A flying robot can float on gusts of wind like a bird, using 150 times less power than it does during propelled flight. It can also adjust its position automatically when the wind changes to catch the breeze and stay aloft.
The main limit on how long a drone can stay in the air is the lifetime of the battery it uses to power its propellers. To save energy, researchers have experimented with drones that soar upwards or glide down using currents of air, but replicating a bird-like hovering has proved more difficult.
Now, at the Delft University of Technology in the Netherlands and her colleagues have developed a flying robot that uses its throttle just 0.25 per cent of the time, on average, while hovering in place.聽 When the robot is flying around, it uses its throttle 38 per cent of the time.
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The team developed an algorithm that lets the drone shift its position as the wind changes to keep itself in the air. 鈥淲hen the wind field changes, it adapts to the environment and changes its position autonomously,鈥� says Hwang. 鈥淚t always tries to find a new position if its current position doesn鈥檛 work 鈥� it鈥檚 very flexible.鈥�
The algorithm works using a modified system of trial-and-error. By measuring the wind speed using its sensors and working out its position with a camera and GPS sensor, it can subtly shift the robot鈥檚 position if it detects that the drone is no longer hovering.
Though Hwang and her team have only tested the robot in a wind tunnel, they hope to soon test it outside where wind conditions can change more suddenly. If it works well, it could be used for long-distance surveys of the ground or ocean, or for monitoring a single spot for an extended period of time.
Adapting to a change in wind for a hovering robot is novel, says at the University of Sheffield, UK, and could prove useful for small robotic flying drones. However, the algorithm takes a few minutes to respond to input from the drone鈥檚 sensors, which might need to be improved upon for fast-changing winds in the real world, he says.
arXiv
