A tiny spinning device that can keep rotating for more than 10 hours without being powered could eventually help vehicles navigate in places where GPS signals cannot reach.
Researchers at Singapore’s A*STAR Quantum Innovation Center have developed a millimeter-sized rotor that floats without physical contact and loses remarkably little energy as it spins.
The device achieved the lowest energy loss ever reported for a mechanical rotor of its size, according to a study published in Nature Communications.
The technology could lead to more accurate gyroscopes, which are essential parts of inertial navigation systems.
Gyroscopes allow vehicles to track changes in their direction and orientation without relying on satellites.
They are especially valuable underwater, underground and in other environments where GPS is weak or completely unavailable.
One of the biggest challenges in creating highly sensitive mechanical sensors is friction. Even small amounts of friction gradually drain energy from a moving object.
Levitation offers a possible solution because an object can move without touching a supporting surface. However, magnetic levitation systems have another problem. Movement through magnetic fields can produce electrical currents known as eddy currents, which drain energy and slow the object down.
The Singapore researchers found a clever way to greatly reduce this effect by taking advantage of rotational symmetry.
As their rotor spins around its central axis, it experiences almost the same magnetic environment throughout every rotation. This prevents many of the eddy currents that would normally slow it down. The researchers found that the spinning motion lost energy around 100,000 times more slowly than the rotor’s sideways and vertical movements.
The team used carefully controlled electrostatic forces to accelerate the floating rotor to 930 revolutions per minute. They then switched off the drive. Inside a high-vacuum environment, the rotor continued spinning for more than 10 hours.
That exceptional stability also allowed the researchers to demonstrate its potential as a gyroscope. The system could detect rotations as slow as 0.0065 degrees per second, putting its sensitivity within the range of commercial-grade gyroscopes.
Computer modeling suggests that further improvements could eventually push the technology into the more demanding “navigation-grade” range. Such sensors could help autonomous underwater vehicles, for example, maintain accurate navigation during long periods when satellite positioning is impossible.
The system has several other advantages. It operates at room temperature, uses passive levitation and combines a relatively large millimeter-scale rotor with high spinning speeds and extremely low energy loss.
Researchers now plan to make the rotor spin even faster, improve its stability and shrink the equipment needed to operate it.
Their longer-term goal is to turn the experimental system into an affordable and practical sensor. If successful, this tiny floating spinner could provide a new way for machines to know exactly where they are going—even when GPS disappears.
