Design Of End-effector Research Articles

Design of a three-finger end effector for optimal grip

This paper presents the design of a three-fingered gripper with two degrees of freedom (DOF) per finger for a total of six (DOF). We show a brief mathematical description of the kinematics involved in the gripper with which to determine the workspace. With the workspace, all possible attachment points are obtained, that will be the points at which the end-effector contacts with the object geometry. To select which of these points is best for hold the object, we proceed to evaluate the force that is exerted on it by mathematical theory called Screw. This force should be the minimum to ensure that do not present sliding as well as avoid damages of the object by excess strength. Due to the fact that the contact points are numerous and evaluate them takes quite time by an algorithm combining, for this reason the optimization algorithm Non-dominated Sorting Genetic Algorithm (NSGA) is implemented. The results of the optimization with attachment points that exert minimal force were presented.

Design of endoscopic micro-robotic end effectors: safety and performance evaluation based on physical intestinal tissue damage characteristics

During the last several years, legged locomotive mechanism has been considered as one of the main self-propelling mechanisms for future endoscopic microrobots due to its superior propulsion efficiency of an endoscopic microrobot inside the intestinal track. Nevertheless, its clinical application has been largely limited since the legged locomotive mechanism utilizes an end effector which has a sharp tip to generate sufficient traction by physically penetrating and interlocking with the intestinal tissue. This can cause excessive physical tissue damage or even complete perforation of the intestinal wall that can lead to abdominal inflammation. Hence, in this work two types of new end effectors, penetration-limited end effector (PLEE) and bi-material structured end effector (BMEE) were specially designed to acquire high medical safety as well as effective traction generation performance. The microscopic end effector specimens were fabricated with micro-wire electric discharge machining process. Traction generation performance of the end effectors was evaluated by direct measurement of resistance forces during contact-sliding tests using a custom-built contact-sliding tester. The safety of the end effector design was evaluated by examination of microscopic intestinal tissue damage using a scanning electron microscope (SEM). Physical damage characteristics of the intestinal tissue and related contact physics of the end effectors were discussed. From the results, the end effectors were evaluated with respect to their prospects in future medical applications as safe end effectors as well as micro-surgical tools.

3P1-A07 細胞操作を支援する二本指マイクロハンド用高機能エンドエフェクタの開発(バイオアセンブラ(2))

In the field of life science, techniques for micromanipulation in the micro area are indispensable. Operation with high accuracy and high efficiency is a significant burden on the operator. To solve this problem, a two-fingered microhand has been developed. The microhand operates two glass needles as end-effector like chopsticks, and manipulates cells with them. But the shape of glass needle is not the best for manipulating cells. In this paper, improved end-effector which replaces the glass needle is described. New design of end-effector is proposed and fabricated by semiconductor processes. Then we perform microbeads transporting experiment and indicate the usefulness of the end-effector.

Development of space end-effector with capabilities of misalignment tolerance and soft capture based on tendon-sheath transmission system

The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture. According to these requirements, an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured. An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed, and it was a guideline of the end-effector design. Furthermore, the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space. The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software. The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture. The translation misalignments in radial directions are ±100 mm, and angular misalignments about pitch and yaw are ±15°.

OCOG: A common grasp computation algorithm for a set of planar objects

This paper addresses the problem of defining a simple End-Effector design for a robotic arm that is able to grasp a given set of planar objects. The OCOG (Objects COmmon Grasp search) algorithm proposed in this paper searches for a common grasp over the set of objects mapping all possible grasps for each object that satisfy force closure and quality criteria by taking into account the external wrenches (forces and torque) applied to the object. The mapped grasps are represented by feature vectors in a high-dimensional space. This feature vector describes the design of the gripper. A database is generated for all possible grasps for each object in the feature vector space. A search algorithm is then used for intersecting all possible grasps over all parts and finding a common grasp suitable for all objects. The search algorithm utilizes the kd-tree index structure for representing the database of the sets of feature vectors. The kd-tree structure enables an efficient and low cost nearest-neighbor search for common vectors between the sets. Each common vector found (feature vector) is the grasp configuration for a group of objects, which implies the future end-effector design. The final step classifies the grasps found to subsets of the objects, according to the common vectors found. Simulations and experiments are presented for four objects to validate the feasibility of the proposed algorithm. The algorithm will be useful for standardization of end-effector design and reducing its engineering time.

Research on Key Technology of Truss Tomato Harvesting Robot in Greenhouse

In order to improve the automated vegetable-harvesting level, a robot system for truss tomato harvesting and two key technologies of picking-point recognition and end-effector design were proposed. An algorithm used the segmentation feature of the color difference 2r-g-b to recognize the truss tomato fruit and the assistant mark. According to the growth characteristics of the stem of tomato truss, the approximate fitting curve of stem and the contour of assistant mark were extracted to generate the optimal picking-point for location of tomato truss. The hardware structure of an end-effector based on flexible transmission was designed, and the function of cutting and grasping could be realized simultaneously by the end-effector. Experimental results show that the success rate for harvesting truss tomato was 88.6%, and the average execution time for picking a truss tomato was 37.2s.

Design, Modeling and Performance Testing of End-Effector for Sweet Pepper Harvesting Robot Hand

This paper presents a new design and modeling fundamentals of gripper and cutting system for 5 degree of freedom robotic arm, designed to harvest sweet peppers in horticultural green house. The design consists of two parallel jaws mounted on gears and operated with the help of servo motor. The same servo motor was used to operate the cutting system which was composed of scissors. The complete system was designed to operate by using one servo motor only. The system model was developed in SolidWorks and tested for different kinematic and dynamic performances. The performance of the gripper and cutting tool system has been evaluated through simulation to determine the design parameters of practical prototype. Based on the design concept, practical prototype of the gripper and cutting system was developed by considering the results obtained by model developed in SolidWorks. The developed prototype was tested to verify the feasibility and reliability of the model developed in Solid-Works. The performance and practical application of the developed prototype was verified and validated by conducting experiments in the lab and greenhouse and comparing the results with simulation results.

Haptic Sensing for Use in Miniature In-Vivo Robotic Grasping Tasks

Haptic Sensing for Use in Miniature In-Vivo Robotic Grasping Tasks

Performance Testing of Thermal Cutting Systems for Sweet Pepper Harvesting Robot in Greenhouse Horticulture

This paper proposes design of end-effector and prototype of thermal cutting system for harvesting sweet peppers. The design consists of two parallel gripper bars mounted on a frame connected by specially designed notch plate and operated by servo motor. Based on voltage and current, two different types of thermal cutting system prototypes; electric arc and temperature arc respectively were developed and tested for performance. In electric arc, a special electric device was developed to obtain high voltage to perform cutting operation. At higher voltage, electrodes generate thermal arc which helps to cut stem of sweet pepper. In temperature arc, nichrome wire was mounted between two electrodes and current was provided directly to electrodes which results in generation of high temperature arc between two electrodes that help to perform cutting operation. In both prototypes, diameters of basic elements were varied and the effect of this variation on cutting operation was investigated. The temperature arc thermal system was found significantly suitable for cutting operation than electric arc thermal system. In temperature arc thermal cutting system, 0.5 mm nichrome wire shows significant results by accomplishing harvesting operation in 1.5 seconds. Also, thermal cutting system found suitable to increase shelf life of fruits by avoiding virus and fungal transformation during cutting process and sealing the fruit stem. The harvested sweet peppers by thermal cutting system can be preserved at normal room temperature for more than 15 days without any contamination.

Test Driven Design of a System for Removing Graffiti from Retroreflective Signs

The remediation of graffiti from highway signs is a labor intensive and potentially hazardous task. Accordingly, this paper presents the initial design stages of tools that could be used to clean graffiti from signs. Two design concepts are presented – one for pedestrian accessible signs and one for overhead signs – and the concepts share a common end-effector design. The paper is primarily aimed at developing an understanding of the interactions between the end-effector's scrubbers and the sign's resultant retroreflectivity. This is accomplished through a factorial experiment to test the effects of load, speed, brush type, and sign surface material on the retroreflectivity. This work shows the feasibility of such a tool for cleaning graffiti from signs along the roadways.

Research, design and experiment of end effector for wafer transfer robot

PurposeWafer transfer robots play a significant role in IC manufacturing industry and the end effector is an important component of the robots. The purpose of this paper is to improve transfer efficiency of a wafer transfer robot through study of its end effector, and at the same time to reduce wafer deformation.Design/methodology/approachFinite element method is adopted to analyze wafer deformation. For wafer transfer robot working in vacuum, for the first time, the authors apply the research of microfiber arrays inspired by gecko to the design of robot's end effector, and present equations between robot's transit acceleration and parameters of microfiber arrays. Based on these studies, a kind of micro‐array bump is designed and fixed to a structure optimized end effector. For wafer transfer robot working in atmospheric environment, the authors have analyzed the effects of different factors on wafer deformation. The pressure distributions in absorption area and calculation formula of maximal transfer acceleration are put forward. Finally, a new kind of end effector for atmospheric robot is designed according to these studies.FindingsThe experiments results show that transfer efficiency of wafer transfer robot has been significantly improved through application of the research in this paper. Also wafer deformation under absorption force has been controlled.Practical implicationsThrough experiments it can be seen that the research in this paper can be used to improve robot transfer ability and decrease wafer deformation in the production environment. Also the studies of end effector lay a solid foundation for further improvement.Originality/valueThis is the first application of the research of gecko‐inspired microfiber arrays to vacuum wafer transfer robot. This paper also carefully analyzes effects of different factors on wafer deformation through finite element method.

A Design of End Effector for Measuring Robot Orientation Accuracy and Repeatability

This paper represents the design of a robot end effector which is supposed to be a tool of measuring the orientation accuracy and repeatability. The motivations and ideas of this testing tool are stated, firstly. Then, its structure parameters are specified and the testing accuracy is computed by mean of analyzing the manufacturing errors and structure stiffness which are measured and simulated by Carl Zeiss CMM and Abaqus, respectively. Moreover, the orientation accuracy and repeatability of Kunshan No.1 and KUKA L16 are tested in terms of ISO 9283 standard using this testing tool and API Tracker3. Finally, the results are analyzed and compared which show that the design of this testing end effector is competent with a high cost-effective ratio.

TOWARD DYNAMIC MANIPULATION FOR HUMANOID ROBOTS: EXPERIMENTS AND DESIGN ASPECTS

This paper discusses a control architecture to equip humanoid robots with dynamic manipulation skills. Such skills are beneficial, as they increase the dexterity of humanoid robots and improve their handling of unforeseen situations. The nature of manipulation poses challenges with respect to environment perception, action planning, and motion control. These challenges are addressed in the paper: a dynamic force/torque (F/T) observer is discussed to reconstruct the environment F/Ts and to improve the interaction control. A method for online motion planning is investigated, which generates trajectories based on different selection criteria. These elements are integrated in a control design for dynamic manipulation and experimentally validated for two tasks: two-handed ball throwing and one-handed ball catching. Based on the experimental results, a modified end effector design with intrinsic compliance is proposed to improve the system performance that is demonstrated in case studies.

On design and development of additional End-Effectors for the Cassette Multifunctional Mover

The divertor area of ITER Vacuum Vessel (VV) consists of 54 modular cassettes which must be replaced three times during the estimated 20 years of operation of the ITER. Cassette Multifunctional Mover (CMM) and Cassette Toroidal Mover (CTM) are used in the cassette remote handling (RH). In this paper we discuss the design and development process for the RH equipment to be used in the ITER environment. Design concepts for the Standard Cassette End-Effector and Central Cassette End-Effector are described and the conceptual design phase methodology is presented. The main improvements of the new End-Effector concept designs are more robust and reliable assembly process with reduced CMM mover assembly accuracy requirement. New Central Cassette locking system was developed to address the high forces and contact pressures emerging during the Central Cassette installation. The chosen design concepts are verified with virtual reality simulations and are fulfilling the requirements defined in the concept design phase, including structural, assembly sequence, safety and reliability.

Silicon end-effectors for microgripping tasks

Micromanipulation is a key task to perform serial assembly of MEMS. The two-fingered microgrippers are usable but require specific studies to be able to work in the microworld. In this paper, we propose a new microgripping system where actuators and the end-effectors of the gripper are fabricated separately. End-effectors can thus be adapted to the manipulated micro-objects without new design and/or fabrication of the actuator. The assembly of the end-effectors on our piezoelectric actuators guarantee a great modularity for the system. This paper focuses on the original design, development and experimentation of new silicon end-effectors, compatible with our piezoelectric actuator. These innovative end-effectors are realized with the well known DRIE process and are able to perform micromanipulation tasks of objects whose typical size is between 5 μm and 1 mm.

An efficient approach of handling and deposition of micro and nano entities using sensorized microfluidic end-effector system

This paper presents a novel approach of handling and deposition of micro and nano entities using a microfluidic end effector system with in situ polyvinylidene fluoride (PVDF) sensing. The microfluidic end effector system consists of a DC micro-diaphragm pump, one region of flexible latex tube, a polyvinylidene fluoride (PVDF) sensor for in situ measurement of micro drag force, and a micropipette. The micropipette of the novel microfluidic end effector system has an internal diameter (ID) smaller than 20 μ m which is used for microfluidic handling and deposition of submicron entities such as carbon nanotubes and DNA. The DC micro-diaphragm pump is automatically controlled via a voltage driver interfaced with a computer in order to effectively and efficiently control suction force and pressure during microfluidic handling and droplet control in micro and nano manufacturing. The design, calibration, and experimental implementation of the novel microfluidic end effector are carried out in the paper. The experimental results show the success rate for depositing carbon nanotubes between micro electrodes can reach close to 80%. Ultimately, the technology will provide a critical and major step towards the development of automated process for manufacturing of micro and nanoelectronics as well as for microfluidic droplet control, and drug delivery.

A novel end-effector design for robotics in image-guided needle procedures.

Robotic end-effectors are being developed to facilitate image-guided minimally invasive needle-based procedures, such as tumour ablation, biopsy, thoracentesis and blood sampling. A novel mechanical end-effector was designed to address the challenges associated with any major needle-based procedure, focusing on liver biopsy and ablation. In this end-effector embodiment, the distal end of a single articulating arm can grip needles and instruments and allows a fairly high number of degrees of freedom of movement during the complex motions associated with positioning and driving needles, as well as the periodic motions associated with breathing patterns. Tightening a cable that runs through the articulations fixes the arm in a rigid state, allowing insertion of the gripped needle. A design is presented that will require electro-mechanical stimulation and remote joystick control. The associated forces of cranial-caudal motion of soft tissue organs affects design constraints. A simulation study defined the process with tissue phantoms with mechanical properties in the range of hepatic tissue and the overlying abdominal wall. The robotic arm coupled with our end-effector could be deployed in an image-guided interventional suite. Such a switch-able and flexible mode for a robotic arm could overcome much of the current limitations for automated needle placements for mobile targets, and could mitigate risks from breathing or patient motion with a rigid needle gripper in place.

Development of a micromanipulator made of diamond having reversal mechanism

In this study we focus on diamond as a structural material for micromechanisms. Diamond is the hardest material on the earth, and has superior antifriction and anticorrosion characteristics. If diamond were applied to a micromechanism, an almost maintenance-free component which requires only a few component exchanges could be fabricated. In addition, since it has a superior anticorrosion characteristic, it can be used in chemical substances and organic tissue; thus, micromechanical components made of diamond have many advantages. Furthermore, when diamond is applied to a micromanipulator, we can expect accurate gripping to be realized because its deformation is small. We have already developed a diamond end effector for micromanipulators, and have obtained several promising results. In this study, we added a reversal mechanism to the positioning unit of this micromanipulator to increase efficiency in assembly tasks, and modified the design of the diamond end effector accordingly. Major modifications were examined through finite element analysis of fabricated shapes and amount of movement. A modified effector was experimentally fabricated based on the analytical results, and its features were examined experimentally. The starting material was 2-μm-thick flat-plate diamond, whichwas processed by laser into a designated shape. A shape-memory-alloy actuator which memorizes the linear shape was used to realize a driving amount larger than those of electrostatic actuators and piezoelectric devices.

A Robotic Mechanism for Grasping Sacks

This paper describes a novel robotic end-effector and a method for grasping deformable objects with undefined shapes and geometry, such as sacks and bags. The first prototype end-effector, designed for applications in the U.S. Postal Service, is comprised of two parallel rollers with gripping surfaces in which the rollers are pushed toward each other. When the end-effector comes into contact with any portion of the deformable object, the rollers turn inwardly so that a graspable portion of the object is dragged between the rollers. The rollers stop rotating when a graspable portion of the material/object is caught in between, allowing the object to be maneuvered by the robot. The object is released when the rollers turn outwardly. The end-effector described in this article can grab and hold filled sacks from any point on the sack, regardless of the sack's orientation. Experimental evaluation of the end-effector has proven the design and implementation remarkably effective. This article describes the hardware, control method, and design issues associated with the end-effector. Note to Practitioners - Delivery and postal services around the world currently use sacks to hold letters, magazines, and small boxes. The considerable weight of these sacks, their lack of handles, eyelets, or other operator interfaces, and the unpredictable shape and size of the packages within create awkward and uncomfortable handling predicaments for mail handlers at all U.S. Postal Service distribution centers. Currently, no robotic hand or end-effector is commercially available to grab and hold sacks effectively, so sacks must be handled manually by postal employees in distribution centers. This paper describes the design of a novel robotic end-effector for manipulating deformable objects with undefined shapes, such as sacks and bags. This device, which does not mimic human hand architecture, is simple and practical; it makes use of the friction between two rotating rollers to grab sack material when it is in close proximity of the end-effector. The rollers cease rotation when sufficient sack material is collected between the rollers to support the sack. They reverse their rotation, and turn outwardly to release the sack again. This end-effector is able to grab a sack at any point, does not require the edge of the sack to be gathered and flattened prior to grasp, does not require the sack to be placed on its bottom, needs no operator intervention, does not use the weight of the sack to lock and secure the sack in the end-effector, and does not damage the sack contents.

2408 走査型電子顕微鏡下におけるマイクロマニピュレーションシステムに関する研究(J22-2 材料特性計測とマイクロ機構,J22 マイクロメカトロニクス,2005年度年次大会)

In this study we focus on diamond as a structural material for micromechanisms. Diamond is the hardest material on the earth, and has superior antifriction and anticorrosion characteristics. If diamond were applied to a micromechanism, an almost maintenance-free component which requires only a few component exchanges could be fabricated. We have already developed a diamond end effector for micromanipulators in air using light microscope, and have obtained several promising results. In this study, we added a positioning device to endure in low-medium vacuum using scanning electron microscope, and modified the design of the diamond end effector accordingly. Major modifications were examined through finite element analysis of fabricated shapes and amount of movement. In this study, first, a simulation using the finite element method was performed to analyze stress distribution on the designed end effector. Then, the end effector made of a thick diamond film was fabricated using a Qsw-YAG laser to evaluate the performance of the system. A shape-memory-alloy was used to obtain sufficient gripping force and flexibility of the operation.