• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.11 s.242
• /
• pp.1534-1541
• /
• 2005

Unlike industrial manipulators, the manipulators mounted on service robots are interacting with humans in various aspects. Therefore, safety has been one of the most important design issues. Many compliant robot arms have been introduced for safety. It is known that passive compliance method has faster response and higher reliability than active ones. In this paper, a new safety mechanism based on passive compliance is proposed. Passive mechanical elements, specifically transmission angle of the 4-bar linkage, springs and shock absorbing modules are incorporated into this safety mechanism. This mechanism works only when the robot arm exerts contact force much more than the human pain tolerance. Validity of this mechanism is verified by simulations and experiments. It is shown that the manipulator using this mechanism provides higher performance and safety than those using other passive compliance mechanisms or active methods.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.21 no.5
• /
• pp.660-666
• /
• 2011

In this paper, we proposed a Particle Swarm Optimization(PSO) to search the optimal link lengths for legged walking robot. In order to apply the PSO algorithm for the proposed, its walking robot kinematic analysis is needed. A crab robot based on four-bar linkage mechanism and Jansen mechanism is implemented in H/W. For the performance index of PSO, the stride length of the legged walking robot is defined, based on the propose kinematic analysis. Comparative simulation results present to illustrate the viability and effectiveness of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.180-185
• /
• 2004

Unlike industrial manipulators, the manipulators mounted on the service robots are interacting with humans in various aspects. Therefore, safety has been the important design issue. Many compliant robot arm designs have been introduced for safety. It is known that passive compliance method has faster response and higher reliability than active ones. In this paper, a new safe mechanism based on passive compliance has been proposed. Passive mechanical elements, specifically transmission angle of the 4-bar linkage, springs and shock absorbing modules are incorporated into this safe mechanism. This mechanism works only when the robot arm exerts contact force much more than the human pain tolerance. Validity of the safe mechanism is verified by simulations and experiments. In this research, it is shown that the manipulator using this mechanism provides higher performance and safety than those using other passive compliance mechanisms.

• The Journal of Korea Robotics Society
• /
• v.14 no.4
• /
• pp.245-250
• /
• 2019

Milli-scale crawling robots have been widely studied due to their maneuverability in confined spaces. For successful crawling, the crawling robots basically required to fulfill alternating gait with elliptical foot trajectory. The alternating gait with elliptical foot trajectory normally generates both forward and upward motion. The upward motion makes the aerial phase and during the aerial phase, the forward motion enables the crawling robots to proceed. This simultaneous forward and upward motion finally results in fast crawling speed. In this paper, we propose a novel alternating mechanism to make a crab-inspired eight-legged crawling robot. The key design strategy is an alternating mechanism based on double four-bar linkages. Crab-like robots normally employs gear-chain drive to make the opposite phase between neighboring legs. To use the gear-chain drive to this milli-scale robot system, however, is not easy because of heavy weight and mechanism complexity. To solve the issue, the double-four bar linkages has been invented to generate the oaring motion for transmitting the equal motion in the opposite phase. Thanks to the proposed mechanism, the robot crawls just like the real crab with the crawling speed of 0.57 m/s.

• The Journal of Korea Robotics Society
• /
• v.12 no.2
• /
• pp.107-115
• /
• 2017

In this paper, four-bar linkage mechanism for the knee joint is developed which is used in prosthetics. But unlike the prosthetics, the feature of this mechanism is that the instantaneous center of rotation of the four-bar linkages can be moved behind the ground reaction force vector so that it can be passively supported without any external power. In addition, this mechanism is developed similar to the structure of the human knee joint for eliminating the sense of heterogeneity of the wearer. In order to design the mechanism with these two objectives, optimization design process is done using the PIAnO tool and detailed design is carried out through optimized variable values. The developed mechanism is attached to the robot which can assist the hip and ankle joints. In order to verify the operation of the developed knee mechanism, an insole type sensor was attached to the shoes to compare data values before and after wearing the robot. Result data showed that wearer wearing the exoskeleton robot with the knee mechanism was the same value regardless of whether the heavy tool is loaded or not.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.5
• /
• pp.591-596
• /
• 2022

Since 4-bar linkage widely used in various industrial fields has a fixed link length, it is inconvenient to add an independent link structure or control device to change the movement of output link. Therefore, this paper proposes a new concept of variable 4-bar linkage mechanism to selectively adjust the movement of the output link to fit desired situations, and applied to the commercial table fans, which is a representative product using a 4-bar linkage system. The optimal rotation angle steps for efficiency are determined experimentally and the appropriate lengths of linkage to fit each step are calculated analytically. Changes in the linkage length are implemented by the rotational motion using a grooved cylindrical cam and the feasibility of the proposed variable linkage mechanism is verified through fabrication and measurement. The presented variable link mechanism is expected to improve the efficiency of industrial robots and fuel valve systems.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.735-739
• /
• 2002

PTB(Power Transfer Breaker) is a device which incorporate the functions of ACB(Air Circuit Breaker) and ATS(Automatic Transfer Switch). ACB is a circuit breaker against overload and ATS is a switching device to transfer the load between two electric power sources. An existing PTB design based upon the 5 bar & cam mechanism has been regarded to be too complex and thus a simpler 4 bar mechanism with trigger lock is proposed. Experimentation and optimization of the trigger lock is presented.

• Journal of the Korean Society for Precision Engineering
• /
• v.2 no.3
• /
• pp.70-76
• /
• 1985

A four-bar mechanism in consideration of the tolerances on link lengths and the clearances in joints is optimally designed by the method of stochastic analysis. The random nature of clearances and tolerances establishes a stochastic optimization design equation in which the parameters in the equation are described by random variables. In order to solve the design equation, the stochastic problem is converted into an equivalent deterministic one. The synthesis of four-bar mechanism for minimum mechanical and structural errors is carried out by the optimization techni- ques using Chebyshev spacing of precision points. By the results from the synthesized mechanism, the generated and desired motions are examined.

• Advances in Computational Design
• /
• v.4 no.3
• /
• pp.197-210
• /
• 2019

Motion generation of a four-bar linkage is a type of mechanism synthesis that has a wide range of applications such as a pick-and-place operation in manufacturing. In this research, the use of meta-heuristics for motion generation of a four-bar linkage is demonstrated. Three problems of motion generation were posed as a constrained optimization probably using the weighted sum technique to handle two types of tracking errors. A simple penalty function technique was used to deal with design constraints while three meta-heuristics including differential evolution (DE), self-adaptive differential evolution (JADE) and teaching learning based optimization (TLBO) were employed to solve the problems. Comparative results and the effect of the constraint handling technique are illustrated and discussed.

• The Journal of Korea Robotics Society
• /
• v.11 no.4
• /
• pp.193-204
• /
• 2016

This paper presents an anthropomorphic finger prosthesis for amputees whose proximal phalanx is mutilated. The finger prosthesis to be proposed is able to make the amputees to perform the natural motion such as flexion/extension as well as self-adaptive grasping motion as if normal human finger does. The mechanism of finger prosthesis with three degrees-of-freedom (DOFs) consists of two five-bar and one four-bar linkages. Two passive components composed of torsional spring and mechanical stopper and only one active joint are employed in order to realize an underactuation. Each passive component is installed into the five-bar linkage. In order to activate the finger prosthesis, it is required for the user to flex and extend the remaining proximal phalanx on the metacarpophalangeal (MCP) joint, not an electric motor. Thus the finger prosthesis conducts not only the natural motion according to his/her intention but also the grasping motion through the deformation of springs by the object for human finger-like behavior. In order to reveal the operation principle of the proposed mechanism, kinematic analysis is performed for the linkage design. Finally both simulations and experiments are conducted in order to reveal the design feasibility of the proposed finger mechanism.