Man trapped by cinema chair footrest returning to default position sadly dies. - Page 1
Forum section: electronics / general

author: Avacee
author_rank: Unknown
timestamp: May 16, 2019, 05:52:10 pm
content: https://www.bbc.co.uk/news/uk-england-birmingham-48297191The article doesn't say if the blown fuse was on an obstruction sensor for the returning footrest or meant the footrest motor received full power.It mentions the force exerted on the poor chap as 3/4 tonne which makes me wonder - just how powerful are the motors in these chairs? (I guess strong enough to cope with the average american :p )Do the footrests typically have a sensor to detect an obstruction?I expect our Health&Safety Executive will be all over this and the cinema chain and/or chair manufacturer are a long way up the proverbial creek.

author: wraper
author_rank: Unknown
timestamp: May 16, 2019, 06:08:54 pm
content: Company that manufactured that crap must be sued and suffer a hefty fine. How in the hell they made it without safety mechanism that detects obstruction and stops movement. In a chance it was there and a blown fuse can make safety mechanism not working while there rest of it keeps working, that's a crappy non safe design nonetheless.

author: helius
author_rank: Super Contributor
timestamp: May 16, 2019, 06:25:10 pm
content: Seems like a solution in search of a problem to me. Why do you need a footrest in a cinema? If you really need a footrest, why cannot it be actuated by a simple lever?

author: Gyro
author_rank: Super Contributor
timestamp: May 16, 2019, 06:31:39 pm
content: Quote from: Avacee on May 16, 2019, 05:52:10 pmDoubtless there is a worm drive or leadscrew involved, making the stalled force very high and impossible to 'reverse' mechanically.It's not clear what the sentence in the report that"Charles Simmons-Jacobs, from the Health and Safety Executive (HSE), said he found it was "impossible" to lift eight of the footrests in the 52-seat theatre."means. I'm not sure if he's talking about some sort of faulty sprung mechanism, or blown fuses preventing the motors from reversing?A design that doesn't have an effective obstacle detection system (either shutting off the motor, or preferably, reversing it) sounds criminal, particularly in a venue where there are likely to be kids.I hope the HSE investigation results in criminal charges.

author: Bud
author_rank: Super Contributor
timestamp: May 16, 2019, 06:39:05 pm
content: With typical overreaction happening in cases like this i expect all cinema theaters in the UK be closed.

author: wraper
author_rank: Unknown
timestamp: May 16, 2019, 06:53:05 pm
content: Quote from: Gyro on May 16, 2019, 06:31:39 pmShould mean that 8 out of 52 seats had the same failure (blown fuse and whatever it was caused by).QuoteSupposedly control panel was not working properly.

author: Gyro
author_rank: Super Contributor
timestamp: May 16, 2019, 06:58:10 pm
content: Quote from: Bud on May 16, 2019, 06:39:05 pmHuh? It's nothing to do with closing cinemas, it's everything to do with someone being crushed to death by an autonomous electric seat in a public venue.

author: wraper
author_rank: Unknown
timestamp: May 16, 2019, 06:58:52 pm
content: Quote from: helius on May 16, 2019, 06:25:10 pmDoes not really work for the footrest unlike for backrest. Also most likely the whole seat was motorized, not just footrest. Haven't seen those in theaters but in Business class seats in airplanes worked pretty well for me.

author: JxR
author_rank: Unknown
timestamp: May 16, 2019, 07:15:12 pm
content: I wonder if killing the power to the theater (or specific circuit) may have helped, since I assume it would remove power to the chairs. Although they could have done just that for all I know. Poor guy, sounds like an awful way to go.

author: sleemanj
author_rank: Super Contributor
timestamp: May 17, 2019, 01:21:07 am
content: Quote from: wraper on May 16, 2019, 06:58:52 pmHuh?Lay-Z-Boy have been making lever actuated recliners since forever.

author: coppercone2
author_rank: Super Contributor
timestamp: May 17, 2019, 01:24:01 am
content: wow they built it to construction equipment standards instead of making ti intentionally weak so it can be destroyed if it malfunctions.fuck vandal proof designHuman interface devices should be built in such a way that a pissed off individual being attacked by one can use primal instincts to disable it, or something like that

author: amyk
author_rank: Super Contributor
timestamp: May 17, 2019, 02:58:58 am
content: There should be an obvious mechanical "emergency stop" quick-release/disconnect lever (like a clutch), which will be a much more reliable and effective method than adding more sensors/intentional fragility like others have suggested --- remember that complexity always adds points of failure, never reduces it.

author: coppercone2
author_rank: Super Contributor
timestamp: May 17, 2019, 03:10:22 am
content: Quote from: amyk on May 17, 2019, 02:58:58 amMaking it weaker is more simple then a lever....nothing to jam up or get broken off etc. You just start forcing it hard to cause something to snap....A lever can always fall off (thats common even in movies.......). How do you get more simple then being able to disable it with brute force? Then even drunk people can do it.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 17, 2019, 03:47:43 am
content: Wow, to me stuff like this should use some kind of clutch design where it will just slip if there is an obstruction. It could also have obstruction detection as to not wear out the clutch mechanism, but if the detection fails then it will just slip or something.I'm just trying to visualize how this happened though, I've been to cinemas with automatic chairs and there is not really any way I can see where it could crush someone. then again it's dark in there so it's hard to really see for sure and not like I go looking for that.

author: amyk
author_rank: Super Contributor
timestamp: May 17, 2019, 11:58:01 am
content: Quote from: Red Squirrel on May 17, 2019, 03:47:43 amI guess it may have been here

author: SparkyFX
author_rank: Frequent Contributor
timestamp: May 17, 2019, 06:37:26 pm
content: Quote from: Red Squirrel on May 17, 2019, 03:47:43 amIt is designed to lift a weight and hold it there (probably without power), so it might even be non-backdriveable, have a gearmotor or linear actuator as a drive. A clutch would let the weight slip downwards (probably on a scissor type mechanism), that means someone could loose a finger or so if that happens and is in the wrong spot of the mechanism.So you can´t really brute force your way out of this when a geared motor or linear actuator drives a mechanism, most obstruction detection systems would stop or stop and reverse if an obstruction is detected (requires a sharp increase in current, end stop switches or proximity switches) or a position not reached within time. Cars do contain quite a few of these methods in power window lifters, sunroof or tailgate actuators, yet they all have to be a compromise to function as the user expects them.In case of a seat i wonder why they did not completely block all areas that should not be accessible, so no one can get in there in the first place, no dirt is getting there and so on.

author: ajb
author_rank: Super Contributor
timestamp: May 17, 2019, 07:22:39 pm
content: Quote from: Red Squirrel on May 17, 2019, 03:47:43 amI was scratching my head at this too, but the article says he was looking for his keys/phone, I guess after the movie ended, so presumably had his head stuck under the mechanism to look under the chair.Quote from: wraper on May 16, 2019, 06:58:52 pmIf they're like the chairs in our local theater, yeah, the whole seat reclines and the footrest comes up all in one motion. This is also heavy duty commercial furniture, not some pine and particle board living room stuff, so a manual lever would be a lot harder to actuate, even for an able-bodied adult, let alone the young/elderly. Also the motorized chairs would probably hold up better anyway, since you physically can't slam them open and closed--the force is always controlled and fairly consistent through its motion.

author: MrMobodies
author_rank: Super Contributor
timestamp: May 17, 2019, 07:41:56 pm
content: I notice some pants do have long wide opening pockets that are so shallow things can easily fall out of them from most angles. I had a few of them some with no zips and it was getting silly with the amount things that kept on falling out that I got of rid them all.I was thinking he got up and the leys slid out.I'd carry around one of those led magnet pickup tools but then that might fall out if is in a pocket that is shallow and loose.

author: wraper
author_rank: Unknown
timestamp: May 17, 2019, 08:03:08 pm
content: Quote from: MrMobodies on May 17, 2019, 07:41:56 pmMy phone fell out when I was leaving airplane because of such stupid pants. I noticed it only when bus was nearing airport, no jet bridge. Was some fun retrieving it back, 1.5 hours wasted.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 17, 2019, 08:06:24 pm
content: Quote from: ajb on May 17, 2019, 07:22:39 pmOhh yeah I had missed that part, makes more sense now.What a way to go though. I feel this is one of those tricky ones where nobody should really get blamed because it's a freak accident, but now that we know it can happen, something should probably be looked at to prevent it.

author: wraper
author_rank: Unknown
timestamp: May 17, 2019, 08:12:56 pm
content: Quote from: Red Squirrel on May 17, 2019, 08:06:24 pmI feel exactly opposite. This is device available for general public, including kids. Zero training given. If there is place where part of the body can be stuck, it eventually will. Searching fallen stuff under the seat is not something uncommon, and making such deathtrap which activates automatically is plain criminal.