Remotely powering a mechanical foot.

[gophert]

If you could do it with just pressure, you could probably get quite a lot of braking cycles from a cylinder of CO2. You'd need a pressure monitor with feedback to the driver to alert you when it was running low, but it might be worth considdering.

CO2 seems like a cool idea but that is the problem, cooling. Evaporative cooling means, each time CO2 pressure is relieved from the cylinder, the cylinder cools. As the cylinder cools, the CO2 pressure drops. If the user is in traffic or switchbacks, I would not count on the brakes working with the same proportional response as it did in the initial driveway tests.