After further experimenting with me previous model, I decided to abandon the springs in favor of more rigid attachment using barbecue skewers, since the spring allowed too much freedom of movement to consistently control the ear’s position. With some further trial and error around the shape and materials used to construct the ears,  I arrived at a system that allowed me to control rotation and forward-backward motion with three strings.

However, I the flexibility of the frame has made it difficult to consistently test the impact my changes would have on ear motion, as pulling on the strings moved the entire body as well as the ears. To solve this problem, I created a new model.

I used this block of wood to set the ears at a more natural angle (70°) and finalize my control system. However, controlling two ears (six strings total) with only two hands is difficult, meaning that the next step in this process will be some automation. I’m planning on attaching four servos, two for each ear, to this model to control the ears. This should let me make sure that this model is giving me the range of motion I will need to prototype behaviors later on.