Control of a mobile robot supporting a task robot on the top

This paper addresses the control problem of a mobile robot supporting a task robot with needs to be positioned precisely. The main difficulty residing in the precise control of a mobile robot supporting a task robot is providing an accurate and stable base for the task robot. That is, the end-plate of the mobile robot which is the base of the task robot can not be positioned accurately without external position sensors. This difficulty is resolved in this paper through the vision information obtained from the camera attached at the end of a task robot. First of all, the camera parameters were measured by using the images of a fixed object captured by the camera. The measured parameters include the rotation, the position, the scale factor, and the focal length of the camera. These parameters could be measured by using the features of each vertex point for a hexagonal object and by using the pin-hole model of a camera. Using the measured pose(position and orientation) of the camera and the given kinematics of the task robot, we calculate a pose of the end-plate of the mobile robot, which is used for the precise control of the mobile robot. Experimental results for the pose estimations are shown.