Hyena's tail and ears convey much of the expression needed for
communication, but the head can also tell more about the state of a hyena. Dr. Holekamp left the decision to incorporate this feature into our design up to the team. Our team decided to take on the challenge and add this extra feature to our robot for added realism and ultimately to give Dr. Holekamp more options in her research with the robot. Below are two pictures of hyenas with their heads both up and down to. We feel that this will get the hyenas attention which will lead to better responses from the other components of the hyena.
Our team had some trouble with implementing a head mechanism. The problem that our team faced was moving such a large piece of the robot. This sort of movement takes a lot of torque and power. The first attempts at this task involved using an arm attached to the largest Servo motor that is sold. Even with the high torque motor the head failed to move, and subsequently broke the motor. To ease the load on the motor, we hollowed out the head to decrease the weight and moved the pivot point up further into the neck. With this adjustment the motor was able to move the head up and down, but struggled, drawing 2.5 amps of current even when it was in its idle state of up. (See above right picture) In response to this our team developed a new plan, to attach a hinge at the base of the neck and lower a wire connected in the head as if it were a draw bridge with the high torque Servo motor. This result was a success with less stress being placed on the motor. The below video shows the first working prototype for the head. As you can see there is an arm which pulls the wire in the head. The PVC piping at the base of the neck if functioning as the hinge for the prototype.
YouTube Video
The video below shows the prototype above reinvented to allow for implementation. The same design concepts are used but in this case, more refined which allows for the head to move up and down seamlessly. This design fits in the hyena model and is controlled with our User interface on the laptop in the background.
