Byung-Ju Yi

Flexure hinge has been commonly used as a substitute for mechanical joints in the design of micropositioning mechanisms. However, inaccurate modeling of flexure hinges deteriorates the positioning accuracy. In this paper, a planar 3-DOF parallel-type micropositioning mechanism is designed with the intention of accurate flexure hinge modeling. For this, a preliminary kinematic analysis that includes inverse kinematics, internal kinematics, and analytic stiffness modeling referenced to the task co

A planar 3 DOF parallel-type micro-positioning mechanism is designed with the intention of accurate flexure hinge modeling. For this, a preliminary kinematic analysis that includes inverse kinematics, internal kinematics, and analytic stiffness modeling referenced to the task coordinate is presented. First, the revolute type of a 1 DOF flexure hinge is considered. The simulation result based on FEM, however, is not coincident to the analytic result. This is due to the minor axial elongation alon

A new parallel-type gripper mechanism is proposed in this work. This device has a parallelogramic platform that can be flexibly folded. Therefore, this mechanism not only can be used to grasp an object having irregular shape or large volume, but also can be utilized as a micro-positioning device after grasping objects. Forward position analysis and platform kinematics are investigated to deal with motion tracking and force control. Kinematic optimization is performed to design a parallel-type gr

Current vascular intervention inevitably exposes a large amount of X-ray to both an operator and a patient during the procedure. The purpose of this study is to propose a new catheter driving system which assists the operator in aspects of less X-ray exposure and convenient user interface. For this, an assembly-type 4-degree-of-freedom master-slave system was designed and tested to verify the efficiency. First, current vascular intervention procedures are analyzed to develop a new robotic proced

A methodology for active spring generation is presented based on antagonistic redundant actuation. Antagonistic properties are characterized using an effective system stiffness. “Antagonistic stiffness” is generated by preloading a closed-chain (parallel) linkage system. Internal load distribution is investigated along with the necessary conditions for spring synthesis. The performance and stability of a proposed active spring are shown by simulation, and applications are discussed.

Omnidirectional mobile robots have been popularly employed in several application areas. However, the kinematics for these systems have not been clearly identified, specially for the redundantly actuated case which is common in omnidirectional mobile robot such as Nomadic model. For such mobile robot systems, exploitation of redundant actuation as well as singularity analysis has not been extensively addressed. In light of this fact, this paper introduces two different kinematic approaches for o

Vascular intervention involves inserting a catheter and guidewire into blood vessels to diagnose and treat a disease in an X-ray environment. In this conventional vascular intervention procedure, the doctor is exposed to considerable radiation. To reduce the exposure, we developed a master–slave robot system. A steerable catheter is employed to shorten the task-time and reduce the contact force applied to the vessel walls during catheter insertion. The steerable catheter helps to select a vascul

The development of a reliable pick-and-place system for industrial robotics is facing an urgent demand because many manual-labor works, such as piece-picking in warehouses and fulfillment centers tend toward automation. This paper presents an integrated gripper that combines a linkage-driven underactuated gripper with a suction gripping system for picking up a variety of objects in different working environments. The underactuated gripper consists of two fingers, and each finger has three degree

Stackable mechanism architecture has demonstrated effective gravity-balancing over entire workspaces. Adjustable balancing is required when balancing is broken due to changing the payload at the distal end of a mechanism. In this paper, adjustable balancing of the stackable mechanism for a variable payload is investigated. For this, balancing conditions for three adjustable balancing methods are suggested, and a new balancing method combining a spring and counterweight is considered as an effect

Abstract A kinematic modeling method, which is directly applicable to any type of planar mobile robots, is proposed in this work. Since holonomic constraints have the same differential form as nonholonomic constraints, the instantaneous motion of the mobile robot at current configuration can be modeled as that of a parallel manipulator. A pseudo joint model denoting the interface between the wheel and the ground (i.e., the position of base of the mobile robot) enables the derivation of this equi

In this paper, a new gravity-balanced 3T1R parallel mechanism is addressed. Firstly, structure description, inverse and forward kinematic modeling are performed in detail. Secondly, Jacobian derivation based on screw theory and singularity analysis using Grassmann Line Geometry is performed, and then optimal kinematic design with respect to workspace size, kinematic isotropy and maximum force transmission ratio are conducted. Thirdly, the gravity balancing design using both counterweights and sp

In performing tasks requiring less than 6 degrees-of-freedom (DOF), lower mobility robots having a parallel structure are effective. This work investigates an asymmetric type 4 degrees-of-freedom parallel mechanism having Schönflies motions. This mechanism would be useful for multi-purpose tasks because it incorporates a transmission linkage with appropriate output modules. The mobility analysis, kinematic modelling, and singularity analysis for the mechanism are performed. Optimal design parame

This paper introduces a family of statically balanced five-degree-of-freedom (5DOF) parallel mechanisms (PMs) with kinematic and actuation redundancy. Moving platforms of this family of PMs can provide 4DOF Schönflies motion. Three applications are considered in this work. The first and second applications use kinematic redundancy to avoid parallel singularities and perform an auxiliary grasping task in sequence. The third application incorporates actuation redundancy into a kinematically redund