In this paper, details of the uses of various robots in the shipbuilding process are provided, with an emphasis on newer developments and applications. The current state of robot applications will be discussed according to the priority of the shipbuilding process. First, various robots for open structures, such as several types of welding carriages and 6-axis articulated robot manipulators, will be reviewed in terms of their mechanisms and applications. Second, several attempts to design autonomous mobile robotic systems for closed blocks of the double-hulled structure of a ship will be discussed in terms of the performance characteristics of their proposed self-traveling mechanisms. Lastly, all corresponding technologies for overcoming structural complexities in closed blocks as well as future directions of robot automation in the shipbuilding industry are also discussed.

Robots in the shipbuilding industry

For controlling a work process carried out by means of a robot (RB), instructions are stored both relating to the positioning of the robot and relating to the very process to be accomplished. The process instructions are stored in the form of process stage instructions (SPS, SPM and SPE) comprising (a) process start stage, during which the process is initiated (the arc is struck, for instance, when arc welding is involved) and the relative movement between object and robot can be started; (b) process main stage, during which the actual process is carried out; and, at least when the process is not directly followed by a further process; (c) process terminal stage, during which the process is terminated (the arc is broken, for instance, when arc welding is involved) and the relative movement between object and robot can be stopped. A control system for a robot includes memory (PM) for robot instructions, including data for specific process parameters, operating means (OP) for storing robot instructions and means (CU, SS, WC) for automatically carrying out the process controlled by the instructions. The operating means have a control lever (34) with motion in at least two dimensions for controlling said specific parameter data, particularly during execution of a process main stage.

Method and control system for controlling an industrial robot

Due to demographical factors, there will be a 25% decline in the national labor pool of eligible 17 to 21 year old men by 1992. As the Navy faces fierce competition with other services and private industry for the dwindling personnel resources of the nation, efforts must be made to consider automating certain tasks, especially those that are hazardous, boring, and labor intensive onboard ships at sea.



The Surface Ship Continuing Concept Formulation (CONFORM) Program (SEA-5014) sponsored the Naval Surface Weapons Center's Robotics Laboratory to identify potential applications of robotic and artificial intelligence systems to operation and mission activities for shipboard use. The results of the investigation concerning applications of robotics to automate the aforementioned tasks are presented. Changes in current manning levels for selected tasks and ship classes, i.e., CVs, CVNs, LPDs, LPNs, and auxiliaries are examined. Future ship designs incorporating robotics, such as the advance based repair (ABR) ship are discussed. Twenty-four applications were cited in the study which include a remote controlled vehicle for flight deck operations, limited tasks in biological, chemical, and radiation environments, computer aided command decision aids, ordnance handling, undersea search, recovery, and salvage, and ventilation duct cleaning. Four of the applications and their subsequent hardware fruition will be discussed.

Robotic and artificial intelligence systems for the naval operational environment

Developed for fully automatic welding of a wide variety of hull block subassemblies the Mitsui robot adopts MIG welding. The welding torch is suspended on a travelling gantry and has seven axes of freedom. Each axis is driven by electric hydraulic pulse motors or electric pulse motors through an open-loop type NC. The position of the welding line is defined by the original input data (welding line position and welding condition) and corrected data obtained from the visual sensing system which is controlled by a mini-computer (main-computer). The robot system is comprised of three sub-systems; a control data generating system, a driving control system and a visual sensing system.

Robot "sees", decides and acts

This arc welding robot is developed, as the first step, for the purpose of automatic horizontal and vertical fillet welding of large steel structures like sub-assembly for shipbuilding. Its characteristics are as follows: 1) It has a hand which acts as a welding torch, suspended on a travelling gantry type structure and can control seven axes simultaneously. 2) The starting and ending points of each welding line are detected, and filler-aiming point on welding line is corrected by means of optical data obtained through an image sensor camera. 3) Instruction to the robot is given by a dialogue mode, utilizing a character display working interactively. 4) With one mini-computer (senior computer), the robots up to four can be controlled as a group. 5) Input data of the robot can be generated by the information concerning the data base of hull structure design and a dialogue mode using a graphic display. Through welding experiments with the robot developed, the authors have found bright prospects to apply it to practical uses. So, as the second steps, they are now developing a robot that has two hands and can do fillet welding on both sides at same time to improve sensing function and welding efficiency.

T Nozaki

Papers

Robot "sees", decides and acts

Development of arc welding robot for shipbuilding (no. i report)