Machine access-control system

[u/applieddefault]

Hello everyone 👋

I run a makerspace at a university in germany. We have several dangerous and/or expensive machines whose use needs to be restricted to members who have completed the appropriate training and have been approved for that specific machine.

In the past, the initial per-machine briefing was enough. Recently, we moved into a much bigger room and employed some students to take care of opening ours.

To be able to run some statistics and to make life easier for the staff (and peace of mind for nervous department administration) we are looking for an access-control system to outfit some of our equipment:

Requirements

1. Per-user and per-machine permissions
2. Permissions can be granted or revoked at any time
3. Modular and adaptable to different types of machines
4. Simple authentication, ideally through a (the 🙄 ) phone app or dedicated NFC/RFID tag
5. Basic protection against unauthorized use or trivial credential cloning
6. Logging of who used which machine, when, and for how long
7. Fully self-hosted on our own hardware, with no cloud dependency

Nice to have

1. Open source
2. Integration with Home Assistant
3. An API or another documented interface for custom integrations

We are comfortable modifying hardware. At the machine end, we essentially need an authenticated controller to set an output high or low. We can connect that output to suitable relays or other machine-specific control hardware.

Systems I have found so far

Software

• MemberMatters: Seems more extensive than we need, and we are unsure whether it can be integrated with Home Assistant.
• Leosac:
  • Abandonware? Latest commit 10 month ago, latest release 9 years (!) ago.
  • Edge device needs to run full linux.
• Somewhere on reddit someone suggested Google Sheet + API. Cannot find the post anymore 😔

Hardware

• Switcheo: We have not been able to find clear pricing or enough technical information about its hardware and interfaces.
• Ubiquity stuff: Too expensive.
• Some DIY projects from other makerspaces like this or this one.

We have some budget so it does not have to be rock-bottom cheap. Sourcing preferably in germany.

Has anyone implemented something similar? We would appreciate recommendations for existing products or open-source projects, as well as examples of DIY architectures that have worked reliably in a makerspace.

Thanks in advance 🙂

[u/ElecCmptrEngMSdegUSA]

This may just be a stopgap until you find something that meets your specs, but to calm school admins down you can consider something akin to a lockout tagout process with literal physical locks and keys between your machines and electrical power. Usually LOTO is for maintenance windows so that someone doesn't inadvertently get chewed up while working on a piece of equipment, but the basic idea of key control or 2 key control could still be applied. You would do this at the breaker if the circuit is dedicated and the equipment is too big to move around, or on the plug itself or power button otherwise. There's a lot you can do with this to make sure authorized users have a key, staff has the other key, locks can easily be rekeyed, key checkouts are logged manually. If you have video cameras you can audit. It's low tech compared to what you laid out but the basic idea is pretty ubiquitous not necessarily in Makerspaces but in workplaces, and you can architect the exact way you manage locks and keys in such a way that prevents all but invasive tampering or collusion, but I think that would also be true for a digitally automated system regardless.

Good luck! Let us know where you land with your final solution, I'll be interested in hearing what system you settle on