• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.10a
• /
• pp.205-206
• /
• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.43-44
• /
• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.35-36
• /
• 2008

• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.2
• /
• pp.97-104
• /
• 2015

A fuzzy controller and a 2-dimensional wire-driven heavy material lifting system helping human operator are proposed in this paper. The 2-dimensional wire-driven heavy material lifting system is a kind of human-assistive systems in which a human is involved in the control loop. Most of the existing human-assistive control systems cannot consider human operator's characteristic. To consider human operator's characteristic, human's operating motion and requirement of reducing operator's force to lift a heavy material are considered in the design process of the proposed fuzzy controller. The performance of the proposed system is verified by experiments.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.23 no.5
• /
• pp.436-443
• /
• 2013

This paper presents design methods of a fuzzy controller and an operator model for a wire-driven heavy material lifting system helping human workers. The wire-driven heavy material lifting system is a kind of human-assistive systems in which a human is involved in the control loop. Thus, human's control characteristics and requirement of reducing worker's force to lift a heavy material are considered in the design process of the proposed fuzzy controller. An automatic weight measurement algorithm during the early stage of lifting is also introduced. Finally, the effectiveness and performance of the proposed system are proved by experiments.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.7
• /
• pp.7-14
• /
• 2009

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.10
• /
• pp.458-463
• /
• 2006

The purpose of this work is to investigate the fundamental properties of the gradual muscle force potentiation. We investigated the dependence of force potentiation on both the pulse-amplitude and the pulse-duration with different ramp-up time. The experimental results showed that the force increment ratio (FIR) during constant electrical stimulation decreased with pulse-amplitude and also with pulse-duration. The FIR was greater with short ramp-up time in both the pulse-amplitude and pulse-width modulation. The feasible mechanism might be that the myosin light chain phosphorylation induces the force potentiation and it occurs only in the fast type muscle fibers which are recruited first. These observations indicate that muscle potentiation must be understood well for the accurate control of muscle force.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.2
• /
• pp.176-183
• /
• 2009

This paper proposes command signal generating method for a wearable robot using the force as the input signal. The basic concept of this system pursues the combination of the natural and sophisticated intelligence of human with the powerful motion capability of the robot. We define a task for the command signal generation to operate with the human body simultaneously, paying attention to comfort and ease of wear. In this study, we suggest a basic exoskeleton experimental system to evaluate a HRI(Human Robot Interface), selecting interfaces of arm braces on both wrists and a weight harness on the torso to connect the robot and human. We develop the HRI to provide a command for the robot motion. It connects between the human and the robot with the multi-axis load-cell, and it measures the relative force between the human and the robot. The control system calculates the trajectory of end-effector using this force signal. In this paper, we verify the performance of proposed system through the motion of elbow E/F(Extension/Flexion), the shoulder E/F and the shoulder Ab/Ad (Abduction/Adduction).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.2
• /
• pp.219-225
• /
• 2015

Because a hydraulic actuator has high power and force densities, this allows the weight of the robot's limbs to be reduced. This allows for good dynamic characteristics and high energy efficiency. Thus, hydraulic actuators are used in some exoskeleton robots and quadrupedal robots that require high torque. Force control is useful for robot compliance with a user or environment. However, force control of a hydraulic robot is difficult because a hydraulic servo system is highly nonlinear from a control perspective. In this study, a nonlinear model was used to develop a simulation program for a hydraulic servo system consisting of a servo valve, transmission lines, and a cylinder. The problems and considerations with regard to the force control performance for a hydraulic servo system were investigated. A force control method using the nonlinear model was proposed, and its effect was evaluated with the simulation program.

• Journal of the Ergonomics Society of Korea
• /
• v.29 no.3
• /
• pp.357-364
• /
• 2010

This study proposes a lower-limb exoskeleton system that is controlled by a wearer's muscle activity. This system is designed by following procedure. First, analyze the muscle activation patterns of human leg while walking. Second, select the adequate actuator to support the human walking based on calculation of required force of knee joint for step walking. Third, unit type knee and ankle orthotics are integrated with selected actuator. Finally, using this knee-assistive system (KAS) and developed muscle stiffness sensors (MSS), the muscle activity pattern of the subject is analyzed while he is walking on the stair. This study proposes an operating algorithm of KAS based on command signal of MSS which is generated by motion intent of human. A healthy and normal subject walked while wearing the developed powered-knee exoskeleton on his/her knees, and measured effectively assisted plantar flexor strength of the subject's knees and those neighboring muscles. Finally, capabilities and feasibility of the KAS are evaluated by testing the adapted motor pattern and the EMG signal variance while walking with exoskeleton. These results shows that developed exoskeleton which controlled by muscle activity could help human's walking acceptably.