# Wheel diameter and wheel track

Somehow it is so obvious how to measure wheel diameter and wheel track that I could not find any information regarding it. Could somebody please provide a link or a sketch on how to precisely measure the distance between the left and right wheel on a 2wd and the distance between the front and rear wheels on a 4wd base as well as wheel diameter?

Thank you

edit retag close merge delete

Can you describe the problem you're having? Are you measuring a CAD model or an actual robot? Most commercial hardware will have this information published in its specification. If it's an actual rover you should be able to get fairly accurate measurements using a tape measure.

( 2019-09-11 06:22:37 -0500 )edit

Perhaps the question of the OP is more: how are those distances and diameters defined exactly? As in: between which and which points should they be measured or determined?

( 2019-09-11 07:16:01 -0500 )edit

Distance between left and right wheel also called wheel separation distance is taken from centre of one wheel to the centre of other wheel. Same goes for rear and front wheel, distance between points of both wheels that touch the ground (I don't think I have seen this one being used anywhere).

If you maybe tell us what you are trying to do we can help better.

( 2019-09-11 08:53:46 -0500 )edit

Yes, @gvdhoom was right. I simply wanted to know the exact points between I have to take the measurement on my real robot. I build a custom robot with random spare parts lying around using linorobot software and simply wanted to make sure that I measure the right values. @Choco93: What do you mean by "I don't think I have seen this one being used anywhere"? At the moment I use 2 wheels and one caster wheel but wanted to switch to 4wd (no steering) for more outdoorability.

( 2019-09-11 12:06:42 -0500 )edit

Please note that you can not measure the wheelbase with a rule for use with odometry for a 4wd. I tried to explain that here (but not sure how good/bad to understand that is). The usual approach is to rotate the robot 360° and to calculate the wheelbase from the odometry values. Problem is that it varies from surface to surface, you better get an IMU.

( 2019-09-11 13:22:23 -0500 )edit

Thanks, at the moment I have an MPU6050. I'll give it a try with two more wheels.

( 2019-09-11 14:04:35 -0500 )edit

I meant I haven't seen it being used in formulas, but the distances will be as I mentioned.

( 2019-09-11 14:05:42 -0500 )edit

Sort by » oldest newest most voted

The right answer I was looking for was provided by @Choco93:

Distance between left and right wheel also called wheel separation distance is taken from centre of one wheel to the centre of other wheel. Same goes for rear and front wheel, distance between points of both wheels that touch the ground.

Thank you.

more