ASAH: An arc‐surface‐adsorption hexapod robot with a motion control scheme

Abstract

Mobile robots with the ability to climb provide significant advantages in equipment contact operation and maintenance. In this work, an arc‐surface‐adsorption hexapod (ASAH) robot is designed for a class of internal cavity‐cylindrical‐type electrical equipment (ICCEE). The target of robot reliable movement on the ICCEE surface obtains its priority to be solved. Therefore, a matched‐specific motion control scheme is proposed. First, the mechanisms, adaptability, and motility of the ASAH robot are analyzed from a kinematic point of view. Subsequently, to solve the arc surface movement problem, this study proposes a novel six‐three‐legged composite gait and a “trapezoidal” foot tip trajectory algorithm, which improve safety in robot support phase movements and adsorption accuracy in the swing phase, respectively. In addition, based on the motion gait and trajectory, an active adsorption scheme is added to compensate for the position error. Finally, both virtual and physical prototype are constructed for performance verification. The simulation results verify the effectiveness of the proposed scheme in facilitating accurate motion on internal and external arc surfaces with different diameters, with an error lower than 5.3 mm/rad and rad/mm for movements in the circumferential and axial directions, respectively. Experimental results and application performance in a nuclear power plant further verify the effectiveness of the gait and trajectory algorithm; an overall success rate of 85% in circumferential movement was achieved with a maximum load weight of 2.63 kg, representing 76% of the robot body weight.