The Animation API was created around the work started by Donovan Buck and Rick Waldron on walking robots—Rick built a quadruped bot, and Donovan, a Hexapod. Turns out, walking robots require a lot of timing on the servos involved, and the Johnny-Five library at the time was only capable of running servos from one degree to another at a maximum speed. This made walking very difficult, because even with servos of the same brand and make, the maximum speed is slightly different. Also, there are situations in which you want different servos to move at different speeds—this was impossible before the Animation API as well.

This led to the development of a function that allows you to set the...