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requirements.md

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Informal Requirements for Door and Door Lock

  1. will not allow a child to get stuck
  2. can be closed/monitored against critters/teenagers
  3. does not require physical keys

Q&A Between Collaborators

What does closed/monitored mean?

  • Does the system need to close the door, or simply engage the lock?

    • TDS: I think just engage the lock. An actuator that could close the door introduces a whole new variety of safety risks.

  • Does monitored mean the state of the lock (e.g., locked/unlocked), or the inside of the fort for motion/presence of critters/teenagers?

    • TDS: Good question. Ideally both.

  • What size of critters are of interest? Mice or raccoons?

    • Mice are going to be hard to keep out entirely, since they can fit through very small spaces.
    • I'm planning to make this tight enough to keep our anything rat-size or larger.

  • Is a physical button, switch, or ability to actuate the lock from the inside acceptable to meet needs 1 and 3?

    • TDS: Yes.

  • Question: Can you expand on monitoring against critters and teenagers more?

    • TDS: For the purpose of the core project, I'd just like to log door open/close events.

  • The original discussion was a "wifi enabled" system, which to me implies status to a remote system that may warn of critters and teenagers. Is this required?

    • TDS: Not required for this project. It's more of a tangent.

  • Alternatives may include an alarm system if motion is detected without authorized entry or outside of normal hours (e.g., 2am entry). Another alternative is local logging or status indicators on the lock system's processor that can be periodically checked.

    • TDS: I'd like to have a notification system that alerts me to motion in the fort outside of regular play hours. I suppose the simple solution would be a Ring-style security camera with motion detection, but where's the fun in that? Either way, a security alert system is outside of the scope of this project, which is the lock system itself.

Safety

  • The door can always be opened from the inside
  • No harm to the occupants of the fort (sharp objects, falling objects)
  • No risk of electrical shock
  • No risk of fire

Power

  • Power source in fort? AC available?
    • TDS: Fort has AC power (via outdoor extension cord). Also planning on solar, possibly DC battery.
    • TDS: I'd like the power usage to be relatively low - 10 watts would be good.
  • Desired/required battery backup?
    • TDS: I'd like this to fail safe (i.e. unlock if power goes out)

Environmental

  • What environmentals do we need to consider?
    • Thermal, yes (min/max temps).
    • Shock/vibration, probably not unless making components (e.g., the lock).
  • What is the min/max temperature expected in the fort? Assume most parts are sheltered from the elements directly (no direct sunlight, no rain/snow on equipment, no wind).
    • The fort has no environmental control and is off the ground. Its temperature is basically the temperature outside.
    • TODO: Throw a temp sensor in the fort to gather data? Issue created: #2

Communication and Control

  • Also, a keypad? Or, where’s the wifi?
    • TDS: The fort is close enough to our house that wifi makes sense as a monitoring option.
    • TDS: I was originally thinking a keypad for entering a passcode, wifi on the board.
  • Will there be a keypad in addition to wifi?
    • TDS: I think so.

Unsorted

  • Electrical components shall be enclosed to restrict access from humans, critters, and the environment.
  • Enclosures shall have a TBD rating (e.g., IP67, IP68, or less?)
  • Enclosures should have access control to limit unauthorized users (i.e., children) from tinkering
  • Wiring shall be enclosed in conduit to prevent damage from external sources (e.g., critter teeth, accidental play such as ball or stick dislodging/pulling cables out)
  • Conduit shall have TBD rating
  • Conduit and enclosures shall be compatible

Open/Uncategorized Questions:

  • What level of redundancy is desired? And where?
    • TDS: I want redundancy for safety needs (i.e. I want high assurance that the kids can exit) but do not need redundancy for security (if something fails and the door does not lock, that's OK).
  • What is the budget? $100? $1000? $10000? Not just piece-parts, but labor and material for say trenching the yard for wired connections, or adding solar per the above, and so on? (Examples are purposefully expensive sounding... I hope no yard trenching)
    • TDS: Around $100, I'm planning to use budget as a nice design-trade metric, so we'll design a couple of options at various price points and risk levels. I'm already pondering solar options, so that won't be factored into the price.