For my project, I made a dog/cat/some 4 legged thing up to the viewers interpretation. The emotion that is portrayed is fear.
It starts off on alert, with pulsing orange lights. Once it calms down, the lights turn off. At this point, if it detects any motion it goes crazy until it wears itself out, and the cycle continues.
There were a couple of technical issues that had to be solved, like servos not playing nice with neopixels on the arduino at the same time, but nothing super serious.
video – https://drive.google.com/file/d/0B6bFUuOZ0DHJRjI0amFveDNjUnc/view?usp=sharing
code – https://drive.google.com/file/d/0B6bFUuOZ0DHJeXFSZGVZLTNXa1k/view?usp=sharing
This is a neat project, I can tell you put a lot of effort into polishing it. I would recommend playing around with ways that you can express fear, in order to make your figure more expressive. I haven’t used those motion sensors, but if they have some analog value for amount of motion, maybe when there’s only slight amounts of emotion, you could have the figure start to shake its leg from nervousness, or back up.