Wasy Research

Uncertainty estimation of laser interferometry measurements

Length or distance measurement with a laser interferometer has an important application in various engineering and scientific fields.

Metrology

Optical measuring instrument: Point auto-focus (PAI) for coordinate and surface texture measurements

Point auto-focus (PAI) optical measuring instrument works based on the principle of following the focus position of a microscope objective lens. This auto-focus mechanism follows the height of the surface of a measured object.

Academic writing

Writing is about “forcing” your idea into others

Writing paper is not about marketing your idea or about conveying your idea to other people. Writing paper is more than that, it is a way to “force” your idea into people so that they use or implement your idea.

Research

Research is a broad ecosystem: All results are important!

Research is a complex ecosystem where all activities and results (in all fields) will be somehow connected, either directly or indirectly, to each other.

GNSS

Evil waveform (EWF) in global navigation satellite system (GNSS) signal

In this post, we will discuss one of GNSS threats, that is evil waveform. Unlike jamming and spoofing, evil waveform is not a type of signal interference in GNSS signals. Instead, evil waveform is a faulty signal transmitted by a real GNSS satellite.

GNSS

The difference between C/N0 and SNR in GNSS signal processing

In signal processing, especially in global navigation satellite system (GNSS), the term signal-to-noise ratio (SNR) and carrier-to-noise density (C/N0) are very fundamental in every analysis aspect.

Tolerancing

Geometric dimensioning and tolerancing (GD&T) and assembly of non-rigid parts

For non-rigid part assembly, the fixturing force will be relevant and needs to be considered carefully in their assembly design.

Metrology

Optical coordinate measuring machine (Optical-CMM): Performance verification and measurement uncertainty estimation

Performance verification and measurement uncertainty estimation of an optical coordinate measuring machine (optical-CMM) are very important aspects assuring that the optical-CMM works within its specification and its measurement results are traceable to the definition of metre.

Metrology

Optical coordinate measuring machine (Optical-CMM): Two fundamental limitations

Optical coordinate measuring machines (Optical-CMM) have advantages over tactile (contact) CMMs, such as more part-feature accessibility, no surface damaging-risk and large surface points capture in relatively a short period of time (compared to tactile CMMs).

Metrology

Digital transformation of dimensional and geometrical measurements

Today era is the time for thorough digitalisation, from product design, process design to data analysis and executive summary making.

Research

Calculus and linear algebra as tools for statistics

Very often, statistics is overlooked by engineers and the importance of statistics is put behind calculus and (linear) algebra.

Applied programming

Prioritising to use built-in functions in interpreted languages

We need to avoid as mush as possible the use of for loop in our algorithm by implementing vectorisation method and using built-in functions as much as possible.

Applied programming

Vectorising linear sequence search in MATLAB programming

To significantly speed up the computation speed in MATLAB, the reduction of for loop should be minimised.

Metrology

CMM measurement uncertainty estimation: ISO 15530-4

The mathematical model of CMM measurements is very complex to reconstruct. ISO 15530-4 presents a method to estimate CMM measurement uncertainty without the need of the mathematical model of CMM measurements.

Metrology

CMM measurement uncertainty estimation: ISO 15530-3

Coordinate measuring machine (CMM) has been used in many manufacturing industries, ranging from aerospace, automotive to consumer product, that mass-produces various types of parts.

Metrology

CMM measurement uncertainty estimation: ISO/DTS 15530-2

ISO/DTS 15530-2 provide a way to estimate coordinate measuring machine (CMM) measurement uncertainties without using any complex calibrated artefacts. Instead, only a performance verified CMM and a standard calibrated gauge block are needed.

Metrology

CMM measurement uncertainty estimation: Relevant uncertainty contributors

GNSS

Meaconing: the most common type of GNSS spoofing interference attacks

Spoofing attack is a radio frequency (RF) signal interference attack that aims to deceive a global navigation satellite system (GNSS) receiver, such as GPS or GALILEO receiver, so that the receiver track and demodulate the spoofing signals, leading to invalid position, velocity and timing solutions.

GNSS

GNSS signal modelling considering channel impairments and spoofing interferences

Signals of global navigation satellite system (GNSS), such as the well-known GPS and GALILEO, are significantly affected by channel impairments and signal interferences.

GNSS

Low frequency radio navigation system for use in natural disaster situations

It is critical to have a navigation system for search and rescue of victims and important assets in a disaster situation.

Metrology

Coordinate measuring machine (CMM): Calibration, performance verification and measurement uncertainty estimation

Calibration, performance verification and measurement uncertainty estimation are important activities for coordinate measuring machine (CMM) machine and measurement.

Metrology

Error sources on coordinate measuring machine (CMM) measurements and environment control

A coordinate measuring machine (CMM) is a complex measuring instrument. Hence, there are many error sources that cause the degradation of a CMM measurement accuracy and the increase of the uncertainty of the CMM measurement results.

GNSS

Channel coding theory: An introduction and comparison of block, Convolutional, Turbo and low-density parity-check (LDPC) codes

In this post, a brief introduction about channel coding theory is presented. The comparison of convolutional, TURBO and LDPC codes for use in global navigation satellite system (GNSS) signals is also presented.

Metrology

Sampling strategy for coordinate measuring machine (CMM) measurements

In any CMM measurements, especially with a tactile-CMM, sampling strategy is very important. This Sampling strategy in CMM measurement affects not only measurement performance, but also measurement accuracy!

Metrology

Part-alignment procedure on coordinate measuring machine (CMM) for dimensional and geometrical measurements

Part-alignment is a compulsory process that needs to be performed for CMM measurements. This process is performed right after the qualification process of CMM probing system. Only after part-alignment is performed, dimensional and geometrical measurements by a CMM can be carried out.