Gripper System Research Articles

Lightweight design of a gripping system using a holistic systematic development process - A case study

Lightweight design of a gripping system using a holistic systematic development process - A case study

Development of Two-Way Self-Adaptive Gripper Using Differential Gear

In this paper, a two-way self-adaptive gripper that has adaptability to external disturbance loads during linear opening/closing pinch actions and adaptability to encompass a variety of shapes during grasping using a single actuator is proposed, unlike the previous self-adaptive robotic grippers capable of only shape adaptation. Therefore, both linear motion adaptability and shape adaptability during parallel grasping situations are enabled by the proposed design of the gripper. Adaptation to the linear pinch motion is provided through the use of a differential gear, the two outputs of which drive the two tips of the gripper. If facing uneven external loads, the differential gear adaptively alters the speeds of the two outputs, resulting in different closing speeds of the two gripper tips. Despite asymmetric closing, very stable grasping can be guaranteed for such a situation. The differential gear can even complete the grasping by intentionally or unintentionally fixing one of the gripper tips. The proposed design is also capable of shape adaptation in the encompassing grasping mode by adopting a parallel-linkage gripper mechanism, consisting of an exoskeleton and 6 internal joints with a spring element. The finger exoskeleton facilitates pinch and spread actions, while the encompassing action is carried out by adjusting the internal linkage. Based on the kinematic analysis and modeling of the proposed gripper, a prototype of the two-way adaptive gripper hardware was developed. Several experiments were performed to verify the feasibility and validity of the proposed gripper system. The actuator using the proposed differential gear was shown to be able to grasp objects in jammed conditions. In addition, the gripper was able to perform grasping actions, such as pinch, spread, and encompassing grasp.

Shape-Adaptive Electrostatic Soft Gripper With Transform Mechanism for Multifunctional Grips

Abstract This paper proposes a shape-adaptive electroadhesion dielectric elastomer actuator (EA-DEA) pad gripper that can actively adapt to the shape of curved objects and quickly handle various objects by combining an EA pad and a multi-layered DEA driven by electrostatic force. This gripper has a rapid release function capable of detaching thin and light objects in less than 0.2 s with bending motion of multi-layered DEA and reverse polarity voltage. Moreover, combined with a transform mechanism that changes the posture of the EA-DEA pad gripper, a multifunctional gripper handling various objects from thin to irregularly shaped objects is implemented. The high voltage controller is configured to generate the variable and reversible voltages required for the control of the developed gripper. To verify the performance and practicality of the proposed multifunctional gripper system, we demonstrate the gripping task in three modes formed by controlling the EA-DEA pad gripper and the transform mechanism to adapt to the object shape. According to the experimental results, this gripper can reliably and rapidly pick and place various objects, such as thin film, hexahedron, cylinders, spheres, irregular shaped, deformable, and fragile objects corresponding to each mode.

Research on Developing of a Reconfigurable Gripping Mechanism with Electric Drive

Abstract The paper consists in analyzing some of the researches on specialized literature regarding to gripping systems and proposing a new solution for a gripping mechanism that can fulfill the increasing requirements imposed by the flexible manufacturing systems regarding the orientation and positioning of parts with variable shape and dimensions. Some general consideration on state of the art in the field of gripping mechanism are presented and main development direction are indicated. The second part of the paper contains in the development of new gripper constructive solution. From the literature analysis the main requirement for a gripping system is the multi-tasking ability. The proposed designed solution uses four parallel open-close jaws/fingers controlled by two electric motors. The actuation of the jaws/fingers for clamping the part is accomplished by a primary motor. The main contribution/improvement refers to the introducing of a second/supplementary motor that is used for the movement of the position of the jaws in order to transform the gripper clamping system from a four-jaw construction to a two-jaw gripper construction and vice versa, thus increasing range of clamped parts.

Design of a small material handling robot gripping and storage system

This paper completed the development status and working principle of the handling robot, analyzed the performance index parameters and system functional requirements of the robot, and proposed an overall design scheme of the handling robot control system. The mechanical structure design of the handling robot was developed, and the selection of the core components of the system was studied and designed in detail based on theoretical analysis and calculation. Secondly, this paper selected the STM32 microcontroller as the core of the handling robot. It completed the circuit schematic diagram of the systems, and investigated the selection of core sensors for the navigation and positioning module, obstacle avoidance module, and wireless communication module. Finally, this paper studied the automatic control part of the handling robot, which mainly included the modeling of the robot’s manipulator, PID control, and MATLAB simulation verification. In addition, the application prospect of the handling robot was explored. It had the advantages of high efficiency, strong practicability, and perfect function, and had certain practical significance in the application of the logistics industry.

Design of multi-stimuli responsive hybrid pneumatic – magnetic soft actuator with novel channel integration

Smart polymeric materials based soft actuators are flexible, lightweight, and can deliver a wide range of actuations. Thus, they are ideal for applications requiring delicate and unconventional motions, such as biomedical and soft robotics. This paper reports a novel multi-stimulus responsive soft actuator that combines the advantages of pneumatic and magnetic systems to achieve multi-plane actuation behavior with high blocking forces at low power input. This novel pneumatic – magnetic (HPM) soft actuator is designed through geometric, nanoparticle alignment, and mechanical criterions. By utilizing 3D printed wires and the compliant matrix, unique micro air channels were manufactured. These distinct internal tubular structures created localized and distinctive bending paths beyond the traditional circular trajectory. Addition of Fe3O4 nanoparticles under a magnetic field exhibited a decrease in stiffness of the elastomer matrix by 85%, increasing the blocking force by 3500%, and decreasing the air pressure input to achieve same degree of actuation. Furthermore, it was observed that the magnetic nanoparticles alignment within the samples enhanced the magnetic deflection and susceptibility. The HPM soft actuator demonstrated its practicability through a gripper system to lift objects greater than its initial width and 3.4 times its own mass. Multi-plane actuation was also demonstrated to complete a circuit and light up an LED. A 5 legged “star” shaped HPM soft actuator was also fabricated to exhibit the multi-stimuli response, reacting to both pneumatic and magnetic stimuli in both air and water environments. Using the advantage of the multi-plane pneumatic/magnetic actuation, such hybrid soft actuator has the capability to be utilized in biomimicking and unconventional applications where unique maneuverability is required.

A design of underwater soft gripper with water pressure sensing and enhanced stiffness

AbstractIn this paper, a hydraulic soft gripper for underwater applications is designed to provide a solution for improving the gripping force as well as the sensing capability of the soft gripper. The soft gripper is made of silicone and has an integrated semi-circular hydraulic network inside. To enhance the rigidity and grasping performance of the soft gripper, we have integrated a restriction layer consisting of a spring steel plate in the soft gripper. Meanwhile, to enhance the sensing capability of this soft gripper, we have designed a water pressure sensor based on resistance strain gauges and integrated it on the spring steel plate. Before fabrication, we determined the structural parameters of the soft gripper by geometric analysis. Then we experimentally evaluated its pressure-bearing capacity, bending performance, the role of spring steel plates, and the accuracy of the sensor.The experimental results show that the spring steel plate improves the gripping force of the soft gripper, the sensor also has high accuracy, and the built four-finger gripping system has good adaptability to objects of different shapes and weights.Compared with the existing solutions, this solution takes a simpler structural form while improving the gripping force and sensing ability of the soft gripper, and integrates the issues of improving the gripping force and sensing ability. The spring steel plate used in this paper not only improves the gripping force of the soft gripper but also provides a stable and reliable platform for installing sensors.

An innovative frictional anchorage system for flat CFRP ribbon strips

Unidirectional carbon fibre-reinforced polymer (CFRP) materials represent a promising alternative to steel because of their lightweight, high tensile strength, and excellent corrosion and fatigue resistance. Stress-ribbon structural systems define the potential application object of unidirectional flat CFRP strips. However, anchorage difficulties make this idea problematic—the typical gripping systems are inefficient for anchoring the CFRP ribbons because of the tremendous thrust forces-induced stress concentration. Thus, the innovative frictional spiral anchorage system of the flat CFRP strips is the object of this study, which formulates the design principles for the frictional joins. Furthermore, the proposed theoretical model minimises the gripping system size, satisfying the CFRP strength limitation when the developed modified Archimedean spiral determines the shape of the contact surface. This work experimentally demonstrates the theoretical concept’s adequacy—the mechanical resistance prediction error does not exceed 7% in the loading range covering the service load conditions. In addition, the manuscript presents several examples of frictional gripping systems, including the stress-ribbon pedestrian bridge prototype, and provides further insights into the frictional anchorage systems.

Sensorized Reconfigurable Soft Robotic Gripper System for Automated Food Handling

This article presents a versatile soft robotic gripper system whereby its fingers can be reconfigured into different poses such as scoop, pinch, and claw. This allows the gripper to efficiently and safely handle food samples of different shapes, sizes and stiffness such as uncooked tofu and broccoli floret. The 3D-printed fingers were tested to last up to 25 000 cycles without significant changes in the curvature profile and force output profile. A benchmark experiment was conducted to evaluate the performance of the gripper and state-of-the-art gripping solutions. Capability of versatile soft gripper was optimized by integrating vision and tactile sensing facilities. An object recognition system was developed to identify food samples such as potato, broccoli, and sausage. Position and orientation of food samples were identified and pick-and-place pathway was optimized to achieve the best gripping performance. Flexible tactile sensors were integrated into soft fingers and closed-loop force feedback control system was developed. This allowed the gripper to automatically explore and select the most stable grip pose for different food samples. Integration of vision and force feedback system ensure that objects detected by the system would be firmly gripped. The reconfigurable soft robotic gripper system has been demonstrated to perform high-speed pick-and-place tasks (∼3 s per item) with object recognition system, making it a potential solution to food and grocery supply chain needs.

ROMERIN: A new concept of a modular autonomous climbing robot

Climbing robots play an essential role in performing inspection work in civil infrastructures. These tasks require autonomous robots with competitive costs and the ability to adapt to different types of environments. This article presents ROMERIN, a new concept of a modular legged climbing robot where each leg is an autonomous robotic module in terms of processing capacity, control, and energy. The legs are equipped with suction cups that allow the robot to adhere to different types of surfaces. The proposed design allows the creation of climbing robots with a different number of legs to perform specific inspection tasks. Although each of the legs acts as an independent robot, they have the ability to share information and energy. The proposed control concept enables the development of climbing robots with the ability to adapt to different types of inspection tasks and with resilience characteristics. This article includes a description of the mechatronic design, the kinematics of the seven degree-of-freedom robotic legs, including the adhesion system, and the architecture of the control and simulation system. Finally, we present experimental results to test the modularity concept, mechanical design, and electronics using a four-legged robot configuration. We analyze the performance of the gripping system in different situations on four different surfaces and the behavior of the control architecture for two different robot body trajectories.

Soft Robotics

Widely used robot systems have a rigid base structure that limits the interaction with their environment. Due to the inflexible attachment points, conventional robotic structures can only manipulate objects with their special gripping system. It can be difficult for these systems to grasp objects with different shapes, handle complex surfaces or navigating in a heavily crowded environment. Many of the species observed in nature, like octopuses are able to perform complex sequences of movements using their soft-structured limbs, which are made up entirely of muscle and connective tissue. Researchers have been inspired to design and build robots based on these soft biological systems. Thanks to the soft structure and high degree of freedom, these soft robots can be used for tasks that would be extremely difficult to perform with traditional robot manipulators. This article discusses the capabilities and usability of soft robots, reviews the state of the art, and outlines the challenges in designing, modelling, manufacturing, and controlling.

Combining Unique Planar Biaxial Testing with Full-Field Thickness and Displacement Measurement for Spatial Characterization of Soft Tissues.

Soft tissues rely on the incredible complexity of their microstructure for proper function. Local variations in material properties arise as tissues develop and adapt, often in response to changes in loading. A barrier to investigating the heterogeneous nature of soft tissues is the difficulty of developing experimental protocols and analysis tools that can accurately capture spatial variations in mechanical behavior. In this article, we detail protocols enabling mechanical characterizations of anisotropic, heterogeneous soft tissues or tissue analogs. We present a series of mechanical tests designed to maximize inhomogeneous strain fields and in-plane shear forces. A customized, 3D-printable gripping system reduces tissue handling and enhances shear. High-resolution imaging and laser micrometry capture full-field displacement and thickness, respectively. As the equipment necessary to conduct these protocols is commercially available, the experimental methods presented offer an accessible route toward addressing heterogeneity. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Unique biaxial testing of soft tissues and tissue analogs Basic Protocol 2: Full-field thickness measurement of soft tissues and tissue analogs Support Protocol 1: Creating and speckling cruciform-shaped samples for mechanical testing Support Protocol 2: Creating custom gripping system to minimize sample handling.

Test Bench Concept for Testing of Gripper Properties in a Robotic Palletizing Process

Palletizing and depalletizing processes require specialized equipment, such as grippers dedicated to the type and dimensions of the goods to be handled. The traditional approach used in the robotisation of palletizing workstations is therefore mainly based on the development of specialized grippers, whose design limits their use in other applications. The article presents a concept of a modular gripper system enabling palletization of goods in collective packaging, including cartons, shrink-wrap packs, and bags. The concept developed involves the construction of a gripper system based on common modules that provide for extensive parameterization of device operation. The authors also propose a test bench to test the properties of grippers in a robotic palletizing process.

A soft gripper with contamination resistance and large friction coefficient

With the development of soft gripper systems, food processing, packaging, and processing technology has seen a significant advancement. The soft gripper must be protected from surface contamination and liquid lubrication; hence, a hydrophobic and contamination-resistant surface is used. There is an urgent need for a soft gripper that meets the functions of hydrophobic performance and contamination resistance, but there has been little study. In this study, the two functions are well achieved by introducing a flexible superhydrophobic surface. A novel design of a flexible superhydrophobic surface-based gripper (SSBG) is proposed by the template method. After a series of testing, it was discovered that the friction coefficient between the SSBG surface and the glass plate, cardboard, and steel plate is larger than that of a standard surface gripper (SSG). At the same time, the contamination resistance of SSBG is particularly important. Because of the existence of the plastron layer, the surface was discovered to be able to repel bacterial colonization. Finally, when the usual gripping force of the SSBG is measured on a 250 ml beaker with contamination and liquid lubrication, it can be shown that the gripping ability is improved by at least 100% and 170% compared to the SSG, respectively. As a result, the SSBG has a high potential for utilization in industrial and therapeutic contexts.

Vacuum System for Reinforcing Fabric Handling

The paper considers questions asotiated with automated systems to produce composite parts. Exist-ing automated systems used in aerospace production are usually based on lay-up technologies. The main objective of the on-going development is to find an affordable production technology for com-posite parts that can be easily automated. The handling with dry reinforcing fabrics is objective of the paper: dry fabric is placed in a suitable mold where it is impregnated by selected type of a matrix and consolidated under vacuum bag afterwards. Based on experiments using standard gripping systems, it was found that local damage of reinforcing fibers occurs. For these reasons, a new vacuum suction-based gripper was developed. As a suction source industrial vacuum cleaner was used, whose perfor-mance can be regulated continuously. Functionality of the suction system was verified on six differ-ent types of reinforcing materials, using two different types of suction grid at three different levels of vacuum cleaner performance. Performed experiments verified suitability of the designed solution for manipulation with dry fabrics without the risk of their damage.

Bimanual Handling of Deformable Objects With Hybrid Adhesion

We present hybrid adhesive end-effectors for bimanual handling of deformable objects. The gripping system is driven by the need to achieve alignment on deformable and irregular surfaces while maintaining a large area of contact for efficient use of the adhesive. The objective of the gripping system is to reduce the internal grasping force needed to securely lift and manipulate objects with two arms, for example, in warehousing and retail environments. The end-effectors are designed with features meant to accommodate surface irregularities in macroscale form, mesoscale waviness, and microscale roughness, achieving good shear adhesion on surfaces with little gripping force. The new gripping system combines passive mechanical compliance with a hybrid electrostatic-adhesive pad so that humanoid robots can grasp a wide range of materials including paperboard and textured plastics with internal grasping forces of 1 N and 0.5 N, respectively. These grasping forces are more than 10 times smaller than without the hybrid pad. As an application, we demonstrate a humanoid robot handling delicate deformable objects ranging from flowers in a plastic sleeve to a 2.4 kg sack of rice with less than 1.5 N of normal gripping force.

Robust Ungrasping of High Aspect Ratio Objects Through Dexterous Manipulation

In this work, we address robotic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dexterous ungrasping</i> , the capability of securely transferring a grasped object from the gripper to the robot’s environment, i.e. the inverse of grasping or picking, through dexterous manipulation. The situation of dexterous ungrasping can commonly be found in many occasions such as placing a Go stone or inserting a battery pack, where it is necessary to carefully perform contact-rich interactions for stable ungrasping. Advancing from our recent work that formulated a planning framework for dexterous ungrasping, this study addresses the robustness of the motion control for executing the planned ungrasping operations, through an analysis of possible failure cases and caging conditions. We also address how the guaranteed robustness facilitates the modeling and planning of dexterous ungrasping and guides the arrangement of a gripper system. A series of experiments demonstrate the effectiveness of the resulting hardware and software system in practical ungrasping tasks.

Simulation Data Driven Design Optimization for Reconfigurable Soft Gripper System

In the soft gripper design work, most of the designs such as gripping width and the design of finger actuator are purely based on experience, and repeated trial-and-error. In most scenarios, the designed actuators cannot achieve the best&#x002F;optimized grasping performance with a specific design type. This optimized design is important especially for the food grasping application, as a minor improvement of the grasping capability will be helpful to increase the grasping success ratio, especially during high-speed pick and place tasks. That motivates us to develop a design optimization framework, focusing on how to achieve an optimized grasping performance with a multi-objective design optimization. In this work, a simulation aided data-driven optimization framework for guiding the design of a reconfigurable soft gripper system is presented. To achieve an effective optimization, a simulation model is developed based on the Simulation Open Framework Architecture (SOFA) platform. This model can predict the bending and grasping behavior under actuation and external loading. This model is then used in a data-driven design optimization framework for optimizing the actuator design. An artificial neural network (ANN) is built based on the simulation results as training data, and used as a surrogate model in a multi-objective optimization framework, to achieve an optimal grasping capability with design constraints. This simulation and optimization capability can significantly reduce the trial-and-error design work, and has a great potential for effectively developing soft robots in industrial applications, such as food manufacturing and health care.

On Aerial Robots with Grasping and Perching Capabilities: A Comprehensive Review.

Over the last decade, there has been an increased interest in developing aerial robotic platforms that exhibit grasping and perching capabilities not only within the research community but also in companies across different industry sectors. Aerial robots range from standard multicopter vehicles/drones, to autonomous helicopters, and fixed-wing or hybrid devices. Such devices rely on a range of different solutions for achieving grasping and perching. These solutions can be classified as: 1) simple gripper systems, 2) arm-gripper systems, 3) tethered gripping mechanisms, 4) reconfigurable robot frames, 5) adhesion solutions, and 6) embedment solutions. Grasping and perching are two crucial capabilities that allow aerial robots to interact with the environment and execute a plethora of complex tasks, facilitating new applications that range from autonomous package delivery and search and rescue to autonomous inspection of dangerous or remote environments. In this review paper, we present the state-of-the-art in aerial grasping and perching mechanisms and we provide a comprehensive comparison of their characteristics. Furthermore, we analyze these mechanisms by comparing the advantages and disadvantages of the proposed technologies and we summarize the significant achievements in these two research topics. Finally, we conclude the review by suggesting a series of potential future research directions that we believe that are promising.

Modular Bioreactor Design for Directed Tendon/Ligament Tissue Engineering.

Functional tissue-engineered tendons and ligaments remain to be prepared in a reproducible and scalable manner. This study evaluates an acellular 3D extracellular matrix (ECM) scaffold for tendon/ligament tissue engineering and their ability to support strain-induced gene regulation associated with the tenogenesis of cultured mesenchymal stromal cells. Preliminary data demonstrate unique gene regulation patterns compared to other scaffold forms, in particular in Wnt signaling. However, the need for a robust bioreactor system that minimizes process variation was also evident. A design control process was used to design and verify the functionality of a novel bioreactor. The system accommodates 3D scaffolds with clinically-relevant sizes, is capable of long-term culture with customizable mechanical strain regimens, incorporates in-line load measurement for continuous monitoring and feedback control, and allows a variety of scaffold configurations through a unique modular grip system. All critical functional specifications were met, including verification of physiological strain levels from 1–10%, frequency levels from 0.2–0.5 Hz, and accurate load measurement up to 50 N, which can be expanded on the basis of load cell capability. The design process serves as a model for establishing statistical functionality and reliability of investigative systems. This work sets the stage for detailed analyses of ECM scaffolds to identify critical differentiation signaling responses and essential matrix composition and cell–matrix interactions.