Hi,

I'm trying to compare certain types of physical movement. I have data (acceleration, velocity, and position) from a physical source for a variety of actions. I would like to compare different actions for similarity.

For example, a good comparison would be hand movement, such as when moving a pen to draw lines and other simple shapes. No two movements will be identical, even for the same shape, but different movements will be similar for the same shape. (This is one of the sources of movement I would like to test).

How would I compare data in such a case to determine if two movements are similar? Furthermore, how do I take into account things like scaling (e.g., drawing a big circle and a little circle)? I don't need to take into account rotation, and I assume I can simply start at origin so translation won't be an issue.

(The application is for a silly game idea. I want to have a little robot-of-sorts mimic the player's drawing behavior over time. I need to create a model that accurately simulates the player's movements closely enough. Thus I have to be able to compare movements to create a reliable model, and also to create inputs to the model in the game. Accuracy is necessary, and I also need to be able to tweak inputs for other characters in the game so they have different movements.)

Use machine learning.

If you don't know it, then it's a good thing to learn as your non-machine learning job will soon become obsolete.

I'd suggest either doing something simple like using random forests, or writing a full blown neural network to do it (plenty of C++ compatible libraries for both). For the former, I recall doing a similar task (classifying exercise type given accelerometer data) using random forests in an machine learning class. For the latter, it's reminiscent of https://quickdraw.withgoogle.com/ although I don't know how many details of that are public.

Have you looked into how they recognize writing with a stylus on a touch-screen? I imagine it's not too different from what you're trying to do.

Classification is only one step. Is it possible get movements from the neural network, though? I want the robot/golem character to be able to draw stuff, too.

I found a copy of that book online and will give it a read soon.