The Power of Risk Analysis in Design - Page 1
Forum section: electronics / general

author: VK3DRB
author_rank: Super Contributor
timestamp: April 17, 2017, 01:10:00 am
content: Risk analysis saves lives.I read this and it appears there was little thought to risk analysishttp://www.smh.com.au/world/boy-crushed-to-death-in-accident-at-revolving-restaurant-20170416-gvlxaw.html. It reminded me that when I was a kid around 10, a friend died on a public playground swing, when his head was crushed between a supporting pole and one of the four large poles suspending a heavy four seat swing. Because of this particular accident, the government then introduced playground equipment standards. Mitigation AFTER the tragic accident. At IBM Wangaratta in the early 1990's, there was a new automatic door that had been in operation for a few months. I discovered that if someone was leaning against a window recess next to the door, say whilst chatting, and the door was activated, their fingers would be severed by the door. I tested this with some pencils - they were cleanly sheared off. The facilities officer immediately rendered the door inoperable until mitigation was put into place.Risk analysis in medical electronics R & D is mandatory. In short, it is risk identification, management and mitigation against death or injury to operator or patient prior to releasing a design.I doubt United Airlines or the Chicago police did a risk analysis with the methods they use to force legitimate passengers off their planes(smashed teeth + sinuses + broken nose + concussion + humiliation including loss of face). Even Ford with its Pinto did a cost benefit analysis on killing or injuring customers.When you design anything - as a technician, engineer, or hobbyist, or home handyman - always do some risk analysis! There are plenty of spreadsheets online to help. There are plenty of examples of no risk analysis being performed on many products that come out of China. IMO, auditable risk analysis records should be mandatory for all mains and rechargeable battery powered electronic products, with or without UL certification.Is this being too bureaucratic?

author: BradC
author_rank: Super Contributor
timestamp: April 17, 2017, 01:23:13 am
content: Quote from: VK3DRB on April 17, 2017, 01:10:00 amNot at all. In my day job a Risk Analysis is a huge part of what I do. What I most often find when sitting down with a client and running through the risks is the standard "Oh, I'd never have thought of that". It's vital to get several heads together to consider the risks, preferrably people not in your immediate field who will look at it from a completely different viewpoint. Pints at the pub are a good way of facilitating this.All too often you hear the "I didn't think about that", or "I never considered you could use it that way". If you mitigated or prevented *all* the risks you'd never get out of bed, so there is always a balance of consequences, but it's important to consider even the small stuff as they often play a role in the chain of events that leads to something much less pleasant.

author: ataradov
author_rank: Super Contributor
timestamp: April 17, 2017, 01:57:25 am
content: It is useful to think about stuff like that in advance, but enforcing arbitrary rules is too much.You will end up with abominations like MISRA and Class B safety. Total bureaucratic BS, that was probably a result of overreaction to some inconsequential accident.There is always a way to harm yourself if you are dumb (or in case of kids, if parents are dumb).That's how we end up with stickers telling you to wear eye protection while using pencils and calculators.

author: NottheDan
author_rank: Frequent Contributor
timestamp: April 17, 2017, 07:59:24 am
content: It is especially fun when you have no working solution to mitigate the risk. On our production line we have people working at height (on stands about shoulder-high) with no railing on front (as that would interfere with the product and the production process. Nobody's ever fallen of but the risk is there of course. We can't put railing on, so the solution is putting the workers on a lead (safety harness on a locking retractor. Problem with those things - they are not watertight nor hygienic and nobody is making food-safe ones.

author: timb
author_rank: Super Contributor
timestamp: April 17, 2017, 11:37:07 am
content: Quote from: VK3DRB on April 17, 2017, 01:10:00 amThere's more to this story than what's in that article. I've been to that restaurant before (it *is* pretty damn cool) and I can't imagine where his head could have gotten lodged.There actually are safety systems in place that stops the mechanism which rotates the floor if it encounters above average resistance (which in and off itself is pretty amazing from a technical perspective; think about it, an entire floor of a building is slowly rotating, which has to take an enormous amount of force, but they can still detect the slightest impedance). In this case the safety system *did* trigger.That's the other thing, the rotation is so slow (it would have to be, otherwise people would get motion sick) I just can't figure out how he got stuck.Plus this restaurant has been in operation for years and there has never been a single injury (let alone a fatality) before this. How many escalator accidents are there every year? (Hair gets caught and off comes their scalp; loose clothes get pulled in and legs are broken, it's not common but it happens.)Anyway, I think this is more of a freak accident than something that could be anticipated. There's also more to the story, guaranteed.

author: SeanB
author_rank: Super Contributor
timestamp: April 17, 2017, 02:14:24 pm
content: My father was involved in building the one here by me, and the engineering was not trivial. the entire restaurant sits on ordinary car tyres ( 10in Mini ones) and is rotated by a single half horsepower motor on a reduction gearbox driving one wheel. Biggest issue was placing all services and such in the central ring, while only having the tables on the floor rotating.The whole rotating floor is many tons, but is not too hard to move as it is on low friction mounts and has good side load bearings to keep it aligned.Been in the building itself a good few times, just never wanted to go there to eat. Harbour view is not exactly high on the priority.

author: ebastler
author_rank: Super Contributor
timestamp: April 17, 2017, 02:45:08 pm
content: Quote from: VK3DRB on April 17, 2017, 01:10:00 amI am absolutely with you on the "do some risk analysis!" part. Thinking about what could go wrong, and what neds to be done to prevent it, should be part of every hobby build -- and, of course, even more so when you build for others, be it as an amateur or professional.I am less sure whether the "spreadsheet" part is helpful for amateurs. If you refer to quantitative risk assessement (assessing severity as a function of probability and impact, with quantitative severity scores pre and post mitigation etc.), I think these can easily cause you to miss the forrest for all the trees.In my view, it is most important to give some good thought to what could go wrong, on a qualitative level.If you get bogged down in quantitative spreadsheets, you might e.g. end up quantifying the risk of electrical shock in your homebrew power supply in loving detail, but overlook the risk that it could catch fire.There may be other spreadsheets, e.g. proposing a list of qualitative risks to consider, and these might be helpful as a reminder -- again, as long as they are not too detailed and don't become a distraction. If you have good examples, I'd appreciate a link!Of course, the above does not apply to the professional domain, where specific risk assessment methods (including quantification of risks and documenting their mitigation) are typically required by the applicable technical standards anyway.

author: rstofer
author_rank: Super Contributor
timestamp: April 17, 2017, 05:34:23 pm
content: Not in any formal way but I try to ask the question: "How is what I'm doing going to hurt me?" I ask this for nearly every non-standard thing I do. Where I store stuff, how I hang it, is it blocking a path, will it fall, and on and on.I'm a little more diligent now that I am aged; in my teens I was simply immortal. Today, not so much. A fall could be a life ending disaster. There will be no more jumping off the patio cover using an umbrella as a parachute.