A monocular indoor vision position measurement method based on the Tukey model

Localization is one of the core technologies of indoor surveying and mapping services. To achieve an accurate indoor navigation and positioning, many indoor navigation and positioning technologies have been introduced. Given that visual sensors can generate an abundant amount of information at low cost and can be easily implemented, the space navigation and positioning method based on vision sensors has become a research hotspot. This paper proposes a robust method for measuring the mobile platform position measurement based on the coding graphic images that are captured by a monocular vision sensor. First, a series of coding graphics for the positioning of the carrier are designed. Coding graphics can be accurately identified through contour matching, and the coordinates of the center of graphics can be obtained by means of moment calculation and coding matching. However, due to the shooting angle, the coding image is deformed, thereby resulting in the residual errors of the image coordinates. Second, the Tukey weight factor model is used to calculate the weight according to the residual of the observed value. The value with a residual error of less than 1s0will be fully utilized, the value with a residual error ranging from 1 s0 to 2s0 will be used with reduced weight, and the values with a residual error outside the range of 2s0 will be suppressed. Third, the space resection methods based on Tukey and unit weights are adopted and used to calculate the position information of the mobile vehicle. Finally, experimental environments are then built, where 22 coding graphics are randomly pasted on the wall, and the coordinates of the coding graphics with accuracies of greater than 1 cm are measured by the total station. Four groups of images are captured, with each group having 9, 12, 11, and 17 available coding graphics of each group. The experiment results indicate that the proposed methods (based on unit weight and Tukey weights can be used to calculate the position of mobile carriers in a room. The method based on Tukey weight obtained better results and improved the plane and elevation accuracies by 29.76%-49.42% and 29.17%-74.07%, respectively. In general, the coding graphics designed in this paper can be accurately identified and positioned, the Tukey weight factor model can effectively identify the observed value residuals, and the space resection method based on the Tukey weight factor model can be used to calculate the position information of the vehicle and obtain better estimates. Therefore, the proposed method can provide high-precision navigation and positioning measurement services for indoor space mobile carriers. © 2020, Science Press. All right reserved.