Robots are often associated with being heavy, mechanized metal objects. In fact, most current legged robots are unsafe, unstable, complex, expensive, and slow. BALLU is a robotic system that uses buoyancy to aid its stability and increase safety. This unique approach makes it intrinsically stable at all times and prevents it from falling. As a matter of fact, it cannot fall. Helium filled balloons make up the upper body. 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 which make up the majority of the robots mass. The current prototype is a biped with two degrees of freedom. Only the knees are actuated (cable driven from the feet). Yet, with only one degree of freedom per leg, the robot can walk forwards, walk backwards, step sideways, turn, hop, and perform other types of motion. 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. In addition to these locomotion capabilities, BALLU’s stability and safety can potentially further advance various aspects of the human-robot interaction experience.
