Gripper System Research Articles

Constructive and Functional Modelling of a Pneumatic Muscle Actuated Symmetric Gripper System with Two Mobile Jaws

Compliance is one of the main requirements to be satisfied by a gripper system. The paper addresses this issue and proposes a compliant, pneumatic muscle actuated gripper system. Constructive and functional models of an innovative gripper system are presented, together with a discussion of its limits.

Pneumatic Muscle Actuated Parallel Asymmetric Gripper System with a Mobile and a Fixed Jaw

Pneumatically actuated gripper systems are frequently used in various applications due to their multiple advantage, and particularly to their specific feature known as compliance. This is what allows manipulation of fragile objects and ensures their soft contact with the gripper jaws. The paper presents and discusses such a gripper system actuated by a pneumatic muscle. Structural, constructive and functional models of a novel gripper system are presented and its main motion characteristics highlighted.

Design and implementation of a multiaxial loading capability during heating on an engineering neutron diffractometer.

A gripping capability was designed, implemented, and tested for in situ neutron diffraction measurements during multiaxial loading and heating on the VULCAN engineering materials diffractometer at the spallation neutron source at Oak Ridge National Laboratory. The proposed capability allowed for the acquisition of neutron spectra during tension, compression, torsion, and/or complex loading paths at elevated temperatures. The design consisted of age-hardened, Inconel(®) 718 grips with direct attachment to the existing MTS load frame having axial and torsional capacities of 100 kN and 400 N·m, respectively. Internal cooling passages were incorporated into the gripping system for fast cooling rates during high temperature experiments up to ∼1000 K. The specimen mounting couplers combined a threaded and hexed end-connection for ease of sample installation/removal without introducing any unwanted loads. Instrumentation of this capability is documented in this work along with various performance parameters. The gripping system was utilized to investigate deformation in NiTi shape memory alloys under various loading/control modes (e.g., isothermal, isobaric, and cyclic), and preliminary results are presented. The measurements facilitated the quantification of the texture, internal strain, and phase fraction evolution in NiTi shape memory alloys under various loading/control modes.

Pneumatic-type surgical robot end-effector for laparoscopic surgical-operation-by-wire.

BackgroundAlthough minimally invasive surgery (MIS) affords several advantages compared to conventional open surgery, robotic MIS systems still have many limitations. One of the limitations is the non-uniform gripping force due to mechanical strings of the existing systems. To overcome this limitation, a surgical instrument with a pneumatic gripping system consisting of a compressor, catheter balloon, micro motor, and other parts is developed.MethodThis study aims to implement a surgical instrument with a pneumatic gripping system and pitching/yawing joints using micro motors and without mechanical strings based on the surgical-operation-by-wire (SOBW) concept. A 6-axis external arm for increasing degrees of freedom (DOFs) is integrated with the surgical instrument using LabVIEW® for laparoscopic procedures. The gripping force is measured over a wide range of pressures and compared with the simulated ideal step function. Furthermore, a kinematic analysis is conducted. To validate and evaluate the system’s clinical applicability, a simple peg task experiment and workspace identification experiment are performed with five novice volunteers using the fundamentals of laparoscopic surgery (FLS) board kit. The master interface of the proposed system employs the hands-on-throttle-and-stick (HOTAS) controller used in aerospace engineering. To develop an improved HOTAS (iHOTAS) controller, 6-axis force/torque sensor was integrated in the special housing.ResultsThe mean gripping force (after 1,000 repetitions) at a pressure of 0.3 MPa was measured to be 5.8 N. The reaction time was found to be 0.4 s, which is almost real-time. All novice volunteers could complete the simple peg task within a mean time of 176 s, and none of them exceeded the 300 s cut-off time. The system’s workspace was calculated to be 11,157.0 cm3.ConclusionsThe proposed pneumatic gripping system provides a force consistent with that of other robotic MIS systems. It provides near real-time control. It is more durable than the existing other surgical robot systems. Its workspace is sufficient for clinical surgery. Therefore, the proposed system is expected to be widely used for laparoscopic robotic surgery. This research using iHOTAS will be applied to the tactile force feedback system for surgeon’s safe operation.

Some Analysis of Automated Guided Vehicle

AGV is mostly used in industrial application to move material around manufacturing facility. Here assembling of AGV is done by using components like chassis, wheels, wiper motors, gear motor, LED sensors, tactile sensor, actuators etc. AGV is designed with the help of electrical design of sensors which are used to control AGV during operation when it is moved on guided path. AGV design was modelled and simulated using catiaV5 software .Design was modelled and drawing preparation was done using catiaV5.Static analysis was done for stress using catiaV5 .Here principal stresses at different point were obtained having different deflection .Graphs are plotted for principal stress verses deflection and Navigation performance of AGV uses electric motor .Thus AGV is used to pick up the object with proper gripping system. A navigation system has been developed using sensors. AGV contains software and hardware components and is primarily used for material handling in industries. Static analysis was done for stress using catiaV5. Graphs are plotted for principal stress vs. deflection. The same analysis can be done for different material depending on loading condition. Stress analysis concept can be used to study dynamic analysis. Optimization of AGV can be possible by using different material. To evaluate the performance simulations were conducted using catiaV5 maintaining a constant setup inputs all over. IndexTerms:Catia,navigation,optimization

Flexible grasping of electronic consumer goods

Automated packaging is becoming more and more interesting for production sites. However, in many companies, the packaging process can only handle a limited amount of products. Most of the time for new products, the packaging system needs to be modified. One of the main components in an automated packaging process is the grasping of the objects that need to be packed. For different products, mostly a different gripping system is required. In this paper, solutions from a research project are presented which enables the flexible grasping of different products. These solutions include flexible pose recognition for different objects, path planning for the recognized objects and finally, a prototypical design for a flexible gripper, which enables handling of various objects of different weight and size.

Intelligent gripper technology for the handling of carbon fiber material

Nowadays, the serial production of Carbon Fiber-Reinforced Polymers remains a challenge for the industry. Their production and application have been limited by the intensive manual work required to produce them and the resulting elevated manufacturing costs. Moreover, the production handling tasks are fulfilled to a limited extent by the gripping systems currently available in the market. The delicate process and specific material requirements of these polymers compromise the feasibility and use of automated gripper systems. An innovative solution for the automated material handling of carbon fiber textiles developed by the wbk Institute for Production Science in cooperation with J. Schmalz GmbH will be presented in this paper. The main focus of this study deals with measuring principles to increase energy efficiency, process reliability and adaptability of a gripping system using low pressure grippers. This study presents suitable solutions for the implementation of low pressure grippers in a production environment.

Design and Smooth Position/Force Switching Control of a Miniature Gripper for Automated Microhandling

Automated microhandling tasks demand miniature grippers equipped with position and force sensors to execute reliable operations. This paper presents the design, implementation, and control of a piezoelectrically actuated compliant gripper with combined position and force monitoring/control capabilities. The gripper structure is devised based on a compliant rotary bearing mechanism with the displacement amplification lever, which endows a simplified architecture than the existing parallelogram-based ones. Moreover, the challenge of achieving a smooth transition between the position and force switching control is addressed by means of a new incremental control scheme. Precision control under the influence of hysteretic nonlinearity is guaranteed by a discrete sliding-mode control algorithm. The scheme is implemented with an field-programmable gate array (FPGA) platform. Experimental investigations are undertaken to verify the effectiveness of the gripper system by executing grasp-hold-release operations of a micro copper wire. The results confirm that the proposed incremental-based switching control outperforms conventional approach in terms of position/force regulation accuracy and operation time.

Scenario-Based Development of Disassembly Systems for Automotive Lithium Ion Battery Systems

The rising number of lithium ion batteries from electric vehicles makes an economically advantageous and technically mature disassembly system for the end-of-life batteries inevitable. The disassembly system needs to cope with the size, the design and the remaining state of charge of the respective battery system. The complex design resulting from the number and type of connection elements challenges an automated disassembly. The realisation of an automated disassembly presupposes the consideration of elements from Design for Disassembly throughout the battery system development. In this paper a scenario-based development of disassembly systems is presented with varying possible design aspects as well as different amounts of end of life battery systems. These scenarios point out the resulting implications on battery disassembly systems in short, medium and long term. Using a morphological box the best option for each disassembly scenario is identified and framed in a disassembly system design. The disassembly systems are explained and the core elements are introduced. Newly developed and innovative disassembly tools, such as a robot that allows a hybrid human-robot-working-space and an advanced battery cell gripper are introduced. The gripper system for the battery cells enables with an integrated sensor an instant monitoring of the battery cell condition. The proposed disassembly element is verified in an experimental test series with automotive pouch cell batteries.

Actuation by Pneumatic Muscles of a Parallel Asymmetric Gripper System

Deployment of pneumatic muscles for the actuation of gripper systems is a solution with numerous benefits, related mostly to the developed force, structural rigidity, compliance and dexterity. The paper discusses a gripper variant with parallel jaws, actuated by a pneumatic muscle. The structure of the mechanism is presented, and the transmission functions of speeds and forces are determined. Due to its construction, the gripper system can be used for precision applications, similar to natural systems.

Symmetrical Pneumatic Muscle Actuated Gripper System with Two Mobile Jaws

The paper argues the possibility of utilising artificial muscles actuated with compressed air in the construction of industrial gripper systems. Their utilisation as motors comes as a response to the increasingly sophisticated requirements these have to satisfy, related to the developed force, structural rigidity, compliance and dexterity. The paper presents a variant of symmetrical gripper system with two mobile jaws actuated by a pneumatic muscle. The main requirements for this gripper are defined, the structure of the mechanism is presented and the transmission functions of forces and velocities are determined. Eventually the paper discusses the construction of the system and its functional limitations.

The Realization of Actuating and Sensing Integrated Gripper System

Most of traditional manipulator does not meet experimental requirements of micromanipulation for its large structure and complicated driven mode. Comparatively speaking, using actuating and sensing performance of IPMC gripper can well be applied to specific micro operations and mechanical testing environment. This paper designs one kind of IPMC gripper of actuating and sensing performance based on micro operation and micro assembly, which is applied to grab the cells and fix under a microscope.

Early Catastrophic Failure of Trochanteric Fixation with the Dall-Miles Cable Grip System

Multi-filament orthopaedic cerclage cables have been used in clinical practice for several decades, and are commonly utilized to provide greater trochanteric fixation following an osteotomy or fracture. We present the first known report of patients who experienced early catastrophic failure following use of the Dall-Miles Cable Grip System (DMCGS). A root cause analysis determined that the jaws of one crimper had an increased distance at closure, resulting in inadequate ultimate fixation strength. It was discovered that operating room staff had not been trained to perform regular calibration checks and the required calibration tool was not included in any of the institution’s DMCGS sets. Surgeons should be aware that these surgical instruments require regular maintenance and should be gauge tested prior to every use.

Design and Control of Shape Memory Alloy Actuated Grippers

Design, investigation and control of two novel Shape Memory Alloy (SMA) wire based gripping systems one operated in open mode and another in closing mode is presented in this paper. A unified design is chosen for both the gripping systems. The gripping systems use SMA wire with a counteracting torsion spring to generated two way motion. Models of the gripping systems are experimentally determined from the open loop step response. Pulse width modulation control (PWM) controller is designed to control the tip displacement of gripping finger. These controllers are compiled to track various stationary and variable (dynamic) trajectories to suit applications that can manipulate objects of varied dimensions. Experimental results show that the grippers are able to track the position rapidly and precisely.

Automated Selection and Dimensioning of Gripper Systems

The selection and dimensioning of grippers have so far been done experience-based in most cases. As there are innumerable solutions for the gripping of a part, it is quite time consuming to find the optimal gripper for a specific part and task. However, there are few methodologies that apply this task, especially considering the flexibility of gripper systems. This paper suggests an approach how to automatically find the right gripper linking economical, flexibility and functional criteria.

Fuzzy Logic Controller Design for A Robot Grasping System with Different Membership Functions

This paper investigates the effects of the membership function to the object grasping for a three fingered gripper system. The performance of three famously used membership functions is compared to identify their behavior in lifting a defined object shape. MATLAB Simulink and SimMechanics toolboxes are used to examine the performance. Our preliminary results proposed that the Gaussian membership function surpassed the two other membership functions; triangular and trapezoid memberships especially in the context of firmer grasping and less time consumption during operations. Therefore, Gaussian membership function could be the best solution when time consumption and firmer grasp are considered.

Design and validation of an in vitro loading system for the combined application of cyclic compression and shear to 3D chondrocytes-seeded agarose constructs

Physiological loading is essential for the maintenance of articular cartilage by regulating tissue remodelling, in the form of both catabolic and anabolic processes. To promote the development of tissue engineered cartilage which closely matches the long term functionality of native tissue, bioreactors have been developed to provide a combination of loading modalities, which reflect the nature of normal physiological loads. This study describes the design and validation of an in vitro mechanical system for the controlled application of bi-axial loading regimes to chondrocyte-seeded agarose constructs.The computer-controlled system incorporates a robust gripping system, which ensures the delivery of precise values of cyclic compressive and shear strain to 3D cell-seeded constructs. Sample prototypes were designed, optimised using finite element analysis and validated performing compressive and shear fatigue mechanical tests. The horizontal and vertical displacements within the bioreactor are precisely controlled by a dedicated programme that can be easily implemented. The synchronisation of the orthogonal displacements was shown to be accurate and reproducible.Constructs were successfully loaded with a combined compressive and shear loading regimen at 1Hz for up to 48h with no appreciable loss of cell viability or mechanical integrity. These features along with the demonstrated high consistency make the system ideally suitable for a systematic investigation of the response of chondrocytes to a complex physiologically relevant deformation profile.

Analysis of Stress Distribution in Tensile Test Specimens Using Modified Versions of a Novel Gripping System

This paper deals with the effect of novel gripping systems developed for tensile testing on the stress distribution inside the test piece. The uniformity of the stress distribution plays a decisive role in measuring the upper yield strength and creep behavior of materials. In this study two modified versions of a recently developed gripping system are introduced and tested together with the original version. The tests consist of measuring the bending stress/axial stress ration during elastic loading of the test piece. The bending stress/average stress ratio was measured using a special strain gauge mounted test piece, which was loaded by elastic tension. The results show that the gripping systems provide the self-alignment of the test piece at the beginning of the loading; therefore they can ensure almost true uniaxial conditions for tensile testing. The average bending stress/axial stress ratio is found to be just 1-2 %, so, the gripping systems can provide the accurate measurement of upper yield strength and creep curves of materials.

A Compact Mechanical Gripper System for Meso-Scale Parts Using a Ball-Roller Joint

In this paper, a compact gripper system is designed to pick up meso-scale parts. A mechanical gripping method is chosen with a new type of joint. Based on the kinematics and material mechanics, the gripper motion is analyzed. Finally, a prototype gripper system based on the design and analysis results is fabricated. The motion principle is checked using laser diodes and position sensing detectors.

In-phase multiaxial fatigue experimental analysis of welded cylindrical 6063-T66 aluminium alloy specimens

This paper is concerned with an experimental and numerical study of the fatigue behaviour of cylindrical 6063-T66 welded specimens subjected to biaxial loading. In-phase torsion-bending fatigue tests under constant amplitude loading were performed in a standard electromechanical machine with a suitable gripping system. The experimental part was focused on the modeling of combined biaxial loading and determining the number of cycles to fracture in the region of low-cycle fatigue. In-phase loading can be treated fairly well using the conventional hypotheses (von Mises or Tresca) on basis of the nominal, structural or local strains or stresses. Based on the experimental results the fatigue design curves are compared to the fatigue data from base metal and weldments.