Author Topic: pots  (Read 2444 times)

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Offline ruddock1234Topic starter

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pots
« on: February 25, 2015, 08:05:49 AM »
would anyone know how a pot is used to control a robotic joint
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Offline mklrobo

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Re: pots
« Reply #1 on: February 25, 2015, 10:31:39 AM »
 :) Hello!
There are alot of different methods for using a pot to control a robot motor; and thus,
a robot joint.
If you want to control a robot joint, then the pot has to be mounted such that it can
move linearly when the joint is moved.
If you want to control a robot motor, then a pot (likely) is mounted remotely,
an controls the motor.
An Analog to digital process can be used to assign power levels,movement in degrees, or any number
of directions that you may want to use, to direct/control your robot joint.
Most robot kits are straightforward with this, and provide programming and free software to program
your robot. I recommend you visit the Forum at Parallax.com, and read some of the threads there,
as they are helpful. This investment in time could answer some questions, and save you heartache. :'(
You can search this forums postings, as it might be already answered by another member. Good Luck!
 ;D ;D ;D
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Offline ruddock1234Topic starter

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Re: pots
« Reply #2 on: February 26, 2015, 08:55:15 AM »
how would I use it in an atonomous situation
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Offline mklrobo

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Re: pots
« Reply #3 on: February 26, 2015, 09:16:50 AM »
 :)Hello!
In an autonomous situation, some motors offer a feedback feature
which lets the microcontroller know (?) where it is at. A good practice
is to have another pot on the arm to confirm the location/angle of the bend.
You could use a servo with feedback, the have a pot on the arm to confirm
the movement to the MCU. A motor driver for the servo, and a feed in from the
pot to an ADC pin, if applicable. A good start would be to set up a fixture &
breadboard for your project, as to give flexibility. Keep me posted.......  ;D ;D ;D
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Offline Schlayer

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Re: pots
« Reply #4 on: February 26, 2015, 12:29:42 PM »
    Potentiometers can be used as feedback for any rotating joint, as they change resistance based on how far they are turned in a particular direction. This can allow for precise position detection of a motorized joint even when using a standard motor instead of a servo motor. If, for instance, you need a joint with a very high torque (such as in a heavy-lifting robot arm) you could use a geared motor and attach the potentiometer such that it rotates with the joint. This allows for you to control the joint and know its position despite the fact that the motor itself (pre-gearing) might rotate hundreds of times before the joint itself (post-gearing) completes a full rotation. As mklrobo mentioned this is a way to create a feedback loop.
   Ex: Your robot may be programmed to rotate the motor in one direction until the potentiometer resistance drops/rises by X amount to change angle by a specified amount, or set to stop when it reaches a certain resistance value of Y to make it stop at some specific angle. This can easily work in reverse as well -- making the robot respond to some motion by executing another specific motion.
   I hope this clears things up!
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Offline ruddock1234Topic starter

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Re: pots
« Reply #5 on: February 28, 2015, 02:05:20 PM »
thank you both. i will make a small scale joint with cheap parts to get a working joint. then i will develop that into a larger scale robot.
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