A trajectory is a series of time-stamped poses, specified in world coordinates. As to where they come from, yes you need tooling to keep from going crazy. At An

A trajectory is a series of time-stamped poses, specified in world coordinates. As to where they come from, yes you need tooling to keep from going crazy. At Anki, they used animation industry tools, so I am told. The solver handles the balance part in real time, using current sensor input.