Standard Drivetrain Comparison

[Andrew Schreiber]

Originally Posted by Chris is me

I don't mean to be harsh - but listing arbitrary "ranks" for types of drivetrains is not a comparison or evaluation by any means. Drivetrains have non absolute tradeoffs and benefits - there is not simply a "best" drivetrain, and certainly not one so obvious you can just list it without an ounce of data to back it up.

Qualitative statements about "best" and "worst" have no place in an engineering discussion.

Correct, squishy things like feelings have very little place* in the decision making process. You need quantitative data rather than your feelings.

I'm not going to pretend that I know all the answers to this but as part of one of my classes I am evaluating drive systems (specifically "swerve" systems) and their programming. This is for autonomous mobile navigation using on board sensors. As part of my proposal I determined some basic criteria with which to evaluate the various options. These are:

The drive systems will be evaluated on the following criteria:
4.1 Mobility
This will be evaluated by analyzing the degrees of freedom of the system and determining if the system is holonomic or not. It will also take into account whether or not the system can move at all.
4.2 Accuracy
This will be measured by determining where the system should end up for a given set of inputs based on the encoder readings of wheels. I will make several runs of a course. This course may be as simple as an "L" shaped course 2' long by 1' wide.
4.3 Ease of Use
I would like to measure how simple it is to code and/or drive each system but do not currently have an objective way of measuring this.

The goal of my project is not to find the "best" solution but to provide subjective data on the available solutions to be evaluated later. Interestingly, Chris and I were discussing this project (I defer to his experience with the VEX system when I have questions) and he suggested evaluating 6wd, nonadrive, and mecanum too. Sadly I just don't have time/budget to do those. Also, Vex mecanums are not available for purchase and designing them myself is beyond the scope of my project.

I digress, I think I provided a decent start on a list of evaluation criteria. Please add on criteria you would like to see (with the caveat that I might steal them for my evaluation).

PS: We also discussed having an autonomous challenge track where a 6wd would drive in auton against the various systems. This was only removed because I didn't feel like building an additional drive train + coding it + building a course. (My budget is coming out of my own pocket)