Going disabled changes the cylinder position

Good Morning-

This time I didn’t hook the spikes up to the digital IO’s in- but instead up to the relays.

When I flip the disable button on the OI the cylinders fire. They then go to that state and stay there- I can’t change their positions and get the expected null movement everywhere else.

I’m terribly worried as, this year, I am actually scared of our robot. Safety FIRST!

Suggestions where to look? I initially set the spikes to 0, and only after a complicated button press do I ‘latch’ them open.


Are you using a single solenoid valve? Those switch to their default position if they don’t receive the signal to go to a different one. Thus, when you hit the disable button the solenoid flips to the default position, which makes the arms move, and then you can’t switch them back because the robot is in disabled mode.

Try using double solenoid valves instead, those will hold their last position if they are given no signal.

Thanks. One of my other mentors mentioned that- he has one, but I haven’t been able to cost-account it yet so I haven’t put it on the robot.

I’ll look at switching those out. This thing terrifies me…

if you must use a single solenoid, have the robot default to the least dangerous position.

The SMC solenoids you received in the kit are double solenoids. If you use those, you’ll be set. They need to be assembled, but that is fairly simple. The air from your pneumatic system goes into the middle inlet on the side with three openings, and the two sides of the cylinder go to the outlets on the side with two holes. The pneumatics manual will explain it better than I can.

Dang. We’re using the FESTOs . We’ll get the SMC’s by the time the competition on there.