Changhyun Cho

Learn More
This paper proposes a wheel-assembly automation system, which assembles a wheel into a hub of a vehicle hung to a moving hanger in a car manufacturing line. A macro-micro manipulator control strategy is introduced to increase the system bandwidth and tracking accuracy to ensure insertion tolerance. A camera is equipped at the newly designed wheel gripper,(More)
This paper proposes a control method that overcomes the instability arising from both the low update rates of the virtual environment (VE) and the time delay in a communication line. The instability arising from the time delay in a communication line can be overcome using the wave variables since time delay on the wave variables is passive. The so-called(More)
A new concept of the exoskeleton-type masterarm, composed of serial links, is introduced in this paper. To provide maximum range of human motion, several redundant joints are added to the serial links. In order to reduce the number of joints to be measured, kinematics of serial links was taken into consideration in design. Three measurable, controllable(More)
This paper proposes a gravity compensator for the roll-pitch rotation which can be operated in hemispherical work space. The gravity compensator comprises two 1-dof gravity compensators and a bevel differential. It is revealed from analyses of energy and torque that the proposed gravity compensator can perform static balancing completely. The gravity(More)
This paper proposes an energy-based control method of a haptic device with electric brakes. Unsmooth motion is frequently observed in a haptic system using brakes during a wall-following task. Since it is generally known that a haptic system using brakes is passive due to brake's characteristics, its energy behavior has seldom been investigated. However,(More)
In displaying a virtual wall using a passive haptic device equipped with passive ac-tuators such as electric brakes, unsmooth motion frequently occurs. This undesirable behavior is attributed to time delay due to slowness in the virtual environment update and force approximation due to the inability of a brake to generate torque in arbitrary directions. In(More)