Constraints and Formulation of Nonlinear Programming Problem for Automatic Wall Inspection by a Mobile Robot

Abstract

By combining image recognition technology and robotics, it is expected to save labor in daily surveys and inspections of social infrastructure. The purpose of this study is automation of wall inspection by a mobile robot and the automatic wall inspection method that meets the three requirements: comprehensive shooting of the wall surface, reliable detection of the recognition target and reducing inspection time. Especially, this paper focus on constraints for image recognition to reliable detection and nonlinear programming problems to reduce inspection time. First, to perform the requirement of comprehensive shooting of the wall surface, we propose the motion plan of the robot and camera module including the setting of the internal parameters of the camera. The method of considering the error that occurs in the robot and camera when shooting wall is also in the method. Next, to perform the requirement of reliable detection of the recognition target, we derived the constraint conditions that enable image recognition with reference to the research on the appearance inspection of the object by the camera module. Furthermore, by using the time required for wall inspection as an objective function and formulating a nonlinear programming problem within the constraints of image recognition, it is possible to achieve the requirement of reducing inspection time. We confirmed that proposed the automatic wall inspection method works correctly in a simulator. In addition, we conducted actual experiments by using a mobile robot to demonstrate the effectiveness of the proposed method. All the QR codes to be recognized which were attached to the wall surface were detected without omission in case of meeting constraints in image recognition. By comparing with other experimental conditions, we confirmed that the time required for the survey was shortened by using the parameters obtained by solving the nonlinear programming problems problem.