What exactly is a window motor and how would I go about coding for one in C++? Is it just a special jaguar? Also, I have some plans for autonomous mode, but I need to know how to rotate something in increments of five degrees. Is there a way to turn a motor a precise number of degrees.
Any help you can offer is appreciated.
Thanks.
Well a window motor is the motor used to raise a window in your car. It is a medium sized motor attached to a gear box that significantly reduces speed but it is a very strong motor. as for coding thats not my area but I couldnt imagine it would be any different from any other motor. I believe you are looking for an encoder to give feed back of how far the motor is rotating, but again that is not my area.
A Jaguar is a speed controller, it is an electronic device connects in between the cRio and a motor, to control how much electric power goes to the motor.
A window motor is an electric motor, just as a CIM or a Fisher Price motor is an electric motor. The window motors turn relatively slowly.
to control how many degrees a motor turns, usually requires an encoder, and a feedback loop such as PID.
squirrel and the man are correct. As far as any programming is concerned, a window motor is identical to any other motor. It sounds like you’re using it as it was intended, which is to reposition elements of your car/robot.
To turn a motor to a precise position, you need an external sensor. Often an encoder is the easiest to mount, but window motors are not designed to have encoders and so don’t have an easy place to mount them. In the past, my team has used window motors to switch an element between two positions with limit switches that are triggered when the element has reached its intended position. If your element has multiple positions, investigate sensors that are triggered by touch but allow the element to move past them (if something continues moving after triggering a limit switch, it bends and sometimes breaks the switch).
Good luck!
Just put a flexible extension on the limit switch lever.
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Note that there are known compatibility issues with the Jaguars and Window motors. You can either remove the locking pins from the Window motors or use Victors or Spikes.
Window motors are very small and not very powerful compared many other motors available to you. I really want to say only 20-40 watts, but I can’t find the motor spec sheet off-hand.
We have controlled them using spikes instead of jaguars with no ill effect, they turn so slowly we haven’t found the need for speed control in any of our applications.
The KOP window motors stall at right around 20 amps and can be controlled by a Spike if speed control isn’t a requirement. However, an ARA window motor might have a different stall current and may require something with greater current capabilities.
Note the “locking pin” issue only applies to those motors that have locking pins like those supplied in previous years KOP. If you are using window motors from the ARA program that may not apply.
These motors work great in applications where speed is not needed. They have a fair amount of torque.
They also work best in applications where they’re not going to stall. They are designed with a thermal cutout that shuts them off for several seconds if they’re asked to push against something that doesn’t move.
In my experience it will take several minutes for the thermal cutout to reset, so plan on the motor being out of commission for at least the rest of the match.
Last year our team used a potentiometer attached to our four-bar arm assembly.
(We did use two window motors.)
Again that doesn’t apply to all window motors get ones from an older Ford or GM that are almost CIM sized and there is no thermal protection built in.
You should have gotten 4 window motors, two right and two left. They have moderate speed and lots of torque. As for coding they use a “spike” relay. The coding should be the same for them as any other spike. With the spike you can reverse the flow of energy making the window motor turn the opposite dirrection.
To make the motor turn in precise increments, requires feedback and motor control. Use an encoder (a potentiometer will probably work and only costs $3 at Radio Shack) and a Victor or Jaguar instead of a Spike to drive it. Then you’ll get to discover the joys of a PID loop, and getting the constants right.
The potentiometer is mounted so it moves as the motor moves, and connected to an analog input.
There were only 2 window motors, weren’t there?
Two motors in the KOP, up to two additional available through the ARA program.