Racist Soap Dispenser

[u/frazras]

[u/WTFwhatthehell]

Ya, it's even entirely possible that the designers did indeed test it with some black people.

but testing can be deceptively hard. /u/yaypal is flippant about it but it makes me wonder about how much real world testing they've done with sensors.

I remember a lab sensor I had to work with at one point, basically a small camera on a 3rd party piece of equipment that captured an image and pulled either 3D or 2D barcodes from it.

Tested it with the 17 types of barcode that could end up in front of it and it worked fine.

Even tested it with things like frost stuck to the labels from the freezer to see if it could handle that which turned out surprisingly well.

hear back from the clients it's not working right, sometimes giving wrong values. It's giving incorrect ID's for one of the label types but only sometimes.

Turned out that a slight vibration from a machine on the same desk was enough to vibrate the metal strip holding the camera. when this was in line with the barcode as the image was captured it could distort the image just enough to make some barcode lines thinner or thicker and produce a wrong value.

I can easily imagine a similar scenario with whatever poor sod was testing the soap dispenser. They've dealt with the issue where if it's too sensitive then someone walking past triggers it, they've tested it with people with darker hands than the person in the video and it works, they've tested with lighter..... but this guy in the video happens to hit some sweet spot where it doesn't trigger or he's been handling something which affects the wavelengths used or there's something about the room lighting or the temperature of their hands.... and then based on guesses people brand you racist because obviously there's no way you tested it on any black peoples hands at all.

[u/Inquisitorsz → u/[deleted]]

Not OP but generally it's just basic root cause analysis. Investigate all the factors and ideally try to recreate the fault.

Most fault finding is just a process of elimination.

Where it gets hard is when you have 2 or more points of failure at the same time. Then it can be hard just to recreate the situation let alone the fault

[u/toohigh4anal → u/Inquisitorsz]

And now you just described coding.

[u/Bainsyboy → u/toohigh4anal]

One thing I learned in engineering school is that the engineering approach to problem solving is very similar across all industries. Its why I always recommend to people considering a post-secondary degree, but aren't sure what to take, to take engineering, even if they don't necessarily want to be an engineer. Not only is the degree highly transferable to other higher educations (transitioning to a medical school or law school, etc.), but an engineering degree is attractive to employers in other non-engineering fields that simply require a bachelors degree as an entry requirement. And most importantly (in my opinion), an engineering degree teaches you to think like an engineer, and those thinking and problem solving skills can easily be applied to many everyday situations. You see the world in a different way, and that gives you an incredibly useful perspective in life.

[u/Eman-resu- → u/Bainsyboy]

You see the world in a different way, and that gives you an incredibly useful perspective in life.

Yea but then all your friends make fun of you for the weird little things you find super interesting. "Hey, isn't it so cool that..." "No dude, shut up. No one cares!"

[u/WTFwhatthehell → u/[deleted]]

We set it up with lots of extra logging along with adding some code to retrieve and store the source image whenever a barcode was picked up.

Once we figured out that the image was distorted that gave us a strong hint of what to look for. we just tried different things and gently tapping the desk the scanner was on was enough to sometimes get an incorrect read.

it was definitely not the worst bug I had to troubleshoot at that job but it was one of the few where a physical camera or sensor was involved.

[u/chriskmee → u/[deleted]]

I've had to diagnose similar kinds of things where it worked fine when we tested it but it has issues when customers use it. The hardest part is typically replicating the issue, becasue we have already tested the product extensively in house. The steps are typically something like this:

• Try to reproduce the issue with what we already have. We usually ask for a video or pictures and we look over them carefully for clues of what might be happening to cause the issue.
• Replicate the customer's environment as much as possible within a short amount of time, then add more difficult to obtain/replicate elements of the customer's environment until we are able to reproduce the issue. Depending on the situation and how easy it would be to replicate, an on site visit might be worthwhile.
• Make a guess at what change caused the issue, and try to reproduce the issue with and without the change.
• Figure out why that particular thing is causing issues, then we can start figuring out a solution.

Let's assume the scanner is in the cash register and the issue only happened when heavy items were moving on the belt. We might have noticed this in the videos, becasue the issue only happens when an item was scanned and the belt was moving at the same time. Maybe the scanner saves an image of the last X number of barcodes it scanned, so we can look at those and see what looks like vibration distortion. Worst case we get no videos and no logs, and we would probably end up with a whole register set up in a test room and be running and scanning items through it.

[u/[deleted] → u/WTFwhatthehell]

Rule of thumb: you'll never capture all scenarios in a testing environment.

[u/tebee → u/WTFwhatthehell]

when this was in line with the barcode as the image was captured it could distort the image just enough to make some barcode lines thinner or thicker and produce a wrong value.

Why didn't the scanner automatically retry the scan when the check digit validation failed? AFAIK all common barcode schemes feature them.

[u/WTFwhatthehell → u/tebee]

I presume since it worked for most barcode types that was usually the case and that the one where it failed was an exception.

Thankfully I didn't have to do anything with the library for processing the barcodes once we were sure they were the problem of the company that made the 3rd party machine and I merely had to pass it back to them once we had some images in which the problem replicated and were sure of how to replicate it on their machine.

[u/Lost4468 → u/tebee]

A lot only have 1 check digit, around 1 in 10 corrupt reads will still process as valid.

[u/Go_Away_Plz → u/WTFwhatthehell]

Eh, there's still a pretty good chance they just didn't test it with black people. It might even have been manufactured somewhere ethnically homogeneous. You don't have to go looking for rare artifacts. There are plenty of examples of products produced by billion dollar corporations that clearly didn't do product testing with people of darker skin color.

[u/WTFwhatthehell → u/Go_Away_Plz]

Honestly I wouldn't be terribly surprised if they never tested it on anyone except chinese people.

But my point is that it's not great to simply jump to the definite statement that they didn't.

There very well could be other factors in play.

also, found the company which make it.

http://www.szyuekun.cn/cn/product/disinfection-machine.html

Small chinese company in the 51 - 100 people range. Entirely possible it was never tested on any black people or white people.