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This research paper aimed to validate two methods for measuring loads during walking with instrumented crutches: one method to estimate partial weight-bearing on the lower limbs and another to estimate shoulder joint reactions. Currently, gait laboratories, instrumented with high-end measurement systems, are used to extract kinematic and kinetic data, but such facilities are expensive and not accessible to all patients. The proposed method uses instrumented crutches to measure ground reaction forces and does not require any motion capture devices or force platforms. The load on the lower limbs is estimated by subtracting the forces measured by the crutches from the subject’s total weight. Since the model does not consider inertia contribution in dynamic conditions, the estimation improves with low walking cadence when walking with the two-point contralateral and the three-point partial weight-bearing patterns considered for the validation tests. The shoulder joint reactions are estimated using linear regression, providing accurate values for the forces but less accurate torque estimates. The crutches data are acquired and processed in real-time, allowing for immediate feedback, and the system can be used outdoors in real-world walking conditions. The validation of this method could lead to better monitoring of partial weight-bearing and shoulder joint reactions, which could improve patient outcomes and reduce complications.

An important task in biomechanics is human body articulations’ internal torques measurement. This is known as a kinetic or inverse-dynamics problem. Its solution requires a combination of kinematic and dynamic measurements with a biomechanical model, involving subject-related anthropometric parameters. The uncertainty-evaluation thereof is here considered. The method poses on a probabilistic model of the associated measurement system, according to the “Guide to the expression of uncertainty in measurement” general principles. We consider a comprehensive set of influence quantities, including markers’ misplacement or parasite movements. The anthropometric parameters’ uncertainty is discussed in detail. The proposed approach helps to identify the most influential experimental factors.

Crutch-assisted walking is very common among patients with a temporary or permanent impairment affecting lower limb biomechanics. Correct crutches’ handling is the way to avoid undesired side effects in lower limbs recovery or, in chronic users, upper limbs joints diseases. Active exoskeletons for spinal cord injured patients are commonly crutch assisted. In such cases, in which upper limbs must be preserved, specific training in crutch use is mandatory. A walking test setup was prepared to monitor healthy volunteers during crunch use as a first step. Measurements were performed by using both a motion capture system and instrumented crutches measuring load distribution. In this paper, we present preliminary tests results based on different subjects - having a variety of anthropometrical characteristics - during walking with parallel or alternate crutches, the so-called three and two-points strategies. Tests results present inter and intra subject variabilities and, as a first goal, influencing factors affecting crutch loads have been identified. In the future we aim to address crutch use errors that could lead to delayed recovery or upper limbs suffering in patients, giving valuable information to physicians and therapists to improve user’s training.

Biomechanical analysis of human movement is based on dynamic measurements of reference points on the subject’s body and orientation measurements of body segments. Collected data include positions’ measurement, in a three-dimensional space. Signal enhancement by proper filtering is often recommended. Velocity and acceleration signal must be obtained from position/angular measurement records, needing numerical processing effort. In this paper, we propose a comparative filtering method study procedure, based on measurement uncertainty related parameters’ set, based upon simulated and experimental signals. The final aim is to propose guidelines to optimize dynamic biomechanical measurement, considering the measurement uncertainty contribution due to the processing method. Performance of the considered methods are examined and compared with an analytical signal, considering both stationary and transient conditions. Finally, four experimental test cases are evaluated at best filtering conditions for measurement uncertainty contributions.

A general probabilistic model of the measurement process is discussed, showing how it can address both static and dynamic measurements. Emphasis is placed on the latter, and two main kinds of dynamic measurements are considered: direct, where the goal is to monitor a phenomenon over time, and indirect, where an alternative representation is sought, such as, typically, the spectrum. It is shown that both cases can be treated in the same framework, through a proper interpretation of the variables involved. Then, direct measurements are investigated in greater detail, and the application of this approach is discussed, in the case of a Markovian model with a uniform prior for the measurand, and an illustrative numerical example is presented. These results may pave the way to a better harmonization of measurements, grounded on a sound scientific foundation.

The paper focuses on the fatigue life assessment of mooring lines for floating offshore wind turbines, deployed on intermediate water depths. The nonlinear hydrodynamic model in the time-domain is preliminarily discussed. Subsequently, several spectrum estimation methods are outlined and embodied to carefully assess the low and high-frequency components of the stress process in the mooring lines and estimate the cumulative fatigue damage by the combined spectrum approach. The spectral reconstruction methods are applied to a reference case study, focusing on three different loading conditions. Current results are discussed and some suggestions are also provided to carefully assess the fatigue life of mooring lines for floating offshore wind turbines.

Biomechanics and thermoregulation of human running are key aspects playing an important role in the training of professional athletes. In the case of a prolonged exercise, as occurs during the marathon race, the intensity and duration of the exercise (in concert with environmental conditions) can affect the thermoregulatory response and the running mechanics. The aim of this study is the design of a novel experiment able to simultaneously capture information concerning the biomechanics of lower limbs and the surface temperature map of the whole body during a prolonged running exercise on treadmill. Kinematics quantities, such as linear and angular displacement, velocity and acceleration of relevant body markers are recorded by a video system, while surface temperature evolution on time is detected by an infrared thermal camera. A group of five amateur athletes, with long experience in long-distance running competitions, was involved in this study. Results for the sample group, in terms of kinematic (displacements and angles) and thermal (local and total-body skin temperatures) quantities, revealed features related to individual response to the effort. Even though the relatively little number of athletes does not permit to infer general conclusions, the combined mechanical and thermal experiment is deemed to be a useful tool for the investigation of endurance running characteristics.

Dynamic measurement are currently deeply studied due to their practical importance and for the benefit that may outcome from a metrological approach, where close attention is paid to the reduction and evaluation of the associated uncertainty. In this communication, a simple and effective method for performing dynamic compensation is presented. This is an extension of a previous work, where the method was firstly introduced and fully developed only for first order systems, whilst here the important case of a second order device is considered and worked out. The effectiveness of the method is proved by the simulation of the behavior of an accelerometer.

The monitoring of sea state conditions, either for weather forecasting or ship seakeeping analysis, requires the reliable assessment of the sea spectra encountered by the ship, either as a final result or intermediate step for the measurement of the relevant wave-motion parameters. In current analyses, different spectrum estimation methods, namely the Welch, Thomson and ARMA models, have been applied and compared based on a set of random wave signals, with different durations, representative of several sea state conditions. Subsequently, two sea spectrum reconstruction techniques were described and applied in order to detect the main sea state parameters, namely the significant wave height, the mean wave period and the spectrum peak enhancement factor. The performances of both spectral analysis and sea state reconstruction methods are discussed in order to provide some preliminary guidelines for practical application purposes. In this respect, based on current results, the Welch and Thomson methods seem to be the most promising techniques, combined with the nonlinear least-square reconstruction technique.

Measurement aims at obtaining a numerical description of objects/events/persons in the real world by means of a measuring system. Measurement is widely used as a key way for obtaining high quality information from the real world, across disciplines. In the present day, there is growing consensus in holding that measurement is characterized by the use of something that qualifies as a “measuring system”. Therefore, we discuss sufficient conditions for an empirical system to qualify as a measuring system and we present a formal model of the measuring system, in terms of empirical relations among objects to be measured and the measuring device. The theory applies to all the main structures of metrological interest – order, difference, intensive and extensive, and we hope that this may help to fill a gap in these studies. We also briefly address practical applications of the theory, including calibration, modelling of measuring devices and performance statement.

A first order probabilistic logic is developed and presented in both intuitive and formal terms. It is shown how it can be successfully applied to the development of probabilistic representations for the main structures and scales involved in (one-dimensional) measurement. As a part of the current debate on the nature of probability in measurement, this result provides a way for overcoming the traditional opposition between Bayesian and orthodox statistics.

The probabilistic modelling of measurement systems is discussed, showing how it provides a practical and effective way for addressing uncertainty evaluation, that does not require any commitment to specific philosophical schools, such as the frequentistic and the Bayesian ones. Firstly, different ways of modelling the same measuring device are compared and discussed, considering both the designer’s and the user’s standpoints. Then philosophical issues concerning both the nature of probability and the probabilistic inferences related to the measurement process are considered, in the perspective of this model-based approach. Applications to education and to the revision of international guides for measurement are finally addressed.

We propose a new approach to addressing the expression and evaluation of uncertainty in measurement, which at the one hand maintains the same original goals of the Guide to the Expression of Uncertainty in Measurement (GUM), as expressed by the original recommendations from the CIPM, on the other significantly differs in proposing how to implement them, for a closer orientation to the needs of the expected users, supported by a sound theoretical background. We suggest that this new approach may overcome some of the setbacks that have been experimented in the years in the application of the GUM, thus helping a wider diffusion of the practice of evaluating measurement uncertainty, by establishing a close link with the current state of the art of measurement science.

Biomechanical measurements applied to upper limbs gesture, characterisation and clinical evaluation are less diffused than lower limbs evaluation where gait analysis is rather common. When dealing with upper limbs a set of critical problems have to be afforded. In walking analysis we know that the movement is cycled and repeatable, instead upper limb gestures are more complex principally because of lack of the periodicity. In this paper we present a protocol to face such problems and obtain an objective biomechanics evaluation of the upper limbs, with the particularity to be focused on a daily life gesture such as drinking. The experimental protocol is presented together with the parameter identified to characterise the movement. Some preliminary results are discussed with reference to a set of healthy and clinical subjects.

The probabilistic modelling of measurement systems is discussed, in regards to uncertainty evaluation and different models representing the same real system from different standpoints are compared. We suggest that proper probabilistic modelling directly yields evaluation of measurement uncertainty, without making any commitment to specific philosophical schools, such as the frequentistic and the Bayesian ones. We suggest that this model-based approach may have advantages in education and in the development of recommended practices in measurement.

Squat weight lift is a common exercise in physical training used both in weightlifters specific training and in general athletes for leg force increment. When weight load on subject shoulders is rather heavy as compared with full body weight, gesture biomechanics becomes critical, since injuries may occur when gesture is not controlled or performed in a wrong way. Experienced trainers are aware of such issues and give proper instructions to obtain best performance at a minimum injury risk. In this work a quantitative approach is presented, supported by biomechanical measurements to determine the effects on main articulations of different postures during the exercise. Preliminary results confirm good practices giving a quantitative indication of joints solicitations.

In the past, ratio scales have been a highly controversial issue between physicists and psychologists as regards the need for an empirical addition operation in order to attain them. This aspect is critical since such an operation is often unavailable in psychophysical experiments, as it is in physics, due to its intensive properties. We propose a reconsideration of ratio scales, showing how they can be obtained when ratio and difference empirical relations are available and when they satisfy proper compatibility conditions. We call such structures “intensive” and provide deterministic and probabilistic axiomatizations in the finite case. We also address the practical applications of these ideas to perceptual measurements.

The instantaneous centre of rotation plays an important role in biomechanical modelling and physical-medical interpretation of human gestures. Therefore, we consider its measurement, based on video-image acquisition and processing of human motion records. Measurement and computational aspects are discussed, including the evaluation of measurement uncertainty and the estimation of the effect of some influence quantities on the determination of the position of the instantaneous centre of rotation.

Measurement aims at obtaining a numerical description of objects/events/persons in real world by means of a measuring system. Measurement is widely used as a key way for obtaining high quality information from the real world. across disciplines. In the present day. there is growing consensus in holding that measurement is characterized by the use of something that qualifies as a "measuring system". Therefore. we discuss sufficient conditions for an empirical system to qualify as a measuring system.

The study and modelling of human movement requires accurate measurement of forces and of kinematic quantities, with proper control and monitoring of measurement uncertainty. The metrological aspects of such experimentation are often overlooked in the biomechanical literature. In contrast, we present here a complete measurement system that combines a double force platform with vision and inertial sensors, with some degree of instrumental redundancy, which permits a cross-validation of different measuring channels. Therefore, the system permits the characterization of a person's movement, enabling, at the same time, the verification of the acquired experimental data. Details are provided on the system and on the measurement procedure, in order that experimentation can be reproduced, if needed, in other laboratories. Then, as a test case, the experimental study of hopping is considered. Experimental results are discussed, with special focus on kinematic quantities, and system performance is discussed, by properly accounting for uncertainty issues.

The detection and acknowledgement of signatures , for condition monitoring and fault diagnostics by wavelet transform, deserves increased attention, due to its property of variable time–frequency resolution, which overcomes limitations of classical time–frequency approaches. In the paper, a diagnostic tool is presented, based on the wavelet transform, able to detect and to quantify the wheel-flat defect of a test train at different speeds and to measure the train speed with proper accuracy. The designed diagnostic tool minimises the hardware requirements, since only one accelerometer is needed, and provides results in real time. The results, achieved by an exhaustive experimental campaign, permit to validate the effectiveness of the diagnostic tool and to demonstrate the advantages of wavelet-based detection of signatures.

Measurements are often an objective support for decision-making, in all fields, scientific, industrial or human-related. In this last case particular care has to be taken as a wrong decision can affect health, life or environment. In order to assess conformity of a critical process with legal prescriptions or with technical requirements, measurement uncertainty strongly affects the decisional process. In such cases, typically the state of the process under investigation is monitored by a set of measured parameters and their belonging to a given “safe” subset of the parameter space has to be checked. Common decision rules are based on expressing measurement results as intervals of values (expanded uncertainty), which results in an on–off acceptance criterion, with an uncertainty region. Alternatively, in order to obtain an explicit evaluation of the risk of taking the wrong decision, it is necessary to express the measurement result as a probability distribution. Due to the importance of the problem, in this article such an approach is addressed in general terms. A complete set of formulas for both uncertainty expression and risk evaluation are provided, their practicability is discussed and two prototype software packages, for supporting both uncertainty evaluation and risk assessment, are presented. Finally, some application examples, including scalar and vector measurements, are presented.

Panel or jury testing is a widely used technique in the measurement of quantities related to human perception. However, despite both scientific and applied interests, the confidence of potential users of this technique is less than in more familiar physical and engineering measurements. This lack of confidence arises mainly due to the lack of standardization and of internationally recognized metrological references for panel testing.Here we discuss some methodological aspects of panel testing, including the construction of the reference scale, the definition and realization of a measuring system based on a previously established scale, its calibration and related uncertainty evaluation. We provide illustrative examples concerning the measurement of the quality of sound (acceptability) of machinery used for the automatic sorting of post, presenting experimental results from tests performed in our laboratory, which seem encouraging.Finally, we propose some possible actions for standardization and for the promotion of a metrological approach.

Automatic face recognition is a widely used biometric identification method, since it is based on standard video surveillance systems and does not require the collaboration of the person to be recognised. The recognition process involves decisions based on the face measurement results. The reliability and robustness of the recognition procedure are critical factors, strongly affected by influence quantities, such as face-camera relative orientation and position, illumination and expression. To improve performance it makes sense to imitate the recognition process in humans, who succeed in recognising faces even from poor quality images. It is therefore interesting to investigate the perception of similarity between faces, with the aim of gaining insight into the process of human face recognition. We report on an investigation that has been carried out by original methods developed in our laboratory for the direct measurement of perceptual quantities. Such methods have been implemented for two complementary recognition procedures, based either on the global appearance of a face or on the detection of specific repere points.

We continue the discussion on the possibility of interpreting probability as a logic, that we have started in the previous IMEKO TC1-TC7-TC13 Symposium. We show here how a probabilistic logic can be extended up to including direct and inverse functions. We also discuss the relationship between this framework and the Bayes-Laplace rule, showing how the latter can be formally interpreted as a probabilistic inversion device. We suggest that these findings open a new perspective in the evaluation of measurement uncertainty.

The study of human movement requires the accurate measurement of the forces and of the kinematic quantities involved. Here we consider hopping, that deserves great attention in the literature, since it combines the activation of a complex sensorimotor control with the relative simplicity of the gesture. The movement of the center of mass and the contact conditions are of special interest. Thus a measuring system that combines digital image acquisition, force measurement based on a force plate and extensive use of inertial sensors, for linear and rotational motion, has been developed and characterized. The results concerning the accurate measurement of contact conditions are specially outlined.

The measurement of quantities according to perception is of great interest for the optimal characterization of the interaction of persons with their living and working environment. The direct approach to such measurements is based on jury-test methods, which at present have only been partially studied from a metrological perspective and are far from being standardised. So this paper presents a thorough investigation of the jury-test methods, both for the construction of reference measurement scales and for the subsequent development of suitable measurement procedures. The cross-validation of complementary tests is addressed, to ensure the reliability of the results, as well as the importance of test protocols and of operator interfaces. As a support to the proposed methodology, two test cases concerning automotive noises are presented in detail and show good results. This study also intends to promote the standardisation of this kind of method.