Feedback Control and Time-Optimal Control about Overhead Crane by Visual Servo and These Combination Control

Overhead cranes are broadly used in industry. However, undesirable load swing is often induced with transportation. Therefore, various researches about control of positioning and swing suppression of crane load have been made. On the other hand, a worker operates a crane skillfully by manual-operation in transportation. Hence, support system and automation of crane operation are expected from the viewpoint of safety and production efficiency. Feedback, time-optimal and these combination controls by visual servo for practical use are described in this section. A visual servo device has the following two types. One type is installed separately from a crane and another type is installed on a trolley. Two problems related to the crane control will be discussed from here. The first problem is feedback control by separate type of visual servo device. Separate type device is the case that the device cannot be installed on the crane. It has to track transportation movement and measure swing of the load. Base-line stereo which has parallel optical axes of two cameras uses parallax where tracked target point is not in the center of camera image and therefore, tracking control is difficult to succeed. Gaze controlled stereo vision device has the mechanism that an intersection point of two cameras optical axes always accords with the target and can catch the target point in the center of camera image. This stereo vision device is made and used it for experiments. Using camera image data and tracking controlled camera angles, crane load can be tracked and at the same time 3 dimensional position of the load can be got. By using these data, feedback control of positioning and swing suppression was applied to crane load in experiments. The second problem is combination control of time optimal control and feedback control by installed type of visual servo device. Installed type device is not necessary to track transportation movement, then that is why 3D-camera fixed to trolley is used. This type device can measure displacements of both swing of the load and rope hoisting. Time optimal control is feed forward control. Trolley acceleration time for swing suppression control is set using exact natural period of load swing that is beforehand estimated. However, when with lack of information of actual rope length, position of center of gravity