First, I have never done anything with robotics, and I don’t know if my project is really a robot or not, but looking at some of the parts available this looks like a good place to start.
What I am trying to accomplish is to automate a mount for a screen in a car that will both extend forward and then rotate 90 degrees from 1 command (momentary switch), then also rotate back to 0 degrees and retract back from another command. The motorization will have to be able to move ~2-3lbs.
Also, I have pretty limited space to do this, approx 10"h x 5"d x 7"w (not including the screen mount/bezel). The forward and back motion will need to be in the 5" dimension and extend ~2".
I have done quite a bit of mechanical design, especially for vehicle application, for this type of thing and am well versed in 12v electronics and circuit design, but this is a new frontier for me.
From my first perusing in the shop area I’m thinking a mini-actuator for the extension motion and then a stepper motor for the rotation. I have no clue what kind of controller or other accessories I’ll need.
So if anyone can help me out on that front or tell me I’m totally off base for what I need that would be much appreciated.
TIA
-Adam
Would the servo controller allow for programming of the 90 degree rotation? Or would I need to come up with a mechanical (or other) stop?
Sorry if these questions are uber ignorant.
Also, if when reversing the motion would I need a second controller to do the rotate first, then retract motion, vs the extend then rotate motion?
Okay, I have most of the other pieces in place for this project, so I am starting to re-visit the motorization aspect. It all makes sense to me except for the servo bracket, which is probably the simplest part of the whole thing and I’m just being thick.
Does the bracket actually attach to the servo horn? Or does it attatch to the body of the servo to re-enforce the structure of the whole assembly?
Again, I’m sure this is really simple and I’m just missing something. Thanks again for all the help!
-Adam
After watching a few videos on some robots and motors trying to figure out the bracket thing, another question has come up. Will the servo be a “snap” like quick motion or more fluid like the actuator? I actually want a slower more fluid motion.
You mentioned that you have no clue what kind of controller to use… You may want to consider a programmable Logic device as a cool way to control various sensors. Just need to know VHDL. A PIC controller is also cool… see amazon.com/Wireless-Digital-Mobile-Robotics-Perspective/dp/193820400X/ref=sr_1_1?s=books&ie=UTF8&qid=1339906634&sr=1-1&keywords=Wireless+Digital+Mobile+Robotics±+A+College+Curriculum+Perspective
A simple approach would be to use a linear actuator (for example the 50mm ~1.97in) L12 linear actuator with R/C input (L12-50-50-6-I, but the gear ratio is up to you). You would need a guide rail to take the actual load (RB-Fra-84, but a lot shorter - we don’t offer any 2" versions at this time).
For the rotation, you can use a servo motor. You would not want all the weight on the servo horn, so you might consider a servo bracket, direct pan system or if the torque is high, a geared pan system.
To control the two, you would use a servo controller. You don’t need anything complicated, and the 08M servo driver (with programming cable) would likely work (it has one digital input for a button, and can be programmed to first extend the linear actuator, then rotate 90 degrees. To work off a 12V supply, you’d need a voltage regulator.
A stepper is fine, but does not retain an absolute position unless you also add limit switches. If you are new, it’s not the easiest to program either.
One controller does it all; you can specify the angle (limit to 90 degrees for example), retract, add timing etc.
Wait for button to be pressed
If button pressed
extend actuator
rotate servo CW 90 degrees
wait for button to be pressed
if button pressed
rotate servo 90 degrees CCW
retract actuator
Likely a bit more complex than this, but hopefully you get the idea.
A servo bracket attaches to either the mounting holes of the servo, or to the horn, depending on which type of bracket you use. For example, the pan/tilt from Lynxmotion uses both types.
It does what you want - if you specify angles which are far apart and there is no time to transition, it will go from angle A to B as fast as possible. If you program intermediate positions, it will be smooth.
