Advances in Research of Wall-climbing Robots: from Biology to Bionics-A Review

Wall-climbing robots can stably ascend vertical walls and even ceilings, making them suitable for specialized tasks in high-risk, confined, and harsh conditions. Therefore, they have excellent application prospects and substantial market demand. However, several challenges remain, including limited load-carrying capacity, short operational duration, a high risk of detachment, and the lack of standardized physical and control interfaces for carrying auxiliary equipment to complete missions. This study analyzes the macro and micro structures and movement mechanisms of typical organisms in terms of negative pressure adsorption, hook-and-claw adhesion, dry adhesion, and wet adhesion. The exploration of biological wall-climbing mechanisms is integrated with the adhesion techniques used in practical wall-climbing robots. Additionally, the mechanisms, properties, and typical wall-climbing robots associated with adhesion technologies were investigated, including negative pressure adsorption, hook-and-claw adhesion, bionic dry adhesion, bionic wet adhesion, electrostatic adhesion, and magnetic adhesion. Furthermore, the typical gaits of quadruped and hexapod robots are analyzed, and bionic control techniques such as central pattern generators, neural networks, and compliant control are applied. Finally, the future development trends of wall-climbing robots will be examined from multiple perspectives, including the diversification of bionic mechanisms, the advancement of mechanical structure intelligence, and the implementation of intelligent adaptive control. Moreover, this paper establishes a solid foundation for the innovative design of bionic wall-climbing robots and provides valuable guidance for future advancements.