AGV system conceptual design: team, layout, simulations

Once the "let's implement" decision has been made, the most creative part of the whole methodology begins: an AGV system design tailored to a specific facility. This is the conceptual stage — before any talks with suppliers — at which you decide who works on the implementation, which routes the vehicles will take, which technology you choose and whether the assumptions add up at all. This article, a spoke of the AGV Implementation Step by Step series, walks you through the conceptual design that is produced immediately after a positive plant readiness audit.

Setting up the project team

A good conceptual design is not produced at a single desk. Start by formally establishing an implementation team with clearly assigned roles — it is responsible for the quality of later decisions. It must include representatives of every department the implementation will affect.

• Production — knows the real rhythm of the line and when material is actually needed at the workstation.
• Logistics and warehouse — describes the flows, volumes and the points where queues form today.
• Maintenance — will assess serviceability and the impact of AGVs on machine availability.
• IT — will verify the requirements for integration with MES/WMS/ERP systems and the state of the network.
• Health and safety — assesses risks from the outset and prepares safety guidelines for mobile robots.

Add to this a project manager who holds everything together, and a sponsor from the plant's management — a person with the mandate to take decisions and unlock the budget. Such a cross-functional team ensures that when planning you take into account the needs and constraints of every party, instead of discovering them only at the commissioning stage. It is worth planning right now how you will work with the future supplier and appointing contact persons.

Process mapping and the target layout

The heart of the concept is a detailed intralogistics layout with the AGV routes marked on it. On the plant drawing, define the optimal travel paths — ones that avoid areas of heavy pedestrian traffic and steer clear of tight bends and places where materials regularly pile up.

Next, mark the pick-up and delivery points. These are the places where the vehicle collects a load (loading stations at machines, pick-up racks) and where it sets it down (drop-off zones, docks, dispatch areas). Each of them must have enough space for manoeuvring and for a buffer station if needed, so that the AGV does not wait idle for access. Design the flow logic: which points to connect with routes, where AGV traffic will cross pedestrian traffic or manual transport, and how to secure those crossings.

Finally, calculate the fleet. Based on the data from the needs analysis, make a preliminary estimate of the number of AGVs — work out how many missions per hour one vehicle can realistically complete and compare that with the total number of transport orders at peak. This is the first, rough answer to the question "how many vehicles?"; the simulation will verify it later.

Technical system requirements

For the flows you have designed, you now select specific technical solutions. This is where the concept stops being a diagram on a drawing and becomes a specification.

Navigation: tape versus laser and SLAM

Decide how the vehicles will find their way in the space. On one side is navigation based on physical infrastructure — magnetic tape on the floor, inductive loops in the floor, RFID markers or codes at set intervals. On the other is natural navigation, without additional infrastructure, in which the AGV scans its surroundings with a laser or camera and moves according to an uploaded map of the facility.

The trade-off is clear. Tape is inexpensive and simple to commission, but inflexible when routes change — every modification means physically re-laying it. Laser navigation and SLAM give you the freedom to change route layouts in software, but are more expensive and require a stable environment that is easy for the scanners to "read". The choice should follow from the nature of the facility: a fixed space or one that is frequently rearranged, and how high the required load positioning accuracy is.

AGV type and the loads handled

Define what the vehicles will carry and how, because this determines the model. One vehicle is suited to towing sets of trailers (towing AGVs), another to lifting pallets from the floor (forklift type), and yet another to transporting small containers or cartons. Check the maximum weight and dimensions of the load and the required lifting height. Also decide on the load transfer concept: will the AGV pick up the pallet from the floor by itself (in which case it needs a fork function), or will you equip the loading stations with roller conveyors that automatically load the pallet onto the vehicle's platform? The wide range on the market makes it possible to match a vehicle to almost any load, but it is the flow concept, not the supplier's catalogue, that should dictate the choice.

Opportunistic versus cyclic charging

Plan the charging stations in places that are easily accessible to the fleet — ideally by the main aisle or at the end of the transport loop. Decide on the charging strategy: opportunistic charging means short top-ups at every available opportunity, so the vehicle rarely drops out of circulation; cyclic charging means going to charge only once the battery has been discharged to a set level. The first approach maintains continuity of work better under a tight takt, while the second simplifies the logic and can be gentler on the cells. Also plan the supporting infrastructure: navigation markers along the routes, levelling of the floor at critical points if necessary, and Wi-Fi coverage along the entire length of the routes, because most fleets communicate with the management system wirelessly. Consult the health and safety team at this stage on safety solutions — scanners that detect obstacles, restricted access zones, emergency stop buttons.

Verifying the concept by simulation

Before you spend money on equipment, check the AGV system design virtually. Computer simulation in specialised logistics process software — for example FlexSim or Plant Simulation — lets you see the flow of materials with the vehicles involved and calculate the expected indicators before anything is installed on the shop floor.

What exactly does such a model give you? Above all, three things: mission lead times, fleet utilisation and a picture of the task queues. The simulation reveals bottlenecks that cannot be seen on a static drawing — for example congestion when two vehicles meet on a narrow section, or a signal that the assumed number of AGVs will not keep up at peak hours. This means you make corrections in the model rather than in costly reality: you change a route, add a passing point or modify the order schedule. The model can also help in the safety assessment — it lets you rehearse emergency scenarios and check whether the zones are sensibly arranged. If you do not have simulation tools, at least analyse the transport takt carefully — how long a single mission takes and whether the fleet can complete all tasks within the required time.

Updating the assumptions and the concept document

Simulation almost always changes something in the original idea — and that is a good thing; that is where its value lies. So at the end of the conceptual phase, update the assumptions documentation: refine the system requirements specification, covering the number of vehicles, the navigation method, hardware and integration requirements, the route layout and the interfaces with production processes.

This document is your most important artefact when you enter talks with the market. It becomes the basis of the request for quotation and a point of reference that lets you compare quotes against the same criteria, instead of being led by sales presentations. If at this stage you want to draw on outside expertise, a good AGV and AMR system integrator will help you finalise the concept and verify the assumptions before they go into the specification.

Summary: what an AGV system design must contain

Before you consider the conceptual stage closed, check that you have a complete set of decisions:

• A project team set up from production, logistics, maintenance, IT and health and safety, plus a project manager and a sponsor.
• A target layout with AGV routes, pick-up and delivery points, buffers and secured crossings.
• A preliminary number of vehicles calculated from the number of missions per hour and the order volume.
• A chosen navigation technology, with the tape vs laser/SLAM trade-off justified.
• An AGV type matched to the weight, dimensions and method of load transfer.
• A charging strategy (opportunistic or cyclic) and the placement of the stations.
• Safety arrangements agreed with health and safety.
• A concept verified by simulation or at least by an analysis of the transport takt.
• An updated requirements specification ready for the request for quotation.

Does the conceptual design have to be done with a supplier?

Not at the start. It is worth going through the conceptual stage in-house, so that you enter talks with the market with clearly defined requirements rather than a blank sheet. Only then do you control the direction of the project and can you compare quotes reliably. An integrator's support can be valuable in verifying the assumptions, but the specification itself should come from you.

What if the simulation shows too few vehicles?

That is exactly why you run it. Increasing the fleet in the model costs a few clicks, not another purchase after go-live. Analyse whether the problem is the number of vehicles, or rather the route layout and the order schedule — sometimes adding a passing point or moving some missions outside the peak solves the problem without enlarging the fleet.