Conventional dexterous grippers are not only heavy and complex but also task dependent. As a result, they cannot provide power, intermediate and precision grasping together. We propose usability evaluation of a novel gripper mechanism which can provide 1-Degree of Freedom (DOF) parallel grasping and 2-DOF independent pinching by using a closed chain architecture. The usability of our design and one commercial product has been evaluated based on various grasping tasks: adaptive grasping, parallel pinching grasping, independent pinching grasping and contact grasping. The success rate has been evaluated to validate the excellent usability of the proposed 3-DOF gripper.

This paper presents a 3-DOF linkage-driven underactuated finger for achieving several different grasp modes. This finger mechanism is constructed by stacking one five-bar mechanism over one double parallelogram. This special architecture allows for installing all of the actuators on the base. A 2-finger robotic gripper having three actuators is developed for performing self-adaptive power grasping, parallel precision grasping, grasping during contact with the environment, and other grasping tasks through changing the orientation of the distal phalanx actively. The performance of the gripper is confirmed through both simulation and practical grasping experiment.

Development of an integrated gripping system for grasping various objects in different work environments is very useful in many practical applications, such as warehouse automation. In this paper, we propose a linkage-driven underactuated gripper combined with a suction mechanism. This underactuated gripper has two fingers which can be controlled independently and each finger is constructed by stacking one five-bar mechanism over one double parallelogram. The special architecture allows for installing all of the actuators on the base. The suction mechanism is used to grasp objects in narrow space and enhance the grasp stability. The ability of grasping various objects is confirmed through practical grasping experiment on a commercial robot arm.

This paper describes design and application of a novel counter-balancing stackable parallel mechanism. The stackable mechanism is designed by combining a five-bar and a couple of parallelograms. This design allows a compact design and wide workspace as compared to prior parallel type counter-balancing mechanisms. A linear geometry of this mechanism guarantees static balancing in the whole workspace. This mechanism was successfully applied to otologic.

Much attention has not been paid to analysis of the open-loop stability for gravity counter-balancing of parallel mechanisms or closed-chain mechanisms. The open-loop stability is crucial especially in passively counter-balanced mechanisms where no actuators are involved. Passive hands-on device is such an example. A general stiffness model is derived for general closed-chain mechanism including counter-weight model. As a measure of the open-loop stability, we employ the determinant of the stiffness matrix. A parallel mechanism having 3 translational DOF (degree of freedom) is employed as an exemplary device. An antagonistically counter-balancing is found the most stable method. We conduct dynamic simulation and experiment to confirm the open-loop stability of the system.

This paper proposes an automatic lighting system using multiple 3-DOF robotic lamps. The robotic lamp is a spherical type parallel mechanism with a unique forward kinematic solution. In order to minimize the dynamic load, three motors are installed at the base frame and a counter balancing design is performed. Using the coordinate transformation between the environment coordinate and the robot coordinate, the position data of the human is converted to three output angles of the robotic lamp. Positions of people are measured by a laser scanner, and in order to track the positions of people accurately by multiple robotic lamps, the Kalman filter algorithm and a data association algorithm were applied. In experiment, three robotic lamps were employed to track three people independently. For each lamp, two tilting angles are controlled for a localized light and the zoom mechanism is employed to control the intensity of the light.

This paper proposes a new spatial 3-DOF parallel mechanism with a unique forward kinematic solution. Using the Scott mechanism as its sub-chain, the mechanism is foldable, which is useful for design of a compact-sized master device. The kinematics of this mechanism is derived and its kinematic characteristics are analyzed in terms of workspace and kinematic isotropy. The mechanism was implemented and tested as a master device to control a virtual construction robot handling a large glass plate.

Humans and mammals possess their own feet. Using the mobility of their feet, they are able to walk in various environments such as plain land, desert, swamp, and so on. Previously developed biped robots and four-legged robots did not employ such adaptable foot. In this work, a biomimetic foot mechanism is investigated through analysis of the foot structure of the human-being. This foot mechanism consists of a toe, an ankle, a heel, and springs replacing the foot muscles and tendons. Using five toes and springs, this foot can adapt to various environments. A mathematical modeling for this foot mechanism was performed and its characteristics were observed through numerical simulation.