A method for fixed-distance line-patrolling of painting robots along the wall based on depth data plane fitting

Abstract During the spraying operation of a painting robot, it is required to maintain a fixed distance from the wall surface. However, factors such as wall unevenness and mechanical constraints are prone to causing distance and angle deviations, which affect the operation accuracy. Addressing the issue of distance deviation, this work proposes a method that solely uses a depth camera to drive the robot for fixed-distance operation along the wall. The method involves constructing an operational reference plane for the actual wall through plane fitting of the wall’s depth information, calculating the deviation angle between this reference plane and the operational datum plane, and driving the actuator to correct the posture, thereby achieving fixed-distance line-patrolling movement. Experimental results show that when the theoretical angle is 5°, the angle between the fitted reference plane and the actual wall is 5.0033°, with a deviation rate of 0.0660%. In actual construction tests, the maximum positive distance error is +2.7 cm, the maximum negative distance error is -3.2 cm, and the absolute deviation rate is 5.9%. There is no cumulative error, and the actual distance always fluctuates slightly around the ideal value. This method can break free from the environmental constraints and cumulative errors of traditional schemes, provide high-precision deviation measurement for the robot, and effectively reduce the distance deviation in the fixed-distance operation along the wall.