Neural network based visual servo for quick-change device alignment in context of fusion reactor remote maintenance

Abstract

The remote maintenance process for fusion reactor is complex, which can be very time-consuming and labor-consuming. This paper proposes a modified neural network based visual servo method to align a quick-change device with robot camera system. A classical position-based visual servo control law is used to guide the robot to reach the desired position. The key target for the above visual servo controller is to obtain a robust pose estimator to calculate the quick-change device pose with respect to the camera. This pose estimator is trained using RepVGG model with a self built image samples. An attention mechanism is added to the neural network to enhance the stability of pose prediction for reflective metal objects. The robot joint speed is also smoothed to reduce the image motion blur effect and make the visual servo process stable. The performance of the proposed visual servo controller was verified on an UR5 robot, and the results show that the stable and rough alignment of the quick-change device can be realized.