It is end of September 2010, and my FRC team (1178) is looking to make a new cart. It will have a pneumatic forklift and be motorized by older robot control parts.
My first question is: Using the joysticks from 2008, can I wire the joystick to two Victor 884’s without having to use an old robot control board/ Operator interface? We want the cart to contain all the wires, and not have any wireless system, so we can use the cart at competitions, and preferably, not have to program anything. Any suggestions would be helpful.
My second question is: Can wire the solenoids to a joystick to have them fire in one direction, hold that position, and then press the button again and have them fire in the reverse direction. Again, we would like to not have to do any programming.
If anyone has already posted this, sorry, could you redirect to their?
Joysticks use the interface to provide a calibrated PWM signal to control the speed controller per the hobby PWM spec for radio control. Some teams have managed to make a simulator using a 555 timer as a PWM generator. If you are going to control more than one motor, it becomes a little complex to use the 555 solution.
As to the solenoids, the switches in a joystick cannot sustain the current needed to drive a solenoid directly nor are they locking style switches. They are momentary only. You can use off the shelf switches from almost anywhere if you just want to turn something on and off. Even Radio Shack has some automotive switches that are suitable for this purpose. Please be careful in your cart design to be sure that no one will be injured by the cart movement in a tight pit area. More than one team has been asked to remove all power (electrical and pneumatic) from a cart due to it’s potential to injure participants.
Thank you Underwriter Lab volunteers for keeping a look out for this issues.
I know its not what you want to hear… but honestly, I think using the old robot controller would be easiest. As Al said, getting joysticks wired up to victors is doable, but does require a certain amount of knowledge that most teams aren’t exposed to (I imagine that going out and building/designing circuits isn’t top on everyone’s list during the build season).
Last year, our team worked on a small pick-and-place robot for off season practice, using the old control system. By simply commenting out a few lines of code, we could bypass the communication with the OI entirely, and feed our inputs (a few switches) into the robot controller directly. So, it’s pretty easy to throw out the OI and any communications for a self contained project like this. If you decide to go this route and want some help getting the code working with the robot controller, feel free to send me a message. I can get you pointed in the right direction.
I’m pretty sure Nathan was asking about pneumatic solenoid valves. The typical dual solenoid valve (e.g. SMC SY3240-5LOU from the 2007 Kit of Parts) isn’t going to cause problems for a joystick switch, and the valve itself will do the desired latching.
There’s an implied problem of providing air pressure. The Kit of Parts compressor can’t be connected directly to the Kit of Parts pressure switch; the current will be a problem in this case. Some additional circuitry will be necessary, though it can be as simple as a single relay.
You may want to look into “servo testers” that are for the hobby rc industry.
They’re a little device that usually uses a potentiometer and a simple circuit to directly output pwm (usually used for calibrating servos, but pwm is pwm). I imagine you could rewire the pot on there to an external one, or just use it as is.
I’ve seen theme everywhere from $5-$30.
Thanks for all the replies, but one of our mentors gave us plans for a cart that doesn’t use pneumatics, it uses a motor or hand crank to raise or lower it.
Pneumatically raised could be dangerous if you’re doing it yourself. The two main concerns are if it is going to have enough strength to lift a robot, it will fire very fast when there is no robot on top.
The other is holding pressure, you don’t want to be working on this and have it start to slowly drift down and pinch somebody.
Properly engineered, Pneumatics are no more (or less) dangerous than motors. The only difference is what you control … in Pneumatics it’s inlet and outlet orifice sizes (and thus gas flow rates) while with motors it’s electric current flow. Both systems are enhanced by feedback and both can be dangerous to those who don’t understand their application.