(Image courtesy of the U.S. Army.)
The field of autonomous vehicle development has made great strides and is now ready to make what was once considered science fiction a reality. The U.S. military is preparing to deploy autonomous air vehicles capable of transforming during flight. This ability to change shape gives this craft greater versatility during flight. For example, since flight conditions are very variable, the ability of an aircraft to enlarge or contract its wings during flight could make it faster or more efficient.
A study was published by the Combat Capabilities Development Command of the Army Army Laboratory of the US Army and Texas A&M University on the fluid-structure interaction which ultimately led to a new tool which can “quickly optimize the structural configuration future vertical lift vehicles while taking proper account of the interaction between air and structure. Fluid-structure interactions involve moving components that are immersed in a liquid or gaseous environment, as is the case with an airplane or submarine, for example. Future vertical lift vehicles include a family of new military aircraft designed to replace older generations and are expected to be developed over the next year using the results of the recent study.
“Consider a [intelligence, surveillance and reconnaissance] mission where the vehicle must quickly get to the station, or rush, then try to stay on the station for as long as possible, or stroll, “said Dr. Francis Phillips, aerospace engineer at the army laboratory. “During the dash segments, short wings are desirable to go fast and be more maneuverable, but for slower segments, long wings are desirable to allow a flight with low power and high endurance.”
With the change of shape or the morphing of vehicles, a balance must be found between the rigidity of a component necessary to maintain structural integrity and the flexibility necessary to allow structural change.
“If the wing bends too much, the theoretical benefits of morphing could be negated and lead to control problems and instability,” said Phillips.
The analysis required for the development of form-changing vehicles is generally very high. The coupling of any given fluid and any structural configuration given during the analysis requires a high level of calculation. The research team overcame this problem by decoupling the fluid and the structures so that additional structural configurations could be analyzed without having to reanalyze the fluid. This means that form-changing vehicles could be developed in a much shorter time than in the past.
NASA is also at the forefront of shape change technologies. A Shapeshifter team from NASA’s Jet Propulsion Laboratory has tested a 3D printed prototype for a miniature robot that could potentially explore other planets by being able to transform itself into a robot that can fly, float or swim. Similar to the craft of the military, the NASA prototype is described as a drone but with functionality for traversing various environments. The team is working on a series of 12 robots that could explore the dangerous and unpredictable landscapes of other planets. JPL principal investigator Ali Agha sees the moon of Saturn Titan, which has lakes, rivers and seas of methane, as a possible destination for the spacecraft prototype.
“We have very limited information on the composition of the surface,” said Agha. “Rocky terrain, methane lakes, cryovolcanoes – we potentially have it all, but we don’t know for sure. So we thought about how to create a system that is versatile and capable of crossing different types of terrain but also compact enough to launch onto a rocket. ”
NASA’s Shapeshifter would be made up of several smaller robots called cobots, each of which would have a small propeller and could move independently of each other over different areas or come together in a sphere to roll over level ground. The robot is still in the conceptual development phase. It is not known when it will be ready for space exploration. The next mission on Titan will be launched in 2026.