork state first, then request a new task, so dispatch does not keep assigning from a stale position. Record radio quality separately for loaded and empty runs; rack blockage changes with load height. Do not accept a new pick while returning to charge.