Positioning and Pressing Elevator Button by Binocular Vision and Robot Manipulator

摘要

There are two key problems of anthropomorphic dual-arm robot up and down floors which are path planning and pressing buttons of elevator automatically. Our research group has solved the problem of robot path planning based on electronic map in early stage. As for the problem of pressing buttons automatically, two issues still need to be handled, including positioning elevator buttons in three-dimensional space and pressing specific button automatically by the manipulator of robot. At present, our research group has achieved the accurate detection and recognition of elevator target button in the image. Besides, for the core issue, a new method of pressing target button automatically by manipulator with binocular vision servo is proposed. First, the binocular measurement is applied to get the distance and declination relationships between robot itself and target button, then we shall find the precise position of target button in visual three-dimensional coordinate system and transform its position into the three-dimensional coordinate system which takes robot shoulder as the origin. Thus, the manipulator movement model can be established by constructing relationships between the declination of three degrees of freedom and the real-time coordinates of manipulator, which contains extension of shoulder joint, Internal rotation of shoulder joint and flexion-extension function of elbow joint, and each of them as a separate dimension. On the basis of this model, the PWM (Pulse Width Modulation) control technology is employed to make the manipulator terminal close to target button autonomously. Finally, with deviation relationships between the manipulator terminal and target button as well as the threshold which is set to modulate manipulator, the goal of pressing target button by manipulator can be achieved eventually. Furthermore, the algorithm was tested on medium-sized wheeled dual-arm robot Hawk and results obtained verify the feasibility of the method proposed above can implement the function of pressing elevator target button by robot manipulator precisely, which manifests good robustness.