Using FlexSim Simulation tool for AGV Modelling

AGV projection using FlexSim simulation tool

Introduction on an AGV

Traditionally, transporting raw material loads, or items in a warehouse or factory is inconsistent. That is, by using forklift trucks, conveyors, or a manual cart, the inconsistency is high. However, Automated Guided Vehicles (AGVs) are consistent and predictable in transporting loads of material. Using the FlexSim Simulation tool you can simulate the AGV and model the necessary operations efficiently.

AGVs glide along predefined tracks of an assembly line, warehouse environment etc., thereby transporting items as per their schedule.  You can use an AGV when there is a requirement to transport high volumes of material repeatedly. Furthermore, the need for human decision making is little.

Main application areas of AGV

  • Kitting area –  For gathering raw materials for the assembly.
  • Assembly area – Moving products through the production process.
  • Staging area – To deliver pallets for production processes.
  • Order picking area – Moving the ordered items either to the docking area or for providing the bins to the picker for picking items.
  • Ad-hoc Delivery – AGVs come with a towing feature as well. So, you can customize the number of trolleys you require for the pick up depending on the order.
  • Shuttle – For use in congested places where human access is difficult or inefficient. Usually AGVs used for this purpose, service narrow aisles transporting high demand items.

Benefits of using an AGV

  • Accountability – Can ensure that the quantity of items picked-up and delivered are same.
  • Automatic line balancing – Can replenish raw materials automatically in production or assembly areas.
  • Cost reduction – Repetitive manual work is certainly expensive. Therefore, AGV reduces the cost by a large degree.
  • Flexibility – You can customize the size and number of the AGVs as per the need of the warehouse.
  • Reduction in product damage – Reliability and precision are ensured when using AGV. Hence, the probability of product damage is low.
  • Repeatability – You can schedule the AGVs to perform tasks repeatedly.
  • Safety – As a result of minimizing human intervention, accidents are avoided.
  • Scheduling – AGV prioritizes tasks and performs them according to the schedules and rules.

Challenges faced when determining Optimum number of AGV’s

Though AGVs have a lot of advantages including increased throughput, and reduced inventory-holding cost, they are expensive investments. Finding the right number and configuration for the AGVs as per the warehouse needs is a critical challenge.

Analytical method of determining the number of AGVs cannot consider all the real-time conditions about the warehouse. A simulation-optimization approach to calculate the optimal number and schedule of AGVs can be a better solution.

Simulation Approach with FlexSim

FlexSim Simulation is a powerful and user-friendly tool that can mimic the warehouse operations accurately. FlexSim has a separate AGV library that helps in quickly building an AGV based simulation.

The user has the liberty to define the park point, the pick-up point and destination point of a task, the path to reach its destination, load or unload the materials, look for next assigned job and many more. One of the most useful features in AGV module is the network path. The network path defines the path in which the AGV will travel thus simulating the real-time environment.

Common commands used in FlexSim to model an AGV system:commands of the FlexSim simulation tool to model an AGV

  • Parking point – to define the AGV’s parking or resting area when it is free.
  • Next Look-For Work – to make the AGV check whether it has any task assigned to it.
  • Look-For work– to pick the highest priority work if more than one task is assigned.
  • Pick-Up point – to define the source point of the task.
  • Drop-Off point – to define the destination point of the task.
  • Network direction – used to provide step by step navigation orders.
  • AGV speed – to assign different speeds for AGV based on the scenarios. Example scenarios include when the AGV is empty, loaded, while moving in a straight line, while turning etc.
  • Battery capacity (AH)- to input AGV maximum battery capacity into the simulation.
  • Recharge– to set the battery recharging time for AGV.

With the above-mentioned commands, Flexsim Simulation tool allows the user to build an AGV model that imitates the real-world AGV behavior. It then provides the performance metrics listed below:

  • Utilization of each AGV (Idle Time, Processing Time, Travel Loaded, Travel Empty, waiting time). These can be captured per shift, per hour, per month, per AGV etc.
  • Total distance travelled by AGVs.
  • Effect on throughput per shift when there is an increase or decrease in the number of AGVs.
  • Minimum number of charging station required for charging AGVs.
  • Minimum battery capacity needed for the workload available in the warehouse.

The above mentioned metrics play a vital role in determining the number and configuration of the AGVs needed for a particular system. Therefore simulation tools prove to be the best approach to simulate AGV system.

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