Quote:
Originally Posted by Roboman01
I understand your system, however, it seems a little jury-rigged, to be frank. Keep in mind that the force exerted by springs changes based on how much they are extended or compressed, unless you use a constant-force spring (obviously). Also, you're relying on a relieving regulator to vent excess pressure in the cylinder. While these are more common than non-relieving regulators, the latter are certainly not rare, and could easily be confused with a pressure-relieving regulator.
In addition, to implement your system, you would need to figure out some way of controlling the regulator. You mentioned hobby servos, which could work, but they are confined to <180 degrees. Sail winch servos are not allowed, and still would not rotate enough to open and close the regulator entirely. They are also much more coarse in their movements, which could limit your true control over the cylinder.
Your system would have a variable force in addition to the variable stroke, since you're varying the pressure, rather than the amount of air in either end. As you should know, reducing the pressure also reduces the force exerted, and the spring on the end that counteracts the cylinder's rod will cause the net force to be near zero, since it's stopping the travel mid-stroke. This is obviously not good for actuating an arm, or anything that will be exerting any sort of force.
|
(emphasis added by me)
1) {response to bold text} These facts are what allows such a system to work. The entire operating principle of the design relies on a variable force being counteracted by a controlled variable force. The two forces cancel out at equilibrium. A constant force spring would not work in this system, the description specifically calls for a variable force device.
2) {response to underlined text} This was a problem with the system as originally described, but I edited the description to account for the force applied by the mechanism being actuated. The forces will still cancel out at equilibrium, assuming the correct bore and spring are chosen based on the direction and magnitude of the forces that will be applied by the mechanism.
3) {response to first line of quoted text} It
is somewhat jury rigged. The system is meant to be implemented on a robot that had previously used multiple solenoids to control a single cylinder, to make it fit within the rules.
Your system would be preferable in this situation, since it requires little to no change to the code and minimal changes to the hardware. however, if I were building the system from nothing, I would prefer my system based on the fact that it would appear easier to program (plus my team has been successful in positioning a rotary device with pots, but has little/no experience with linear positioning, as far as I am aware).
4){red paragraph} It wouldn't be terribly difficult to use a window motor or a RS-395 (with an appropriate transmission, possibly from a servo [minus the mechanical stops]) to control the regulator, assuming fairly accurate pots are used and/or the values used in the code are properly adjusted.