Publications
"A Novel Low-Profile Shape Memory Alloy Torsional Actuator", Smart Materials and Structures, 19 (2010) 125014 (9pp)
This paper presents low-profile torsional actuators applicable for mesoscale and microscale robots. The primary actuator material is thermally activated Ni–Ti shape memory alloy (SMA), which exhibits remarkably high torque density. Despite the advantages of SMAs for actuator applications—high strain, silent operation, and mechanical simplicity—the response time and energy efficiency limit overall performance. As an alternative to SMA wires, thin SMA sheets are used to fabricate effective yet compact torsional actuators. Also, instead of using conventional Joule heating, an external Ni–Cr heating element is utilized to focus heat on the regions of highest required strain. Various design parameters and fabrication variants are described and experimentally explored in actuator prototypes. Controlled current profiles and discrete heating produces a 20% faster response time with 40% less power consumption as compared to Joule heating in a low-profile (sub-millimeter) torsional actuator capable of 180° motion.
"Toward the Development of a Hand-Held Surgical Robot for Laparoscopy", Transaction on Mechatronics (Published IEEE online July 25 2010)
Minimally invasive surgery (MIS), which typically involves endoscopic camera and laparoscopic instruments may seem to be the ideal surgical procedure for its apparent benefits. However, in comparison to open surgeries, the spatial and mechanical tool limitations posed on surgeons are so high that often MIS is foregone for complex cases and even when it is possible, the procedure requires a high dexterity, caliber, and experience from the surgeon. Particularly, suturing procedure through MIS is known to be extremely challenging. We are working toward the development of a robotic hand-held surgical device for laparoscopic interventions that enhances the surgeons' dexterity. The instrument produces two independent DOFs, which is sufficient for enabling MIS suturing procedure in vivo. The end-effector's orientation is controlled by an intuitive and ergonomic controller and its position is controlled directly by the surgeon. Different control modes, handles, and end-effector kinematics are primarily evaluated using a virtual reality simulator before choosing the best combination. A proof-of-concept prototype of the device has been developed.
"Robotic Hand-Held Surgical Device: Evaluation of End-Effector's Kinematics and Developpement of Proof-of-Concept Prototypes",
Medical Image Computing and Computer-Assisted Intervention – MICCAI 2010, Volume 6363/2010, 432-439.
"Motion Teaching Method for Complex Robot Links Using Motor Current",
International Journal of Control, Automation, and Systems, 2010 8(5):1072-1081.
Conventional robot motion teaching methods use a teaching pendant or a motion capture device and are not the most convenient or intuitive ways to teach a robot sophisticated and fluid movements such as martial arts motions. Ideally, a robot could be set up as if it were a clothing mannequin that has light limbs and flexible yet frictional joints which can be positioned at desirable shape and hold all the positions. To do the same with a robot, an operator could pull or push the links with minor forces until the desired robot posture is attained. For this, a robot should measure the applied external force by using torque sensors at the robot joints. However, torque sensors are bulky and expensive to install in every DOF joints while keeping a compact design, which is essential to humanoid robots. In this paper, we use only motor current readings to acquire joint torques. The equations used to compensate for the effect of gravity on the joint torques and the self-calibration method to earn link parameters are presented. Additionally, kinematic restrictions can be imposed on the robot’s arms to simplify the motion teaching. Here, we teach the Kendo training robot with this method and the robot’s martial art motions are demonstrated.
"Experimental Evaluation of Several Strategies for Human Motion Based Transparency Control",
Experimental Robotics Springer Tracts in Advanced Robotics, 2009, Volume 54/2009, 557-565.
"How Can Human Motion Prediction Increase Transparency?", ICRA 2008: 2134-2139.
"Design and Acceptability Assessment of a New Reversible Orthosis", IROS 2008: 1933-1939.
"Anthropomorphic Robot Arm and Hand for Interactive Humanoids",
PhD Thesis, Seoul National University Press 2007.
"The Three-Degree-of-Freedom Anthropomorphic Oculomotor Simulator",
International Journal of Control, Automation, and Systems Vol.4, No.2 p227-235, April 2006.
"Motion Teaching Method for Complex Robot Links Using Motor Current Sensing",
International Conference on Control, Automation and System ICCAS 2005, Seoul, Korea.
"TheAnthropomorphic Oculomotor with Three-Degree-of-Freedom Spherical Parallel Link",
International Symposium of Robotics ISR 2004, Paris, France.
"A Biomorphic Simulator of 3D Eye Movements",
International conference advanced robotics ICAR 2003, Portugal.
Surgical Instrument http://www.wipo.int/pctdb/en/wo.jsp?WO=2010112609
WIPO International Patent Filed (WO/2010/112609) IPC: A61B 17/29 (2006.01)
Pub. No.: WO/2010/112609 International Application No.: PCT/EP2010/054471
Chain-Linkaged Motorized Laparoscopic Surgical Tool for Minimally Invasive Surgery, EU Patent Fr 0952186.
Universal-JointedMotorized Laparoscopic Surgical Tool for Minimally Invasive Surgery, EU Patent Fr 0952187.
The Automated Belt Punching Machine, Reg.No. 10-2006-008017 (1-1-2006-0603556-05) Korean Intellectual Properties Office.