Kazuyuki Sasajima

A three-dimensional measuring technique for surface asperities

Abstract A measuring system has been developed as a first step in the evaluation of the three-dimensional characteristics of machined surface roughness. The measuring device consists of a conventional profilometer of the stylus type and a precision table moving perpendicular to the tracing direction of the stylus. Surface asperity heights were sampled as digital data at the nodes of the matrix on the surface to be measured. Measurements were made automatically by a controller. Asperities of many machined and worn surfaces were measured using the system, and three-dimensional representations and contour maps are given. It is shown that the measuring device is sufficiently accurate to be of use in investigating the three-dimensional characteristics of asperities.

An optimum sampling interval for digitizing surface asperity profiles

Abstract The statistical measurement of surface asperities has been computerized but little research has been done to realize surface asperity profiles using digital data. A method of obtaining the optimum sampling interval for accurate computer simulation of asperity profiles by the linear interpolation of discrete data is proposed. The sampling interval is calculated by applying the autocorrelation function so that the difference between original and simulated profiles is within acceptable limits.

Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact

There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.

Development of a Novel Artifact as a Reference for Gear Pitch Measuring Instruments

The pitch accuracy of a gear is graded on the order of 0.1 μm in ISO 1328-1; therefore, it is necessary for gear measuring instruments (GMIs) to be able to measure gears with the required high accuracy. GMIs are evaluated by measuring a calibrated gear or a gearlike artifact. It is, however, difficult to obtain a measurement uncertainty of less than 0.1 μm. The reason for this difficulty is that a gear artifact has a form error and surface roughness, and that the measurement position on the gear face differs slightly from the calibrated position. In view of this situation, we propose a novel multiball artifact (MBA), which is composed of equally spaced pitch balls, a centering ball, and a datum plane. The pitch balls are assumed to act as gear teeth by calibrating the angular pitch between the centers of each pitch ball. The centering ball and the datum plane are used to set a reference axis of the virtual gear. We manufactured an MBA with the pitch balls arranged on a curvic coupling. The angular pitch deviation between the centers of each pitch ball was calibrated using a coordinate measuring machine (CMM) and adopting the multiple-orientation technique. A master gear was also calibrated for comparison. The measurement uncertainty for the cumulative angular pitch deviation was 0.45 arc sec for the MBA and 1.58 arc sec for the master gear. The MBA could be calibrated with small uncertainty compared with the master gear. After the calibration, a virtual gear of the MBA was built using the calibration value. The virtual gear was measured using the gear-measuring software on the CMM. The measurement value was equal within the range of uncertainty of calibration value. It is verified that the superiority of the MBA to the gear artifact is due to the following reasons: (1) The balls can be manufactured with an accuracy of several tens of nanometers. (2) The calibrated result for the MBA is almost independent of a probe-positioning error because the centers of each pitch ball can be measured at multiple points. (3) In setting the reference axis, the gear artifact generally uses a datum cylinder, in contrast, the MBA uses more accurate ball.

An in-line digital filtering algorithm for surface roughness profiles

Abstract The authors develop a fast algorithm for low- and high-pass Gaussian digital filters, executed while one discrete datum of a traced profile is sampled. In this report, the 8-step, modified running–box-function filter is presented. The transmission characteristics of this new filter are very close to those of the Gaussian digital filter given in ISO 468-1982. In addition, the conditions for using this filter are given for practical use.

Optimized measurement strategy for multiple-orientation technique on coordinate-measuring machines

Coordinate-measuring machines (CMMs) are widely used to measure the characteristics of various geometrical features. The measurement results using CMMs include systematic errors. To eliminate the systematic errors, the multiple-orientation technique is effective for rotationally symmetric workpieces such as cylinders or gears. However, there are Fourier components of the calibration curve that cannot be analyzed on the basis of the number of orientations; therefore, the number of orientations was set to be larger than the number of required Fourier components. Such a method takes, however, a very long time and it is difficult to maintain a stable environment during the measurement. In this paper, we propose a new measurement strategy for reducing the total number of orientations by compensating the deficient Fourier components using the measurement result with another number of orientations. When the lowest common multiple of integers m and n is set to be larger than the number of required Fourier components, the calibration result can be obtained from m + n − 1 orientations. To select m and n most efficiently, the combination should not include a common prime number. The effectiveness of the combination measurement strategy for the multiple-orientation technique was demonstrated by calibrating a multiball artifact and a gear.

Crash warning for intersection and head-on car collision in vehicle-to-vehicle communication

This paper investigates performance of the IEEE 802.11p based vehicle-to-vehicle communication for car crash warning to avoid head-on car crash and car crash at a road intersection. It is important in a car crash warning application that each vehicle receives a sufficient amount of information (i.e., a sufficient number of frames) in time to avoid a potential crash. When vehicles transmit a large number of frames, as CSMA/CA used in IEEE 802.11p creates a large number of collisions between frames, this results in low throughout of the frames to receiving vehicles. This paper uses the following two measures to evaluate the performance and suitability of IEEE 802.11p for car crash warning communication; the number of frames that each vehicle receives per second, and the length of time duration in which the number of frames that each vehicle receives per second exceeds the predetermined threshold. In obtaining these measures, this paper considers realistic scenarios of capture effect in CSMA/CA, unlike the existing studies. We further consider scenarios of avoiding head-on car crash and car crash at a road intersection, because car crash at a road intersection occurs often, and head-on car crash presents one of the most difficult communication conditions due to the additive effect of the speed of two vehicles approach each other. Our simulation results show the following. For head-on car crash scenarios, when there are up to approximately 150 vehicles in the communication range of a vehicle, the vehicle can successfully receive at least the predetermined number of frames per second. For car crash at a road intersection, the number of cars in vehicles communication range increases to approximately 200 in order to successfully receive at least the pre-determined number of frames per second. Our simulation results also show that the length of time duration in which the number of frames that each vehicle receives per second exceeds the predetermined threshold is much longer with car crash at a road intersection than with head-on car crash.

Congestion control and energy savings for V2P communication crash warnings with proximity relying

Vehicle-to-pedestrian wireless communication (V2P) and vehicle-to-vehicle communication (V2V) have become popular in communications research areas. Crash warning systems are promising applications of V2V and V2P. Compared with V2V, channel congestion due to more pedestrian terminals such as smartphones and increased battery consumption due to V2P are recognized as major problems for developing V2P applications. To address these problems, Proximity Relying (PR) is proposed in this work. In PR, a terminal does not need to send its own information if neighboring terminals send their information. This results in mitigating congestion levels and saves battery life. The performance of PR depends on the number of neighboring terminals. Simulations are employed to evaluate the relationship between the number of neighboring terminals and congestion levels, which are measured as the number of terminals to meet crash warning requirements.

V2V communication quality with multi-antenna in field assessments and simulations

In automotive and ITS industries, quality of wireless communication technologies becomes a hot research topic, as wireless technologies have been applied not only to entertainment or information applications, but also to mission critical safety applications. These safety applications have challenges, such as, large speed of wireless transmitter/receiver in a vehicle, critical radio environments, for example building canyons and tunnels. Moreover, in crash warning applications by using peer-to-peer (vehicle-to-vehicle, V2V) communications, vehicles have to exchange their locations, speeds, and directions between neighboring vehicles, within a few seconds prior to potential vehicle crashes, even in freeway intersections crowded with over 100 vehicles. In this paper, we will first introduce crash warning applications with V2V communication and its preliminary field assessment. Then we will introduce our simulation results of V2V communication quality for crash warning applications with considering radio interference from neighboring vehicles. Then we will introduce various multi-antenna solutions, including MIMO (Multi Input Multi Output) that will improve the V2V communication quality to help more vehicles exchange data within shorter time periods even in areas crowded with many vehicles, including their advantages and challenges for automotive and ITS applications.

An evaluation of surface asperity profile changes in truncation processes using optical interferometric microscope

Abstract The truncation process as running-in wear was applied to evaluate surface asperity changes as removal at the top of its asperity profile. The measurement was done using an optical interferometric microscope. Whole surface profile was measured by the microscope supported by the stitching technique. The specimen was relocated on the microscope utilizing Hirth coupling as a hardware technique. Data obtained from a truncated specimen were precisely relocated to the original untruncated specimen by computer software in three dimensions. Then the profile change was obtained by deducting truncated data from the original data. The profile change was calculated as removed volume. The volume changes are plotted against a sliding length. As the software relocation technique needs the unchanged profile of a valley part, the evaluation is limited to where the truncation height is higher than −1.28 sigma (the standard deviation of untruncated original profile height). The present research can detect very little volume change that cannot be measured by other conventional methods, such as the gravimetric method. The advantages of the present method are as follows. It is possible to compare the truncated surface profile with the original untruncated surface profile in three dimensions. Thus, the inclination of the truncation surface can be evaluated and any other local changes can also be assessed. From this information the profiles of truncated surfaces will be linked to functions, and new parameters for truncation profile will be presented.