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When the hook mass is greater than the load mass or the load has a distributed mass property, the load sway of the crane system can be considered as a double-pendulum. At this point, the crane system has two kinds of natural angular frequency which greatly increases the difficulty of the dynamic analysis and the controller design. To this end, the linear dynamics of a 2-D overhead crane with double-pendulum...
Magnetic bearings have been used in flywheel energy storage systems for improving their performance due to the main advantage of contact-free operation.However, the gyroscopic coupling, parameter coupling and imbalance force affect the operating performance and stability of an magnetic suspended flywheel energy storage system with asymmetric rotor,therefore, a cross feedback based control method is...
Crane systems are used in many situations, such as production facilities and outdoor operations. Load vibration generated through increased load mass and high speed operation has to be suppressed for efficiency and safety motion. In this study, we propose an s-shaped motion trajectory generation method that can suppress load vibration. The trajectory consists of the acceleration period, constant-velocity...
Stability of full order flux observer based speed sensorless control system is studied in the paper. By small signal analysis method, the whole control system is linearized and transfer function from speed reference to practical speed is obtained. Examining pole distribution of transfer function, stability analysis is carried out. The impact of motor parameter error on speed identification system...
This paper proposed a novel method which is the combination of traditional cross feedback control and sliding mode control for the problem of gyroscopic coupling and imbalance disturbance in the rotor system of magnetic suspended wind turbines when they rotate under high speed situation. Firstly, the mathematical model of a radial four-degree-of-freedom active magnetic bearing rotor system is derived...
Because the gyroscopic coupling effect and the imbalance force typically generate undesirable vibrations in the rotor system of magnetic suspended wind turbines when they rotate under high speed situation, a novel cross feedback based control method is proposed. Firstly, the dynamic model of a radial four-degree-of-freedom active magnetic bearing rotor system is derived. Next, a double stage cross...
This study presents a simple S-curve trajectory generation method for rotary crane motion that can suppress residual load sway using only horizontal boom motion without load sway sensing. If load sway can be suppressed without measuring it, reduction in sensor cost can be achieved. Furthermore, employing simple velocity trajectory patterns such as trapezoidal and S-curve patterns, which are widely...
Because natural frequency of the rope-load oscillation system affects the stability and performance of the control system, the controller design should consider robustness with respect to rope length. If the control system considers the effect of rope length variance, the crane's motion can be controlled without a sensor system for measuring it. This paper presents a control method based on linear...
To suppress two-dimensional load sway caused by the horizontal boom motion of a rotary crane, both horizontal and vertical boom motions are generally used. However, it would be more energy efficient and safer if a control scheme were developed that only used horizontal boom motion, eliminating the need for any vertical boom motion. In addition, if we can suppress load sway without the need to measure...
This paper presents a motion trajectory generation method for mechanical systems such as feed drive tables, gantry cranes, and material handling systems, which can be widely used in industrial applications. These systems are operated using S-curve acceleration and deceleration trajectory, and controllers that allow only such a simple motion trajectory are employed from the viewpoints of controller...
Because horizontal boom motion of a rotary crane generates two-dimensional load-sway, skilled labor is required to control the rotary crane, and automatic control system that achieves boom positioning and load-sway suppression simultaneously has been widely studied thus far. Although vertical and horizontal boom motion is employed for the load-sway suppression in most existing studies, it seems undesirable...
Micron-size channels have been made inside silicon by femtosecond laser-assisted HF etching. The etching is guided by localized carriers generated via two-photon absorption. Its potential of 3-D drilling has been demonstrated.
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