Sang Choi

Practical industrial robot zero offset calibration

Current manufacturing trends require industrial robot to be more and more accurate in order to accomplish more and more complicated manufacturing processes. Robot calibration enables standard robots to achieve higher accuracies. Many complex and/or expensive calibration methodologies have been developed and implemented successfully. However, they are difficult to be used in the manufacturing floor because of the cost and flexibility. Therefore, a calibration method that can be used to calibrate robots easily and economically will have a big market impact. Among all robot kinematics parameters, robot zero offset has a much larger influence on robot positioning accuracy. To accurately calibrate the robot zero offset, we developed a practical industrial robot zero offset calibration method that can be used in the manufacturing floor without high skill requirements of the operators. The method is based on tracking a laser line in the robot workspace. The robot joint angles are recorded during the tracking. Using the joint angle data, the robot zero offset can be estimated. The estimated value is then used to offset the encoder to evaluate the estimated values.

Applications and requirements of industrial robots in meat processing

Many tasks in the meat processing industry involve repetitive and physically demanding work. Therefore, the workers are highly susceptible to repetitive-strain injuries to their hands, wrists, elbows, and back. Additionally, quality control and hygiene requirements are vital to this industry. For these reasons, industrial robots have been considered for automating processes such as animal slaughtering, meat cutting and meat selecting. This paper presents an assessment of the requirements for industrial robots in meat processing. Results from a conducted study are disclosed for the existing and potential robotic applications. The meat processes in detail, requirements, challenges and barriers of robotic automation are described, robotic research activities are introduced, existing robotic applications are analyzed and studied and potential applications are proposed and discussed.

Lead-through robot teaching

This paper presents a lead-through method and device for industrial robots and more particularly the design and calibration of a portable lead-through teaching device. Most industrial robots are programmed by a teach-and-playback approach. In some applications, maneuvering robots using the joystick or keypad on the teach pendant along the desired path is not easy or intuitive. To solve this problem, lead-through teaching methodologies have been developed by researchers from both academia and industries for more efficient and intuitive teaching of discrete point or continuous-path robot programs. We developed a portable lead-through teaching device, which is designed to be calibrated by moving the device to predetermined reference poses.

Vibration analysis in robotic ultrasonic welding for battery assembly

This paper presents the vibration analysis of a robotic system, which performs ultrasonic welding of metal tabs on rechargeable batteries commonly used for hybrid or electric vehicles. A robotic battery-welding cell was set up, battery tab welding was performed and the vibration data was collected by using accelerometers and LVDT sensors. The data was analyzed and we learned if/how the vibration affected the robot arm and the battery object under various welding configurations.

Automatic offline program calibration in robotic cells

The latest trends show that industrial robots have been used more and more to increase productivity and quality in general industries other than the traditional automotive industry. Instead of programming the robot by teaching the positions, offline programming has become more popular. User can simulate the programs in the computer first and the productivity can be increased tremendously. One critical step for the offline programming is that the robot cell needs to be calibrated first before the programs can be used in real world. This paper will introduce sensor based calibration methods to automatically calibrate the tool-data and work-object of the robot program.

Vibration anaysis in robotic ultrasonic welding for battery assembly

We present an industrial robotic system that demonstrates the capability to perform the ultrasonic welding of metal tabs on battery cells on the electric vehicles. We investigate the robotic ultrasonic welding by performing robotic welding of the battery module tab of general or/and specific configuration, collecting and analyzing vibration data at various locations of interest on the robot and workpiece, and finally identifying the technical challenges, demonstrate, or propose feasible solutions.

Ultra-flexible production systems for automated factories

Conveyor based transportation systems are used in today manufacturing environments. The main concept we introduce in this paper is using mobile platforms to move parts, tools and fixtures between workstations in a manufacturing environment instead of conveyors. A conveyor-based production system is a fixed transportation system, hard mounted and not reconfigurable, any change in the conveyors path is costly, time-consuming and difficult. Mobile platforms allow for a more flexible manufacturing environment as it only requires a change in the software to reroute the transportations paths and accommodate the changes to the production flow and workstations. This concept paper addresses two objectives: 1) describe some of the existing mobile platform used in industry today 2) introduce the concepts and a simulation of the ultra-flexible production system.

A modular air-gap crawler for motor and generator in-situ inspection

In order to cover different motor/generator air gap configurations, a modular, flexible and on-site reconfigurable inspection crawler is desired. This paper presents a highly extendable modular air-gap crawler design and implementation. A functional module is designed to connect with drive modules on the sides and then connect to another functional module and drive module and so on. Different sizes of linkage between the modules and drive module tracks are employed to fit various slot size and slot teeth to wedge ratio of the stator which the crawler tracks ride on. The modular air-gap crawler is designed and built, and has been tested on mock-up and actual motor and generator units. Visual inspection has been conducted by use of the modular air-gap crawler robot. And testing results are presented and discussed.

Service robots: An industrial perspective

This paper presents the overview and the introduction of commercialized robotic products in the industrial service, maintenance and repair sectors. General facts of the industrial service are briefly described, and then we focus on four specific applications including motor /generator inspection, solar panel inspection /cleaning, tank inspection and pipe inspection. For each application, service process characteristics, operational details, technical challenges, requirements are described. Robotics solutions with commercialized products of each application area were introduced and detailed with special features and specification.

StrapMaster: A robotic band-strapping system

This paper presents a robotic system that performs the steel-strapping process of coils for the metals industry. In the metal coil manufacturing plant, the packaging of coil-product is conventionally performed by dedicated machines specially designed for different strapping modes, such as outer circumference, eye-cross/parallel, vertical, horizontal or sheet pack. In most cases in the current industry, several of these mode-specific strap machines are serially lined-up in order to perform the required strapping sequence. We developed a self-contained robotic system consisting of a pair of 6-dof articulated arms, where the two arms are cooperating with each other to perform three different types of strapping modes. Compared to the conventional machine setup, this robotic solution reduced the floor space to 30% and reduced the equipment cost down to 65%, yet met the cycle-time requirement. The steel-coil strapping process is described, and the conventional and robot method are detailed and analyzed in a technical and economical perspective.