Design Of Gripper Research Articles

A low-cost underactuated compliant gripper with multifunctional jaws for precision manipulation

Precision manipulation tasks often require the use of compliant grippers to handle small and delicate objects accurately. This paper proposes a novel low-cost underactuated compliant gripper with integrated position and force sensors for precision manipulation. The gripper has a millimeter-scale grasping range and can adapt to objects of varying sizes and shapes. This is made possible by a flexure motion transmission mechanism that can undergo significant deformation, an underactuated seesaw flexure mechanism, and a pair of multifunctional jaws. Analytical models based on the pseudo-rigid-body approach are developed to analyze the kinematic, static, and dynamic characteristics of the gripper design. Finite element simulations are conducted to investigate the static and dynamic performance of the gripper. The gripper prototype is fabricated using 3D printing technology for a series of experimental tests. The results of these experiments demonstrate that the developed gripper has excellent motion tracking capabilities and high motion and force resolutions, enabling precise and accurate manipulation tasks. Furthermore, the gripper is capable of successfully grasping objects of different sizes and shapes through parallel and enveloping grasps.

New classification of industrial robotic gripping systems for sustainable production

Robotics is an overarching trend in modern high-tech production, contributing significantly to automation. They are used in various industries to perform multiple tasks, and their number is constantly growing. Robots interact with the production object with the help of gripping systems, which are an essential component of industrial robots and manipulators designed for reliable grasping. Therefore, the process of design and rational selection of grippers for considering production conditions receives considerable attention worldwide. The article offers a comprehensive approach to the design of gripper systems as an integral element of the “gripping system – part – environment – production equipment” system to ensure further rational selection considering specific production conditions. A scientific approach to assessing the design of gripping systems was proposed to systematize knowledge in designing gripping systems. In the paper, the principal structural scheme of the robotic gripping system was developed, and the purpose of elements and design requirements were determined. Also, the sequence of stages in the process of selecting the elements of the gripping system has been proposed. The comprehensive system “gripping system – part – environment – production equipment” has been identified considering the mutual influence of structural elements. This work may be helpful to engineers and researchers while designing new gripping systems or selecting the most suitable one from the database. It can improve the rational selection of the element base and the structure of the gripping system by systematizing the experience in the gripper system design. Moreover, due to modern trends in automation and digitalization, the presented classification and coding system for gripping systems can be used in Computer Aided Process Planning and Computer Aided Gripping Systems Design systems. It can help to realize the approach “from the part geometry to the gripping systems design”. Also, it will ensure the production planning stage’s effectiveness due to reducing the time for robotic gripping systems’ design and increasing production safety, flexibility, autonomy, and performance.

Design and Testing of a Single-Tentacle Soft Gripper with an Embedded Suction Cup

In this work, the design and the experimental characterization of a soft gripper which takes inspiration from the octopus tentacle is presented. The system is a single silicone–based pneumatic soft actuator which is able to perform bending motion thanks to its particular geometry and, due to the presence of an embedded suction cup, it can provide enhanced adhesion to the object surface of the goods to be grasped. Firstly, the design aspects as well as the fabrication process of the single-tentacle soft gripper are described. Then, its performances in terms of bending behavior, static deflection, shape variation under applied load and detachment force of the suction cup are evaluated. The experiments include grasping tests of spherical payloads with different weights. This gripper might have impact in the grasping and manipulation of delicate products like mozzarella in the agrifood field.

A user-friendly toolkit to select and design multi-purpose grippers for modular robotic systems

Robotic grasping is a billion-dollar industry with significant growth potential for the next decade. Unsurprisingly, technology providers and integrators are increasingly assisting in optimising production efficiency by implementing industrial robots and the necessary end-effectors into production lines. However, still too often in today’s robotic applications, dedicated grippers are designed to perform single tasks therewith adversely increasing cycle times and robot cell spaces due to constantly switching grippers from a tool magazine. In order to reduce handling costs and to cope with mass customisation, versatile grasping of various objects with multi-purpose grippers is key in evolving to modular assembly systems.Nowadays, thoughtful selection and design of robotic grippers is still mainly restricted to expert knowledge due its ad hoc and multi-objective nature. However, gripper selection and design should be tailored to the properties of the objects to be grasped, and the tasks to be executed. As a result, current solutions often end up being partly appropriate and/or over-dimensioned. The use of software tools to support this complex decision-making process is needed but limited so far.This paper presents a user-friendly toolkit that assists in selecting appropriate robotic grippers for grasping pre-specified ranges of objects. For this, a web API has been established for accessing the available gripper database and selection methodology. Additionally, this toolkit assists in designing multi-functional jaws for impactive grippers, and lay-outing individually positioned astrictive grippers. The underlying optimiser will try to find the most ideal grasping points on each object in accordance with quality metrics and constraints, and this for each of the selected grippers. To demonstrate the functionality of the presented toolkit, two case studies on impactive and astrictive gripper designs have been worked out involving 3D mechatronic and 2D sheet metal parts.

Hybrid-Driven Origami Gripper with Variable Stiffness and Finger Length.

Soft grippers due to their highly compliant material and self-adaptive structures attract more attention to safe and versatile grasping tasks compared to traditional rigid grippers. However, those flexible characteristics limit the strength and the manipulation capacity of soft grippers. In this paper, we introduce a hybrid-driven gripper design utilizing origami finger structures, to offer adjustable finger stiffness and variable grasping range. This gripper is actuated via pneumatic and cables, which allows the origami structure to be controlled precisely for contraction and extension, thus achieving different finger lengths and stiffness by adjusting the cable lengths and the input pressure. A kinematic model of the origami finger is further developed, enabling precise control of its bending angle for effective grasping of diverse objects and facilitating in-hand manipulation. Our proposed design method enriches the field of soft grippers, offering a simple yet effective approach to achieve safe, powerful, and highly adaptive grasping and in-hand manipulation capabilities.

Additively manufactured vacuum grippers for the flexible handling and assembly of hairpin coils in electric motor production

Hairpin technology has recently become the predominant winding technology for the manufacturing of stators used in electric traction motors. In contrast to conventional winding techniques, the manufacturing process chain is based on rectangular wire which is bent into a three-dimensional U-shape – so-called hairpin coils. These hairpin coils have to be individually gripped and assembled to form the stator winding. There can be hundreds of hairpin coils in a single stator, which can also differ in shape. Therefore, gripping and moving the individual hairpin coils is a challenging task in terms of flexibility and cycle time. This paper presents an approach to meet the outlined requirements using additively manufactured vacuum grippers. A concept is investigated in which the vacuum is generated in a conventional vacuum ejector and fed to the vacuum gripper via hose lines. In contrast, the concept of a functionally integrated vacuum gripper manufactured by a new laser-sintering process with automated continuous fibre reinforcement is presented. Based on the laser-sintering process, a lightweight vacuum gripper with an integrated vacuum ejector can be manufactured in a single process step without additional costs for purchased parts. After a review of the state of the art in both hairpin-specific and additively manufactured lightweight grippers, experimental test series are carried out concerning the vacuum quality and the grip strength of the different vacuum gripper designs. Pull-off tests show that high holding forces of several Newtons are possible proving the basic usability of vacuum grippers for hairpins, even though the achievable vacuum quality of the functionally integrated vacuum gripper is lower than that of the conventional ejector. Comparison of the novel approaches with a conventional mechanical hairpin gripper regarding weight, production costs and production time show promising improvements.

Investigation of the mechanics of the grappling circuits of robotic manipulators for adaptive uniform gripping objects

There are many designs of robotic manipulator grippers. In this work, a study of adaptive gripping schemes for objects with a spherical shape was carried out. To evaluate the grip, pressure sensors are used, installed on the phalanges of the “fingers” of the grip, the values of which are preset in a certain range. However, there is no universal sensor that responds optimally to the entire range of pressures from very high to minimal values. Therefore, each such pressure sensor has its own range of values; they correspond to the nominal operating mode of the sensor. The European Union has established standards for fruits and vegetables. The shape of these products is approximately spherical, with some slight variations in shape in lemons and oblong tomatoes. The mechanical properties of apples, pears and tomatoes, etc. were also measured. That is, for each type of such product there must be a specific sensor with a specific small range of force changes. In addition, the gripper must, when in contact with the object with all its “fingers,” create equal forces for uniform grasping. To investigate this, grips with flexible traction elements, having several phalanges on the fingers and having an adaptation to the surface of the fetus in their structure, are analyzed here.

Design and implementation of an underactuated gripper with enhanced shape adaptability and lateral stiffness through semi-active multi-degree-of-freedom endoskeletons

Grasping is a key task for robots to interact with humans and the environment. Soft grippers have been widely studied and some have been applied in industry and daily life. Typical soft grippers face two challenges: lack of stiffness and insufficient adaptability to various objects. Inspired by the human hand, this paper proposes a soft-rigid hybrid pneumatic gripper composed of fingers with soft skin and rigid endoskeletons, and an active palm. Through different combinations of the four joints’ locking states within the rigid endoskeleton, each finger obtains 9 different postures in its inflating state and 13 different postures in its deflating state, endowing the gripper with the capability of adapting to a wider variety of objects. Simultaneously, due to the endoskeletons, the lateral stiffness of the gripper is significantly enhanced (load-to-weight ratio∼7.5 for lateral grasping). We also propose a series of grasping strategies for grasping objects with different sizes and shapes to utilize the versatile configurations of the gripper. Experiments demonstrated that the gripper conformed well to the surfaces of cylindrical and prismatic objects and successfully grasped all tool items and shape items in the Yale–CMU–Berkeley object set.

Design and fabrication of multi-material pneumatic soft gripper using newly developed high-speed multi-material vat photopolymerization 3D printer

Design and fabrication of multi-material pneumatic soft gripper using newly developed high-speed multi-material vat photopolymerization 3D printer

A Novel Hybrid Gripper Capable of Grasping and Throwing Manipulation

Throwing motion is known for phenomenally fast rearrangement, sorting tasks, and placing the object outside the limited workspace with less effort. However, in the robotics domain, despite many simple yet versatile, mechanically intelligent grippers reported earlier, they focus primarily on achieving robust grasping and dexterous manipulation. This article presents a novel design of a single actuator driven hybrid gripper with mechanically coupled rigid links and elastic gripping surface; this arrangement provides the dual function of versatile grasping and throwing manipulation. The gripper comprises a latching mechanism (LM) that drives two passive rigid fingers by elongating/releasing the coupled elastic strip. Elongating the gripping surface enables the gripper to adapt to objects with different geometries, vary surface contact force characteristics, and store the energy in the form of elastic potential. A mechanism to discharge the stored potential energy gradually or instantaneously is essential when the intended task is to place the object free from impact or away from the limited reachable workspace. The proposed LM can swiftly shift from a quick release to a gradual release of the stored elastic potential for greater object's acceleration during throwing and no acceleration while placing. By doing so, the object can be placed at the desired location even farther than the manipulator's reachable workspace. We report the proposed gripper's design details, development, and experimentally demonstrate the versatile grasping, impact-free placing, and throwing capabilities.

Structural Designs of Novel Deployable Polyhedral Grippers for Noncontact Capturing Missions

Abstract Deployable polyhedral grippers have attracted increasing attention for their priority in noncontact capturing missions. Enrichment of these grippers may benefit the conduction of various capturing tasks. In this paper, novel deployable polyhedral grippers are presented. A design flow is proposed for the structural designs of diverse grippers. The core problem during the construction is reducible to the structural designs and combination of multiple synchronously deployable modules. Each module, containing three faces connected by two revolute joints, can realize one-degree-of-freedom deployment. Type synthesis of synchronously deployable modules adopting different layouts of revolute joints is conducted. The mobility and kinematics of these modules are analyzed to verify the achieved motion. As examples, four deployable polyhedral grippers based on different polyhedrons and deployment diagrams are presented. The deployment performance of the prototype proves the validity of the proposed design method and exhibits the potential of these deployable polyhedral grippers for diverse capturing missions.

Design and Simulation of Robot Gripper and Conveyor System for Workstations

Abstract: Intelligent manufacturing is going to boom in the upcoming years. The characteristic features of Industry 4.0 are fully automated production facilities where all processes are controlled in real-time and take into account the changing external conditions. The core of the Industry 4.0 is made up of digitalization and robotics, in particular, the use of collaborative robots and MES. MES (Manufacturing Execution System) is a specialized system designed to solve the problems of synchronization, coordination, analysis, and optimization of production. It involves the use of conveyor belts for rapid transportation of products. Industries where conveyor belt systems are excelling include automotive, computer, good, packaging, print finishing, bottling and canning, chemical, pharmaceutical, aerospace and food processing The safety conditions in fundamental industrial jobs are dangerous and harmful combined with ineffective manual work as a result of rising need for mass manufacturing. In industries, automation is the use of technology to jobs that were previously handled by humans. It is a potent instrument that can aid companies in enhancing quality, production, and efficiency. A typical type of mechanical handling equipment that transports things from one place to another is a conveyor system. These systems consist of conveyor belts that are designed to work seamlessly with robotic arms and other automated equipment. Increased automation and mass production rate reduces the lead time and increases the profit of a firm. The deployed robotic arms are immensely capable of handling various tasks with increased flexibility. Using a robotic arm with an end effector as a gripper to hold/pick and place the material from the conveyor belt improves the product flow process. The project comes with the NodeMCU firmware and an integrated Wi-Fi chip, the ESP8266 12E. To connect with the controller via a mobile phone, a web page would be constructed using HTML and coded using the Arduino IDE's C language. At either end of the conveyor belt, 2 robotic arms with 2 degrees of freedom (D.O.F.) would be placed. Using one arm to place the product on the belt and a second to pick it up at the other end. Also calculating the analytical data of the system that is involved in reallife industrial processes along with the simulation of entire system for the UR10 industrial robot, using the RoboDK simulation software. Through the usage of this system, productivity is boosted with improved safety of the working environment, become more effective, be more flexible, and have higher levels of job satisfaction

A nested optimization approach for robot gripper multi-objective optimization problem

Robot Gripper Design Optimization Problem is a well-known multi-objective optimization problem explored by various approaches in previous studies over the last few decades. The continuous parameter z plays an important role in determining a robot gripper's minimum and maximum gripping forces. However, previous studies have utilized a simple loop approach in which the value of z is iteratively increased by a constant value from 0 to 50 to determine the gripping forces of a solution. This approach limits the solution space by treating the continuous z parameter as a discrete variable. To overcome this limitation, we propose a nested optimization approach in which a single-objective optimizer is embedded within the fitness function of the main optimizer to determine the optimal value of z. The proposed approach is evaluated using a single-optimizer Simulated Annealing (SA) nested within multi-objective optimizers such as Multi-Objective Gray Wolf Optimizer (MOGWO), Multi-Objective Particle Swarm Optimization (MOPSO), Multi-Objective Artificial Algae Algorithm (MOAAA), and Non-Dominated Sorting Genetic Algorithm (NSGA-II). Experimental results demonstrate that our approach significantly outperforms previous studies and achieves the best-known performance. The findings of the study indicate that this method can present a novel framework for researchers in tackling design optimization challenges, encouraging a reevaluation and possible improvement of conventional techniques.

Decontamination of a robot used to reprocess reusable surgical instruments

Using robots to handle medical devices in the decontamination area of the Central Sterile Supply Department (CSSD) can reduce risks and address staff shortages. The gripper design must allow reliable cleaning using standard CSSD procedures to avoid build-up of biofilms and possible cross-contamination between different instrument trays and the gripper's functionality. This study explores the design of the robot's gripper regarding cleanability, aiming to determine whether successful cleaning can be achieved even after prolonged drying for a working shift of 8h. We optimized a gripper for cleanability and used it to assess the spread of different test soils depending on different forms of motion. Subsequently, we analysed the cleanability using sheep's blood as test soil, reprocessing the gripper in different assembly configurations after 4 and 8h of drying, and measuring residual protein. Based on our investigations, we documented the spread of contamination depending on the type of motion of the gripper's components. Sheep's blood exhibited the highest dispersion among the test soils, permeating through thin crevices. Importantly, all samples displayed residual protein levels below the warning threshold, irrespective of drying time and gripper disassembly or cleaning position. Cleaning in a device-specific optimized position achieved results comparable to cleaning the disassembled individual components. These findings indicate that cleaning even after one working shift of 8h and without the labour-intensive disassembly of the gripper is feasible, supporting the future use of robots to handle contaminated medical devices in the CSSD decontamination area.

A 3D Printing‐Enabled Artificially Innervated Smart Soft Gripper with Variable Joint Stiffness

AbstractThe manufacturing industry has witnessed advancements in soft robotics, specifically in robotic grippers for handling fragile or irregular objects. However, challenges remain in balancing shape compliance, structural rigidity, weight, and sensor integration. To address these limitations, a 3D‐printed multimaterial gripper design is proposed. This approach utilizes a single, nearly fully automated 3D printing process to create a universal gripper with almost no assembly work. By processing functional polymer, polymer nanocomposite, and metal wire simultaneously, this technique enables multifunctionality. The gripper achieves different gripping configurations by adjusting joint stiffness through Joule heating of conductive polylactic acid material, ensuring shape conformance. Embedded metal wires, created using an in‐house wire embedding technique, form reliable high‐current‐loading interconnections for the conductive joints acting as the heater. Additionally, an integrated soft sensor printed in thermoplastic polyurethane (TPU) and conductive TPU detects compression levels and discerns handled samples. This study showcases the potential of 3D multimaterial printing for on‐demand fabrication of a smart universal gripper with variable stiffness and integrated sensors, benefiting the automation industry. Overall, this work presents an effective strategy for designing and fabricating integrated multifunctional structures using soft, rigid, and conductive materials, such as polymer, polymer nanocomposite, and metal through multimaterial 3D printing.

Design and optimization of the magnetic field-driven spherical gripper with adjustable stiffness

This paper presents a new gripping technique that merges the variable stiffness characteristics of conventional magnet-controlled and negative-pressure spherical grippers to produce a spherical gripper capable of securely grasping large and structurally diverse objects. The proposed method incorporates the smart rheological material from magnet-controlled grippers with the particle-jamming smart structure used in negative-pressure grippers. The gripper comprises a magnetic control device and a spherical variable stiffness body. Simulation analysis was used to optimize its structure and enhance the efficiency ratio of the magnetic control device. The flexible variable stiffness body was initially designed to be cylindrical to increase interlocking with objects. Experiments were conducted to evaluate the gripping efficiency and adaptability of the magnetron spherical gripper, which were designed to simulate real-world application requirements. These results suggest that the magnetically controlled spherical gripper can achieve a gripping efficiency of approximately five and securely grasp objects with a relative bladder diameter ranging from 20 % to 130 %. Furthermore, it can stably grip objects up to an offset distance of 15 mm without requiring sensor assistance. The enhanced magnetic field-powered spherical gripper exhibits superior adaptability and efficiency in gripping compared to its counterpart. In addition, it boasts robust resistance against environmental interference.

Intelligent Soft Robotic Grippers for Agricultural and Food Product Handling: A Brief Review with a Focus on Design and Control

Advances in material sciences, control algorithms, and manufacturing techniques have facilitated rapid progress in soft grippers, propelling their adoption in various fields. In this review article, a comprehensive overview of the design and control aspects of intelligent soft robotic grippers tailored specifically for agricultural product handling is provided. Soft grippers have emerged as a promising solution for handling delicate and fragile objects. In this article, the recent progress in various gripper design, including fluidic and mechanical grippers, is elucidated and the role of advanced control approaches in enabling intelligent functions, such as object classification and grasping condition evaluation, is explored. Moreover, the challenges and opportunities pertaining to implementation of soft grippers in the agricultural industry are thoroughly discussed. While most demonstrations of soft grippers and their control strategies remain at the experimental stage, in this article, it is aimed to provide insights into the potential applications of soft grippers in agricultural product handling, thereby inspiring future research in this field.

Kinematic Design and Prototyping of a Gripper with Grasping and Scooping Capabilities Driven by the Redundant Degrees of Freedom of a Parallel Robot

Abstract A new gripper design is proposed to offer grasping and scooping capabilities to a parallel robot. This enables the parallel robot to manipulate not only large objects, but also thin objects lying on flat surfaces. Moreover, this gripper is driven directly by the redundant degrees of freedom of the parallel robot to which it is integrated. Thus, by eliminating actuators from the gripper, weight is drastically reduced, thereby making it possible to take advantage of the full payload of the parallel robot. The kinematic architecture of the gripper is first presented, notably, the kinematic implications of using an epicyclic mechanism. Then, the kinematic model developed to integrate the gripper to a (6+3)-degree-of-freedom robot is presented. Trajectory planning strategies for both grasping and scooping are then presented together with the parameters used. Finally, the experimental validation of these manipulation methods is discussed briefly to assess foreseeable improvements to the gripper itself as well as the trajectory planning aspect of the manipulation methods.

Design and implementation of shape‐adaptive and multifunctional robotic gripper

AbstractThis paper presents a multifunctional underactuated two fingered adaptive grippers for grasping a wide range of objects in different working scenarios. Two layered‐based novel multifunctional gripper design is proposed by stacking a multijointed closed‐chain mechanism over a multijointed double parallelogram mechanism to achieve a maximum number of grasping techniques. The multijointed closed‐chain mechanism is employed to perform power, shape‐adaptive grasping, and a multijointed double parallelogram mechanism is used to perform scooping, parallel, and pinch grasping. For stable shape‐adaptive/power grasping, the proposed design allows more contact points between the object and the contact surface of fingers as compared to previous gripper mechanisms. Moreover, a complete mathematical model relating the contact forces at the links of each finger to the linear actuation force and spring torque is developed to conduct stability analysis of the proposed gripper design. Finally, simulations and several experiments are performed using real objects in a reconfigurable environment to demonstrate and validate the stable grasping capabilities of the proposed gripper.

Flexible Tactile-Sensing Gripper Design and Excessive Force Protection Function for Endovascular Surgery Robots

Flexible Tactile-Sensing Gripper Design and Excessive Force Protection Function for Endovascular Surgery Robots