Past Work

  To avoid confidential company information, this page only includes general keywords and web found pictures.

Industrial Manipulator Development

 Up to now, most of big size industrial manipulators are developed and commercialized by only a few companies; ABB, FANUC, KUKA, and YASKAWA. Those companies have high-quality of robot technology, but their robots are expensive and hard to be customized by individual customer's needs. We localized the big size of manipulators and customized their functions to adapt into Samsung's factories. In this project, I was a charge of "Motion Planning & Control," and had developed a number of motion control technologies. Currently, 14 numbers of manipulators are successfully operating in Samsung Corning Precision's factory. Following shows what kinds of technique I developed and researched.

    1. Project Goals

6-DoF Glass Handling Robot Development for Gen.11 & Gen.8 LCD Glass.
(Here, "Gen" is an abbreviated word of "Generation" from LCD industry. Generally, "Gen.11" means  the glass size of 3000 x 3320mm. )

    2. Technical Issue & Achievement
  • Task Controller
I developed two types of path-planners; Joint/Cartesian space path-planners. The Joint space path-planner is called "Motor Overdrive," which produces position commands based on motor N-T curve, so that it enables to use the maximized RPM & Torque over its motor spec. The Cartesian space path-planner is called "Velocity Path-Planner," which includes special functions such as 

    i) Automatic Acceleration/Deceleration Time Decision
    ii) Singularity Avoidance Path-Planning (Patent Preparation)
    iii) Conveyor Tracking Control (Co-Work w/ Jinseok Kim)
  • Motion Controller
It consists of Inverse Kinematics (IK) & Inverse Dynamics Controller. To guarantee repeatability and safety, Analytical IK, closed-form solution, is implemented. Compared with conventional IK, it is enhanced with

    i) Wide Configuration Control over 720 degree of joints
    ii) Wrist Interpolation Inverse Kinematics for Singularity Avoidance (Patent Preparation)
    iii) Tool Collision Detection & Exchanger

Dynamics is also implemented based on Newton-Euler Method. It is considered
    i) Tool dynamics
    ii) Auto tool calibration functions.
  • Servo Controller
Servo controller uses a serial PPI controller. Since a serial manipulator has a vibration problem, varied gain system is developed. Position & Velocity gain set is prepared by joint speeds and changed by linear interpolation method.

Auto Gain Tuning - Iterative Learning Control (ILC)

  "Gain Tuning" is one of the conventional but most important issues in robotics. It usually takes 2~4 hours to optimize the gains, since each robot has different and unknown dynamic properties. Even more each robot performs different motions, the required gain is different. Thus, auto tuning method, which does not based on dynamics modeling, is strongly required.
 I propose Motion Based Gain Tuning approach which uses "Iterative Learning Control (ILC)." Firstly, the ILC is learned until tracking errors become to zero.
   Secondly, the ILC system is converted to two parallel servo controllers, then using regression method and known input & output, optimized gains are obtained.  

Auto Teaching & Apparatus

"Teaching" is the most basic work to operate a robot. However, it is also known as one of the burdensome works to users, since the real workspace is quite small or there are a bunch of object which impede free-motion. Thus, it requires many inspectors to prevent a collision while "teaching." For example, it takes about 3~4 hours with 3 inspectors to teach LTRs glass-inserting-motion into a narrow cassette. The glass size is 3000 x 3320mm and the margin between the glass and a cassette is only 3 mm.

 I proposed a sensor based auto teaching system, in which system a robot is guided by several laser-spot sensors. The sensors are equipped with the tip of the black fork hand, and the robot move around the cassette gathering 3 dimensional position information of the cassette. Automatically, the robot calculates and inspects via points and a target point.

<LCD Transfer Robot with Cassette>
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 Spot Laser Sensor>
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Industrial Transfer Robot

 Our robot group is mainly developing SCARA type robots; Wafer Transfer Robot (WTR) & LCD Transfer Robot (LTR). This kind of robot requires extremely high speed and low vibration to raise up productivity in semiconductor & LCD plants. To use maximum speed under torque limit, the acceleration(ACC) and deceleration(DEC) time is optimized with each motion. I made a torque optimization approach which predicts motor-torque based on dynamics model and varies its ACC&DEC time. Theoretically, this approach achieved 7% of time reduction and this approach will be applied 2012.
  In addition, I am also performing vibration analysis, which is now the most important issue in robot industry. I cannot mention about details, however a vibration reduction technique is implemented and it is showing a great performance in Samsung's factory.

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Dual Manipulation with 7-DoF Redundant Arms

My robot engineer career is started with Dual Manipulation Project in Samsung, which is designed for factory automation using two set of 7-DoF redundant arms and one waist joint. My task was covering all the parts of motion planning such as from kinematics to Impedance & Collaboration Control. Followings show what I researched and developed with details. These achievement is finally used for LCD TV assembly demonstration. It was a good chance to test my knowledge and experience from schools.

  • Kinematics & Inverse Kinematics Dev. w/ Analytical & Numerical Solution
  • Redundancy Resolution Control w/ Modified Arm Angle [Patent]
  • D-H Parameter Auto Calibration using vision (Co-worked w/ Chigun An)
  • Impedance Control
  • Real time collision detection
1) Redundancy Resolution Control w/ Modified Arm Angle

 Disclosed is a teaching and playback method using a redundancy resolution parameter determined in conjunction with a joint structure, for a robot, and a method to apply analytic inverse kinematics to a robot having an elbow with an offset and a computer-readable medium of controlling the same. A reference plane variable with the joint structure is generated and an angle between the reference plane and an arm plane of the robot is used as the redundancy resolution parameter. The robot is taught and its operation is played back in differential inverse kinematics or analytic inverse kinematics using the resolution redundancy parameter.
<Concept of Redundancy Resolution Control> <Definition of Reference Plane for Modified Arm Angle>

[1] D. Park, K. Lee, C. An, and Y. Hong. “Teaching and playback method based on control of redundancy resolution for robot and computer-readable medium controlling the same.” US Patent 12 923 650, Apr. 21, 2011. [PDF]

Dynamic Movement Primitives with Obstacle Avoidance [07'~08']

 Robots in a human environment need to be compliant. This compliance requires that a pre-planed movement can be adapted to an obstacle that may be moving or appearing unexpectedly. Here, we present a general framework for movement generation and mid-flight adaptation to obstacles. For robust motion generation, Ijspeert et al developed the dynamic movement primitives, which represent a demonstrated movement with a differential equation. This equation allows adding a perturbing force without sacrificing stability. We extend this framework such that arbitrary movements in end-effector space can be represented - which was not possible before. Furthermore, we include obstacle avoidance by adding to the equation of motion a repellent force - a gradient of a potential field centered around the obstacle. In addition, this article studies the effect of different potential fields and shows how to avoid obstacle-link collisions within this framework. We demonstrate the abilities of our framework in simulations and with an anthropoid robot arm.

  • Supervised Learning (Dynamic Movement Primitives)
  • Obstacle Avoidance by Potential Field Approach
  • 7-DoF Redudant Manipulator
  • Null-Space Elbow Avoidance

[1] H. Hoffmann, P. Pastor, D. Park, and S. Schaal. “Biologically-inspired dynamical systems for movement generation: Automatic real-time goal adaptation and obstacle avoidance”, IEEE International Conference on Robotics and Automation, 2009. [PDF]

[2] D. Park, H. Hoffmann, P. Pastor, and S. Schaal. “Movement reproduction and obstacle avoidance with dynamic movement primitives and potential fields”, IEEE-RAS International Conference on Humanoid Robots (Humanoids 2008) [PDF]

[3] D. Park, H. Hoffmann, and S. Schaal. “Combining dynamic movement primitives and potential fields for online obstacle avoidance”, Adaptive Motion of Animals and Machines (AMAM08), Cleveland, Ohio, 2008 [PDF]

Manipulation for Rover Robot & DSC System [07'~08']

  This project is to see the feasibility that a small manipulator performs soil-analysis in other planets. We used a PhanTom 3-DoF Arm with CCD camera, which picks and places a soil sample into a capsule. Then, it send the capsule to Differential Scanning Calorimetry (DSC) system, which separates water from soil and analyze its components. To control this robot, I applied Dynamic Movement Primitives (DMPs) mentioned above and accomplished a successful demonstration.

This project is supported by Jet Propulsion Laboratory (JPL) and demonstrated in there. Followings show the keywords.

  • PhanTom 3-DoF Robot Arm
  • iSight Webcam (Color CCD Lens)
  • Differential Scanning Calorimetry (DSC) system
  • Dynamic Movement Primitives (DMPs)
<Entire Manipulation System> <Soil-Analysis Capsule
and DSC System>

Turning Pattern Generation using Spin Momentum on HRP2 [05'~06']

 This research is performed for bachelor thesis in Arai Lab, Osaka Univ. I verified the possibility of dynamic turning motion using the angular momentum while robot's rotating under Resolved Momentum Control. This turning motion consists of robot body's angular momentum and the spin state of the sole of foot. The spin makes it easy to conserve the entire angular momentum. Finally, it shows that dynamic turning motion allows the larger turning than other static turning motion. Followings show the keyword.

    • Resolved Momentum Control
    • Running Pattern Generation (Squat) 
    • Slip Observer (Spin) 
<Turning Control Experiment> <Turning Pattern Generation Flow>

Control System for Pneumatic Humanoid [06']

  This research is performed in Asada-Hosoda Lab, Osaka Univ. The goal of this research is to design a linear control system for McKibben, which is an artificial muscle of Pneumatic Humanoid. Since McKibben uses compressed air, we proposed PWM - air flow control system which controls the on/off air valve. 
  • Mckibben (Artificial Muscle)
  • PWM Pneumatic Control
  • H4 Controller

Eco-Be! League for Robocup [06']

  Eco-Be! is a mini-soccer robot which was for a new league in RoboCup. The goal of this project is developing a mixed reality soccer system as a standard platform. The entire system consists of Citizen Eco-Be! robots, Camera, virtual ground (PDP TV), and control server. I participated in developing infrared transmission device and motion plan. The system was demonstrated in Robocup-Japan 2006.
 Followings show the keyword.
    • Mini Soccer-Robot
    • Path Planning
    • Robocup Kitakyushu Japan 2006.5.3 ~2006.5.6

<RoboCup Japan 2006 DEMO> <Eco-Be! League Concept>
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