Hyunhwan Jeong

Multi-jointed integrated medical instrument system for single port access laparoscopic surgery

In this paper, we present a new medical instrument system for the single port access laparoscopic surgery. Our instrument system makes that surgeon can control the instrument intuitively and has 6 degree of freedoms(DOFs), enough for single port access laparoscopic surgery. This multi-joint structure makes easy to avoid obstacle in laparoscopic surgery. We detail the design concept of our medical instrument system using the 3D design model and manufactured the hardware instrument system. To examine the effectiveness of the device, we obtain the work space of the device and check whether the stiffness of tendon-driven instrument system is enough for the operation.

Evaluation of 3d grasps with physical interpretations using object wrench space

In this paper we propose an intuitive and practical grasp quality measure for grasping 3D objects with a multi-fingered robot hand. The proposed measure takes into account the object geometries through the concept of object wrench space. Physically, the positive measure value has a meaning of the minimum single disturbance that grasp cannot resist, while the negative measure value implies the minimum necessary helping force that restores a non-force-closure grasp into a force-closure one. We show that the measure value is invariant between similar grasps and also between different torque origins. We verify the validity of the proposed measure via simulations by using computer models of a three-fingered robot hand and polygonal objects.

Evaluation of grasps for 3D objects with physical interpretations using object wrench space

In this paper, we present a practically useful and intuitive grasp quality measure that takes into account the shapes of object geometries and the torque limits of finger actuators. The proposed grasp quality measure is defined by the distance between the convex hulls of the absolute grasp wrench space (a-GWS) and the object wrench space (OWS), where a-GWS and OWS are, respectively, created by the active wrenches from the robot fingers with limited torque bounds and the uniform distribution of unitary normal disturbances on the surface of a polyhedral object. The computational algorithm for the grasp quality measure also yields the information of which spots of the object are fatal under the disturbance, which makes the algorithm practically useful. We demonstrate the validity of the proposed measure through numerical examples.

In-hand rolling motion planning using independent contact region (ICR) with guaranteed grasp quality margin

In this paper, we propose an in-hand motion planning algorithm for 3D objects under rolling contacts. By assuming the in-hand motion is quasi-static, we apply the concept of independent contact region (ICR) to determine stable boundaries of finger contact points during the in-hand motion. A specified level of grasp quality margin representing the ability to bear external load is guaranteed. The overall scheme contains two motion planning phases: one is the motion planning with fingers simultaneously rolling over the object surface, and the other is the planning associated with switching fingers of contact and non-contact. Simulation/experimental results are provided to show the feasibility of the proposed algorithm.

Stiffness characteristics of new modular type antagonistic tendon-driven joint systems

This paper presents a new antagonistic tendon-driven joint (TDJ) which has an advantage of enhanced stiffness characteristics. Detailed mathematical analyses on the stiffness of typical TDJs are worked out to compare the stiffness among them. Prototypes of the proposed TDJ design are introduced in the form of packaged modular structure that merges two TDJs generating a combined roll-pitch motion or similar ones. Numerical examples are given to confirm the superior stiffness of the proposed TDJ design.

Design and analysis of KU hybrid hand — Type II

In this paper, we present the second version of the KU hybrid hand system. The presented hybrid hand system is designed not only to grasp an object but also to do versatile in-hand motions of the grasped object. We also present the workspace and the grasp motion analysis of the KU hybridd hand for two different modes (anthro-pomorohic & conventional hand mode).

Independent contact region (ICR) based in-hand motion planning algorithm with guaranteed grasp quality margin

In this paper, we propose an in-hand motion planning algorithm using independent contact regions(ICRs) and object wrench space(OWS). The original ICR intended to provide grasp robustness under positioning errors of finger-tips, while we apply the ICR to determine the stable boundaries of multiple contact points during the in-hand object manipulation. We consider two planning phases; one is the in-hand motion planning with all fingers simultaneously rolling over the object surface, and the other is the planning associated with switching fingers between contact and non-contact phases. The in-hand motions is so planned as to maintain a given grasp quality margin. The effectiveness of the proposed algorithm is verified through a 2D grasp simulation.

Posture and workspace analysis of KU hybrid robotic hand

In this paper, we present kinematic and posture analysis of KU hybrid hand, which allows two different operation modes. We analyze kinematic structure and workspace of the KU hybrid hand. We test the ability of KU hybrid hand in making various grasp configurations using standard grasp taxonomy. We also present in-hand motion planning with rolling contact.

A new grasp quality measure considering the physical limits of robot hands

In this article, we introduce the extended grasp wrench space (GWS) to identify the applied location and the magnitude of the critical external wrench. We jointly use the task wrench space (TWS), which is made up of all possible external wrenches produced from the unit normal force to the surface points of the grasped object (i.e., the object wrench space [OWS]). In the extended GWS, the torque bound of each joint of the robot hand is considered to determine the grasp capability. Through convexity analysis and a linear programming technique, we propose a new way of obtaining an enhanced grasp measure which shows a clear physical meaning. We verify the proposed grasp analysis and quality measure using a visual grasp simulator and polygonal objects of various shapes.