Research on Automatic Locating Method for Large Hydraulically-Driven Loading Arm Based on Visual Servo

An automatic docking method for connecting the loading-arm robot with the oil pipeline was proposed. The kinematic modeling of the loading arm, the design of loading arm control system and the visual servo system were introduced. Firstly, the transformation matrixes from the coordinate system established on the terminal joint to the based coordinate system of the loading arm were derived, rotary angles of the loading arm's joints can be detected from the encoders, then the pose of the terminal joint can be obtained. Secondly, the control program of the loading arm was developed on a Linux operating system with a Xenomai real-time kernel. Thirdly, based on the target position detected by the visual servo system, the loading arm can be automatically controlled to dock with the oil pipeline. Finally, the docking method of the loading-arm robot was verified by experiments, the test results also showed that the position errors of the loading arm were below 40mm, with the special mechanical guidance, the position errors were within the allowable range.