Exactly. I appreciate design simplicity whenever possible as well, so this concept sprang to mind when I read that you were interested in community input on the brake/clutch mechanism. I'm glad it was helpful.
The brake would have to be calibrated to engage only when quick directional forces (like those involved in a user falling onto or under the support bar) are applied to the system. In this situation the brake would engage, lock into place and "catch" the user. For unlocking the brake, it might be safest to build in an unlock mechanism that can only be reached when the user is safely standing upright and out of harm's way - probably in the housing where the bar meets the railing. This way if the user falls and is hanging from the bar, the brake can't be unlocked accidentally by some awkward motion of the bar itself as they try to pull themselves up. Once the user is upright again, the brake can be unlocked and they can resume going down the stairs.
You also got me thinking - the brake is a good solution for descending a staircase, but how would this device function for a person ascending a staircase? Maybe a linear ratchet approach? Similar to this: https://www.youtube.com/watch?v=mDbLJR_bcZU?
The railing may be the key to this - a typical "smooth" railing for use with the brake on the way down the stairs and a second ratcheted railing installed above it for going up the stairs? To go upstairs, the bar and catch or brake engages each time the user steps up onto a higher step, then locks into place as the user pulls on it to lift their body up. When the user reaches a stable standing position after reaching that next step - the brake/catch would disengage so the user can then push/slide it further up and lock into position for a brace to pull on for the next step? Does that make sense?
Also - when going up stairs, would a second bar unfold in some way to extend behind the user so that it could catch them if they start to fall backwards?
I'm very interested in how the brake/clutch mechanism of your idea will be designed. I recently saw a product that may be useful for you. It's a smart tool used to improve the task of lifting and moving large, heavy sheets of 4ft. by 8 ft. building materials such as sheetrock or plywood. It uses a clamping mechanism that allows the user to grip the sheet with one hand and carry it without putting as much stress on their back. A similar functioning device could be applied to your idea if it were rotated 90º to match the angle of travel along a stairway railing.
I think it's clear that this kind of idea will make a significant impact on the future of fall prevention for seniors. It's highly accessible right now via existing gaming technology and there are already a few somewhat related products out there that we can learn from (though none that target this problem of fall prevention specifically). This idea can be used in a group setting for seniors who would prefer to make use of it as a social tool, or it can be done in the privacy of one's own home benefitting more introverted or self conscious first time users. Whatever the preferences of the seniors we're trying to serve, fall prevention is the common denominator.
The real question then becomes what the program design or theme of the "games" will be? Will an actual game design be most popular among seniors? If so, which kind of game? Shuffleboard? Bocce? Golf? Or would a more instructional, training model work better? Lots of options here.
As you can tell from the other idea I posted - (https://challenges.openideo.com/challenge/fall-prevention/ideas/incentivized-mobility-strengthening-program-for-well-being-and-independence) - I want to focus on prevention of falls before they happen by targeting the hip and leg muscles most involved in falls. Start by using foam rolling to loosen these areas and then add some simple exercises to strengthen them. Even if users don't actually follow through on the exercise portion, the foam rolling alone will drastically improve a senior's ability to avoid falls. I believe this is the information we need to help educate seniors about, using whichever vehicle or game design model that works best to do so.