With spinning wheels, moving masses, and $675,000 in research grants, Craig Woolsey of Virginia Tech aims to help improve the manoeuvrability, robustness and reliability of underwater, air, and space vehicles.
Woolsey, of Virginia Tech’s aerospace and ocean engineering faculty received a $375,000 US National Science Foundation (NSF) Faculty Early Career Development Program (CAREER) Award and a $300,000 Office of Naval Research (ONR) Young Investigator Award to study the design of advanced controls and control mechanisms for unmanned vehicles.
A number of unmanned vehicles, such as the US Air Force’s Predator aerial vehicle and underwater exploratory vessels, are said to perform well in limited manoeuvres with humans controlling them from the ground or from ships, Woolsey explained.
But what if the Predator, in addition to taking off, flying within a limited range, and taking photographs as ordered, could sense an anti-aircraft missile coming its way and take evasive action? Or that an unmanned submarine could be sent out to sea on its own – without being tethered to a ship – to track the boundaries of El Nino?
Such vehicles would have to use sophisticated control devices and advanced control algorithms in order to perform complex manoeuvres, Woolsey said. His research for both the NSF and ONR projects will reportedly extend new methods of advanced control design to underwater vehicles by incorporating the important effects of lift, drag, and other fluid forces.
Woolsey and his graduate students are building a spherical underwater vehicle with internal rotors. These rotors are like the mechanisms used in many spacecraft to control where the spacecraft points, he explained.
‘As a first step, we’ll program the vehicle and have it perform manoeuvres similar to those of an unmanned spacecraft,’ Woolsey said. ‘The next step will be to add a streamlined hull and a propeller and control how the vehicle swims.’ Woolsey also is exploring the use of moving masses for underwater vehicle control.
One of the goals of his project is to find ways to perform successful manoeuvres with most of the controls inside the vehicle. ‘In the ocean, external controls such as propellers and rudders are subject to corrosion and biological fouling and unusual problems like seaweed,’ he said. For unmanned ocean vehicles to operate on their own for long periods, their controls mechanisms would have to be protected – just as the controls for spacecraft have to be protected from intense forces and heat when re-entering the atmosphere. The devices and control strategies Woolsey is developing can be used for both of these applications.
Another goal is to design controls that will enable the underwater vehicle to move at a low velocity or even hover without being thrown off course by disturbances from waves or currents.