Design and analysis of wall-climbing robot with passive adaptive parallel mechanism

Wall-climbing robots (WCRs) are widely used for inspecting and maintaining large ship facades to ensure structural safety and reliable performance. However, most existing WCRs hardly pass through facades with variable curvature and dense obstacles because of their rigid mechanisms with limited degrees of freedom and inflexible motion. We propose an omnidirectional mobile WCR integrating a passive adaptive parallel mechanism and omnidirectional steering hauling mechanism. Using the atlas method design criteria, a passive adaptive parallel mechanism combining rotational and translational units was developed, compensating for height differences and fitting angles during wheel rolling on irregular surfaces. By mounting the omnidirectional steering hauling mechanism on the parallel mechanism, specific motion modes enable the robot to flexibly adjust the wheel directions for navigating constrained environments. Considering the adhesive force direction change with curvature, an index representing the varying angle allows us to establish mechanical equilibrium relations and calculate the minimum magnetic force required to ensure stable adhesion. Circuit analysis of the permanent magnet module yielded optimal parameters to enhance adhesion efficiency and stability. Experiments demonstrate that the developed robot can adhere stably and move flexibly on facades with variable curvature and localized obstacles, showing promise for ship inspection and maintenance.