TU Delft develops drone that behaves like a bird

A drone carrying out measurements in a rainforest may eventually no longer need to remain airborne continuously. Researchers Salua Hamaza and Anton Bredenbeck from TU Delft have developed a drone that, inspired by birds, can use its sense of touch to locate a branch, align itself with it, and then switch off its motors. The research has been published in Nature npj Robotics.

The researchers see applications for drones that need to monitor their surroundings autonomously for extended periods, for example in forest canopies or complex industrial environments. Landing on a branch could significantly reduce a drone's energy consumption, but doing so reliably is challenging. During the final phase of landing, the drone's gripper can obstruct its cameras. The researchers therefore opted for a different approach: not just seeing, but also feeling.

Landing with a robotic hand

The drone is equipped with a lightweight, three-fingered robotic hand fitted with tactile sensors. During landing, it flies a figure-eight search pattern while opening and closing its hand. As soon as a finger touches the branch, the sensor registers the contact. By combining multiple contact points, the drone can determine where the branch is located and how it is oriented.

The drone then adjusts its position until all three fingers have stable contact. The hand subsequently grips the branch firmly, allowing the drone to switch off its motors. If the grip fails, the drone retreats to a safe hovering position and tries again.

Reliable in experiments

According to the researchers, the method remained reliable during flight experiments, even when the initial estimate of the branch's position, orientation, and size was incorrect. This suggests that touch could complement visual perception, particularly when cameras become less reliable.