Jimin Lee

Compliant Joint Actuator With Dual Spiral Springs

The main motivation behind the creation of a compliant actuation system is to provide safety, capability of storing energy, and improved performance levels in dynamic tasks. The choice of the proper compliance level pertaining to robots depends on the specific purposes of the robots. In this paper, a dual-spiral-spring actuation system (DSSAS) is proposed to provide high compliance and deformation values for wearable robots. Among many different applications of wearable robotic systems, we aim for systems in which safety and compliance are more important than the control bandwidth of the joints. A spiral spring is selected to take advantage of the characteristics of high levels of compliance and deformation compared to other elastic components. The proposed dual-spiral-spring actuation system uses two spiral springs in opposite directions, as the spiral spring generates torque only in one direction. First, we present the characteristics of the spiral spring for a compliant joint. Then, the design and performance of the DSSAS are demonstrated by experiments.

Robot Hand Synergy Mapping Using Multi-factor Model and EMG Signal

In this paper, it is investigated how a robot hand can be controlled from a human motion and an EMG signal in a tele-operation system. The proposed method uses a tensor to represent a multi-factor model relevant to different individuals and motions in multiple dimensions. Therefore, the synergies extracted by the proposed algorithm can account for not only various grasping motions but also the different characteristics of different people. Moreover, a synergy-level controller which generates motion and force of the robot is developed with postural synergies and an EMG signal. The effectiveness of the proposed new mapping algorithm is verified through experiments, which demonstrate better representation of hand motions with synergies and greater performance on grasping tasks than those of conventional synergy-based algorithms.

Approach of Team SNU to the DARPA Robotics Challenge finals

This paper presents the technical approaches including the system architecture and the controllers that have been used by Team SNU at the DARPA Robotics Challenge (DRC) Finals 2015. The platform THORMANG we used is a modular humanoid robot developed by ROBOTIS. On top of this platform, Team SNU developed the iris camera module and the end effector with passive palm in order to increase success rate of the tasks at the DRC Finals. Also, we developed the software architecture to operate the robot intuitively, in spite of degraded communication. The interface enables operator to select sensor data to be communicated during each task. These efforts on the hardware and the software reduce operation time of the tasks, and increase reliability of the robot. Finally, the controllers for THORMANG were developed to consider stability as the first priority, because the humanoid robot for rescue should perform complex tasks in unexpected environments. The proposed approaches were verified at the DRC Finals 2015, where Team SNU ranked 12th place out of 23 teams.

Classification of grip configuration using surface EMG

Surface EMG is a bio-potential signal from muscles, which has been used in various fields such as medical diagnosis and engineering applications. The surface EMG from forearm muscles can be used for the classification of the hand configurations because the surface EMG on the forearm is related to wrist and hand motion. In this paper, four hand grip configurations are classified depending on which fingers are used for the grasping of a cylindrical shape object. The experimental results show the feasibility of classifying grip configurations using surface EMG signals on the forearm.

Team SNU's Control Strategies for Enhancing a Robot's Capability: Lessons from the 2015 DARPA Robotics Challenge Finals

This paper presents the technical approaches used and experimental results obtained by Team SNU Seoul National University at the 2015 DARPA Robotics Challenge DRC Finals. Team SNU is one of the newly qualified teams, unlike 12 teams who previously participated in the December 2013 DRC Trials. The hardware platform THORMANG, which we used, has been developed by ROBOTIS. THORMANG is one of the smallest robots at the DRC Finals. Based on this platform, we focused on developing software architecture and controllers in order to perform complex tasks in disaster response situations and modifying hardware modules to maximize manipulability. Ensuring stability and modularization are two main keywords in the technical approaches of the architecture. We designed our interface and controllers to achieve a higher robustness level against disaster situations. Moreover, we concentrated on developing our software architecture by integrating a number of modules to eliminate software system complexity and programming errors. With these efforts on the hardware and software, we successfully finished the competition without falling, and we ranked 12th out of 23 teams. This paper is concluded with a number of lessons learned by analyzing the 2015 DRC Finals.

Low stiffness design and hysteresis compensation torque control of SEA for active exercise rehabilitation robots

Rehabilitation robots for active exercise requires compliant but consistent torque (or force) assistance (or imposition) while passive rehabilitation robots are programmed to execute certain movements for patients. This kind of torque assistance in the rehabilitation system can be provided by using SEA (Series Elastic Actuator). In this paper, low stiffness SEA and spring hysteresis compensation are proposed for the robust and accurate torque control of the rehabilitation robot. C-DSSAS (Compact Dual Spiral Spring Actuation System) is developed to implement the low stiffness SEA and a hysteresis compensation method is proposed for robust accurate torque control. Pros and cons of low stiffness SEAs are dealt with in order to explain validity of proposed application. In addition, proposed hysteresis compensation torque controller has backlash-based polynomial model and passivity-based control. Experiments of active exercise of knee were performed wearing the knee rehabilitation device using the C-DSSAS with hysteresis control. The experimental results demonstrate its improved performance of the robot in terms of the robustness and accuracy.

Effect of Tumbling Time on Quality Characteristics of Ham From Retail Cuts of Hind Leg

The effect of tumbling time(0, 1, and 2hr) on quality characteristics of cured-smoked pork retail cuts (Bolgi, Seolgit, Boseop, Dogani, Satae) of hind leg was investigated. Quality analyses indicated the retail cuts of pork hind leg are variable except for proximate composition. The Satae ham had the lowest (P0.05) effect on proximate composition, pH, color, texture properties, and sensory properties of ham. However tumbling decreased cooking loss for Satae ham tumbled for 2hr(P

Effect of Electrical and CO 2 Stunning Methods on Incidence of PSE Pork

The objective of this study was to investigate the incidence of PSE pork depending on different stunning conditions at slaughterhouse. The carcass weights were significantly lower in the normal pork(74.6 kg) than those in the severe PSE pork(76.9 kg) and light PSE pork(77.0 kg). The groups of PSE pork showing the light or the severe PSE sign had significantly lower backfat thickness and intramuscular fat contents when compared to the normal pork(p stunning(33 %) than high-voltage stunning(500 V, 72.96 %) when they were slaughtered with the same slaughtering condition except the stunning method. The stunning method was very effective to reduce the incidence of PSE pork. Therefore, the result from this study suggested that the stunning methods had a significant effect on the incidence of PSE pork. Also, the low-voltage stunning and stunning methods were highly recommended to control and maintain the pork quality.

Team SNU’s Control Strategies to Enhancing Robot’s Capability: Lessons from the DARPA Robotics Challenge Finals 2015

This paper presents the technical approaches used and experimental results obtained by Team SNU at the DARPA Robotics Challenge (DRC) Finals 2015. Team SNU is one of the newly qualified teams, unlike the 12 teams who previously participated in the December 2013 DRC Trials. The hardware platform THORMANG, which we used, has been developed by ROBOTIS. THORMANG is one of the smallest robots at the DRC Finals. Based on this platform, we focused on developing software architecture and controllers in order to perform complex tasks in disaster response situations and modifying hardware modules to maximize manipulability. Ensuring stability and modularization are two main keywords in the technical approaches of the architecture. We designed our interface and controllers to achieve a higher robustness level against disaster situations. Moreover, we concentrated on developing our software architecture by integrating a number of modules to eliminate software system complexity and programming errors. With these efforts on the hardware and software, we have successfully finished the competition without falling and ranked 12th out of 23 teams. This paper is concluded with a number of lessons learned by analyzing the DRC Finals 2015.

New Media Content Platform using 6 –DOF Industrial Robot and 3D Game Engine

Recently, development of robot technology has been actively investigated that industrial robots are used in various other fields. However, the interface of the industrial robot is limited to the planned and manipulated path according to the target point and reaching time of the robot arm. Thus, it is not easy to create or change the various paths of the robot arm in other applications, and it is not easy to control the robot so that the robot arm passes the specific point precisely at the desired time during the course of the path. In order to overcome these limitations, this paper proposes a new-media content management platform that can manipulate 6 DOF industrial robot arm using 3D game engine. In this platform, the user can directly generate the motion of the robot arm in the UI based on the 3D game engine, and can drive the robot in real time with the generated motion. The proposed platform was verified using 3D game engine Unity3D and KUKA KR-120 robot.