Getting Started

For this challenge you'll need to control cranes moving around in the warehouse - you'll be given a list of palettes to pick up and a list to drop off. You'll need to write a set of instructions for the vehicles in advance, and then we'll time how long it takes them to complete.

Contents

• Locations
• AGVs
• Simulator UI
• Instructions and Scheduling
• Scenarios
• Success

Locations

The warehouse model you're given is in three dimensions, and you'll need to refer to locations to store and retrieve stock. The simulator refers to locations in the form x.y.z.

Aisles

The X component refers to the aisles, which run horizontally and are numbered from 0 to 8.

Some aisles can be used to store palettes, and the others are used to drive vehicles along.

Stacks

The Y component refers to the stacks, which run along each aisle and are numbered from 0 to 14.

Each stack location effectively represents a floor tile.

Cells

The Z component refers to the cells, which are stacked on top of each other to create a stack. Stacks in vehicle aisles with no storage space don't have any cells.

A cell can store 1 palette.

There are two special stacks/locations, which are represented on the diagrams above (and in the sim) as coloured squares:

• The pickupStack is where you'll pick up palettes to store - you'll have to empty this stack for your solution to be considered successful. It's shown in green, and located at 0.0.
• The dropoffStack is where you'll deliver any palettes that need to be extracted from the system. Each scenario will define a list of palettes that must be delivered for your solution to be considered valid. It's shown in red, and located at X.0 where X represents the total number of aisles.

AGVs / Cranes / Forklifts / Drivers

AGVs (automated guided vehicles) are the items you'll be moving around the warehouse. In this simulation they can be considered interchangably between human forklift operators or automated cranes - the principles are the same. (Image credit: CNET).

AGVs can occupy any stack that isn't a storage location. Storage locations contain racking and have cells which can store palettes, so can't be driven over. Conversely, you can't store palettes on a non-storage stack, as it doesn't have any racking to store palettes (and is needed for access). This stops you blocking yourself into a corner.

You can instruct AGVs to navigate to anywhere in the locationIndex, which includes:

• A stack ('floor tile') location in the form X.Y, that is a non-storage location.
• A stack location in the form X.Y that is a storage location (the simulation will automatically correct to the nearest adjacent non-storage location).
• A valid cell storage location in the form X.Y.Z. As above, the simulation will correct the instruction to the nearest valid non-storage stack location.
• One of the special stacks, either pickupStack or dropoffStack.

AGVs will automatically choose a route to navigate between the current location and your chosen destination. The sim has no sense of acceleration or cornering - AGVs progress at a steady rate of one stack per second.

The simulator UI

The simulation UI is where you'll validate your solutions to each scenario. It takes two text inputs from you, and runs them against each other:

• The scenario definition. We'll release these, although you are welcome to try writing your own to test your approach. This defines the initial state of the simulation and lists palettes you'll need to store and retrieve. This text file should be the input to your solution.
• The instruction list. This is a list of instructions, addressed to AGVs, for work to be carried out to meet the requirements of the scenario. This text file should be the output from your solution.

Both text files are delimited by (first) spaces and (second) line breaks. Your instructions shouldn't contain extra whitespace, indentation or comments.

The UI contains a model of the warehouse in the centre, which will change as the simulation runs. It also contains two panes, the AGV pane and the Sim pane. You can show or hide these panes at any time using the toggle buttons (shown in blue on the diagram above).

The logs (shown in red) give you information about the currently running simulation. If there's a simulation running you'll see a timestamp in ms in the form [123] before the comment. Regardless of the time factor, these timestamps will always be in wristwatch time.

Instructions and Scheduling

Each instruction takes the following form:

[AGV-id] [action] [parameter]

Each instruction is addressed to an AGV, indexed from 0. Each instruction contains an action, and an optional parameter.

Here's a list of acceptable instructions:

Scheduling

You're responsible for scheduling work for the AGVs - there are no instructions to wait for another AGV to complete their task. The time it takes an AGV to complete any task is known, so you should always know what task your AGVs are performing.

Scenarios

Success

Read all this? Why not try our worked examples?