Verification Of Machines Research Articles

CAD-based measurement planning strategy of complex surface for five axes on machine verification

Dimensional inspection of engineering components comprising free-form surfaces demands accurate measurement of a large number of discrete points, such that the actual shape may be fully characterized. This paper presents an on-machine verification (OMV) measurement planning strategy for CAD-based measurement of such components on five-axis machines. The main shortcoming of the conventional methodology with coordinate measuring machines (CMMs) has been identified to do with relation to repetitive position error. However, by employing the CAD model and on-machine platform, the proposed methodology maximizes the measurement accuracy, and such problem does not exist. The steps are as follow: adaptive sampling strategy is used to obtain effective measured points, probe path optimization, verification, post-processing, and measurement. The OMV process of surface on “S”-shaped test piece is implemented, and the obtained deviation is compared with another set of data measured on a coordinate measurement machine.

Design Criteria, Modeling, and Verification of Tubular Transverse Flux Machines for Force-to-Current Ratio Improvement in Direct Drive Applications

Tubular transverse flux machines (TFMs) generally exhibit high force densities and are interested in various direct-drive applications. Due to essentially 3-D distribution, the design and modeling of the TFM is quite difficult and time-consuming. This paper presents the design criteria of a tubular TFM to maximize the force-to-current ratio developed for direct drive applications. Analytical equations are derived to establish the relationship between the force-to-current ratio and the leading design parameters of the machine. In addition, the validity of the derivation is verified by extensive 3-D finite-element computations and experiments on a prototype machine. It is shown that for a given set of volumetric constraints, the force-to-current ratio is more sensitive to the stator segment length than other leading parameters. The results have provided a basis for design optimization, and will aid the design process of the tubular TFM, especially when targeting demanding applications where high force density is crucial.

Overview of NIST Activities on Subsize and Miniaturized Charpy Specimens: Correlations With Full-Size Specimens and Verification Specimens for Small-Scale Pendulum Machines

NIST in Boulder, CO investigated the correlations between impact test results obtained from standard, full-size Charpy V-notch (CVN) specimens and specimens with reduced thickness (subsize Charpy V-notch specimens (SCVN)) or reduced or scaled cross section dimensions (miniaturized Charpy V-notch specimens (MCVN)). A database of instrumented impact test results was generated from four line pipe steels: two quenched alloy steels, a tempered alloy steel, and a 18 Ni maraging steel. Correlations between specimen types were established and compared with the previously published relationships, considering absorbed energy (KV), ductile-to-brittle transition temperature (DBTT), and upper shelf energy (USE). Acceptable correlations were found for the different parameters, even though the uncertainty of predictions appears exacerbated by the expected significant experimental scatter. Furthermore, we report on the development of MCVN specimens for the indirect verification of small-scale pendulum machines (with potential energies between 15 J and 50 J), which cannot be verified with full-size verification specimens. Small-scale pendulum machines can now be verified at room temperature with certified reference specimens of KLST type (3 mm × 4 mm × 27 mm), supplied by NIST at three certified KV levels (low energy (LL), 1.59 J; high energy (HH), 5.64 J; and super-high (SH) energy, 10.05 J). These specimens can also be used to verify the performance of instrumented Charpy strikers through certified maximum force values. Certified reference values for both KV and maximum force were established by means of an interlaboratory comparison (Round-Robin), which involved nine qualified and experienced international laboratories.

Diagonal in space of coordinate measuring machine verification using an optical-comb pulsed interferometer with a ball-lens target

This paper presents a new optical method of coordinate measuring machine (CMM) verification. The proposed system based on a single-mode fiber optical-comb pulsed interferometer with a ball lens of refractive index 2 employed as the target. The target can be used for absolute-length measurements in all directions. The laser source is an optical frequency comb, whose repetition rate is stabilized by a rubidium frequency standard. The measurement range is confirmed to be up to 10m. The diagonals of a CMM are easier to verify by the proposed method than by the conventional artifact test method. The measurement uncertainty of the proposed method is also smaller than that of the conventional method because the proposed measurement system is less affected by air temperature; it achieves an uncertainty of approximately 7μm for measuring lengths of 10m. The experimental results show that the measurement accuracy depends on noise in the interference fringe, which arises from airflow fluctuations and mechanical vibrations.

Evaluation of the use of a Laser Tracker and an Indexed Metrology Platform as Gauge Equipment in Articulated Arm Coordinate Measuring Machine Verification Procedures

The development of new gauges and alternative calibration and verification techniques applied to articulated arm coordinate measuring machine (AACMM) has been approached in different ways. In this work the analysis of the use of a laser tracker (LT) as reference instrument in calibration and verification procedures for AACMM together with an indexed metrology platform (IMP) replacing the conventional one-dimensional gauges is presented. This technique avoids the need of materializing the length required in a conventional gauge, increasing the flexibility for defining test positions and broadening the definition of reference lengths depending on equipment calibration or verification requirements. The use of the IMP in this verification procedure enables a reduction of testing time and space needed in the data capturing process. The results obtained showed the suitability of the proposed procedure using the LT as reference instrument.

Modeling and Simulation for Overhead Hoist Transporter System in Computer Integrated Manufacturing; A Case Study on the Food Processing Business

Computer integrated manufacturing, CIM, has attracted many interests both in academic research and practical implementation. Design and implementation of a CIM project involves the massive modeling, simulation, and verification of production operations, machines, and operators. Overhead hoist transporter, OHT, is one of the effective tools for the automated material handling system that often applied in CIM projects to ultimate the utilization of footprint of a factory. This paper presents a case study for the OHT system design in a CIM project for automated food processing production line. The effectiveness of the number of OHTs installed for the production line and the proper operation scenarios for different production planning are studied. Modeling and simulation results are performed to suggest an efficient OHT system design for the CIM project.

Volumetric Error Model of Large CNC Machine Tool and Verification Based on Particle Swarm Optimization

Volumetric error has large effect on machine tool accuracy; improving CNC machine tool accuracy through error compensation has received significant attention recently. This paper intends to represent volumetric error measurement based on laser tracker. The volumetric error is modeled by homogenous transformation matrix with each coordinate corresponding to each motion axis. Based on parts of spatial points volumetric error, the geometric errors which affect volumetric positioning error are verified through particle swarm optimization with the L2 parameters as the target function. The chebyshev orthogonal polynomials are applied to approximate geometric errors.

Certified Miniaturized Charpy Specimens for the Indirect Verification of Small-Size Impact Machines

Abstract Small specimen test techniques are becoming ever more popular as the need increases to characterize mechanical properties by the use of the smallest possible amount of material, because of various restrictions on material availability, irradiation, testing space, and other factors. The National Institute of Standards and Technology (NIST) is currently developing certified miniaturized Charpy V-notch (MCVN) specimens for the indirect verification of small-scale impact testing machines. The same materials used for NIST standard verification specimens are being evaluated at three energy levels (low, high, and super-high). Two specimen types are being investigated, denominated KLST (from the German Kleinstprobe, or “small specimen”) and RHS (reduced half-size). Several instrumented impact tests on miniaturized KLST and RHS specimens of low, high, and super-high energy have been performed and analyzed. The variability of MCVN data has been compared to that of full-size Charpy data from the same lots of test specimens. Although this can be considered as just the preliminary phase of this project, the results indicate that MCVN verification specimens can be used for the indirect verification of small-scale instrumented impact testers, both in terms of absorbed energy and maximum force.

Machine tools for large parts

This paper reviews the design, engineering principles and applications of machine tools specially developed for large parts. Large workshop machines are commonly used for manufacturing, where the impact of the general engineering principles differs substantially from those applied to conventional size machines. Portable machines are used during assembly and operation due to mobility, agility and energy constraints. Such large dimensions produce an amplification factor of any error source, so verification and calibration of such large or portable machines becomes even more critical than in conventional machines. The paper also includes future trends and unsolved challenges.

Characteristic Analysis on the Influence of Misaligned Rotor Position of Double-Sided Axial Flux Permanent Magnet Machine and Experimental Verification

While axial flux permanent magnet (AFPM) machines are manufactured, their wrong assembly can be possible, such as misaligned PM rotor position of double-sided machine. Once the machines are assembled, detecting the misaligned rotor is hard, so the designers are required to have deep insight in its related and unexpected characteristics to prevent them focusing on other possible errors. Therefore, this paper deals with the characteristic analysis on the influence of the misaligned rotor position of double-sided AFPM machine and its experimental verification. In general, the AFPM machines have been analyzed by 3-D finite-element method (3-D FEM) due to their structural features, but it requires very long analysis time to consider various factors. For this reason, analytical approach is presented in order to consider all the cases of the misaligned rotor positions, and it is confirmed to be practical to detect the positions and to reduce analysis time with high reliability. With the analytical approach, the misaligned rotor position characteristics, such as back-emf and its total harmonic distortion are analyzed. Furthermore, all the analysis results are validated by 3-D FEM results and experimental verification.

Integrated Design of Symbolic Controllers for Nonlinear Systems

Symbolic models of continuous and hybrid systems have been studied for a long time, because they provide a formal approach to solve control problems where software and hardware interact with the physical world. While being powerful, this approach often encounters some limitations in concrete applications, because of the large size of the symbolic models needed to be constructed. Inspired by on-the-fly techniques for verification and control of finite state machines, in this note we propose an algorithm that integrates the construction of the symbolic models with the design of the symbolic controllers. Computational complexity of the proposed algorithm is discussed and an illustrative example is included.

Finite element analysis of a force transducer

Force transducer have been designed on the basis of theories of thin rings and design plays an important role in various applications like verification of material testing machines, monitoring force components in different cutting tools, agriculture related applications, hardness testing machines etc. Generally, some assumptions and approximations have been made for deriving analytical expressions for stress / strain analysis / deflection of force transducers. For more rigorous validation of analytical derived expressions, numerical methods need to be used. In the present study, a ring shaped force transducer, commonly used for force measurement, has been studied using finite element analysis. The study provides scope for the effect of nominal quantities over the design of ring shaped force transducers.

Finite element analysis of a force transducer

Force transducer have been designed on the basis of theories of thin rings and design plays an important role in various applications like verification of material testing machines, monitoring force components in different cutting tools, agriculture related applications, hardness testing machines etc. Generally, some assumptions and approximations have been made for deriving analytical expressions for stress / strain analysis / deflection of force transducers. For more rigorous validation of analytical derived expressions, numerical methods need to be used. In the present study, a ring shaped force transducer, commonly used for force measurement, has been studied using finite element analysis. The study provides scope for the effect of nominal quantities over the design of ring shaped force transducers. Keywords: Force transducer, finite element analysis, stress, strain, deflection.

SpaceWire State Machine Verification Based on Model Checking

SpaceWire is a high-speed data transmission bus standard proposed by ESA for the aerospace applications. Hosted by the National Astronomical Observatories, Chinese Academy of Sciences, the Space Solar Telescope project takes the SpaceWire bus standard as space communication link. The SpaceWire communication circuit implemented by our group is a part of the SST project. In order to improve the fault detection and fault correction capacity and the reliability of the SpaceWire bus, we add a more error analysis and data storage module into the original six state modules of the standard protocol in the exchange layer.We adopt the formal verification method based on the model checking to verify the finite state machine of the SpaceWire control module. The properties expressed by the high-order temporal logic formula are verified automatically to be true by the SMV model verifier of the Cadence Company. Verification results show that our SpaceWire bus implementation and the additional error analysis and data storage module are faithful to the protocol specification. Therefore, we also can integrate SpaceWire bus circuit into the SST project.

The Stable Revivals Model in CSP-Prover

The stable revivals model R provides a new semantic framework for the process algebra Csp. The model R has recently been added to the realm of established Csp models. Within the Csp context, it enhances the analysis of systems with regards to properties such as responsiveness and stuckness. These properties are essential in component based system design. In this paper we report on the implementation of different variants of the model R within Csp-Prover. Based on Isabelle/HOL, Csp-Prover is an interactive proof tool for Csp refinement, which is generic in the underlying Csp model. On the practical side, our encoding of the model R provides semi-automatic proof support for reasoning on responsiveness and stuckness. On the theoretical side, our implementation also yields a machine verification of the model R's soundness as well as of its expected properties.

Verification of scope-dependent hierarchical state machines

A hierarchical state machine (H sm) is a finite state machine where a vertex can either expand to another hierarchical state machine ( box) or be a basic vertex ( node). Each node is labeled with atomic propositions. We study an extension of such model which allows atomic propositions to label also boxes (S hsm). We show that S hsms can be exponentially more succinct than S hsms and verification is in general harder by an exponential factor. We carefully establish the computational complexity of reachability, cycle detection, and model checking against general L tl and C tl specifications. We also discuss some natural and interesting restrictions of the considered problems for which we can prove that S hsms can be verified as much efficiently as H sms, still preserving an exponential gap of succinctness.

Machining Accuracy Improvement by Automatic Tool Setting and On Machine Verification

This paper proposes a methodology for improving the machining accuracy based on auto tool setting & work-piece measuring on the machine using laser tool setting system & inspection probe. In this study, laser tool setting systems were analyzed as considering principles, convenience and efficiency and auto tool setting method and operating macro software were developed. As compared with conventional manual tool setting and touch-type auto tool setting, the importance of automatic non-contact tool setting using laser tool setter has been discussed. Also correct tool-setting methods in accordance with different tool shapes and sizes were defined and pocket features were machined by each of setting tools and measured by the inspection probe system to verify machining accuracy. Lastly we tried to demonstrate the superiority of laser tool setting systems by analyzing the cutting results when the CNC machining center was fitted with laser tool setting system.

A Refinement-Based Compositional Reasoning Framework for Pipelined Machine Verification

We present a refinement-based compositional framework for showing that pipelined machines satisfy the same safety and liveness properties as their non-pipelined specifications. Our framework consists of a set of convenient, easily applicable, and complete compositional proof rules. We show how to apply our compositional framework in the context of microprocessor verification to verify both abstract, term-level models and executable, bit-level models. Our framework enables us to verify machine models that are significantly more complex than the kinds of models that can be verified using current state-of-the-art automated decision procedures. For example, using our framework, we can verify a 32-bit, 10-stage, executable pipelined machine model. In addition, our compositional framework offers drastic improvements in the context of design debugging over monolithic approaches, in part because bugs are isolated to particular steps in the compositional proof and because the counter examples generated are much smaller.

Uncertainty in Reference Values for the Charpy V-notch Verification Program

Abstract We present a method for computing the combined standard uncertainty for reference values used in the Charpy machine verification program administered by the National Institute of Standards and Technology. The technique is compliant with the ISO Guide to the Expression of Uncertainty in Measurement and models the between-machine bias using a Type B distribution. We demonstrate the method using actual data from the Charpy machine verification program.

Analysis of Charpy Impact Verification Data: 1993–2003

Abstract Indirect verification tests used to verify the performance of Charpy impact machines according to ASTM Standard E23 were evaluated by the National Institute of Standards and Technology (NIST), and the data from these tests are collected in a database. The data include the capacity and the pendulum design of the impact machine, the energy obtained for each specimen tested, the reference energy for the specimen lot tested, and the test date. The principal use of this data is to track the performance of individual impact machines. However, the data also provide an opportunity to evaluate existing and proposed requirements for the indirect verification of Charpy impact machines. The results of more than 16 000 verification tests are used to compare the current verification requirements of ASTM Standard E23 with those of ISO Standard 148–2. Discussions focus on the identification of reasonable, practical, and meaningful verification requirements that might be proposed for use in both documents.