Hop to It

Quadcopter drones have found applications across a number of fields, including photography, videography, agriculture, surveillance, search and rescue operations, and even package delivery. Their ability to hover, fly in tight spaces, and capture stable aerial footage has proved to be very valuable in many industries.

However, despite their wide range of useful applications, quadcopter drones face significant limitations, primarily due to their energy consumption. Flight is inherently energy-intensive, and quadcopters rely on batteries to power their motors and other electronic systems. The weight of the battery and the energy required for sustained flight severely limit both the duration of flight and the payload capacity of these aerial vehicles.

The limited flight time of quadcopters poses a challenge in many scenarios, especially those requiring extended aerial surveillance or mapping missions. Additionally, the weight of the battery directly impacts the amount of additional payload a drone can carry, such as cameras or sensors. As a result, there is a trade-off between flight time and payload capacity, making it difficult to extend both simultaneously.

After observing how birds deal with these problems by fusing aerial and ground movements, a team at the City University of Hong Kong have developed a novel type of quadcopter drone that can not only fly, but also hop. By bouncing along on its travels, this vehicle can significantly extend the life of its battery. This innovation also enables the drone to carry a larger payload without quickly exhausting its energy supply.

The design of the system is incredibly simple — the researchers have essentially created a pogo stick that a drone can hop around on. It is made up of an upper and lower segment, connected by bearings and fasteners, as well as rubber bands. The rubber bands provide a spring action that launches the drone back up in the air after it is compressed on contact with the ground. This assembly is attached to a commercial Crazyflie drone via an elastomer mounting hook, although the system could be adapted to work with virtually any type of quadcopter.

The drone flies by adjusting the throttle of its motors, decreasing their speed such that the vehicle comes into contact with the ground, then increasing the throttle to lift back off with the help of the pogo leg. This process is repeated, and corrections are made during the bounce to control the direction of travel.

In continuous flight, the battery will keep this particular drone in the air for a bit over six minutes. Using the pogo leg, the vehicle can stay in operation for about 20 minutes. The pogo action does slow down the vehicle’s travel speed, however. It would be possible to cover more ground in a flight-only mode. But, if the goal is to cover a smaller area, but continue operating for longer — as would be needed in search and rescue operations, for example — then hopping offers a distinct advantage.

Given the simplicity of the device and its ability to interface with so many existing drones, it may prove to be useful for a wide range of applications in the future. It could also reduce the need for large charging infrastructures as well, which could save a lot of cash — all by putting a stick with a rubber band on the bottom of a drone.