# Multi-Agent Simulation Environment for Logistics Warehouse Design Based on Self-Contained Agents
## 5 Experiment to Compare Development Costs  
### Purpose of Experiment  
The purpose of this experiment is to examine the features of development cost reduction and architectural modifiability, by developing the simulation model of logistics warehouse using the existing simulation modeling environment and the environment implemented based on the proposed architecture. This section explains the experimental result of development cost comparison between the proposed simulation environment and the widely used multi-agent simulator NetLogo. We have chosen NetLogo as a compared multi-agent simulation environment. Because NetLogo is expected to reduce the amount codes that need to be written compared to other MAS platforms, as these features are built-in:  
1. A GUI with a simulation space visualization function. Basically, there is no need to add visualization descriptions to the code. 2. Default primitives for manipulating simulation space and objects in the grid world, which is highly compatible with warehouse simulations. Figure 8: Example structure of multiagent simulation model using prototyped simulation modeling environment. Figure 9: Composition of agents, agent workplaces and network environment. 3. A function to output graphic charts of the simulation model's values without additional descriptions. For fairness, we outsourced the development of the simulation model using NetLogo to a software developing company. We only conveyed the simulation model's requirements, input, and output requirement of the simulation model. We did not specify the internal data structure or an agent's communication sequence. We validated the developed model and ensured the validity of experiment in the following manner:  
1. First, when we outsourced the simulation model development, we only provided a description of the simulated system and the requirements of the simulation model, as well as the specifications of the inputs and outputs. 2. Second, based on the requirements, we asked the software developing company to design how to implement the agents using NetLogo, i.e., how to implement the internal states and how to make them cooperate with each other. 3. Third, we reviewed the presented design by the software developing company and asked them to modify the functional discrepancies to the developed model using our modeling environment, so that the functions of the material-handling equipment can be the same. We did not specify how to write the code. We ensured the validity of the experiment by asking them to write the code based on their standard method so that we did not tamper with the experimental results. In addition, we did not disclose our intention to use the outsourced model for development cost comparison. 4. Finally, we checked the delivered source codes to see if there was any unfairness in comparing the development cost. Developed Simulation Model of Logistics Warehouse with Various Robots and Material-Handling Equipment  
The modeling target was an area of a logistics warehouse where several cooperating robots and material-handling equipment were introduced. The area is in charge of the shipping process of picking, sorting, and carrying items from inventory shelves to the shipping area based on the customer's orders. The model includes the function to calculate the productivity of the shipping process. The shipping process consists of the following subsystems:  
* Racrew AGV Picking System: At the beginning of the shipping process, it is necessary to pick items specified by the customer orders from the inventory shelves. The classic configuration to pick items is that people carry a cart with them, walk to the shelf storing the desired items, pick the items from the shelf, then put the items into the sorting bucket in the cart. Finally, the cart goes through the rest of the shipping process, such as item inspection and packing. However, this way of picking is not efficient because people need to walk long distances to finish their picking tasks.