Module-Enhanced Slope-Adaptive and Hazard-Aware Hexapod Robotic System for Safe Roof Inspection

Roof inspection is essential yet perilous in construction, with falls causing 24% of fatal work injuries. While drones allow rapid surveying, they often lack close-range precision, and ground-based robots struggle with pitched, irregular rooftops. To address these challenges, this paper presents a module-enhanced hexapod robot designed for autonomous roof inspection. Our system incorporates three key innovations: (1) a Bézier-curve-based gait algorithm for enhanced stability, (2) a fuzzy-logic slope adaptation controller for effective navigation on inclined surfaces, and (3) an infrared sensor–based edge detection mechanism to prevent hazardous falls. The robotic system employs an 18 degrees-of-freedom six-legged walking platform equipped with an inertial measurement unit for real-time posture adjustment and eight strategically positioned infrared sensors for comprehensive hazard detection. The stability-enhanced gait system utilizes third-degree Bézier curve trajectories to optimize foot placement and minimize body oscillations during locomotion. The fuzzy logic controller dynamically adjusts the robot's posture based on real-time slope measurements, maintaining the center of gravity within the conservative support polygon. The edge detection system combines threshold-based filtering with hierarchical path planning to enable proactive hazard avoidance. Extensive tests—combining virtual simulations with real-world trials on roofs up to a 6/12 pitch (26.6°)—demonstrate 33%–39% improvements in stability metrics compared with conventional hexapod control methods. The system achieved over 90% hazard detection accuracy, while maintaining safe edge clearances of 0.28–0.32 m. Real-world validation confirmed the system's effectiveness across various roof configurations, including challenging structural transitions such as ridge lines and valleys. These results confirm the robot's effectiveness in mitigating fall risks and underscore its potential to advance autonomous operations in challenging, sloped environments, contributing significantly to construction safety and inspection efficiency.