This elevator was written in Elixir as part of the TTK4145 Real-time Programming course at the Norwegian University of Science and Technology.
Upon startup, nodes on the same network will automatically find each other and connect, creating a cluster of nodes, each node controlling one elevator.
The flow of information during normal operation can be described roughly in pseudocode
Boot all modules
Continuously look for new nodes on the network, and add to our cluster
ButtonPollers poll the Driver
When button is pushed
Add the order to all watchdogs in the cluster
If the order is a cab order
Add the order to a queue of orders on the node the button was pressed
If the order is of any other type
Bidhandler asks all nodes in cluster for a bid on the order
Each node returns a bid based on a cost function
Bidhandler chooses the best bid
Add order to queue of orders on the selected node
Once an order is in the order queue, the FSM will pop off the top element and communicate with the elevator through the Driver layer.
The program consists of several modules. It is written mostly using GenServer calls and casts to more easily facilitate communication across different nodes on the network.
Controls the elevator through a TCP port. Contains all the functions necessary to control all the features on the elevator. We can get and set lights, we can fetch what floor the elevator is on, set motor direction, etc...
Polls all the buttons on the elevator and communicates with the BidHandler and OrderHandler.
Makes sure all orders are completed. Will redistribute orders to other elevators if they take too long to complete.
Handles the request queue and order queue on the current node.
Agent which makes sure the elevator is only restarted once when a cab order is not cleared in time.
Agent to keep track of the direction of travel.
Agent to keep track of current floor.
Agent to keep track of door state.
Finite State Machine for the elevator.
Communicates with other nodes to facilitate which node gets an order.
Add Erlang Solutions repo
wget https://packages.erlang-solutions.com/erlang-solutions_2.0_all.deb && sudo dpkg -i erlang-solutions_2.0_all.deb
Update package manager
sudo apt-get update
Install the Erlang/OTP platform and all of its applications
sudo apt-get install esl-erlang
Install Elixir
sudo apt-get install elixir
Assuming you're on Ubuntu/Debian
apt install tmux
The elevator can be run as a D simulator found here
Change the directory of the SimElevatorServer calls to the directory where you downloaded the simulator
To run the elevator, open any terminal window and run
mix compile && mix escript.build && ./elevator 0