scholarly journals A Structure for Accurately Determining the Mass and Center of Gravity of Rigid Bodies

2019 ◽  
Vol 9 (12) ◽  
pp. 2532 ◽  
Author(s):  
Meibao Wang ◽  
Xiaolin Zhang ◽  
Wenyan Tang ◽  
Jun Wang
Keyword(s):  
Rigid Bodies ◽  
Center Of Gravity ◽  
Mobile Platform ◽  
Practical Applications ◽  
Transformation Matrices ◽  
Novel Structure ◽  
Measurement Results ◽  
Load Cells ◽  
Structure Simulation ◽  
Weighing Method

Measuring the mass and Center of Gravity (CG) of rigid bodies with a multi-point weighing method is widely used nowadays. Traditional methods usually include two parts with a certain location, i.e., a fixed platform and a mobile platform. In this paper, a novel structure is proposed to adjust the mobile platform for eliminating side forces which may load on the load cells. In addition, closed-form equations are formulated to evaluate the performance of the structure, and transformation matrices are used to estimate the characteristics of the structure. Simulation results demonstrate that repeatability of the proposed structure is higher than the traditional one and there are no side forces. Moreover, the measurement results show that the relative error of mass was within 0.05%, and the error of CG was within ±0.3 mm. The structure presented in this paper provides a foundation for practical applications.

scholarly journals Design and Development of a 3dB Quadrature Patch Hybrid Coupler

2018 ◽  
Vol 7 (2.6) ◽  
pp. 217
Author(s):  
B Sekharbabu ◽  
K Narsimha Reddy ◽  
S Sreenu
Keyword(s):  
Integrated Circuit ◽  
High Frequency ◽  
Return Loss ◽  
Coupling Factor ◽  
Power Combiners ◽  
Measurement Results ◽  
Structure Simulation ◽  
Hybrid Coupler ◽  
Port Device ◽  
Circuit Technology

In this paper a -3 dB, 90-degreephase shift RF quadrature patch hybrid coupler is designed to operate at 2.4GHz. Hybrid coupler is a four-port device, that’s accustomed split a signaling with a resultant 90degrees’ section shift between output signals whereas maintaining high isolation between the output ports. The RF quadrature patch hybrid coupler is used in various radio frequency applications including mixers, power combiners, dividers, modulators and amplifiers. The desired hybrid coupler is designed using FR-4 substrate with 1.6mm height in High Frequency Structure Simulation (HFSS) and the same is fabricated and tested. The designed Hybrid coupler is examined in terms of parameters like insertion Loss, coupling factor and return Loss. The simulation and measurement results are compared. Major advantages of the RF quadrature patch hybrid couplers are that they are compatible with integrated circuit technology.

Improving Techniques in Statically Equivalent Serial Chain Modeling for Center of Mass Estimation

2014 ◽  
Author(s):  
Bingjue Li ◽  
Andrew P. Murray ◽  
David H. Myszka
Keyword(s):  
Center Of Mass ◽  
Original System ◽  
Rigid Bodies ◽  
Joint Angles ◽  
Practical Applications ◽  
Serial Chain ◽  
System Of Rigid Bodies ◽  
Final Development ◽  
Data Error ◽  
Insight Into

Any articulated system of rigid bodies defines a Statically Equivalent Serial Chain (SESC). The SESC is a virtual chain that terminates at the center of mass (CoM) of the original system of bodies. A SESC may be generated experimentally without knowing the mass, CoM, or length of each link in the system given that its joint angles and overall CoM may be measured. This paper presents three developments toward recognizing the SESC as a practical modeling technique. Two of the three developments improve utilizing the technique in practical applications where the arrangement of the joints impacts the derivation of the SESC. The final development provides insight into the number of poses needed to create a usable SESC in the presence of data collection errors. First, modifications to a matrix necessary in computing the SESC are proposed. Second, the problem of generating a SESC experimentally when the system of bodies includes a mass fixed in the ground frame are presented and a remedy is proposed for humanoid-like systems. Third, an investigation of the error of the experimental SESC versus the number of data readings collected in the presence of errors in joint readings and CoM data is conducted. By conducting the method on three different systems with various levels of data error, a general form of the function for estimating the error of the experimental SESC is proposed.

A Complete, Continuous, and Minimal Product of Exponentials-Based Model for Five-Axis Machine Tools Calibration With a Single Laser Tracker, an R-Test, or a Double Ball-Bar

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Peng Xu ◽  
Benny C. F. Cheung ◽  
Bing Li
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Rigid Bodies ◽  
Error Model ◽  
Laser Tracker ◽  
Calibration Model ◽  
Transformation Matrices ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Calibration is an important way to improve and guarantee the accuracy of machine tools. This paper presents a systematic approach for position independent geometric errors (PIGEs) calibration of five-axis machine tools based on the product of exponentials (POE) formula. Instead of using 4 × 4 homogeneous transformation matrices (HTMs), it establishes the error model by transforming the 6 × 1 error vectors of rigid bodies between different frames resorting to 6 × 6 adjoint transformation matrices. A stable and efficient error model for the iterative identification of PIGEs should satisfy the requirements of completeness, continuity, and minimality. Since the POE-based error models for five-axis machine tools calibration are naturally complete and continuous, the key issue is to ensure the minimality by eliminating the redundant parameters. Three kinds of redundant parameters, which are caused by joint symmetry information, tool-workpiece metrology, and incomplete measuring data, are illustrated and explained in a geometrically intuitive way. Hence, a straightforward process is presented to select the complete and minimal set of PIGEs for five-axis machine tools. Based on the established unified and compact error Jacobian matrices, observability analyses which quantitatively describe the identification efficiency are conducted and compared for different kinds of tool tip deviations obtained from several commonly used measuring devices, including the laser tracker, R-test, and double ball-bar. Simulations are conducted on a five-axis machine tool to illustrate the application of the calibration model. The effectiveness of the model is also verified by experiments on a five-axis machine tool by using a double ball-bar.

A Simple Ultra-Wideband Magneto-Electric Dipole Antenna With High Gain

Frequenz ◽  
2017 ◽  
Vol 72 (1-2) ◽  
Author(s):  
Chen-yang Shuai ◽  
Guang-ming Wang
Keyword(s):  
Electric Dipole ◽  
Simple Structure ◽  
High Gain ◽  
Dipole Antenna ◽  
Ultra Wideband ◽  
Main Beam ◽  
Impedance Bandwidth ◽  
Practical Applications ◽  
Measurement Results ◽  
Feeding Structure

AbstractA simple ultra-wideband magneto-electric dipole antenna utilizing a differential-fed structure is designed. The antenna mainly comprises three parts, including a novel circular horned reflector, two vertical semicircular shorted patches as a magnetic dipole, and a horizontal U-shaped semicircular electric dipole. A differential feeding structure working as a perfect balun excites the designed antenna. The results of simulation have a good match with the ones of measurement. Results indicate that the designed antenna achieves a wide frequency bandwidth of 107 % which is 3.19~10.61 GHz, when VSWR is below 2. Via introducing the circular horned reflector, the designed antenna attains a steady and high gain of 12±1.5dBi. Moreover, settled broadside direction main beam, high front-to-back ratio, low cross polarization, and the symmetrical and relatively stable radiation patterns in the E-and H-plane are gotten in the impedance bandwidth range. In the practical applications, the proposed antenna that is dc grounded and has a simple structure satisfies the requirement of many outdoor antennas.

scholarly journals Parallel matrix multiplication circuits for use in Kalman filtering

2019 ◽  
Vol 32 (4) ◽  
pp. 479-501
Author(s):  
Rafal Długosz ◽  
Katarzyna Kubiak ◽  
Tomasz Talaśka ◽  
Inga Zbierska-Piątek
Keyword(s):  
Kalman Filtering ◽  
Matrix Multiplication ◽  
Autonomous Driving ◽  
Data Rate ◽  
Active Safety ◽  
Practical Applications ◽  
Additional Problem ◽  
Measurement Results ◽  
Cmos Implementation ◽  
Numerous Time

In this work we propose several ways of the CMOS implementation of a circuit for the multiplication of matrices. We mainly focus on parallel and asynchronous solutions, however serial and mixed approaches are also discussed for the comparison. Practical applications are the motivation behind our investigations. They include fast Kalman filtering commonly used in automotive active safety functions, for example. In such filters, numerous time-consuming operations on matrices are performed. An additional problem is the growing amount of data to be processed. It results from the growing number of sensors in the vehicle as fully autonomous driving is developed. Software solutions may prove themselves to be insuffucient in the nearest future. That is why hardware coprocessors are in the area of our interests as they could take over some of the most time-consuming operations. The paper presents possible solutions, tailored to specific problems (sizes of multiplied matrices, number of bits in signals, etc.). The estimates of the performance made on the basis of selected simulation and measurement results show that multiplication of 3?3 matrices with data rate of 20 100 MSps is achievable in the CMOS 130 nm technology.

scholarly journals High-resolution MEMS inertial sensor combining large-displacement buckling behaviour with integrated capacitive readout

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Brahim El Mansouri ◽  
Luke M. Middelburg ◽  
René H. Poelma ◽  
Guo Qi Zhang ◽  
Henk W. van Zeijl ◽  
...  
Keyword(s):  
High Resolution ◽  
Inertial Sensor ◽  
Large Displacement ◽  
Capacitive Transducer ◽  
Isolation Technique ◽  
Practical Applications ◽  
Wide Range ◽  
Measurement Results ◽  
Trench Isolation ◽  
The Internet Of Things

AbstractCommercially available gravimeters and seismometers can be used for measuring Earth’s acceleration at resolution levels in the order of $${\mathrm{ng}}/\sqrt {\mathrm{Hz}}$$ ng ∕ Hz (where g represents earth’s gravity) but they are typically high-cost and bulky. In this work the design of a bulk micromachined MEMS device exploiting non-linear buckling behaviour is described, aiming for $${\mathrm{ng}}/\sqrt {\mathrm{Hz}}$$ ng ∕ Hz resolution by maximising mechanical and capacitive sensitivity. High mechanical sensitivity is obtained through low structural stiffness. Near-zero stiffness is achieved through geometric design and large deformation into a region where the mechanism is statically balanced or neutrally stable. Moreover, the device has an integrated capacitive comb transducer and makes use of a high-resolution impedance readout ASIC. The sensitivity from displacement to a change in capacitance was maximised within the design and process boundaries given, by making use of a trench isolation technique and exploiting the large-displacement behaviour of the device. The measurement results demonstrate that the resonance frequency can be tuned from 8.7 Hz–18.7 Hz, depending on the process parameters and the tilt of the device. In this system, which combines an integrated capacitive transducer with a sensitivity of 2.55 aF/nm and an impedance readout chip, the theoretically achievable system resolution equals 17.02 $${\mathrm{ng}}/\sqrt {\mathrm{Hz}}$$ ng ∕ Hz . The small size of the device and the use of integrated readout electronics allow for a wide range of practical applications for data collection aimed at the internet of things.

On the Incorporation of Multi-Modality Image Registration into the Radiotherapy Treatment Planning Process

2003 ◽  
Vol 2 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Hazim A. Jaradat ◽  
Wolfgang A. Tomé ◽  
Todd R. McNutt ◽  
M. Elizabeth Meyerand
Keyword(s):  
Treatment Planning ◽  
Planning Process ◽  
Rigid Bodies ◽  
Analytical Estimate ◽  
User Input ◽  
Transformation Matrices ◽  
Radiation Therapy Treatment Planning ◽  
Primary Image ◽  
Direct Use ◽  
Planning Ct

A technique is presented that allows the direct use of physiological image sets in the radiation therapy treatment planning process. When fused to the treatment planning CT, physiological image studies may allow one to define physiological tumor subvolumes consisting of areas of possible chronic hypoxia, areas of high perfusion, areas of high diffusion, and areas containing high choline concentrations. These physiological tumor subvolumes could be selectively boosted to increase local control of malignant brain tumors once one has determined which of these physiological tumor subvolumes predicts for local tumor recurrence after conventional radiotherapy. In this technique a user assisted automatic registration technique is used that is based on an analytical estimate for the transformation matrix needed to register two rigid bodies. The only user input needed is three non-collinear points selected based on landmarks in the primary image and the corresponding three points in the secondary image. Since this registration technique uses two sets of at least three user-defined landmark points each of which has some selection error associated with it, the final registration will have an error that depends only on the selection error associated with the point sets. Since physiological image studies are acquired at the same setting as the T1- w MRI their spatial orientation with respect to the T1- w MRI is known. Therefore, the registration of multiple physiological image studies to the treatment planning CT can be accomplished by first correlating them to the T1- w MRI, and in a second step the T1- w MRI is then registered to the treatment planning CT. The desired registration of the physiological image studies to the treatment planning CT is then accomplished by simply composing the appropriate transformation matrices.

scholarly journals Method for determining the spatial position of the center of gravity of machines

2019 ◽  
pp. 71-82
Author(s):  
I. A. Blinov
Keyword(s):  
Mathematical Model ◽  
Computer Model ◽  
Center Of Gravity ◽  
Spatial Position ◽  
Coordinate Method ◽  
The Core ◽  
Measurement Results ◽  
Minimum Number ◽  
Mathematical Processing ◽  
Processing Of Measurement Results

Having analyzed traditional methods for determining the coordinates of the center of gravity of machines, we developed a three-coordinate method using the simplest and most affordable means of hanging products with a crane beam. The method differs from analogues in the minimum number of weighings when there are no force-measuring means as a component of the measuring circuit. We introduce a mathematical model, which is the core of the method, and a computer model which minimizes the complexity of mathematical processing of measurement results

scholarly journals Spatiality in small area estimation: A new structure with a simulation study

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Yadollah Mehrabi ◽  
Amir Kavousi ◽  
Ahmad-Reza Baghestani ◽  
Mojtaba Soltani-Kermanshahi
Keyword(s):  
Spatial Correlation ◽  
Small Area ◽  
Small Area Estimation ◽  
Synthetic Data ◽  
Practical Applications ◽  
Small Areas ◽  
Area Estimation ◽  
Novel Structure ◽  
Specific Behaviour ◽  
Average Mean Square Error

In numerous practical applications, data from neighbouring small areas present spatial correlation. More recently, an extension of the Fay–Herriot model through the Simultaneously Auto- Rregressive (SAR) process has been considered. The Conditional Auto-Regressive (CAR) structure is also a popular choice. The reasons of using these structures are theoretical properties, computational advantages and relative ease of interpretation. However, the assumption of the non-singularity of matrix (Im-ρW) is a problem. We introduce here a novel structure of the covariance matrix when approaching spatiality in small area estimation (SAE) comparing that with the commonly used SAR process. As an example, we present synthetic data on grape production with spatial correlation for 274 municipalities in the region of Tuscany as base data simulating data at each area and comparing the results. The SAR process had the smallest Root Average Mean Square Error (RAMSE) for all conditions. The RAMSE also generally decreased with increasing sample size. In addition, the RAMSE valuess did not show a specific behaviour but only spatially correlation coefficient changes led to a stronger decrease of RAMSE values than the SAR model when our new structure was applied. The new approach presented here is more flexible than the SAR process without severe increasing RAMSE values.

Practical Applications of HORNET to Inspect Walls of Structures

2016 ◽  
Vol 28 (3) ◽  
pp. 320-327 ◽  
Author(s):  
Yuhei Tokura ◽  
◽  
Kohei Toba ◽  
Yogo Takada
Keyword(s):  
Economic Growth ◽  
Low Cost ◽  
Growth Period ◽  
Practical Applications ◽  
Manual Inspection ◽  
Dangerous Situation ◽  
Measurement Results ◽  
Inspection Process

[abstFig src='/00280003/07.jpg' width=""300"" text='Photograph of HORNET catching onto a wall' ] During the high economic growth period in Japan, the development of new infrastructures was promoted and numerous bridges and buildings were constructed. Currently, the walls of bridges and buildings are inspected manually. This manual inspection process is expensive and time-consuming, and inspectors may be placed in dangerous situation. In this study, a robot that moves stably on a wall while maintaining a distance from the wall was developed to enable low-cost, safe inspection. Several characteristics of the robot were measured, and the possibility of using the robot in practical applications was assessed based on the measurement results.

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