Modeling and Diagnosis of Motion Error of Multi-Axis Machines Using a Ball Bar Test

1996 ◽  
Vol 118 (3) ◽  
pp. 531-539 ◽  
Author(s):  
Shyr-Long Jeng ◽  
Wei-Hua Chieng ◽  
An-Chen Lee
Keyword(s):  
Degrees Of Freedom ◽  
Advanced Technology ◽  
Polar Coordinates ◽  
Motion Error ◽  
Double Ball Bar ◽  
Technology Products ◽  
Ball Bar ◽  
Contouring Accuracy ◽  
Circular Interpolation

The contouring accuracy of a multi-axis machine has a critical effect on the quality of many advanced technology products. One of the best approaches to assessing the contouring performance of machine tools is through double ball bar measurement. During circular interpolation motion, the machine traverses, with two axes at a time, a circular trajectory, with each axis subject to sinusoidal changes in acceleration, velocity, and position. The motion error is measured by detecting the relative distance between a point on the spindle nose and another point on the machine table and plotting this distance in polar coordinates. The present paper derives mathematical models and diagnosis procedures for first and second-order motion error resulting from the active degrees of freedom of a multi-axis machine. The theoretical results are verified by both computer simulation and double ball bar testing experiments.

A New and High Precision Measurement Method of Spindle Rotation Induced Error and its Performance Research

2007 ◽  
Vol 10-12 ◽  
pp. 727-731 ◽  
Author(s):  
Z.C. Du ◽  
P. Zhang ◽  
Jian Guo Yang ◽  
M.S. Hong
Keyword(s):  
Frequency Domain ◽  
Measurement Method ◽  
Cnc Machine ◽  
Motion Error ◽  
Machining Center ◽  
Double Ball Bar ◽  
Spindle Rotation ◽  
Ball Bar ◽  
Measuring Experiment ◽  
The Cross

The accuracy of spindle rotation is one of the most important precision indexes of CNC machine tools. And the spindle rotation induced error is one of the main influence factors of cutting accuracy. It will greatly affect the shape precision and surface roughness of workpiece. A new measurement method of the spindle radial rotation induced error is proposed using the cross grid encoder. The Spindle rotation induced error of machining center is analyzed in frequency domain and time-frequency domain separately to comparably study the measurement results by KGM 182 grid encoder and Double ball bar. The results indicate that the performance of the cross grid encoder test for measuring the CNC machine tool motion error is better than that of the Double ball bar, especially in the details of motion errors because of its unique characteristics. A wavelet packet algorithm is developed to analyze the singularity of signal. On machine measuring experiment has been carried out on a new Cincinnati 750 Arrow II vertical machining center. The measuring experiment result shows that the spindle radial rotation induced error of the machining center is about 0.6 μm and the cycle time is every rotation time.

Driving Torsion Scans with Wavefront Propagation

2020 ◽  
Author(s):  
Yudong Qiu ◽  
Daniel Smith ◽  
Chaya Stern ◽  
mudong feng ◽  
Lee-Ping Wang
Keyword(s):  
Potential Energy ◽  
Force Field ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Initial Guess ◽  
Field Development ◽  
Force Field Development ◽  
Wavefront Propagation ◽  
Open Source Software Package

<div>The parameterization of torsional / dihedral angle potential energy terms is a crucial part of developing molecular mechanics force fields.</div><div>Quantum mechanical (QM) methods are often used to provide samples of the potential energy surface (PES) for fitting the empirical parameters in these force field terms.</div><div>To ensure that the sampled molecular configurations are thermodynamically feasible, constrained QM geometry optimizations are typically carried out, which relax the orthogonal degrees of freedom while fixing the target torsion angle(s) on a grid of values.</div><div>However, the quality of results and computational cost are affected by various factors on a non-trivial PES, such as dependence on the chosen scan direction and the lack of efficient approaches to integrate results started from multiple initial guesses.</div><div>In this paper we propose a systematic and versatile workflow called \textit{TorsionDrive} to generate energy-minimized structures on a grid of torsion constraints by means of a recursive wavefront propagation algorithm, which resolves the deficiencies of conventional scanning approaches and generates higher quality QM data for force field development.</div><div>The capabilities of our method are presented for multi-dimensional scans and multiple initial guess structures, and an integration with the MolSSI QCArchive distributed computing ecosystem is described.</div><div>The method is implemented in an open-source software package that is compatible with many QM software packages and energy minimization codes.</div>

U.S. Exports of Advanced Technology Products (ATP) to China

2009 ◽  
Author(s):  
Alexander B. Hammer ◽  
Robert B. Koopman ◽  
Andrew Martinez
Keyword(s):  
Advanced Technology ◽  
Technology Products

The Development of a Myoelectric Training Tool for Above-Elbow Amputees

2012 ◽  
Vol 6 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Michael R Dawson ◽  
Farbod Fahimi ◽  
Jason P Carey
Keyword(s):  
Degrees Of Freedom ◽  
Learning Task ◽  
Robotic Arm ◽  
Signal Acquisition ◽  
Myoelectric Prosthesis ◽  
Training Tool ◽  
Myoelectric Prostheses ◽  
Training Systems ◽  
Targeted Muscle Reinnervation

The objective of above-elbow myoelectric prostheses is to reestablish the functionality of missing limbs and increase the quality of life of amputees. By using electromyography (EMG) electrodes attached to the surface of the skin, amputees are able to control motors in myoelectric prostheses by voluntarily contracting the muscles of their residual limb. This work describes the development of an inexpensive myoelectric training tool (MTT) designed to help upper limb amputees learn how to use myoelectric technology in advance of receiving their actual myoelectric prosthesis. The training tool consists of a physical and simulated robotic arm, signal acquisition hardware, controller software, and a graphical user interface. The MTT improves over earlier training systems by allowing a targeted muscle reinnervation (TMR) patient to control up to two degrees of freedom simultaneously. The training tool has also been designed to function as a research prototype for novel myoelectric controllers. A preliminary experiment was performed in order to evaluate the effectiveness of the MTT as a learning tool and to identify any issues with the system. Five able-bodied participants performed a motor-learning task using the EMG controlled robotic arm with the goal of moving five balls from one box to another as quickly as possible. The results indicate that the subjects improved their skill in myoelectric control over the course of the trials. A usability survey was administered to the subjects after their trials. Results from the survey showed that the shoulder degree of freedom was the most difficult to control.

scholarly journals Development and assessment of a telesonography system for musculoskeletal imaging

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mohammed Obaid ◽  
Qianwei Zhang ◽  
Scott J. Adams ◽  
Reza Fotouhi ◽  
Haron Obaid
Keyword(s):  
Degrees Of Freedom ◽  
Ultrasound Images ◽  
Ultrasound Probe ◽  
Rural And Remote ◽  
Significant Delay ◽  
Remote Communities ◽  
Internet Connection ◽  
Good For ◽  
4 Degrees Of Freedom

Abstract Background Telesonography systems have been developed to overcome barriers to accessing diagnostic ultrasound for patients in rural and remote communities. However, most previous telesonography systems have been designed for performing only abdominal and obstetrical exams. In this paper, we describe the development and assessment of a musculoskeletal (MSK) telesonography system. Methods We developed a 4-degrees-of-freedom (DOF) robot to manipulate an ultrasound probe. The robot was remotely controlled by a radiologist operating a joystick at the master site. The telesonography system was used to scan participants’ forearms, and all participants were conventionally scanned for comparison. Participants and radiologists were surveyed regarding their experience. Images from both scanning methods were independently assessed by an MSK radiologist. Results All ten ultrasound exams were successfully performed using our developed MSK telesonography system, with no significant delay in movement. The duration (mean ± standard deviation) of telerobotic and conventional exams was 4.6 ± 0.9 and 1.4 ± 0.5 min, respectively (p = 0.039). An MSK radiologist rated quality of real-time ultrasound images transmitted over an internet connection as “very good” for all telesonography exams, and participants rated communication with the radiologist as “very good” or “good” for all exams. Visualisation of anatomic structures was similar between telerobotic and conventional methods, with no statistically significant differences. Conclusions The MSK telesonography system developed in this study is feasible for performing soft tissue ultrasound exams. The advancement of this system may allow MSK ultrasound exams to be performed over long distances, increasing access to ultrasound for patients in rural and remote communities.

scholarly journals Review: Sensors for Biosignal/Health Monitoring in Electronic Skin

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2478
Author(s):  
Hyeon Seok Oh ◽  
Chung Hyeon Lee ◽  
Na Kyoung Kim ◽  
Taechang An ◽  
Geon Hwee Kim
Keyword(s):  
High Performance ◽  
Active Component ◽  
Tactile Sensor ◽  
Wearable Devices ◽  
Advanced Technology ◽  
Electronic Skin ◽  
Points Of View ◽  
External Stimuli ◽  
Flexible Component

Skin is the largest sensory organ and receives information from external stimuli. Human body signals have been monitored using wearable devices, which are gradually being replaced by electronic skin (E-skin). We assessed the basic technologies from two points of view: sensing mechanism and material. Firstly, E-skins were fabricated using a tactile sensor. Secondly, E-skin sensors were composed of an active component performing actual functions and a flexible component that served as a substrate. Based on the above fabrication processes, the technologies that need more development were introduced. All of these techniques, which achieve high performance in different ways, are covered briefly in this paper. We expect that patients’ quality of life can be improved by the application of E-skin devices, which represent an applied advanced technology for real-time bio- and health signal monitoring. The advanced E-skins are convenient and suitable to be applied in the fields of medicine, military and environmental monitoring.

Ultrajet Mesodiagnostic Probabilistic Model for Surface Layer’s Variable Defectiveness of Complex Technology Products

2021 ◽  
Vol 882 ◽  
pp. 289-295
Author(s):  
Andrey Leonidovich Galinovskiy ◽  
Aleksandr Aleksandrovich Barzov ◽  
Mary Alekseevna Prokhorova
Keyword(s):  
Surface Layer ◽  
Sufficient Conditions ◽  
Calculated Data ◽  
Hydrodynamic Effect ◽  
Topographic Features ◽  
Technology Products ◽  
Complex Technology ◽  
Materials Used ◽  
Necessary And Sufficient

Technologically, ultrajet mesodiagnostics (UJM) consists of local hydroerosive indentation by ultrajets (UJ) of water on the surface of the analyzed object (OA) and the subsequent study of the results of this minimally invasive microdestructive effect on its surface layer. Obviously, mathematical models’ construction of the functional relationship between the informative-physical signs of hydroerosive UJ destruction and the surface layer’s state parameters of various OA, primarily their defectiveness, is very important for the development of this potentially promising technology for ensuring the quality of critical products, mainly aviation and other industries. In this regard, the work proposes a probabilistic UJM model, which consists of analyzing the kinetics of the formation of an aggregate set of eroded particles, as a process caused by a combination of appropriate necessary and sufficient conditions for its implementation. The former include the topographic features of the microdefectiveness’ characteristics of the surface layer material, and the latter consist of a certain variational-force hydrodynamic effect of the diagnostic UJ on it. This approach made it possible to obtain calculated data related to probabilistic distribution of the UJ-eroded particles’ sizes of hypothetical OA, as a coordinate function describing the microdefects’ concentration in its surface layer. These functions are close to the available results of experimental UJM of typical and promising materials used in the manufacture of machinery technology.

scholarly journals Simultaneous Measurement Method and Error Analysis of the Six Degrees-of-Freedom Motion Errors of a Rotary Axis

2018 ◽  
Vol 8 (11) ◽  
pp. 2232 ◽  
Author(s):  
Chuanchen Bao ◽  
Qibo Feng ◽  
Jiakun Li
Keyword(s):  
Simultaneous Measurement ◽  
Error Compensation ◽  
Degrees Of Freedom ◽  
Translational Motion ◽  
Laser Interferometry ◽  
Positioning Error ◽  
Motion Error ◽  
Measuring Device ◽  
Six Degrees Of Freedom ◽  
Rotary Axis

Error measurement of a rotary axis is the key to error compensation and to improving motion accuracy. However, only a few instruments can measure all the motion errors of a rotary axis. In this paper, a device based on laser collimation and laser interferometry was introduced for simultaneous measurement of all six degrees-of-freedom motion errors of a rotary axis. Synchronous rotation of the target and reference rotary axes was achieved by developing a proportional–integral–derivative algorithm. An error model for the measuring device was established using a homogeneous transformation matrix. The influences of installation errors, manufacturing errors, and error crosstalk were studied in detail, and compensation methods for them were proposed. After compensation, the repeatability of axial and radial motion errors was significantly improved. The repeatability values of angular positioning error and of tilt motion error around the y axis and x axis were 28.0″, 2.8″, and 3.9″. The repeatability values of translational motion errors were less than 2.8 μm. The comparison experiments show that the comparison errors of angular positioning error and tilt motion error around the y axis were 2.3″ and 2.9″, respectively. These results demonstrate the effectiveness of our method and the error compensation model.

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