Robert L. Norton

Improved Laboratory prototype electrolarynx (LAPEL): Using inverse filtering of the frequency response function of the human throat

The electrolarynx (EL) provides a valued means of verbal communication for people who have lost their larynx. Existing ELs have some drawbacks such as harsh, raucous, and unpleasant sound and the presence of background noise. This study presents an experimental analysis of two commerical ELs and describes the development and testing of an improved LAb-oratory Prototype ELectrolarynx (LAPEL) which more accurately simulates the sound of a natural larynx and has lower background noise. This natural sound is obtained by determining the frequency response function (FRF) of the tissue of the human neck and using this information to tailor the input signal to the EL by inverse filtering such that its output spectrum resembles that of the natural larynx. The result was subjectively judged to have a superior and more natural sound than existing electrolarynxes.

Effect of manufacturing method on dynamic performance of cams—An experimental study. part I—eccentric cams

Abstract Eight eccentric cams, each made by a different manufacturing technique have been tested on a sspecially designed Cam Dynamic Test Fixture (CDTF). Acceleration waveforms have been measured on the follower system and transformed to the frequency domain. These frequency spectra have been averaged over selected bandwidths between zero and 6400 Hz and these data subjected to statistical analysis to determine significant differences between manufacturing methods. All of the manufacturing techniques listed show significant differences in at least some of the frequency bandwidths in terms of the total “noise” or r.m.s. error produced in the acceleration waveform. The results indicate that some common manufacturing methods for cams are significantly better than others with respect to fidelity to the theoretical acceleration waveform, and quietness of running.

Effect of manufacturing method on dynamic performance of cams—An experimental study. Part II—double dwell cams☆

Abstract Six double dwell cams made to four different designs by six different manufacturing techniques have been tested on a specially designed cam dynamic test fixture. Acceleration waveforms have been measured on the follower system and transformed to the frequency domain. These frequency spectra have been averaged over selected bandwidths between zero and 3200 Hz and these data subjected to statistical analyses to determine significant differences between manufacturing methods, and cam designs. All of the manufacturing techniques listed show significant differences in at least some of the frequency bandwidths in terms of the total “noise” or r.m.s. error produced in the acceleration waveform. The results indicate that some common manufacturing methods for cams are significantly better than others with respect to fidelity to the theoretical acceleration waveform. The manufactufacture is also shown to interact significantly with the cam acceleration design chosen.

Analytical Study of Reachable Workspace for 2-RPR Planar Parallel Mechanisms

In both planar and spatial parallel mechanisms, selection of the structural parameters for a desired workspace generally employs the use of numerical methods. However, using the closed-form solution, if it exists, facilitates workspace-based design and optimization of the mechanism, and may significantly reduce the required time and calculation for finding the workspace of the mechanism. This paper presents a general and comprehensive closed-form solution for the reachable workspace of a 2-RPR planar parallel mechanism. The workspace of the mechanism is analyzed step-by-step in detail and its boundary is derived analytically. Since the solution is closed-form, it has high accuracy and reliability. Furthermore, the provided solution can be employed to solve the workspace of similar mechanisms in a closed-form manner including other n-RPR planar parallel mechanisms.Copyright

Four-bar and geared five-bar linkage analysis programs for the Apple computer

Abstract The increasing availability and decreasing cost of the personal microcomputer to the student and practicing engineer has revolutionized the approach to mechanism design. Many quite sophisticated linkage design and analysis programs have been available for many years, such as LINCAGES[1], KINSYN[2], DRAM, ADAMS[3] and IMP[2]. These typically require a medium-to-large computer with expensive graphics terminals. MICRO-KINSYN has recently been adapted for a modified Apple computer, but it uses a coprocessor and additional memory which adds to its cost over the standard Apple computer. Other kinematics programs for personal computers are becoming available, such as Barkers[4] for the IBM PC. Kot and Bendickson[5] have adapted Erdmans ‘Linkages’ techniques to the Apple computer. The programs described here (called FOURBAR and FIVEBAR) were written to serve as analysis tools rather than for synthesis. They presume that the user has selected a potential four-bar (FB) or geared five-bar (GFB) linkage design by some means and wishes to analyze its behavior. The programs are designed to operate in a standard Apple IIe or 64K II + machine with no memory enhancements other than the standard language card. The programs also make extensive use of the computers graphics capabilities to depict the linkage and its coupler curve in all positions calculated as well as to plot positions, velocities and accelerations of selected points on the linkage. Thus the user can quickly test his potential design for viability based on velocity and acceleration considerations. Design by successive analysis is thus expedited. The geared five-bar linkage (GFB) offers the designer greater flexibility in output path configuration than the four bar due to the fact that it has three additional design parameters: namely, gear ratio, phase angle and an additional link[6]. The coupler curves for this linkage are of higher order than those of the four bar, when the gear ratio is not unity.

An Integrated Acoustic Evaluation of Engineering Materials

Sound propagation characteristics of various materials have been investigated. A methodology to evaluate and compare the acoustic responses of metallic and non-metallic materials was developed and validated. Various materials were acoustically examined under impact loading using a test set-up consisting of a solenoid-driven hammer, a microphone, and software to record, Fourier transform, and analyze the sound response. Materials studied for acoustic behavior included steel, cast and wrought aluminum, gray cast iron, titanium, and various composites. All materials were ranked based on their reduction of sound pressure compared to a reference material of hardened tool steel. Test data were normalized on an A-weighted scale to account for the enhanced sensitivity of the human ear at certain frequencies. The effects of specimen geometry and material composition on the resulting sounds were also incorporated in the investigation. A complete microstructural analysis was conducted on each material to relate its acoustic behavior to intrinsic material characteristics. The experimental and analytic tools and knowledge developed in this study were further applied in a manufacturing setting to redesign an impact stop for noise reduction. The proposed prototypes were tested in the industrial environment, and the results compared to the findings from the study. These developments will be systematically presented and discussed.Copyright

Reduction of Impact and Vibration in an Industrial Cam-Follower System Using the Splinedyne Method: A Case Study

The splinedyne method of cam design is a variation on the poly-dyne method that uses B-spline functions to obtain superior control of follower motion and its derivatives in combination with a dynamic model of the follower train to minimize vibration in the follower at any one design speed. This paper presents the results of the application of this technique to an automated assembly machine cam-follower train whose vibratory behavior before redesign was limiting machine speed and causing increased product scrap rate due to impacts and vibrations. The improved splinedyne system contributed to a measured 14% increase in production rate in combination with a 1% reduction in scrap rate from that station.© 2002 ASME

Dynamic Modeling of the Typical Industrial Cam-Follower System: Part 1 — Single-Degree-of-Freedom Models

The extant literature on cam-follower system dynamic modeling is limited to the application configuration as commonly used in internal combustion valve trains. Many industrial application cam-follower trains are differently configured and require a somewhat different dynamic model. This paper develops several models suitable for these devices and compares their results to that of the classic valve-train model.© 2002 ASME