Accidental Piston Retraction

[Alan Anderson]

Originally Posted by 1075guy

Yup. Normal operation, and an excellent case for using a double-action solenoid to improve safety.

It only improves safety if there's something dangerous about disengaging the cylinder. In our 2007 robot, we intentionally designed a system to use a single solenoid so that a tetra holder would release when the robot was disabled. Disabling the robot was a regular feature of that game. This year, we'll probably have pneumatic brakes on a subsystem to hold it in place when we're not actively driving it, and since we can't actively drive it when the robot is disabled, a single solenoid makes sense for that application too.

We always use dual solenoids when we don't want something changing unexpectedly. Often that's a safety issue, but sometimes it's just because activating a mechanism at the wrong time could earn us a penalty.