11-30-2020, 08:47 AM
(11-30-2020, 07:41 AM)jamincan Wrote: It's standard for any system where the doors opening/closing is automatic for obvious reasons. ION is an example that clearly shows that train manufacturers already have the technology to individually control the doors. You end up trading one problem for another, though. Instead of a simpler system where all doors operate simultaneously, you have a more complicated system that could now fail in some other way.
I assume it’s inertia. At one time, it would have been a substantial undertaking to build any sort of independent control into the door system. First you need a way of getting per-door signals from the cabs to the doors; and next unless the individual operation is entirely automatic you need some way of providing controls for each door. But now, with everything computerized, it’s much easier to push all the complexity into software. This doesn’t make the problem disappear entirely, but providing the individual control becomes a coding problem, rather than a whole bunch of additional hardware.
One thing I’d like to know: does the cab display show the status of each door individually? I don’t actually know.
Although it occurs to me that if the open/close cycle were localized to each door then the overall train could simply have a single open/close command for all doors, even while individual doors can retry on their own. There is no need for a door that won’t close to immediately tell the rest of the train about it — until it’s given up on retrying, it can just signal that it’s still closing and so it will appear as a very slow closing door to the rest of the system. But I’m less sure about this part because I don’t know where the logic to re-open and then try closing again actually is — in the door mechanism or in a central control point. In a modern system it doesn’t matter though.