DESIGN AND FABRICATION OF RUNNING CHEETAH MECHANICAL TOY USING FOUR-BAR LINKAGE

Four-bar is the simplest planar 1-DOF closed loop linkage. It has been studied for centuries for its versatility and simplicity. In this paper a novel design method to obtain a four-bar linkage given a path and its endpoints will be presented. This method will then be applied to a case study of making a model that produces a specified movement based on reference animation. The mechanism obtained had an average root-mean-square of position error of roughly 14.3 pixels for front leg and 25.9 pixels for hind leg. This number is quite small compared to the perimeter of the traced path, which are 530 pixels and 617 pixels for front leg and hind leg respectively. A prototype model of the designed mechanism was fabricated to verify its manufacturing viability and to confirm the correctness of the path generated.

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Consistency of the Empirical Distributions of Navigation Positioning System Errors with Theoretical Distributions—Comparative Analysis of the DGPS and EGNOS Systems in the Years 2006 and 2014

Sensors ◽

10.3390/s21010031 ◽

2020 ◽

Vol 21 (1) ◽

pp. 31

Author(s):

Mariusz Specht

Keyword(s):

Normal Distribution ◽

Root Mean Square ◽

Statistical Tests ◽

Position Error ◽

Positioning System ◽

Navigation Systems ◽

Mean Square ◽

Positioning Systems ◽

Position Errors ◽

System Errors

Positioning systems are used to determine position coordinates in navigation (air, land and marine). The accuracy of an object’s position is described by the position error and a statistical analysis can determine its measures, which usually include: Root Mean Square (RMS), twice the Distance Root Mean Square (2DRMS), Circular Error Probable (CEP) and Spherical Probable Error (SEP). It is commonly assumed in navigation that position errors are random and that their distribution are consistent with the normal distribution. This assumption is based on the popularity of the Gauss distribution in science, the simplicity of calculating RMS values for 68% and 95% probabilities, as well as the intuitive perception of randomness in the statistics which this distribution reflects. It should be noted, however, that the necessary conditions for a random variable to be normally distributed include the independence of measurements and identical conditions of their realisation, which is not the case in the iterative method of determining successive positions, the filtration of coordinates or the dependence of the position error on meteorological conditions. In the preface to this publication, examples are provided which indicate that position errors in some navigation systems may not be consistent with the normal distribution. The subsequent section describes basic statistical tests for assessing the fit between the empirical and theoretical distributions (Anderson-Darling, chi-square and Kolmogorov-Smirnov). Next, statistical tests of the position error distributions of very long Differential Global Positioning System (DGPS) and European Geostationary Navigation Overlay Service (EGNOS) campaigns from different years (2006 and 2014) were performed with the number of measurements per session being 900’000 fixes. In addition, the paper discusses selected statistical distributions that fit the empirical measurement results better than the normal distribution. Research has shown that normal distribution is not the optimal statistical distribution to describe position errors of navigation systems. The distributions that describe navigation positioning system errors more accurately include: beta, gamma, logistic and lognormal distributions.

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Adaptive Feedforward Control of a Pressure Compensated Differential Cylinder

Applied Sciences ◽

10.3390/app10217847 ◽

2020 ◽

Vol 10 (21) ◽

pp. 7847

Author(s):

Konrad Johan Jensen ◽

Morten Kjeld Ebbesen ◽

Michael Rygaard Hansen

Keyword(s):

Control System ◽

Root Mean Square ◽

Motion Control ◽

Experimental Verification ◽

Feedforward Control ◽

Position Error ◽

Mean Square ◽

Model Uncertainties ◽

Feedforward Controller ◽

Adaptive Feedforward

This paper presents the design, simulation and experimental verification of adaptive feedforward motion control for a hydraulic differential cylinder. The proposed solution is implemented on a hydraulic loader crane. Based on common adaptation methods, a typical electro-hydraulic motion control system has been extended with a novel adaptive feedforward controller that has two separate feedforward states, i.e, one for each direction of motion. Simulations show convergence of the feedforward states, as well as 23% reduction in root mean square (RMS) cylinder position error compared to a fixed gain feedforward controller. The experiments show an even more pronounced advantage of the proposed controller, with an 80% reduction in RMS cylinder position error, and that the separate feedforward states are able to adapt to model uncertainties in both directions of motion.

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Design Method for Lattice-Skin Structure Fabricated by Additive Manufacturing

Volume 2B: Advanced Manufacturing ◽

10.1115/imece2014-38645 ◽

2014 ◽

Cited By ~ 2

Author(s):

Yunlong Tang ◽

Yaoyao Fiona Zhao

Keyword(s):

Complex Geometry ◽

Lattice Structure ◽

Design Method ◽

Mapping Function ◽

Second Step ◽

Parameter Distribution ◽

Skin Structure ◽

Traditional Design ◽

Novel Design

Parts with complex geometry structure can be produced by AM without significant increase of fabrication time and cost. One application of AM technology is to fabricate customized lattice-skin structure which can enhance performance of products with less material and less weight. However, most of traditional design methods only focus on design at macro-level with solid structure. Thus, a design method which can generate customized lattice-skin structure for performance improvement and functionality integration is urgently needed. In this paper, a novel design method for lattice-skin structure is proposed. In this design method, FSs and FVs are firstly generated according to FRs. Then, initial design space is created by filling FVs and FSs with selected lattice topology and skin, respectively. In parallel to the second step, initial parameters of lattice-skin structure are calculated based on FRs. Finally, TO method is used to optimize parameter distribution of lattice structure with the help of mapping function between TO’s result and lattice parameters. The design method proposed in this paper is proven to be efficient with case study and provides an important foundation for wide adoption of AM technologies in industry.

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Metaheuristic data fitting methods to estimate Weibull parameters for wind speed data: a case study of Hasan Polatkan Airport

The Aeronautical Journal ◽

10.1017/aer.2020.136 ◽

2021 ◽

pp. 1-33

Author(s):

A. Kaba ◽

A. E. Suzer

Keyword(s):

Wind Speed ◽

Numerical Methods ◽

Root Mean Square Error ◽

Objective Function ◽

Mean Square Error ◽

Root Mean Square ◽

Statistical Tests ◽

Mean Square ◽

Flight Delays

ABSTRACT Flight delays may be decreased in a predictable way if the Weibull wind speed parameters of a runway, which are an important aspect of safety during the take-off and landing phases of aircraft, can be determined. One aim of this work is to determine the wind profile of Hasan Polatkan Airport (HPA) as a case study. Numerical methods for Weibull parameter determination perform better when the average wind speed estimation is the main objective. In this paper, a novel objective function that minimises the root-mean-square error by employing the cumulative distribution function is proposed based on the genetic algorithm and particle swarm optimisation. The results are compared with well-known numerical methods, such as maximum-likelihood estimation, the empirical method, the graphical method and the equivalent energy method, as well as the available objective function. Various statistical tests in the literature are applied, such as R2, Root-Mean-Square Error (RMSE) and $\chi$ 2. In addition, the Mean Absolute Error (MAE) and total elapsed time calculated using the algorithms are compared. According to the results of the statistical tests, the proposed methods outperform others, achieving scores as high as 0.9789 and 0.9996 for the R2 test, as low as 0.0058 and 0.0057 for the RMSE test, 0.0036 and 0.0045 for the MAE test and 3.53 × 10−5 and 3.50 × 10−5 for the $\chi$ 2 test. In addition, the determination of the wind speed characteristics at HPA show that low wind speed characteristics and regimes throughout the year offer safer take-off and landing schedules for target aircraft. The principle aim of this paper is to help establish the correct orientation of new runways at HPA and maximise the capacity of the airport by minimising flight delays, which represent a significant impediment to air traffic flow.

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Novel Design Method for Bus Approach Lanes with Bus Guidance and Priority Controls for Prioritizing Through and Left-Turn Buses

Journal of Advanced Transportation ◽

10.1155/2019/2327876 ◽

2019 ◽

Vol 2019 ◽

pp. 1-15

Author(s):

Shijie Shu ◽

Jing Zhao ◽

Yin Han

Keyword(s):

Design Method ◽

Integrated Design ◽

Signal Timing ◽

Left Turn ◽

Urban Networks ◽

Control Optimization ◽

Priority Method ◽

High Degree ◽

Novel Design

Transit priority is a useful way of improving transit operations in urban networks. However, the through and left-turn buses are rarely prioritized simultaneously at isolated intersections in the existing studies. This paper presents a variable bus approach lane design with a bus guidance and priority control model, which can reduce the delay of both the through and left-turn buses. The variable bus approach lanes can be dynamically used for the through and left-turn buses during the various periods of a signal cycle by the integrated design of geometric layouts and signal timing. A detailed bus guidance and priority control optimization model is formulated to guide the buses entering the appropriate bus approach lanes, and it provides optimal signal priorities for buses. The effectiveness of the proposed method is validated by a case study and numerical experiments. The results show that, on average, the total passenger delay can be reduced by 5% for every 30 veh/h and 40 veh/h increase in the volume of through buses and left-turn buses, respectively. Moreover, a comparison between the proposed method and the conventional transit priority method reveals that significant improvements can be made in reducing delays using the proposed method even at intersections with high degree of the saturation.

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Supplemental Material for Examining the Reliability of Interval Level Data Using Root Mean Square Differences and Concordance Correlation Coefficients

Psychological Methods ◽

10.1037/a0023351.supp ◽

2011 ◽

Keyword(s):

Root Mean Square ◽

Correlation Coefficients ◽

Mean Square ◽

Concordance Correlation ◽

Level Data

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PERANCANGAN SISTEM PEMBELAJARAN MOBILE (M-LEARNING) BERBASIS ANDROID PADA MATERI BANGUN DATAR DAN BANGUN RUANG

AIMS Jurnal Accounting Information System ◽

10.32627/aims.v1i2.16 ◽

2018 ◽

Vol 1 (2) ◽

pp. 1-17

Author(s):

Tedi Budiman

Keyword(s):

Mobile Learning ◽

Design Method ◽

Case Study Method ◽

Application Development ◽

Software Application ◽

Rapid Application Development ◽

User Design ◽

Design Software ◽

Application Programs

One example of the growing information technology today is mobile learning, mobile learning which refers to mobile technology as a learning medium. Mobile learning is learning that is unique for each student to access learning materials anywhere, anytime. Mobile learning is suitable as a model of learning for the students to make it easier to get an understanding of a given subject, such as math is pretty complicated and always using formulas.The design method that I use is the case study method, namely, learning, searching and collecting data related to the study. While the development of engineering design software application programs that will be used by the author is the method of Rapid Application Development (RAD), which consists of 4 stages: Requirements Planning Phase, User Design Phase, Construction Phase and Phase Cotuver.

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