GNSS Brief discussions on uncertainty contributors of GNSS-based positioning (Part 3) Pseudorange is the distance between a global navigation satellite system (GNSS) satellite and a receiver when the offset of the receiver clock (with respect to GNSS timeline) is not yet corrected.

GNSS Brief discussions on uncertainty contributors of GNSS-based positioning (Part 2) In this post, we will start from the highest view of how we can estimate a position from at least four GNSS satellite ranging signals.

GNSS Brief discussions on uncertainty contributors of GNSS-based positioning (Part 1) In this blog series, we will discuss about uncertainty contributors on GNSS positioning and open a way to estimate the uncertainty for reliable positioning.

Metrology Productive metrology: Evaluating the cost of part inspections In this third post, we will discuss how the measurement cost affects the total production cost as well as how to correctly calculate the measurement cost to support a decision making for machine selection so that we can lower the total production cost.

Metrology Productive metrology: The relation between uncertainty and economic benefit In this second post about productive metrology, we will discuss how a measurement uncertainty can affect the economic benefit of metrology.

Metrology Productive metrology: The role of metrology to transform data into know-how or wisdom Metrology has been commonly seen as “cost-centre”. In this first post in the topic of “productive metrology” that is metrology as “profit-centre”, we will start by discussing the philosophical goal of metrology to gain know-how or wisdom.

Metrology Error compensation for coordinate measuring instrument: Error separation and self-calibration Rehearsal method is a method to separate combined or coupled errors into separated individual error elements. By separating the combined errors into individual errors, the error quantification of an instrument can be performed without a calibrated artefact and/or calibration instrument.

Metrology Error compensation for coordinate measuring instrument: The mathematical model of 3-axis coordinate measuring machine (CMM) The mathematical model of a measuring instrument is important for building the error compensation system for the instrument.

Metrology Error compensation for coordinate measuring instrument: Steps and calibration instruments For the implementation of error compensation on measuring instruments or machine tools, there are steps to follow, that are the reconstruction of an error map (via mathematical modelling via analytical or empirical methods) and the calibration process to quantify and characterise the error map.

Metrology Error compensation for coordinate measuring instrument: introduction and types Error compensation is an important process to produce an accurate measuring instrument. Any measuring instruments, although inherently constituted by accurate and precise components, always have some degree of error.

Metrology X-Ray computerised tomography (X-ray CT) for industrial part measurement: History, working principle, measurement procedure, applications and characteristics X-Ray computerised tomography (X-ray CT) has the ability to non-destructively measure internal features of a part that is made of different materials including metals and non-metals.

Metrology Mathematical geometrical fitting: Direct least-square fitting of circle geometry (with tutorial and code) Circle is a non-linear geometry that has a non-linear mathematical model. In this post, a closed-form and deterministic method to fit a circle from points (e.g., obtained from a measurement) by using direct least-square (DLS) estimation method is presented.

Metrology Mathematical geometrical fitting: Automatic measurement algorithm case studies In this post, practical case studies of algorithm implementations for automatic geometrical perpendicularity and cutting tool measurements are presented.

Metrology Mathematical geometrical fitting: Data filtering of measurement points Data filtering is a process to reduce noises or supress certain components or information contained in measurement data by using a specific kernel (filter).

Metrology Mathematical geometrical fitting: Initial solution problems Any iterative optimisation algorithms, used to optimise non-linear and multi-modal objective functions, always require an initial solution estimation.

Metrology Mathematical geometrical fitting: Non-linear geometry least-squared fitting (with tutorial) The fitting process for non-linear geometry is more complex than that for the linear geometry fitting. Non-linear geometry includes circle (2D and 3D), sphere, cylinder, cone and torus as well as more complex geometries such as free-form surfaces.

Metrology Mathematical geometrical fitting: Linear geometry least-squared fitting (with tutorial) The least-squared fitting of linear geometry is solved by transforming a non-linear objective function of residuals into a linear objective function of the residuals.

Metrology Mathematical geometrical fitting: Concept and fitting methods One of instrumental aspects in dimensional, geometrical and surface texture measurements is an algorithm to mathematically fit a geometry to spatial points. These spatial points are captured and digitised by a measuring instrument.

Metrology Optical measuring instrument: Focus variation microscopy (FVM) for coordinate and surface texture measurements Focus variation microscopy (FVM) is an optical coordinate measuring machine (CMM) that is able to measure both micro-scale part geometry and areal surface texture. An FVM machine can have an up to 5-axis motion system.

Metrology 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.

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.

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.