Material Flow Analysis
One of the cornerstones of a successful AGV system is an accurate calculation of how many vehicles are required to do the work.
On nearly every application, customers want to quickly hone in on the expected cost of the system so that they can determine the ROI or payback they can expect for a project. One of the important factors affecting cost lies in how many AGVs are required to do the work.
An accurate analysis of the material flow starts with detailed knowledge of what materials must be moved to support operations. Material pick up locations, drop off locations, required timing, and frequency are all critical factors that will determine whether your automated material delivery systems will adequately support your needs. In some cases this analysis can be very simple with just a few pick up points and drop off points needing to be serviced a few times per hour. In other cases this can be very complex with tens of thousands of pickup and drop off points, linked by a complete network of paths where traffic must be carefully metered to maximize flow. In either case, a detailed electronic drawing is important to make sure we fully understand the travel distances and aisle clearances that are required.
In simpler applications or when only rough estimates are required, we build a flow diagram to represent all of the movements that the AGV will perform. We then develop a spreadsheet calculation to estimate the number of AGVs that will be required to do the work. Factors that go into the spreadsheet are the load transfer (pick up and drop off) times, travel time, battery charging/transfer times, traffic metering/control time, and of course the number of transfers that must take place each hour. Care must be taken to make sure to properly account for daily or seasonal peaks to make sure the system does not create a bottleneck.
In more complex applications, the required input information is similar; however, a computer model is built to fully simulate the material flow. These simulation models have proven to be very accurate and clearly show how you might improve material flow by making relatively minor changes to a facility. Similarly, simulation models are very helpful when analyzing how changes to production or operations will change the material flow requirements.
To obtain accurate material flow results from either a spreadsheet calculation or from a simulation, the baseline assumptions about the system and operation of the AGVs must be accurate. That is why it is extremely important to have experienced AGV experts building these analytical tools.