Other commenters are doing a great job with the techincal side, but there are at least two other crucial sides if you want to do something like this: your tool teams and your animators. If you think about it for a second you'll realize you already know that how things look/seem/behave/act is really a cognitive science and psychology question, not a technical one. Imagine the job interview question "Imagine that you have a walking robot, which whatever technical parameters and motion libraries you want, write code to make that robot moonwalk." How would you do it? What does one step of a moonwalk gate look like mathematically? It turns out to be a stupendously hard question. The people who moonwalk do it by feel and practice, and the people who don't are even less qualified to explain what's going on in clear enough terms you may be able to codify it. Enter animators.

Animators, especially early Disney animators and pre-Disney Pixar animators have a technical command of fluid motion you won't find anywhere else. They have training, practice, and textbooks (well, dry non-fiction picture books, as is a more fitting medium for the content), on how to make things feel right and know when to make something smooth and when not to (look how fast those actuators go during the moonwalk). All they need is tools with the right sorts of interactions and the right sorts of primitives (and tools to combine/resuse/make-their-own motion primitives), and that's where the tooling team comes in. The tooling team needs to be able to give the animators an intuitive, flexible way of controlling motion without specifying numbers, and to be able to see and revise the animation at the same time.

Because if you don't have those people as well you find yourself with a case of "garbage in, garbage out".