Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: erickulcyk on February 05, 2012, 01:30:18 PM

Title: Question about Wheel Encoders
Post by: erickulcyk on February 05, 2012, 01:30:18 PM

Hi guys,

I was wondering what you guys would suggest for wheel encoders on a four wheeled robot.  Currently we are using this http://www.newark.com/jsp/search/productdetail.jsp?SKU=06B1972&CMP=AFC-GB100000001 (http://www.newark.com/jsp/search/productdetail.jsp?SKU=06B1972&CMP=AFC-GB100000001) optical encoder.  However, the output seems to be really inconsistent when driving the wheels at a constant speed.  What encoders are considered good quality?  Does anyone know what the darpa cars or the google cars use for encoders? 

Thanks,
Eric

Title: Re: Question about Wheel Encoders
Post by: Soeren on February 05, 2012, 07:29:47 PM

Hi,

Quote from: erickulcyk on February 05, 2012, 01:30:18 PM

[...] the output seems to be really inconsistent when driving the wheels at a constant speed.

What is their resolution?
What wheel size do you use?
How did you mount the sensors?
Did you remember to add pull-up resistors to each of the 3 channels?
Did you put a cap over the supply terminals?
How do you read them?
How does the inconsistency manifests itself (in numbers)?

The encoders you have should work extremely well if handled correctly, but they don't accept as much positional tolerance as a home made sensor would.