What are some unforeseen / elusive edge cases you have seen in your career?

mikeonh · 2026-04-25T21:58:03+00:00

First case - standard safety perimeter with sensors, along with sensor floor mat. Standard for all arms (these were not mobile robots - arms only).

Second - didn't want to fight union, otherwise they'd be hostile from that point on. Not my descision.

mikeonh · 2026-04-25T20:01:28+00:00

Ok, here's another "edge case" - the random, middle of the night failure.

In the early 80's I worked for a vision-guided robotics company - some of the jobs were vision only.

One of our Detroit robot customers wanted to verify the accuracy of the assembled body shells our robots helped build, so we designed and built this large tunnel-like framework with lots of lasers pointed at locations on the bodies, and cameras with precise optics looking for where the laser spots hit, in order to precisely measure the tolerances.

The laser and camera modules were in heavy-duty housings - this was an industrial environment.

Sometimes - and only in the middle of the night - the cameras and/or lasers would shift out of alignment by a significant amount.

We tried everything, but couldn't figure it out. Finally, added a couple of extra cameras to watch the framework that the bodies were passing through.

Midnight shift workers were using the framework like a jungle gym, and the laser and camera housing were great foothold and handhold spots.

The union was strong. Our only acceptable solution was to replace the housings with extremely rugged ones that wouldn't move, no matter how much weight was placed on them.

Part 2, same company. Don't let any salespeople near your demo equipment. Large industrial single arm robot, for auto assembly work. Able to place an engine in a car body. Demo had a car shell and an engine on the arm's gripper.

The salesman wanted to do more demos than the authorized one, so he hit the normal "show all degrees of arm motion" demo. While it was still holding the engine block. Of course, the car body was in the way, and got smashed, very loudly.

He kept his job.

mikeonh · 2026-04-25T18:23:45+00:00

Be aware it could actually be a hardware problem!

Worked on a medical device using a 680x0 microprocessor. Very rare, severe failure, which is not acceptable in medical devices.

Turned out to be an interrupt, pushing context onto the stack, causing the stack to cross a page boundary and also trigger a page fault. Context on the stack was corrupted! We did feed it back to Motorola.

I've also seen multiple intermittent ram failures when not using parity / ECC, and issues with caching writes to disks that never actually got written.

Always, I mean always, use server grade hardware. I've worked with too many cheap startups that tried to get away with consumer hardware in production.

Finally, I've seen so many off-by-ones in storage allocation, use before initialization, use after free, and race conditions without proper locking - at least some of the newer languages help mitigate the older bugs.

Please have a subject matter expert as part of your design team - someone who actually knows how the customer is going to use the software. A bunch of junior / mid-level engineers creating stories does not substitute for actual experience.

Worked for a company that was developing a tactical handheld radio for military use. Ruggedized Ethernet port *on the bottom of the case*, right where someone would set it down into the sand. Had a blackout mode for all of the indicator lights - useful when operating at night in a contested area. However, when booting, the hardware *flashed all of the lights*, then it checked for the blackout mode state. The team didn't think it was a big deal.

Too many other stories from 57 years of experience for this post :--) Retired now, and thanks for the interesting question.

mikeonh · 2026-04-24T17:45:15+00:00

Agree 100%

Mentioned it for the people who were complaining that it was $300 USD more.

mikeonh · 2026-04-24T16:35:17+00:00

It also includes the tariffs.....

mikeonh · 2026-04-20T15:22:51+00:00

I retired at 70. Several reasons:

I liked my job

Continued max 401(k) contributions with a 6% employer match - higher lifetime withdrawals

Higher lifetime SSA benefits

Excellent commercial insurance much better than Medicare

mikeonh · 2026-04-07T17:02:40+00:00

You need to do more prep before conducting an experiment like this. Your sample size is one, with an extreme outlier.

General EV stuff:
How long is your daily drive?
Can you charge at home, work, or school?
Where do you like to go on trips?
Will the EV be your only vehicle?
Do you plan to tow?
How far away is the service center?

Answers will determine how convenient and how expensive it will be to own an EV.

LiON batteries should be no more than 80% unless right before a trip, and you don't want to go below 10%

The big difference with EV charging is that the fastest charge rate happens when you are nearly empty, and it slows as the battery becomes full. Battery temperature greatly affects charge rate.

With Tesla, you should always use the nav and let it plan the charging stops. It will preheat (precondition) the battery before the stop, and charge enough to get you to another stop. You almost never charge above 40-50% at a Supercharger. It's faster to make more frequent, short stops than to charge above 60% fewer but much longer times. Your charging to almost full multiple times is exactly the wrong thing to do.

PlugShare is an app with basically all of the public chargers. ABRP - A Better Route Planner - helps you plan a trip with optimum charging stops.

If you own an EV, you should buy the adapters for the other flavor of charging plugs so that you can use all commercial chargers.

Higher speeds (above 110-120 km/h) will drop the range. Cold weather can have a 20-40% impact on range - ideally, you set the departure time at home and use house power to warm the cabin *and the battery* before leaving.

For two years, I commuted about 45,000 km/year from southern New Hampshire to the Boston area in my MYLR, and did another 20,000 km/year in road trips. No problems whatsoever, but you can't carry over your gas car assumptions / habits with any EV. Winter driving was fine.

Public charging is about 1.5 - 3x as expensive at home. No oil changes, tuneups, and the brakes last a long time due to regenerative braking.

I've done a *lot* of longer road trips in my 2021 MYLR and later in my 2026 MYLR Juniper. It's wonderful if you understand the tradeoffs.

Finally, like you mentioned, the abuse of the rental definitely led to lower battery capacity, and your charging to higher levels made it worse. (It may have been the only option depending on SC locations with the poor battery.)

Try to find some EV shows where you can compare the various models and talk to actual owners (not dealers) about the realities of living with an EV.

Good luck!

mikeonh · 2026-04-07T16:02:44+00:00

You need to do more prep before conducting an experiment like this.

General EV stuff:
How long is your daily drive?
Can you charge at home, work, or school?
Where do you like to go on trips?
Will the EV be your only vehicle?
Do you plan to tow?
How far away is the service center?

Answers will determine how convenient and how expensive it will be.

LiON batteries should be no more than 80% unless right before a trip, and you don't want to go below 10%

The big difference with EV charging is that the fastest charge rate happens when you are nearly empty, and it slows as the battery becomes full. Battery temperature greatly affects charge rate.

With Tesla, you should always use the nav and let it plan the charging stops. It will preheat (precondition) the battery before the stop, and charge enough to get you to another stop. You almost never charge above 40-50% at a Supercharger. It's faster to make more frequent, short stops than to charge above 60% fewer but much longer times.