Gripper System Research Articles

Young’s Modulus Measurement for Polysilicon Thin Film by Tensile Testing

Young’s modulus of polysilicon thin film was measured by means of a tensile tester equipped with electrostatic force grip system. The images of gauge marks on a specimen were captured by a high-speed digital CCD camera and the tensile strain was calculated from the images. Polysilicon thin film specimens were tensile tested for evaluating the resolution of the measurement system. The polysilicon specimens were 1.7 µm thick, 20 and 50 µm wide, and 100 and 500 µm in gauge length. The linear stress-strain curve was obtained and Young’s modulus was measured. The mean Young’s modulus ranged from 162 to 175 GPa, which agreed with the theoretical value and the measured values using the bulge method. The resolution and the comparison to the differential method were discussed.

An overview of the University of Louisiana robotic gripper system project

This paper summarizes a concluded 5-year funded research project (1994-1999) addressing the automated handling and manipulation of limp material, without distortion, deformation or damage. A series of prototype gripper systems (fixed-dimensioned and reconfigurable) were developed and integrated with Adept Series manipulators to demonstrate the gripper applicability to the textiles and apparel industry. A sensor-based control system based on the hierarchical control architecture paradigm (Valavanis and Saridis, Intelligent robotic systems: theory, design and applications, Kluwer, Amsterdam, 1992) controlled the operation of the integrated robotic gripper system. The research concluded with the conceptual and theoretical design of a reconfigurable robotic gripper system (RGS) followed by simulation-based design parameter validation, controlled by a fuzzy logic controller (for both position- and suction-based control). RGS simulation studies demonstrated the distortion-free manipulation of limp material panels of a variety of shapes and sizes.

Development of an Articulated Gripper for an Underwater ROV.

An adaptive multifinger gripper system was developed for underwater ROV. The system, named The Artifact 'K' apture Operator (TAKO) gripper, provides soft and adaptive envelope grasp with three articulated fingers. Each finger comprises five segments and performs like an octopus tentacle. The gripper has 15 segments in total, yet they are coordinately driven by one single motor and tendon mechanisms. This design allows the gripper system compact, light weight, and less expensive. The TAKO gripper is mounted on an underwater ROV named Triton that is a research oriented test platform developed at Santa Clara University. The TAKO-Triton integrated test was carried out successfully for the artifact pick-up operation from the bottom of the water.

Determination of G12 by means of the off-axis tension test.

Abstract The determination of the intralaminar shear modulus G 12 in composite materials is by no means a straight forward task. Several different tests and procedures have been proposed, with the off-axis test achieving popularity as a result of its apparent simplicity. A review of the most significant studies and proposals connected with the determination of G 12 by means of the off-axis tension test is presented in this paper. The majority of the contributions can be classified in two general approaches. The first approach contains the proposals to modify the gripping system in order to allow the ideal deformation of the specimen. Particular attention is paid to the use of rotating grips and the results obtained. Reasons why other authors did not achieve satisfactory results are explored. In the second approach a coherent correction scheme, based on an iterative procedure applied to measurements obtained from the test, is presented. Finally, the dependence of the correction factor, based on the Pagano and Halpin analysis, upon the properties of the material is discussed.

AE—Automation and Emerging Technologies: Automatic Mushroom Harvester Development

This paper describes research which demonstrates that robotic harvesting of high-quality mushrooms, for the fresh market, is entirely feasible. The work was undertaken in two stages. First, systems capable of automatic mushroom location, sizing, selection, picking, trimming, conveying and transfer were conceived and implemented on a specially designed laboratory development rig. Once the sub-systems and integrated control software had been proven, the second stage of producing a pilot robotic harvester, based on these ideas, was carried out. Machine vision and image analysis algorithms were used for mushroom location and sizing. A separate strategy algorithm was written for selecting the most appropriate mushroom picking order. Overall system control was achieved using a single 486 DX33 MHz personal computer. Separate suction cup end-effectors were produced for picking in confined (less than 300 mm) or open headroom spaces. New delicate handling techniques for conveying, trimming and transferring mushrooms using flexible fingers, high-speed knives and a padded pneumatic gripper system, were developed. Both the laboratory rig and the pilot harvester were evaluated using imitation mushrooms constructed from dental plaster and a wide range of cultivated Agaricus bisporus mushrooms. In trials on a commercial farm, an average of over 80% of the mushroom pick attempts were successful.

Reattachment of the greater trochanter using the Dall-Miles cable grip system in revision hip arthroplasty

Clinical and radiographic results of trochanteric osteotomy after revision hip arthroplasty in 62 hips were reviewed. The osteotomized fragment had been reattached using the Dall-Miles cable grip system in each hip. The patients’ average age at operation was 64.4 years (range, 40–86 years). The average duration of follow-up was 30.0 months (range, 12–60 months). Trochanteric nonunion was found in 19 hips (30.6%). Trochanteric nonunion developed in 14 (38.9%) of 36 hips with each cable attached around the medial cortex bone, in 2 (16.7%) of 12 hips with each cable passed in a drill hole, and in 3 (21.4%) of 14 hips with one cable passed through a hole and the other attached around the medial cortex. Fragmentation developed in 18 hips (29.0%). In 3 of these 18, the fragments had migrated close to the acetabular component. Cable breakage was seen in 4 hips (6.5%), and bone absorption around the cable in the medial cortex was seen in 17 hips (27.4%). There were 16 hips (25.8%) that presented symptoms at the greater trochanter, including spontaneous pain and tenderness. When the Dall Miles cable grip device is used for reattachment of the greater trochanter, attention should be paid to the condition of the trochanteric bed, the tension of the abductor muscles, and to the placement of the cables and the H-shaped grip.

インプラント挿入後における大腿骨骨幹部骨折の治療経験

Aim;The purpose of this study was to assess whether plate and cable-wire can be used in the treatment of periprosthetic femoral shaft fractures.Patient and Methods;We treated 7 cases of 6 patients (all females) who exhibited periprosthetic femoral shaft fractures. The age of the patients ranged from 73 to 94 years (average; 79.1 years). The prostheses that had been inserted before were 6 components of THA or BEA (3 were cemented, 3 non-cemented), and one intramedullar nail. The case involving the intramedullar nail, not with standing, the fractures were categorized by Johansson's classification: 4 cases were type I fracture, and 2 were type III. All cases were treated by open reduction, using the Dall-Miles Cable Grip System (Howmedica product) in 5 cases and the Cable-Ready Cable Grip System (Zimmer product) in 2, and were clinically and radiologically assessed after the open reduction.Results;Regardless of not using external fixation, refractures did not occurr in any of the cases. Except for 2 patients with severe dementia or hemiparesis, the initiation of weight-bearing after open reduction was relatively early, ranging from 14 to 40 days (average; 26.2 days).Conclusion;It was concluded that plate and cable-wire can be used for the treatment of periprosthetic femoral shaft fractures.

Precise piezoelectric prehension

Piezoelectric actuators are well established for use in expensive optical equipment. Within the last decade, relatively inexpensive piezoelectric actuators have become established technology in pneumatic switching and the first piezoelectrically driven impactive robot grippers are just starting to emerge. Although this article concentrates largely on the use of piezoelectric actuators for use in robot gripping systems, the potential for applications outside this field is immense.

Assessment of skin improvement treatment efficacy using the photograding of mechanically-accentuated macrorelief of thigh skin

The assessment of the efficacy of skin improvement treatments could be obtained by several different instrumental tests. In parallel to these techniques, a visual evaluation more closely related to the consumer's considerations would be of value for the assessment of slimming treatments efficacy. A method of macrorelief scoring of skin has been developed as an alternative to usual clinical assessment. It consisted of acquiring macroscopic views of the most representative areas of women's cellulite. Photographs were taken after application of a gripping system around the thigh, used to increase the orange peel look of the skin over a restricted area (200 cm(2)) and then classified by observers according to reference groups of cellulite intensity. This publication presents the validation of this photograding method and the results of the first 2-month double-blind placebo-controlled clinical study performed on 30 subjects with this technique associated with: (i) B mode ultrasound imaging in order to correlate scorings with instrumental measurements of thigh adipose tissue thickness variations and (ii) self-evaluation questionnaire aiming at evaluating the overall appraisal and attitude towards the two products. The results clearly showed that the effects of 'slimming products' on the skin's macrorelief improvement could be evaluated objectively using this photograding technique. Moreover, the method described here allows delayed scoring of cellulite intensity from a restricted examination area independent of whole-subject appearance, thus decreasing subjectivity.

Design fundamentals of a reconfigurable robotic gripper system

Discusses the design and modeling fundamentals of a multi-degree-of-freedom reconfigurable robotic gripper system (RGS), designed to automate the process of limp material handling, reliably and without distortion, deformation, and/or folding. The reconfigurable gripper design draws upon a previously reported flat surfaced, fixed-dimensions gripper system (Kolluru et al., 1998). The design consists of four arms in a cross-bar configuration, with a flat surfaced, fixed dimensions, suction-based gripper unit mounted on each of the arms. The kinematic and dynamic performance of the reconfigurable RGS is analyzed theoretically and then validated using Integrated Design Engineering Analysis Software (I-DEAS) simulation software.

Suction Control of a Robotic Gripper: A Neuro-Fuzzy Approach

This paper discusses a fuzzy logic control system designed to determine, regulate and maintain the amount of suction needed by a robotic gripper system to perform reliable limp material manipulation. A neuro-fuzzy approach is followed to determine the amount of desired suction (depending on experimentally derived data and plant characteristics). A knowledge-based valve controller is then designed to generate, regulate and maintain the amount of suction calculated by the neuro-fuzzy suction module. The performance of the overall suction control system is compared with actual experimental results obtained when using a prototype gripper system to handle limp material. Further, performance of the fuzzy logic based valve controller is compared to conventional PD and PID controllers. The proposed control scheme is found to enhance the overall functionality of the prototype robotic gripper system.

Problems of Dall-Miles Cable Grip System in re-attachment of greater trochanter

Problems of Dall-Miles Cable Grip System in re-attachment of greater trochanter

Survival assessment of die-marked drill pipes:: integrated static and fatigue analysis

Drill pipes under operational loads may fail in static or fatigue mode. Static failures are evaluated at two critical levels: the rotary table level (surface level) and the dogleg level, whereas fatigue failure occurs in a pipe section at the dogleg level due to the cumulative effect of fatigue damage in a number of drilling events. The current practice of static and fatigue failure analyses is based on a smooth pipe surface condition. In practice, however, dies of gripping systems mark the pipe surface during making and breaking operations (screwed and unscrewed to connect and disconnect two pipes). These marks on the pipe surface cause stress concentrations, which make a pipe more susceptible to both failure modes. This paper presents an integrated approach for static and fatigue failure analysis, considering the effects of stress concentrations due to die-marks from different gripping systems. Thus, the approach is intended to assist engineers in assessing the overall survivability of drill pipes through a detailed failure evaluation considering the effect of die-mark related stress concentrations in representative field conditions.

The outcome of trochanteric reattachment in revision total hip arthroplasty with a cable grip system: Mean 6-year follow-up

We have reviewed 251 hips that were revised by the senior authors with subsequent reattachment using the Dall-Miles Cable Grip System. Of these patients, 223 were available for follow-up. A trochanteric slide osteotomy was used for most cases ( n = 170), and the remainder had conventional trochanteric osteotomy to facilitate surgical exposure. Follow-up period was 1 to 8 years. Forty-eight percent ( n = 108) of the hips had a previous trochanteric osteotomy. Thirteen percent ( n = 30) had a prior trochanteric nonunion. Of the 223 hips, 91 % ( n = 204) of the trochanters remained attached to the trochanteric bed when reapproximated by the cable grip system. The 2 multifilament cables were passed medially through drill holes in the lesser trochanter in 67% ( n = 149) of cases. Of the hips, 16% ( n = 35) had 2 cables passed through bone lateral to the prosthesis, and 17% ( n = 39) had cables passed 1 medial and 1 lateral to the prosthesis. Cable breakage was noted in 10% ( n = 23) of cases. Of those 23, 70% ( n = 16) were stainless steel. Unraveling of the cable occurred in 18% ( n = 41) of cases. There were 19 nonunions (9%). Of the 19 nonunions, 74% ( n = 14) were stainless steel. The trochanter was reattached to bone in 9 hips, to cement in 4 hips, and to a proximal femoral allograft in 6 hips ( P = .0001). Eight of the 19 hips (42%) had the cables placed lateral to the prosthesis ( P = .0002). When bone-to-bone apposition was achieved at surgery, the nonunion rate was 4%. In this difficult group of revision procedures, the Dall-Miles Cable Grip has provided reliable trochanteric fixation. Factors associated with successful trochanteric healing include use of vitallium cables, use of a trochanteric slide osteotomy, cables passed medially through the lesser trochanter, cerclage rather than intramedullary placement, and bone-to-bone apposition.

Collaborative test programme results for 0°BD tensile properties on carbon–epoxy AS4/8552 and carbon– cyanate M55J/954-3 composite materials and some considerations on EN 2561 test standard

A collaborative test programme has been undertaken on modified epoxy matrix 8552 reinforced with AS4 carbon fibres, and cyanate 954-3 reinforced with M55J high modulus carbon fibre, both in the form of unidirectional prepreg. To date more than 300 specimens have been tested according to the EN 2561 standard (tensile test parallel to the fibre direction). Different testing conditions such as tabbed and untabbed specimens, dry and wet conditioning, 23 and 70°C test temperature, 7° bevelled or squared off 90° tabs, and the influence of different gripping systems (mechanical and hydraulic) were studied. Average strength values and Young's modulus values are presented with their standard deviations for these materials at every tested condition. In tensile strength measurements, the importance of using tabs for the gripping system and tested material is demonstrated.

Stress concentration incorporated fatigue analysis of die-marked drill pipes

Fatigue damage of drill pipes occurs in the pipe section at the dogleg region (where the drill pipe changes its drilling direction) due to alternating bending stress during rotation of the pipe. The pipe section may fail due to the cumulative effect of fatigue damage in a single drilling event, or in a number of drilling events. Moreover, dies of gripping systems mark the pipe surface during making and breaking operations (screwed and unscrewed to connect and disconnect two pipes). These marks on the pipe surface cause stress concentration. This paper develops a method for fatigue analysis of drill pipes taking into account the alternating bending stress at the dogleg, the direct axial stress due to hanging weight of drill pipes and the stress concentration due to die-marks on the pipe surface. The application of the method is demonstrated by evaluating cumulative fatigue damage for a number of drilling events and different gripping systems which produce die-marks of different depths. Results have revealed that higher die-mark depths accelerate fatigue failure, which can be predicted more accurately by the method presented in this paper.

Modeling, analysis, and performance evaluation of a robotic gripper system for limp material handling

This paper presents an analytical model of a flat surfaced robotic gripper designed to automate the process of reliable, rapid and distortion-free limp material handling. The designed gripper prototype is integrated with an industrial robot manipulator. The gripper geometry and its grasp stability are justified. Performance of the overall system is experimentally tested, based on a set of industry dictated operational constraints. It is found that the gripper system has high reliability, grasp stability, and that it is capable of rapid rates of manipulation.

Mechanical design, operation and direction prediction of the AMADEUS gripper system

The mechanical design, construction, operation and initial performance of a prototype innovative dextrous underwater end effector are described. The three-fingered hydraulic device utilizes continuously flexible fingers to perform grasping and manipulation. Finger movements are produced by the elastic deformation of bellows elements due to internal pressure. A single degree of freedom knuckle joint at the base of each finger enables the device to be used across a wide range of object sizes. A comparison between theoretical and actual non-contact movements for this type of flexible finger is also included.

Grasping force measurement for dynamic grasp stability assessment

Grasping dynamic stability is an important quality index for robotic grasping. Previous studies on the grasping stability usually consider the problem under the quasi-static assumption. This paper systematically investigates the grasping dynamic behavior from both theoretical and simulation aspects for the purpose of practical measurements. The dynamic stability of a grasping system is related to the contact type between the grasped object and the fingers, the grasping configuration, the control law of the fingers, and the passive compliance of the fingers. Starting from the dynamic equations of the grasping system, Liapunov stability theory is used to study the grasping dynamic stability problem. Simulation was conducted in support of the theoretical hypothesis. A gripper system was developed incorporating real time three-dimensional grasp force sensing for each of the fingers with some initial experimental results given.

A Real-Time, Hierarchical, Sensor-Based Robotic System Architecture

A robotic system architecture is presented and its real-time performance, when used to control a robotic gripper system for deformation-free handling of limp material, is evaluated. A major problem to be overcome has been the integrability and compatibility issues between various components of the developed system. The software and hardware protocols and interfaces developed to control and coordinate the subsystem operations and interactions are presented. The performance of the developed real-time, hierarchical, sensor-based robotic system architecture is found to meet and satisfy a set of system operational constraints and demands as dictated by the industry.