Many modern robotic designs take their inspiration from nature, resulting in advances like flying micro-drones that maneuver by flapping their wings. These flapping-wing robots are smaller, quieter, and more agile than their fixed-wing counterparts, making them well-suited for surveying and monitoring.

However, due to the constant motion of the wings and limited weight capacity, internal sensing poses a challenge. Zheng et al. overcame this hurdle and developed a self-powered sensor to monitor flapping-wing robot motion. Their sensor integrates nanogenerators into the wings, providing a lightweight and accurate mechanism to track wing angle and flapping frequency.

“The proposed method will provide real-time wing motion status to assess flight reliability and provide additional parameters to the control system without consuming any airborne energy from the robots,” said author Xiaosheng Zhang.

The authors integrated the nanogenerator material directly onto the surface of the wing using advanced manufacturing techniques and developed a theoretical model to translate the output signals into motion parameters. With this sensor, they measured wing pitch angle to within 0.7 degrees and oscillation frequency to within 0.1%.

The team plans to expand their method to monitor other relevant parameters for this class of robots such as aerodynamic drag. They hope access to this data can aid in the design of better robots.

“Monitoring the aerodynamic parameters in real-time on board the robot can have significant implications for the design of the mechanical components and flight control system,” said author Zhonglai Wang.

Source: “Nanogenerator based self-powered motion monitoring for flapping wings of bio-inspired flying robots,” by Hao Zheng, Xu Zeng, Yunfei Wang, Yan Wang, Zhonglai Wang, and Xiaosheng Zhang, Applied Physics Letters (2023). The article can be accessed at