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For complex tasks such as tying a knot, simply creating a robot hand with many degrees of freedom is insufficient. It is also important to extract the requirements of the task, design the hand based on these requirements, and implement functions to use the hand effectively. Thus, in this study, we have designed a robot hand with three fingers each having three degrees of freedom and developed basic functions to realize rope-knotting tasks. In experiments, the designed robot hand and functions were applied to performing various manipulations during rope-knotting tasks, and the redundancy provided by the structure could be utilized to generate motions. [ABSTRACT FROM AUTHOR]

In this study, we examine robotic proximity perception for both reactive control and 3D point-cloud acquisition using a multi-fingered robot hand. A reactive controller adjusts the relative position and orientation between the fingertips and the target object, while the robot-hand system gathers point-cloud data related to the shape of the object. An experimental result showed that the accuracy of the point-cloud generated using proximity perception was equivalent to or better than that of the point-cloud generated using a vision sensor. Based on the results, we propose proximity-based point-cloud acquisition using 'non-contact perception' motion to search the object's surface while preventing unintended collisions. The motion is then combined with the approaching and twisting motions of the robot hand. This enables multi-angles object detection complementarily with reactive fingertip control. Our experiments reveal that the proposed method can generate data-rich point-clouds for various general objects. [ABSTRACT FROM AUTHOR]

This study investigates object picking focusing on object arrangement patterns. Objects stored in distribution warehouses or stores are arranged in regular patterns, and the grasping strategy for object picking is selected according to the object arrangement pattern. However, object arrangement patterns have not been modeled for object picking. In this study, we represent objects as polyhedral primitives, such as cuboids or hexagonal cylinders, and model object arrangements by considering occlusion patterns for object model surfaces and considering whether the adjacent object occluding the surface is moveable. We define grasp patterns based on combinations of the grasp surfaces and discuss the grasping strategy when the grasp surfaces are occluded by adjacent objects. We then introduce newly developed gripper for picking arranged objects. The gripper comprises a suction gripper and a two-fingered gripper. The suction gripper has a telescopic arm and a swing suction cup. The two-fingered gripper mechanism combines a Scott Russell linkage and a parallel link. This mechanism is advantageous for the gripper in reaching narrow spaces and inserting fingers between objects. We demonstrate the picking up of arranged objects using the grippers. [ABSTRACT FROM AUTHOR]

Cell production systems for assembly operations generally require tool changes using several hands and a customized work table. The initial setting and resetting of the assembly system are costly. We implemented a system comprising the use of only two hands and without the requirement of tool changers. In addition, multiple sensors are used to perform tasks robustly to avoid errors. The peg-in-hole task is performed robustly against errors without the precise positioning of objects. The objective is to develop a system that is lean and agile and can be set up quickly. We evaluate this system based on the task-board and assembly tasks during the assembly challenge in the industrial robotics category of the World Robot Summit 2018. [ABSTRACT FROM AUTHOR]

Duplicating the complexity of the human thumb with a robotic one is a difficult task for engineers, when taking into consideration the necessary miniaturization and robustness requirements. Miniaturization is required to fit all the components within the size of a human hand; however, the reduction in size of the components affects the strength of the transmission. Several robotic hands with active thumbs were designed. Most of these had the abduction/adduction joint rigidly connected to the electrical motor and gearhead. This is a non-optimal solution because although miniaturized, the transmission is back-drivable and thus the motor gearhead is exposed to shocks. In this paper, we present the design of a non-back-drivable rotary mechanism with intrinsic compliance for a robotic thumbab/adduction joint. The mechanism enables switch off of the power supply once a desired posture is stable, thus avoiding accidental dangerous releases of the grasped object, absorbs the impact forces generated at the instant of grasping and dissipates the repeated strains that are induced during manipulation. The mechanism was developed and tested. Detailed kinematic, static and stiffness analyses are presented as well as experimental measurements which demonstrate suitable performance for our application (max efficiency ~0.85, critical load 1.2 Nm, energy absorbed 1.5 J). [ABSTRACT FROM AUTHOR]

Large instruments are not suitable for laparoscopic surgery because they cannot pass through trocars, which are typically less than 12 mm in diameter; however, operating on large internal organs with a slender instrument is often difficult. To overcome this limitation, we have proposed an 'assemblable instrument', whose parts are inserted through trocars and assembled inside the abdominal cavity to form a large instrument. We have previously reported the development of assemblable hands that require two trocars for assembly. In this paper, we propose a simple three-fingered hand whose function is limited to retracting or grasping, but whose assembly requires a single trocar. We develop two types of finger units: one for a retracting hand and the other for a grasping hand. The two finger units can be connected to a single main unit of the hand. We conduct in vivo experiments. The retracting hand can retract several large internal organs and lift up the stomach with its three fingers from the bottom. The grasping hand can grasp the spleen stably with its two fingers from the bottom. [ABSTRACT FROM AUTHOR]

An electro-conjugate fluid (ECF) is a type of dielectric and functional fluid that generates a powerful jet flow when subjected to high DC voltage. Although a high voltage is needed to generate the jet flow, the current is quite low at several microamperes, resulting in a total power consumption of several milliwatts. Using this smart fluid, we can develop micro fluid-driven mechanical components without any bulky pumps. Also, it is clarified that the power density of the ECF jet is higher when the electrode pair is miniaturized; therefore, it is suitable for micro actuators. Here, we propose and fabricate three types of soft actuators with an antagonistic configuration: (i) micro artificial muscle cells, (ii) a McKibben-type micro artificial muscle actuator using the ECF effect and (iii) a micro finger actuator with two chambers to bend. The actuators basically consist of a silicone rubber tube covered with a fiber sleeve and a micro pressure source using the ECF effect. Next, we apply and integrate these actuators into a micro robot hand, driven with ECF jets. The driving characteristics of the micro artificial muscle actuator and the integrated micro ECF hand with ECF fingers were fabricated and experimentally investigated. The experimental results show that this ECF jet actuation is effective for driving soft micro hands. [ABSTRACT FROM AUTHOR]

The classical mapping methods were developed based on anthropomorphic robot hands. Normally, they are not applicable or cannot provide satisfactory performance if the robot hand is non-anthropomorphic. This paper presents a virtual circle mapping method dealing with the three-fingered non-anthropomorphic robot hand. The basic idea is to express the operator's motion by a virtual circle determined by the three fingertips. Four sets of parameters are used to describe the circle: circle radius, central angles, circle center and circle orientation. By transforming the four sets of parameters from the human frame to the robot frame, the information of relative positions between the fingertips is delivered. The robot fingertip positions are then computed according to the transformed parameters. The concept is introduced and implemented on a specific three-fingered non-anthropomorphic robot hand. The simulation results and the experiments have shown that the proposed method is able to obtain better workspace matching and, thus, the operator can tele-control the robot hand more intuitively. [ABSTRACT FROM AUTHOR]