not certain how this would work exactly but why couldn't you affix a sensor to a dog that would let you know when his bladder was about to be full.
now you would know ahead of time that he has to go, a computer could sound an alarm that the dog would hear and get to know and then pop open a door to automatically let the animal out.
the implications of a silent version that you could affix to a friend , the human type could be very entertaining-- vfrackis, May 03 2009 As stupid as this idea is, it might be applied to diapers/babies. Just so they never go for long with a dirty diaper. Fishbone for not mentioning that. I haven't searched but I would guess a diaper alarm is already in the halfbakery files, if not, it should be.-- zeno, May 03 2009 zeno, I think that would be a detector for after the event. vfrackis' idea would give you a forewarning. But without some indication of how it would work, it's not really an idea.
You could probably put a pressure sensor and transponder (like tyre pressure sensors) inside the bladder but (a) I don't think bladder pressure increases a lot until just before you really, really gotta go and (b) you'd need to stop it rolling around and blocking the outlet.-- MaxwellBuchanan, May 03 2009 "Where no dog has gone before"
Star Trek backslang.-- skinflaps, May 03 2009 Perhaps direct pressure is not what you need to measure, perhaps weight on the supporting ligaments / connective tissue is what's needed.-- RayfordSteele, May 05 2009 I'll never think of the phrase 'boldly go' the same way again.-- RayfordSteele, Aug 27 2009 random, halfbakery