Maxon helps underwater 'bug' clean up

Designed by Florida-based SeaRobotics and currently undergoing testing by the US Navy, the Robotic Hull Bio-mimetic Underwater Grooming System (HullBUG), is a small robot (roughly 50cm long) designed to crawl on the hull of a ship and remove barnacles, algae and other organisms. Although small, sea creatures in sufficient numbers severely impair the hydrodynamics of a vessel – increasing drag, fuel consumption, and hydroacoustic stealth. It is estimated that the US Navy spends an additional $500 million each year due to such fouling. Conventional anti-fouling paint is expensive and continually bleeds heavy metals, polluting the marine environment. Moreover, at least once a decade, the paint must be stripped off and replaced. For sizeable ships, this means producing – and paying for the safe disposal of – tonnes of toxic waste. HullBUG, by comparison, is incredibly cost-effective and can be deployed by a single person. In choosing a motor supplier, engineers had to consider several key requirements. The motors would need the reliability to work in a challenging environment, and possess sufficient power, speed, and torque to cope with resistance from the cleaning tool, the hydrodynamic force of the host vehicle in motion, and friction from the wheels or tracks. The motor would be required to deliver these characteristics within strict size constraints, whilst being economic enough to ensure that the potential loss of a BUG in operation would not make its deployment prohibitively expensive. "After extensive component research, we chose to use maxon motors and gearheads," says SeaRobotics Research Engineer, Dr. Kenneth Holappa. "Maxon Motors not only provided a very cost effective solution, but they were highly efficient and extremely simple to implement." HullBUG uses several maxon EC 45 flat motors to provide drive, and an EC-4pole 45 powers the robot's grooming tool. Another powerful motor, an EC 90 flat, drives an ingenious negative pressure attachment device that keeps the robot attached to the hull. Paul Williams, senior sales engineer for Maxon Motor UK, said: "The fact that a single maxon motor has been chosen to keep the device from losing grip and sinking without trace reflects our lengthy track record of producing strong, dependable motors."