Instructions

The crane has a load but it is not visual. The mass of the boat, the gyro disk and the load at the tip of the crane are all at the same order of magnitude. This is for making the effects more pronounced. Note that, in order to make the gyro have a prescribed velocity before the motion starts it is spun up from 0 to 0.8 time units. The crane is turned approximately 90 degress from 0 to 0.7 time units to make the lifting operation effect the roll of the ship more.

Case 1: Stabilization of boat of crane induced roll.
Step 1: Enable only motor 1 and motor 2. There is no spinning gyro, hence no active stabilization. Observe how the ship rolls.

Step 2: Enable motor 1, motor 2 and motor 4. Observe how the gyrodisk stabilizes the rolling motion.

Case 2: Nutation effect from inertial disk.
Step 1: Enable only motor 3. Observe how the nutation moment rotates the disk and boat.

Step 2: Enable motor 3 and motor 4. Observe how the spinning disk becomes an inertial disk i.e. orientation stable in space.

Abstract

This research reports on using inertial devices to control ship motion induced by on-board cranes. Norwegian industries are constantly assessing new technologies and methods for more efficient and safer production in fish farms. Norwegian fish industries share a common problem: namely, to install new equipment and lift personnel in a safe and controllable way from ships. This paper deploys the Moving Frame Method (MFM) to analyze the motion of a system constituting of a crane and a gyroscope mounted on a ship. The crane is a simple two-link system that transfers produce and equipment to and from barges. An inertial flywheel—a gyroscope—is used to stabilize the barge during transfer. The MFM describes the system dynamics using modern mathematics. Lie group theory and Cartan’s moving frames are the foundation of this novel approach to engineering dynamics and the notation is taken from geometrical physics. This together with Hamilton’s principle enables an effective way of extracting the equations of motion. This work uses the Caley Hamilton Theorem and the Rodriguez’s formula to reconstruct the rotation matrix during numerical integration. This project extends previous work. It accounts for the dual effect of both the crane and the stabilizing inertial device. Furthermore, this work accounts for buoyancy and motor induced torques. Furthermore, this work displays the rotating ship in 3D, viewable on mobile devices. WebGL is a JavaScript API for rendering interactive 3D and 2D graphics within any compatible web browser without the use of plug-ins. This paper presents it results as a 3D simulation. The long-term results of this work leads to a robust 3D active compensation method for loading/unloading operations offshore. Finally, the interactivity between the crane and the stabilizing gyro anticipates the impending time of artificial intelligence when machines, equipped with on-board CPU’s and IP addresses, are empowered with learning modules to conduct their operations.

Josef Flatlandsmo
Torbjørn Smith
Ørjan Ommedal Halvorsen
Johnny Vinje