Gear ratio selection is typically based upon theoretical top speeds or pushing power, but oftentimes, this isn't the criterion, and is a poor model for actual events. Sprint distance can play a much bigger factor for agile defense.
In this, we'll take a look at how to optimize based on reaching a certain point first, rather than being as "fast" as possible.
A simplified hybrid "H" drive provides convertible pushing power. This solution offers a very lightweight option to teams in the FIRST Community with limited machining capability.
An example of improper gear ratio selection, and a possible solution to model robot battery voltage to improve simulation accuracy. Also includes my thoughts on drivetrain gear ratio selection.
4-Wheel Independent Pivot Drive allows for dynamic and controlled reorientation (twisting) of the chassis in Crab drive mode. The mathematics behind two different Crab twist modes are exploreed.
Basic mathematics behind the control of an 4-wheel independent Pivot Drive-Train. A companion paper, Crab-with-a-Twist, describes the math needed for twisting crab-drive on the move.
Learn the ideas, look up the formulas. The other way round will drive you mad - Joe Johnson [more] 
