Rename kill switch to emergency stop

[Claudio-Chies]

Description

The Idea is to rename Kill with Emergency Stop as it is more descriptive and is much more expressive than a simple "kill"

Currently the PR changes the messages and all internals excluding the Parameters, there i'm not sure if changing the parameter names is a good idea, but would have to be done to be consistent.

With this we would then have an "emergency stop" action, this only changes the wording, not the functionality

open for discussion, would like some feedback on the idea
@dakejahl @MaEtUgR

[github-actions]

No flaws found

[dakejahl]

Emergency Stop seems objectively better, but Kill is well understood, shorter, easier to say, etc

It feels like the same thing when "Return to Launch" was renamed to "Safe Recovery". The second is more accurate, but the first is well known and easier to say (RTL). I don't think I will ever say "It's safe recovery-ing". In the same way I would tell an operator to "map the kill switch", but then need to explain that it's actually the "emergency stop switch". So I don't know. Ardupilot calls this "Motor Emergency Stop" so I do tend to lean towards Emergency Stop, ignoring the historical baggage.

[hamishwillee]

Emergency stop is used in industrial settings to indicate a mechanism to immediately turn off dangerous equipment as quickly as possible, prioritizing user safety over machine "survival". That is what the feature does.

I don't like it as much kill switch though because to me "stop" means "stop moving" - the only context I would use this term normally is in a car, where it means I'm stopping as quickly as I humanly can.
But a flying drone doesn't stop: it plummets.

By contrast, a "Kill switch" conveys "killing the machine itself", and the plummeting then follows :-)

Upshot, Not wrong, but I don't feel that this will significantly improve things, so not worth the effort.
I haven't looked closely at the actual changes, but I will do so if I am in the minority.

[dakejahl]

By contrast, a "Kill switch" conveys "killing the machine itself", and the plummeting then follows :-)

Yes. Without saying the quiet part out loud. I would say it depends on your perspective.

Motor Emergency Stop would clear up the "stop" confusion. Probably why AP went with it. But I do like the good old kill switch to save my drone. "QUICK, hit the Em-er-gen-cy Mo-tor Stop Switch!"

[Claudio-Chies]

Drones are more and more becoming industrial machines ;) but i get what you mean, i agree that its not a massive improvement, but i feel its a slight more "polished" improvement.
kill switch feels natural because were used to it, the short form would be E-Stop, which is also used as such in industrial applications, so not that bad of a tongue breaker

[hamishwillee]

Drones are more and more becoming industrial machines ;) but i get what you mean, i agree that its not a massive improvement, but i feel its a slight more "polished" improvement. kill switch feels natural because were used to it, the short form would be E-Stop, which is also used as such in industrial applications, so not that bad of a tongue breaker

True, but that would be replacing Kill switch with a term "E-Stop" I have never heard.

Suggest you take it to the dev call.

[hamishwillee]

Did you get a chance to ask in the dev call?

[MaEtUgR]

I plan to kill the kill switch to solve a lot of the confusion and renaming it just before that would only add churn.
The discussion about naming is valuable though. I would plan to keep termination as the term for the functionality, immediately shutting off all actuators for the emergency case but that's up for discussion.

I should write down the clear design plan for that change such that I can reference it in all these discussions and from the beginning on people can bring in their feedback directly.

[dakejahl]

I should write down the clear design plan for that change such that I can reference it in all these discussions and from the beginning on people can bring in their feedback directly.

That would be great. What is the issue with "kill"? And how is "terminate" any better?

At least with Emergency Motor Stop it's the term used for industrial equipment. I could get used to saying "e-stop", and I guess I don't care that much, but if we're going to change it we should have solid justification.

[hamishwillee]

What he said ^^^ .

I plan to kill the kill switch to solve a lot of the confusion and renaming it just before that would only add churn.

Propose we close this PR until @MaEtUgR has made his changes.

W.r.t. kill switch or whatever, I do think documenting what you want to achieve before we start is important. In particular it took me a long time to differentiate between kill and terminate, and I'm still not sure why you would do one and not the other.

While you're at it you might want to see if logically this fits in with the other key actuator states - disarm, prearm, arm, and the weird states where you're armed but the motors aren't turning - such as in hand launch of plane.

I am happy to be involved in this discussion.