AGVs & AMRs as Alternatives to Tow Line Conveyance – Robotics Business Review

In a recent call with a customer, I was told they were looking to build a new facility and investigating installing a tow-line to index our build carts down the assembly line. The company really liked the flexibility and scalability of an automated guide vehicles (AGV) or autonomous mobile robots (AMR), but they believed a tow line may have a higher ROI.

On the surface, this customers initial inclinations seemed plausible. The assembly line under evaluation was 20 build stations, with moving build carts that were designed for up to 4000 lbs each. As we dug into the application, however, we quickly realized that it was not necessarily true that tow lines are vastly more cost efficient than AGVs. The same holds for AMRs, but given the weight of the product in this assembly line, an AMR solution was not appropriate.

Two ConsiderationsThe analysis began with a review of the processs takt time, that is, the time needed to complete a product to meet customer demand. The customers process was set to 46 minutes. We also examined how much time is allocated to each workstation before the line must index forward.

When assessing a process with long takt times for AGV vs tow line conveyance, there are two key considerations:

Build Carts and AGVsWith more time in station, AGVs have more time to move between stations. It is therefore critical to understand if the AGV must be dedicated to each build cart or if the carts and AGVs can be separate entities.

In many instances, there is no technical need for the AGV to be permanently connected to its companion frame cart that sits on top of it. In these scenarios, tunneling AGVs are a feasible solution that can lead to cost savings. This simulation highlights how only a small number of AGVs can be used to index an entire assembly line.

As the name implies, a tunneling AGV is a vehicle that tunnels underneath a build cart and engages via a pin mechanism. While the pin is engaged, the cart is coupled to the AGV and moves to where the AGV takes it. Once the AGV positions the carts in their next stop, the AGV disengages and is free to go move something else.

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AGVs & AMRs as Alternatives to Tow Line Conveyance - Robotics Business Review