A mechanism is established for the dual-foot biped robot with the vacuum sucker composed of three flexible hinge suction cups, and the curvature range in which the robot can move is analyzed. Based on the static force analysis, the force and torque equilibrium equations are derived under different rotation angles. The stability constraint equations are built for the suction cup radius and the gravity center position of the robot under the anti-sliding and anti-turning-over conditions. Through MATLAB optimization simulation, the minimum adsorption force for guaranteeing stability is solved, and the relationships between the climbing safety factor and the foot joint angle, the gravity center position are given and analyzed. The results show that the safety factor is nonlinear to the foot joint angle, its minimum value is obtained at robot horizontal pose, and the robot stability can be adjusted by the gravity center position. The physical prototype robot is developed and implemented to indicate that the proposed robot can climb and rotate on the wind turbine blade.
 Elkmann N, Felsch T, Förster T. Robot for rotor blade inspection[C]//2010 1st International Conference on Applied Robotics for the Power Industry. Piscataway, USA: IEEE Computer Society, 2010: 1-5. Zhang H X, Zhang J W, Liu R, et al. Design of a climbing robot for cleaning spherical surfaces[C]//IEEE International Conference on Robotics and Biomimetics. Piscataway, USA: IEEE Computer Society, 2005: 375-380. 谈士力,王建成,苏建良,等.球形壁面爬行机器人研制[J].机器人,2002,24(6):517-520,529.Tan S L, Wang J C, Su J L, et al. Development of mobile robot moving on the sphere surface[J]. Robot, 2002, 24(6): 517-520,529. 桂仲成,陈强,孙振国.多体柔性永磁吸附爬壁机器人[J].机械工程学报,2008,44(6):177-182.Gui Z C, Chen Q, Sun Z G. Wall climbing robot employing multi-body flexible permanent magnetic adhesion system[J]. Journal of Mechanical Engineering, 2008, 44(6): 177-182. Leon-Rodriguez H, Hussain S, Sattar T. A compact wall-climbing and surface adaptation robot for non-destructive testing[C]//International Conference on Control, Automation and Systems. Piscataway, USA: IEEE Computer Society, 2012: 404-409. Xue D Y, Chen Z, Xu X H, et al. Research of an omni-directional wall-climbing robot[C]//6th World Congress on Intelligent Control and Automation. Piscataway, USA: IEEE, 2006: 9247-9251. Shao J, Li X F, Zong C G, et al. A wall-climbing robot with gecko features[C]//Proceedings of 2012 IEEE International Conference on Mechatronics and Automation. Piscataway, USA: IEEE Computer Society, 2012: 942-947. Silva M F, Tenreiro Machado J A, Tar J K. A survey of technologies for climbing robots adhesion to surfaces[C]//IEEE 6th International Conference on Computational Cybernetics. Piscataway, USA: IEEE Computer Society, 2008: 127-132. Tummala R L, Mukherjee R, Xi N, et al. Climbing the walls[J]. IEEE Robotics and Automation Magazine, 2002, 9(4): 10-19.  Bahr B, Li Y, Najafi M. Design and suction cup analysis of a wall climbing robot[J]. Computers and Electrical Engineering, 1996, 22(3): 193-209.  Zhu J, Sun D, Tso S K. Development of a tracked climbing robot[J]. Journal of Intelligent and Robotic Systems: Theory and Applications, 2002, 35(4): 427-444. Yi Z Y, Gong Y J, Wang Z W, et al. Development of a wallclimbing robot for ship rust removal[C]//IEEE International Conference on Mechatronics and Automation. Piscataway, USA: IEEE Computer Society, 2009: 4610-4615. Yoshida Y, Ma S G. A wall-climbing robot without any active suction mechanisms[C]//IEEE International Conference on Robotics and Biomimetics. Piscataway, USA: IEEE Computer Society, 2011: 2014-2019. 毛志伟,杨志斌,周少玲,等.双足移动型爬壁机器人吸盘力学性能研究[J].机械设计与制造,2010(8):159-161.Mao Z W, Yang Z B, Zhou S L, et al. Research of mechanical properties of sucker for biped-type wall-climbing robot[J]. Machinery Design & Manufacture, 2010(8): 159-161. Guan Y S, Zhu H F, Wu W Q, et al. A modular biped wall-climbing robot with high mobility and manipulating function[J]. IEEE/ASME Transactions on Mechatronics, 2013, 18(6): 1787-1798.  段军,孙树栋,曹飞祥.一种仿壁虎机器人吸盘组设计与抗倾覆能力分析[J].机床与液压,2012,40(17):76-78,25.Duan J, Sun S D, Cao F X. Design and anti-overturning capability analysis of a gecko inspired robot's sucker group[J]. Machine Tool & Hydraulics, 2012, 40(17): 76-78,25.