Self‐Powered In Situ Sensing for Planetary Gearbox via Floating Freestanding‐Layer Mode Triboelectric Nanogenerator

Abstract Planetary gearboxes, a critical component in industrial transmission systems, present significant challenges for condition‐monitoring technologies owing to their complex motion characteristics. Traditional monitoring methods are often susceptible to environmental noise interference and rely on external power supply systems, complicating maintenance and increasing costs. This study presents an in situ sensing system for planetary gearboxes using a floating freestanding‐layer‐mode triboelectric nanogenerator (FF‐TENG) integrated on the side of planet gear. By utilizing the inherent axial micromotion characteristics during operation, the system employs a floating‐electrode structure with adaptive gap adjustment to prevent contact wear between the electrode and the dielectric layer, which significantly enhances system durability. Key parameters are systematically analyzed to examine the FF‐TENG's output characteristics and working mechanism. The FF‐TENG exhibited outstanding speed‐monitoring capabilities across diverse rotational speeds. Furthermore, a local maximum mean discrepancy improved transformer encoder model is designed. The model achieved 98.4% accuracy in fault diagnosis across different rotational speeds and fault modes. Then, FF‐TENG is applied to the planetary gearbox of a robotic arm, realizing in situ sensing of its motion behavior. This research introduces a self‐powered in situ sensing system for planetary gearboxes using TENG, providing a new approach for rotating machinery in situ sensing.