Two sketches of harmony interfaces

In my idea, I want to draw a solar system. Sun controls the speed of the complete musical piece. Interaction with other planets can change the harmony and instrument. When everything is set up, user can use their mic to sing. Computer would detect the pitches of user’s voice and adjust major or minor of the harmony to make this piece a great auto-accompaniment music maker. The solar system will start to run when user starts to sing.

The detailed ways to interact with planets have still not been decided yet. A rough thought is to drag them to different positions without leaving their own tracks. One circle will be devided into a few parts and each part will be one set of harmony.