Susumu Kouno

Automatic measurement and control of the attitude of crane lifters: Lifter-attitude measurement and control

Abstract The spreaders and lifters on cranes are usually controlled to stop at the same time as their trolleys are stopped. Despite the use of adequate control systems, however, the lifters usually have comparatively large sway movements, due to their free suspension from the trolleys through pulleys, hooks and cables. It is therefore important to accurately measure the attitude of the lifters, in order to suppress such sways by means of secondary control. The authors have previously proposed a maintenance-free automatic measurement and control system which accurately measures the lifter’s attitude, using a servo-type accelerometer and a double-rigid-body pendulum model for the system, and completely eliminates the sway of the lifter. However, the measurement/control system takes action only after the trolleys are stopped. This paper extends the previous approach, and presents an on-line automatic measurement and control system that enables the lifters to stop at the same time as the trolleys are first stopped.

Measurement of Speed, Height and Direction of SeaWaves Using Optical Range Sensors

The present paper proposes a sensing system for the speed, the height and the direction of sea waves. The measurement of the three quantities is achieved using three optical range sensors which are adequately located over the sea near the platform. For realizing this, the sensor outputs are modeled as outputs of a linear dynamic system and a Kalman filter and maximum likelihood method are applied. Not only a case of one sea wave but also a case of two overlapping sea waves with different directions are considered. The validity of the system is finally verified with simulations and experiments