I am building a new drive system for the AIMEC robot and am using REXC motors with optical encoders.
The drive system is 2 motor skid/steer with rear castor. I need a PID controller as I want to do odometry and also travel in straight lines, so the Jrk 12v12 looks really good!
The encoders are HEDS-5545 and the Zagros page says “Encoder Pulses per Revolution : 63500” which seems a huge count? The Agilent datasheet says that standard resolutions are between 96 and 1024 counts per revolution, so I am confused on this?
Can anyone help me with the following questions:
Will the Pololu Jrk 12v12 work with these encoders?
Are any other Pololu motor controllers better suited?
Would 2 of these controllers given the same command (speed) data move in a relatively straight line?
Thanks in advance for any help, it’s much appreciated!
Unfortunately, we do not have any motor controllers that support quadrature encoders (they’re on our list of things to make, but it’s a long list!). Regarding the pulse count, you’re probably looking at counts per wheel/gearbox output revolution. If you have a thousand counts per rotation on the motor and a 63.5:1 gear ratio, you’ll get the kind of counts/rev you’re describing. By the way, you could make things easier for people replying to your post by putting in links to the things you’re talking about.
With the jrk controllers, you could use one of the channels off of each encoder and use the frequency feedback mode to have the jrk take care of running the motors at the same speed, but you would still have to keep track of position yourself, so it’s probably not worth it: at the point where you’re keeping track of the counts yourself, you could just use a simpler serial motor controller that doesn’t have the feedback features. For instance, the qik 2s12v10 has two channels, with the same drive capability per channel, for a lower price.
Thanks for the prompt reply!
I do understand that I cannot use the full quadrature encoders, but what I am looking for is a speed controller(s) that can run the robot in straight lines with accurate speed control, would I get this using the single channel feedback on the Jrk?
Sorry about not giving a link. but the Zagros URL does not change when you go to the motor page? The link is:
zagrosrobotics.com/Index.asp the item is MR300
Do you think these encoders (HEDS-5545) will work with the Jrk? (I read that the REX C drives have about 40,000 pulses per wheel revolution), or will I need to divide it with something like a 4017 to reduce the counter pulse by 10?
Again thanks for all your help with this.
It should work, though going straight is generally difficult. With just trying to maintain the same speed on both sides, you won’t really know what kind of error has accumulated. It should be much better than no closed-loop speed control, though.