Controling Pnumatics with joystick.

[Tytus Gerrish]

you can slow down the rate the cylinder with adjustable orifices . but the way the valves work is they pressurise one side of the cylinder and vent the other to atmosphere. there is no way to stop the cylinder mid-stroke with the avalable first hardware.

[Chris is me]

Originally Posted by Tytus Gerrish

you can slow down the rate the cylinder with adjustable orifices . but the way the valves work is they pressurise one side of the cylinder and vent the other to atmosphere. there is no way to stop the cylinder mid-stroke with the avalable first hardware.

I believe 1075 did it in 2004 and 2007.

[Tytus Gerrish]

that's great it would be nice to see how they did it.

[craigcd]

Correct me if I’m wrong, but there is no rule in the pneumatic section for the robot build that states that the valves must fail open so the pressure in the cylinder is released after the power is off. The rules do not restrict the 3 position center blocked valve. If you go for the strict interpretation of the rules then all 2 position valves are illegal because the "working pressure" cannot be relieved at the pressure relief valve.

[45Auto]

Correct me if I’m wrong, but there is no rule in the pneumatic section for the robot build that states that the valves must fail open so the pressure in the cylinder is released after the power is off.

The valves must be open when the power is off so the vent valve can relieve all stored pressure. See rule R73.

<R73> The pressure vent plug valve must be connected to the pneumatic circuit such that, when manually operated, it will vent to the atmosphere to relieve all stored pressure. The valve must be placed on the ROBOT so that it is visible and easily accessible.

[Tytus Gerrish]

Originally Posted by 45Auto

The valves must be open when the power is off so the vent valve can relieve all stored pressure. See rule R73.

<R73> The pressure vent plug valve must be connected to the pneumatic circuit such that, when manually operated, it will vent to the atmosphere to relieve all stored pressure. The valve must be placed on the ROBOT so that it is visible and easily accessible.

if they use a doubble-acting valve for the cylender and 2 single-acting valves to stop the exhaust they would fail open and allow the whole system to purge

[bstrong1218]

Originally Posted by Tytus Gerrish

if they use a doubble-acting valve for the cylender and 2 single-acting valves to stop the exhaust they would fail open and allow the whole system to purge

That's very close to the test we ran prior to ordering the 3-way solenoid.

This document shows a way to control position that appears to comply with <R73> and <R74> after adjusting the single-acting solenoid to fail open (not closed like they specify):
http://www.chiefdelphi.com/media/papers/1476

It would be nice to use a 3-way, center closed solenoid, but my team hasn't seen a way to do it that is less complex than the above design and complies with both <R73> and <R74>.

[45Auto]

if they use a doubble-acting valve for the cylender and 2 single-acting valves to stop the exhaust they would fail open and allow the whole system to purge

Wouldn't that connect more than one valve to a cylinder input?

<R74> Each commanded motion of a pneumatic cylinder or rotary actuator must be accomplished via the flow of compressed air through only one approved pneumatic valve. Plumbing the outputs from multiple valves together into the same input on a pneumatic cylinder is prohibited.