Curvature Detection with an Optoelectronic Measurement System Using a Self-Made Calibration Profile

So far, no studies of material deformations (e.g., bending of sports equipment) have been performed to measure the curvature (w″) using an optoelectronic measurement system OMS. To test the accuracy of the w″ measurement with an OMS (Qualisys), a calibration profile which allowed to: (i) differentiates between three w″ (0.13˙ m−1, 0.2 m−1, and 0.4 m−1) and (ii) to explore the influence of the chosen infrared marker distances (50 mm, 110 mm, and 170 mm) was used. The profile was moved three-dimensional at three different mean velocities (vzero = 0 ms−1, vslow = 0.2 ms−1, vfast = 0.4 ms−1) by an industrial robot. For the accuracy assessment, the average difference between the known w″ of the calibration profile and the detected w″ from the OMS system, the associated standard deviation (SD) and the measuring point with the largest difference compared to the defined w″ (=maximum error) were calculated. It was demonstrated that no valid w″ can be measured at marker distances of 50 mm and only to a limited extent at 110 mm. For the 170 mm marker distance, the average difference (±SD) between defined and detected w″ was less than 1.1 ± 0.1 mm−1 in the static and not greater than −3.8 ± 13.1 mm−1 in the dynamic situations. The maximum error in the static situation was small (4.0 mm−1), while in the dynamic situations there were single interfering peaks causing the maximum error to be larger (−30.2 mm−1 at a known w″ of 0.4 m−1). However, the Qualisys system measures sufficiently accurately to detect curvatures up to 0.13˙ m−1 at a marker distance of 170 mm, but signal fluctuations due to marker overlapping can occur depending on the direction of movement of the robot arm, which have to be taken into account.

Search for Available Biomechanical Technologies Suitable for Use in Physical Education Classes

Introduction: One of the most important physical education tasks in school is to learn motor actions. Biomechanical technologies can promote to this process. A school lesson is different from a sports training, so it is necessary keep in mind its specifics. The purpose of the article is to analyse the existing professional biomechanical complexes for their suitability for use in physical education classes. Methods: We studied articles on sports biomechanics and selected 20 professional biomechanical complexes. These complexes can be divided into four technological groups: Optoelectronic Measurement Systems (OMSs), Electromagnetic Measurement Systems (EMSs), Image Processing Systems (IMSs), Inertial Sensory Systems (IMUs). Besides that, we identified 10 crucial categories to estimate opportunity to use biomechanical complexes in school lessons: cost, complexity of setting up and using, assistance need, portability, universality, room volume, construction traumatic, place for using, promptness, volume of data. Thus, each complex was evaluated according to 10 criteria. The biomechanical complex was excluded from further consideration if it got a critical limitation at least one of the criteria. Results: None of the professional biomechanical complexes can be considered suitable for use in physical education classes. As alternative we propose using free biomechanical software and smartphone camera with slow-motion caption.

Multi-Channel Optoelectronic Measurement System for Soil Nutrients Analysis

To solve the problems that occur when farmers overuse chemical fertilizers, it is necessary to develop rapid and efficient portable measurement systems for the detection and quantification of nitrogen (N), phosphorus (P), and potassium (K) in soil. Challenges arise from the use of currently available portable instruments which only have a few channels, namely measurement and the reference channels. We report on a home-built, multichannel, optoelectronic measurement system with automatically switching light sources for the detection of N, P, K content in soil samples. This optoelectronic measurement system consists of joint LED light sources with peak emission wavelengths of 405 nm, 660 nm, and 515 nm, a photodiode array, a circuit board with a microcontroller unit (MCU), and a liquid-crystal display (LCD) touch screen. The straightforward principle for rapid detection of the extractable nutrients (N, P, K) was well-established, and characterization of the designed measurement system was done. Using this multi-channel measurement system, available nutrients extracted from six soil samples could be measured simultaneously. The absorbance compensation, concentration calibration, and nutrition measurements were performed automatically to achieve high consistency across six channels. The experimental results showed that the cumulative relative standard deviations of 1.22%, 1.27%, and 1.00% were obtained from six channels with known concentrations of standard solutions, respectively. The coefficients of correlation for the detection of extracted nutrients of N, P, K content in soil samples using both the proposed method and conventional lab-based method were 0.9010, 0.9471, and 0.8923, respectively. Experimental results show that this optoelectronic measurement system can perform the measurement of N, P, K contents of six soil samples simultaneously and may be used as an actual tool in determining nutrients in soil samples with an improvement in detection efficiency.

Optoelectronic measurement of wrist movements in various casts and orthoses used in scaphoid fractures

We developed an optoelectronic motion analysis protocol to measure anatomical and functional ranges of wrist motion in Colles’-type and scaphoid-type splints and casts. The protocol was used to study the restriction of wrist motion in casts and splints in ten healthy volunteers. Scaphoid-type casts were no more restrictive to wrist motion than Colles’-type casts, but casts were significantly more restrictive than removable splints. Removable splints were more restrictive than no immobilization. Results suggest there is no benefit in using scaphoid-type casts rather than Colles’-type casts to reduce wrist motion.