Abstract
There is a hypothesis that insists that sperm whales melt and congeal sperm oil in their head to adjust their buoyancy. This paper describes an underwater robot with a buoyancy adjusting system based on the sperm oil hypothesis. First of all, we chose paraffin wax as a substitute of real sperm oil and measured its buoyancy increase between liquid and solid states. Paraffin wax's melting point is relatively low and its volume difference between liquid and solid states is large. Then, we designed and developed an underwater robot. Six syringes filled with paraffin wax were installed in the robot and the wax was heated by nichrome wire to melt it. We measured robot's buoyancy increase and succeeded in making the robot surface and change its posture.
