Sung-Rak Kim

A practical approach for minimum‐time trajectory planning for industrial robots

– The purpose of this paper is to maximize the speed of industrial robots by obtaining the minimum‐time trajectories that satisfy various constraints commonly given in the application of industrial robots., – The method utilizes the dynamic model of the robot manipulators to find the maximum kinematic constraints that are used with conventional trajectory patterns, such as trapezoidal velocity profiles and cubic polynomial functions., – The experimental results demonstrate that the proposed method can decrease the motion times substantially compared with the conventional kinematic method., – Although the method used a dynamic model, the computational burden is minimized by calculating dynamics only at certain points, enabling implementation of the method online. The proposed method is tested on more than 40 different types of robots made by Hyundai Heavy Industries Co. Ltd (HHI). The method is successfully implemented in Hi5, a new generation of HHI robot controller., – The paper shows that the method is computationally very simple compared with other minimum‐time trajectory‐planning methods, thus making it suitable for online implementation.

A compensation method of the errors in palletizing work cell on the conversion from an off-line generated program to a real job program

This paper presents a compensation method for considerable pose errors when a simulated program is used for a real palletizing work cell. Since most robot poses are generated by off-line programming (OLP) software recently it is very important to compensate the errors. To show the severity of the errors, the errors are examined when there is no compensation first. To compensate the errors, a palletizing application-oriented method is presented here. It extracts the errors between simulation and real one and makes a transformation matrix for the compensation. The errors are minimized by the proposed geometric method. Also, each position after the compensation is checked for collision-free condition using an algorithm in the controller. Finally, this method is applied to the real palletizing application and the validation is shown.

On-line minimum-time trajectory planning for industrial manipulators

In this paper, a method for the on-line minimum-time trajectory planning for industrial manipulators was proposed assuming that the path is specified and the maximum allowable actuator torques are limited. The typical on-line trajectory planning strategy in industry is to find polynomials that follow the given path while satisfying the kinematic constraints. Although this traditional method is widely used in industry, it has a major shortcoming, which is, by using the constant kinematic constraints that neglect the manipulator dynamics, it lowers the global efficiency of the manipulators dynamic capability. We demonstrated that this existing shortcoming of the traditional method could be overcome considerably by taking the manipulator dynamics into consideration. In the proposed method, the dynamic calculation was performed only at certain points on the given path, which is effectively utilized to determine the kinematic constraints. The experimental results implied that this method could improve the traditional trajectory planning method for industrial manipulators.

Optimal Design of Passive Gravity Compensation System for Articulated Robots

In this paper, the optimal design of a spring-type gravity compensation system for an articulated robot is presented. Sequential quadratic programming (SQP) is adopted to resolve various nonlinear constraints in spring design such as stress, buckling, and fatigue constraints, and to reduce computation time. In addition, continuous relaxation method is used to explain the integer-valued design variables. The simulation results show that the gravity compensation system designed by proposed method improves the performance effectively without additional weight gain in the main workspace.

Systems and algorithms for development of the robot safety function

As interests on the safety for manufacturing robots have grown, robot safety functions have become an important part of the robot system. The robot safety functions are required to flexible tasks such as a human-robot collaboration. In particular, because the safety issue is related to personal injuries, reliable safe systems are necessary. This paper presents systems and algorithms for the electronically controlled robot safety function which is developed in Hyundai Heavy Industries Co. Ltd.

Reliable object detection and segmentation using inpainting

This paper presents a novel object detection and segmentation method utilizing an inpainting algorithm. Inpainting is a concept of recovering missing image regions based on their surroundings, which were originally used for restoration of damaged paintings. In this paper, we newly utilize inpainting to judge whether an object candidate region includes the foreground object or not. The key idea is that if we erase a certain region from an image, the inpainting algorithm is expected to recover the erased image only when it belongs a background area (i.e. only when there is no object in it). By measuring the similarity between the inpainted region and the original image region, our approach filters out false detections while maintaining true object detections. Furthermore, we take advantage of the inpainting for object segmentation, since our approach is designed to explicitly distinguish foreground areas from its background. Experimental results confirm that our approach applied to baseline detectors enables better recognition of objects, obtaining higher accuracies. We illustrate how our inpainting-based detection/segmentation approach benefits the object detection using two different pedestrian datasets.

Industrial robot manipulators with redundancy: YH050 case

This paper presents an analysis of inverse kinematics solutions for YH050 which is an industrial robot manipulator developed by Hyundai Heavy Industries Co. We propose three methods: numerical approach, geometrical approach and combined approach. These approaches are addressed through theoretical explanation and experimental verification.

Sensor Guided Laser Welding Robot System

In order to obtain a good result in the laser welding process, the laser welding technology for manufacturing an automobile body is studied in this research. The robot, the seam tracking system, and CW Nd:YAG laser are used for the laser welding robot system. Especially, the development of the laser-stripe sensor is highlighted. The laser-stripe sensor can measure the profile of the welding object and obtain the gap and seam line. Moreover, the working distance of the sensor can be varied. The control scheme of the whole system is also presented. The profile and gap measurement and the seam tracking experiments were carried out to validate the operation of the system.

Dynamic modeling of flexible glass substrate transfer robot arm and meandering estimation

This paper presents dynamic modeling of glass substrate transfer robot arm that use timing belts for power transmission. The methods proposed in the existing literature are limited in practical use because the dynamic models require a high computational burden or can generate a large error. We propose a simple dynamic model that considers the elasticity of the timing belt in order to estimate the path errors of the robot. The experimental results show that the proposed dynamic model can predict the path errors within maximum 8 %.