A visual selfpositioning method for inspection robot based on symmetrical tangential artificial landmarks The artificial landmark positioning technology is one of the visual positioning methods of the inspection robot. Although this technology has simple algorithm and low maintenance cost, it is difficult to be widely used due to the limitations in some special environment. For example, people are not allowed to set a large number of landmarks on the ground in some workshops. In this paper, we propose a visual selfpositioning method based on the symmetrical tangential artificial landmarks. The basic idea of this method is: firstly, a small number of tangential artificial landmarks are set on the walls or machine tools on both sides, secondly, the perspective model and triangulation method are used to realize the selfpositioning of the inspection robot. The experimental results show that the method is simple to operate and has high positioning accuracy, which can meet the needs of the inspection robot.

Trajectory Correction and Optimization of a Flexible Manipulator Based on a Visual Servo The tokamak invessel robot is a 10DOF flexible invessel inspection robot designed for carrying out scanning and maintenance of a tokamak in a complicated environment. Due to the large size of the TIR, the flexible deformation of the TIR is significant, which leads to a low end positioning accuracy and trajectory accuracy. This paper analyzes the factors leading to the deformation of the TIR and establishes a model of the pose error caused by these factors. Based on the model, an error compensation method is proposed based on an optimization method. According to the the principle of visual servo, the end position deviation is calculated by using the image obtained by the visual unit. The detected deviation is used to control the end position of the TIR and optimize and reduce the deviation. Experiments are carried out on a 1:1 model of a tokamak vessel, and the results show that the proposed method can effectively improve the end positioning accuracy.