Skip to main content

A useful module for production system simulation and optimization

Project description

prodsys logo

prodsys - modeling, simulating and optimizing production systems

Build-sucess PyPI PyPI - Python Version Docu DOI

prodsys is a python package for modeling, simulating and optimizing production systems based on the product, process and resource (PPR) modelling principle. For more information, have a look at the documentation.

Installation

To install the package, run the following command in the terminal:

pip install prodsys

Please note that prodsys is currently only fully compatible with Python 3.11. Other versions might cause some errors.

Getting started

The package is designed to be easy to use. The following example shows how to model a simple production system and simulate it. The production system contains a single milling machine that performs milling processes on aluminium housings. The transport is thereby performed by a worker. At first, just import the express API of prodsys:

import prodsys.express as psx

We now create all components required for describing the production system. At first we define times for all arrival, production and transport processes:

milling_time = psx.FunctionTimeModel(distribution_function="normal", location=1, scale=0.1, ID="milling_time")
transport_time = psx.FunctionTimeModel(distribution_function="normal", location=0.3, scale=0.2, ID="transport_time")
arrival_time_of_housings = psx.FunctionTimeModel(distribution_function="exponential", location=1.5, ID="arrival_time_of_housings")

Next, we can define the production and transport process in the system by using the created time models:

milling_process = psx.ProductionProcess(milling_time, ID="milling_process")
transport_process = psx.TransportProcess(transport_time, ID="transport_process")

With the processes defined, we can now create the production and transport resources:

milling_machine = psx.ProductionResource([milling_process], location=[5, 5], ID="milling_machine")
worker = psx.TransportResource([transport_process], location=[0, 0], ID="worker")

Now we define our product, the housing, that is produced in the system. For this example it requires only a single processsing step:

housing = psx.Product([milling_process], transport_process, ID="housing")

Only the sources and sinks that are responsible for creating the housing and storing finished housing are misssing:

source = psx.Source(housing, arrival_time_of_housings, location=[0, 0], ID="source")
sink = psx.Sink(housing, location=[20, 20], ID="sink")

Finally, we can create our production system, run the simulation for 60 minutes and print aggregated simulation results:

production_system = psx.ProductionSystem([milling_machine, worker], [source], [sink])
production_system.run(60)
production_system.runner.print_results()

As we can see, the system produced 39 parts in this hour with an work in progress (WIP ~ number of products in the system) of 4.125 and utilized the milling machine with 79.69% and the worker for 78.57% at the PR percentage, the rest of the time, both resource are in standby (SB). Note that these results stay the same although there are stochastic processes in the simulation. This is caused by seeding the random number generator with a fixed value. If you want to get different results, just specify another value for seed parameter from the run method.

production_system.run(60, seed=1)
production_system.runner.print_results()

As expected, the performance of the production system changed quite strongly with the new parameters. The system now produces 26 parts in this hour with an work in progress (WIP ~ number of products in the system) of 1.68. As the arrival process of the housing is modelled by an exponential distribution and we only consider 60 minutes of simulation, this is absolutely expected.

However, running longer simulations with multiple seeds is absolutely easy with prodsys. We average our results at the end to calculate the WIP to expect by utilizing the post_processor of the runner, which stores all events of a simulation and has many useful methods for analyzing the simulation results:

wip_values = []

for seed in range(5):
    production_system.run(2000, seed=seed)
    run_wip = production_system.post_processor.get_aggregated_wip_data()
    wip_values.append(run_wip)

print("WIP values for the simulation runs:", wip_values)

We can analyze these results easily with numpy seeing that the average WIP is 2.835, which is in between the two first runs, which gives us a more realistic expectation of the system's performance.

import numpy as np
wip = np.array(wip_values).mean(axis=0)
print(wip)

These examples only cover the most basic functionalities of prodsys. For more elaborate guides that guide you through more of the package's features, please see the tutorials. For a complete overview of the package's functionality, please see the API reference.

Run prodsys as a webserver with REST API

prodsys cannot only be used as a python package, but can also be used as a webserver by interacting with its REST API. All features of prodsys are also available in the API and allow easy integration of prodsys in operative IT architectures.

The API is based on the FastAPI framework and utilizes the models API of prodsys. To use prodsys as a webserver, you can use the official docker image which can be obtained from dockerhub:

docker pull sebbehrendt/prodsys

To start the API, run the following command:

docker run -p 8000:8000 sebbehrendt/prodsys

The API documentation is then available at http://localhost:8000/docs.

Contributing

prodsys is a new project and has therefore much room for improvement. Therefore, it would be a pleasure to get feedback or support! If you want to contribute to the package, either create issues on prodsys' github page for discussing new features or contact me directly via github or email.

License

The package is licensed under the MIT license.

Acknowledgements

We extend our sincere thanks to the German Federal Ministry for Economic Affairs and Climate Action (BMWK) for supporting this research project 13IK001ZF “Software-Defined Manufacturing for the automotive and supplying industry https://www.sdm4fzi.de/.

MIT License

Copyright (c) 2023 sebastian.behrendt

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

prodsys-0.8.3.tar.gz (124.3 kB view details)

Uploaded Source

Built Distribution

prodsys-0.8.3-py3-none-any.whl (165.8 kB view details)

Uploaded Python 3

File details

Details for the file prodsys-0.8.3.tar.gz.

File metadata

  • Download URL: prodsys-0.8.3.tar.gz
  • Upload date:
  • Size: 124.3 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No
  • Uploaded via: poetry/1.6.1 CPython/3.11.4 Windows/10

File hashes

Hashes for prodsys-0.8.3.tar.gz
Algorithm Hash digest
SHA256 3278165a00e2a0803417cce3fed0ba66ee6458e894b88f4a4d10b170c1101ce1
MD5 e0fca69bd18460f7e1d643ce5981b45a
BLAKE2b-256 2af2aa49b315d7cafbf179f923ddd95c6b7336b4da7db58cfff2434088da7b1c

See more details on using hashes here.

File details

Details for the file prodsys-0.8.3-py3-none-any.whl.

File metadata

  • Download URL: prodsys-0.8.3-py3-none-any.whl
  • Upload date:
  • Size: 165.8 kB
  • Tags: Python 3
  • Uploaded using Trusted Publishing? No
  • Uploaded via: poetry/1.6.1 CPython/3.11.4 Windows/10

File hashes

Hashes for prodsys-0.8.3-py3-none-any.whl
Algorithm Hash digest
SHA256 f69f7f0b05dbac7474e845b42a406034e96eb2f4f0f14d9cf0f1f8b39f47bfc6
MD5 6b08de1ba3ccdbf869d031920df066f2
BLAKE2b-256 3839ca0a5936ea08b4b706b9e69a1db605473c4b06f5f9267c60d1080567030b

See more details on using hashes here.

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page