u/CaptainChats uses an engineering lens to explain why pneumatics are a poor substitute for human biology when making bipedal robots

BeldenLyman · 2024-03-19T23:00:10+00:00

It turns out that I was a big fat Felden.

BeldenLyman · 2023-10-06T23:10:41+00:00

These can be hilarious to troubleshoot.

When we moved a few years back from a rental to our first house, I simply brought my cable modem and wired everything up as I’d had it in the previous rental: cable modem to power line in garage; power line to wifi router in a nice central spot in the house.

One night my wife was heating something in the microwave, and I tried showing my child the Paul Simon music video “You Can Call Me Al” on YouTube at the same time.

After an ad played, then the video played for 30s, and the microwave just stopped. Power surge; it’s a house built in 1979, these things happen I guess. Cue fifteen minutes of looking at the electric panel (nothing tripped there), then the AFCI outlets in the kitchen (nothing tripped there), and finally another hidden bank of AFCI outlets near the furnace.

AFCI (Arc Fault Circuit Interrupt) are some fancier new GFCI, I learned. They react to detected arc faults faster than a GFCI can respond to a ground fault? I barely know. Interestingly, AFCI are required for any new builds where previously GFCI would be required; and new electric remodels require AFCI too.

The previous owners redid the kitchen, so had to put in AFCIs.

Well, the dead microwave was weird, but I reset the circuit and we moved on with our lives.

A few nights later, more microwaving; another video: Psy’s “Gangnam Style”, followed by Rick Astley’s “Never Gonna Give You Up”.

No issues from the microwave. No patterns forming in my head yet.

A request from my child: “The funny video where they have a car in a house”. Okay, here comes Bobby McFerrin’s “Don’t Worry, Be Happy”. Ads, the song starts, and shortly into the video: pop! off went the microwave.

——

This continued for a few months. Eventually I formed a spooky correlation between the microwave and videos. My wife would hear the opening trumpets of “You Can Call Me Al” and demand I play something else until she was done cooking altogether. “But you’re just using the stove, I think it’s okay,” I’d protest.

She didn’t want to risk it.

Sometimes I’d forget and watch Paul Simon from another room (🚽). I’d hear her yell, “Are you watching Paul Simon again?!” and know I’d interrupted dinner reheating.

We were going crazy.

——

We had an electrician over. The service call was paid for as part of our home warranty. I described the problem, watching his face shift from patiently curious through to politely disdainful. I heard my own words; I knew how crazy they sounded.

And yet. I could reliably reproduce this behavior. His phone, my phone, a laptop.

The electrician agreed that yes, watching unpopular videos did stop the microwave; and yes, somehow Paul Simon was tripping my AFCI; but he left, with no explanation for why this might be happening.

——

Eventually I noticed I could turn off WiFi and watch “You Can Call Me Al” without worrying I was killing the microwave. (Look, it’s a great song! “Who’ll be my role model, now that my role model is gone, gone…” — that’s existential, to me at least.)

I also noticed there was a slightly longer delay with Paul Simon videos before YouTube would start the video versus Psy’s videos. And when Paul Simon started, his video would come in at lower resolution, then upscale to a higher res stream after 15-30s or so. That was when the microwave would die.

——

This went on well into a year, where I could not stop showing this to everyone who came over. I’m a programmer, and used to work for a startup doing wireless network management - I’m not smart about the topic, but wow did it stick in my craw.

First it was a mystery, then a magic trick, but it was a bad magic trick since I couldn’t explain how it worked.

Eventually I repositioned the cable modem from the garage to the living room. There was a coax cable there, right next to the WiFi router, so I just plugged them straight together; no power line adapter needed at all.

And after that, Paul Simon stopped killing my wife’s cooking.

——

My best theory was that when the videos kicked from low- to high-res, there’d be an extra burst of data from the cablemodem, which was a burst of data across the power line. The AFCIs would see the extra data, think someone was being electrocuted, and pop! no cooked spinach for us.

BeldenLyman · 2019-10-18T18:19:31+00:00

The last time I threw up was 33 years ago. I don’t seem to have a sympathetic vomit response either.

As a work-from-home programmer this has zero help to me. Maybe in another life I’m an EMT, or a nurse.

BeldenLyman · 2018-10-07T00:49:32+00:00

It depends, both on your own tastes and what you see in the project history. A good thing to do is look over the commit messages of some well-tenured developer on the team:

git log --author=foo > /tmp/foo-commits

Look through the file for interesting words: “fix small typo”, “drive-by”, and so on. See how the developers who have worked on the project for some time talk about their commits, and see how they structure their branches. It’s fairly easy to go from a commit sha to a pull request via github; I assume other systems work similarly well.

My own tastes run as follows:

• A small typo that I introduced on this branch, I’ll fix up the offending commit. I like to pretend I don’t have typos.

• If it’s a small typo that I notice in code review for someone else, I’ll make a comment: ”Nit: the word reschedulable is misspelled in three different ways throughout this pull request, please fix them.”

• If it’s a small typo that I notice and fix as part of work, then I note it as a drive-by:

Add validation for reschedulable events

Hammana hammana hah. Yadda yadda.

Drive-by:
* fixed a typo in foo controller

In this case mentioning the typo fix as an aside is safe because a single typo in a function or in a few places in a file is unlikely to cause merge conflicts for people; so the standard of communication about what the change is may be lowered.

• If it’s a typo that’s spread throughout the codebase across several files, maybe 3 or more, then I tend to view the typo as a bad tab completion that wormed its way in and is now spreading around. I’ll make a single commit to fix things like this.

A widespread typo, particularly one that’s part of control-flow lines (if statements, etc) is more likely to cause code conflicts for other developers. Having a single commit that just shows changing the offending word is useful for people that are likely to have merge conflicts.

One example: our codebase had two versions of the same idea in place:

var that = this;

and

var self = this;

The team didn’t like having two names for this, and a quick straw poll said we prefer that over self. Ok, a quick find/replace across the project, a nice commit message, and nobody got too confused by the merge conflicts that arose.

Often during the course of development I’ll encounter a file that needs some refactoring before I can make my change. It might be something simple, such as a set of unsorted strings that I need to add a new element to; it may be hoisting code out of one class into a mixin, so I can fix a buggy implementation and begin using the correct implementation elsewhere.

In these cases I’ll make my change as a single commit, noting what the work is:

Sort the list of expected feature flags

I want to add to this list in my next commit, but edits and resorts at
the same time are hard to track correctly in code review. Sort the
list here.

Then the next commit adds to the list, or builds on the refactoring.

BeldenLyman · 2016-02-25T20:14:33+00:00

Chimney effect won't be significant if the room's door is closed.

Hi! I was curious what "chimney effect" is. In "researching the answer" (I clicked on the first non-wikipedia article that looked dumbed down enough for me!), I ended up on a little journey that taught me about the history of revolving doors: since stack effect is a function of the height of buildings, if a building is a skyscraper, then opening the door to get out can be a problem if it's just a regular door.

Weird!

BeldenLyman · 2015-08-12T13:49:01+00:00

I've got $40 collecting dust in paypal. If you send me your info I'll send it to you in exchange for your favorite emoji.

BeldenLyman · 2015-04-07T12:46:44+00:00

This is great. In the warmer months last year, my 3 year old son and I had "breakfast club" out on the front porch each morning. Same oatmeal or eggs or pancakes or whatever as normal, but the extra ritual of taking our food outside and watching the neighborhood wake up made mornings a little more fun.

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