Soo-Ho Kim

Modularized Control Architecture of an Embedded Controller for Mobile Welding Robot in the Shipyard

The present study describes the development of controller hardware and control software for a mobile welding robot, which can move in the transverse and longitudinal directions (Moving Tasks), perform the welding tasks of the U-shaped parts and bracket parts in a double hull structure (Welding Tasks), and detect points of the welding path (Sensing Tasks). Controller hardware consists of a main controller and a welding machine controller. The main controller, which is mounted on the mobile welding robot, consists of a CPU board, a motion controller, and an incremental encoder type AC servo motor driver. The welding machine controller, which is mounted on the welding machine located on the outside of the double hull structure, controls the welding machine. Communication between the two controllers is made via the RS485. Control software consists of 4 layers: Task Manager, Task Planner, Actions for Task, and Task Executer. Each Layer consists of modules such as the Action Module, Motion Generator Module, Servo Module, etc. Suitable combinations of modules enable the control software to perform the required tasks. Control software is developed using C programming under QNX Operating System, which is well known to have a reliable hard-realtime performance.

The experiments of wearable robot for carrying heavy-weight objects of shipbuilding works

The purpose of this research is to assess an applicability of wearable robot for the shipbuilding works. We developed two types of wearable robot that can be separated by actuation mechanism; one is directly actuated by electric motors and another is actuated by electro-hydraulic actuators. The lifting capacity of both of the robot is currently about 30kg. We performed field tests in 7 kinds of workplaces for handling and installing heavy-weight objects such as pipeline outfitting components, small metal components, and heat insulation box for two weeks. We focused on whether the wearable robot is applicable to rough and tough shipbuilding environments which include bumpy and sloped metal terrain, steep and narrow staircase, longitudinal stiffener. From the experimental result we verified that the wearable robot could be helpful for assisting workers in several shipbuilding workplaces. We also assessed what should be improved for the application based on the workers requirements.

Development of a Portable Welding Robot for Welding Jobs in Ship Blocks

This paper represents a portable robot for use in the welding process of the double hulls in shipbuilding yards. It has 5 degrees of freedom and 3kg of payload. Its body weight is 17.3 [kg] so that human workers can carry it by hand to the work place. Its body is mainly made of magnesium and aluminum alloys. Since the robot is placed about 25m apart from its controller, EtherCAT is adopted for reliable connection between the robot and controller through a single light cable. RTX real-time kernel and KPA EtherCAT master are used to control the robot on a Windows XP environment. The performance of the developed robot is satisfactory to the requirement in welding tasks of U-type cells in shipbuilding yards.

Auto Path Generation and Active Compliance Force Control Using 3-axis Grinding Robot

In this paper, an auto path generation and an active compliance grinding control using 3-axis farce sensor are presented. These control algorithms enable the grinding robot to follow unknown path of various workpiece shape pattern. The robot is able to go grinding along unknown paths by position controller managing tangential direction angle and cutting speed, with only information about the start position and the end position. Magnitude and direction of normal force are calculated using force data that go through low pass filter. Moreover, normal and tangential directions are separated for force control and velocity control, respectively.