Path Planning for Wall-climbing Robot in Volume Measurement of Vertical Tank

To meet the requirements of measuring the vertical tank volume, a measurement method combining a laser tracker and a wall-climbing robot is designed. In order to realize efficient and accurate measurement, a measuring path of the robot is planned based on MPD (measuring points distribution). Firstly, two measurement methods are adopted to adapt to the circumferentially and vertically sparse MPD respectively. Since the relationship between the measuring path and accuracy is not clear, a tank model is created to analyze the influence of MPD on the time and accuracy, and then the path pattern and its parameters are determined. Finally, simulation and physical experiments are carried out on the point cloud of a tank wall and a real tank respectively. A loss function is proposed to evaluate the path, and the field measurement results are compared with those of the total station method. The results show that the measurement based on the planned path can be completed quickly, and the measurement errors in both simulation and experiments are less than 0.04%, bringing an overall loss smaller than that of currently used measurement methods.