BALLU the Humanoid Blimp Robot Will Never Fall Over

BALLU (Buoyancy Assisted Lightweight Legged Unit) is a robot with a body made of helium balloons and a pair of thin articulated legs - it uses buoyancy to aid its stability and increase safety, and cannot fall. The robot was created by Dennis Hong at UCLA's Robotics & Mechanisms Laboratory. Although the entire robot is not lighter than air and will not float, the buoyancy force from the body assists lightweight legs to stay upright keeping the robot in a stable, standing posture. All actuation, communication, and power components are built into the feet. Only the knees are actuated, and yet with only one degree of freedom per leg, the robot can walk forwards, walk backwards, step sideways, turn, and hop. This is achieved with correct timing of the actuation of each knee along with careful consideration for momentum, drag, joint velocity, joint friction, and joint elasticity. For this early prototype, the actuation of the knees are triggered manually via wireless remote control.