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Nowadays, inertial sensors have shown great popularity in gait analysis, thanks to their advantages in terms of costs, encumbrance and usability in outdoor settings. The accuracy achieved by inertial-based systems in detecting gait events is however not as high as that obtained with lab-based equipment, even if many authors have presented methods to fill this gap. In particular, the segmentation of gait patterns into different cycles, and the determination of the stance and swing parts of each cycle are two key phases in the gait analysis process, as they are needed to extract all the spatio-temporal parameters. Thus, an accurate detection of initial contact (IC) and final contact (FC) events is necessary. Among the different methods presented in the literature, we chose a wavelet-based one, which used the vertical component of the acceleration extracted from an inertial sensor on the waist, and we investigated the changes in detection accuracy when varying the numerical values of a parameter (i.e., the wavelet scale value). Gait patterns of five healthy subjects were recorded by a waist-mounted inertial sensor, and by a stereophotogrammetric system, taken as reference: IC and FC events were then extracted and compared, obtaining an estimation for each scale. Precision, Sensitivity, and $\rm F1_{\mathbf {score}}$ curves showed that IC events are well estimated in the range of scales 29–87, while FC events in the range 24–65, at a sampling frequency of 250 samples/s. In these ranges, mean error, variability and RMSE values showed lower values for the estimated IC events (RMSE

Metrological characterization of Medical Force Platforms is usually limited to their static behavior, as the dynamic analysis is often expensive and time consuming, usually performed by means of very complex and bulky devices. In this study a novel method for the evaluation of the Force Platform dynamic behavior has been proposed by means of a prototypal movable dynamic calibrator, developed in a previous work and that is used to determine five performance indices: Normalized Ratio Bandwidth, Harmonic Distortion, Root Mean Square Trueness, Surface Uniformity, Force uniformity. In particular the dynamic calibrator has been applied to a prototype strain gauges force platform, by loading it on five different points (4 points corresponding to the anterior and rear footing points and the center of the plate) with 3 force amplitudes $(400\pm 100\mathrm {N},700\pm 175\mathrm {N},900\pm 225\mathrm {N})$ at 8 frequencies (1, 2, 3, 4, 5, 6, 8, 10 Hz). Finally, the values of the above indices have been processed and plotted in a kiviat chart and compared with the reference values selected by the authors, in order to describe the dynamic performances of the platform in one image. The results showed a nonuniform behavior over the plate footboard, especially in its center, suggesting the need for a perspective in depth study to better evaluate its causes.

Several studies have showed the positive effect that real-time presentation of centre of pressure (COP) has on stability. Typically the COP position is depicted in real-time on the screen and it is required that the participant uses this additional information to regulate his/her postural sway. In order to perform the motor task, it requires an attentional load that influences the postural performance. Up-to now no study has focused on the effect that modality of VBF presentation could have on postural control and how it depends on the attentional load needed. Goal of this study was to compare the effects that two different modalities of Visual Biofeedback (VBF) presentation, which require different focus of attention, could have on postural stability. The CoP coordinates were extracted from force plate data and elaborated in real-time to implement two VBFs: VBFsquare, where the CoP is shown on a screen together with a square stability area, extracted from anthropometric feature; and VBFsmile, which let the participants know if they are or are not in the stability area by an emoticon image. Two groups of twelve healthy young subjects executed the protocol in two different sequences composed of the following conditions: noVBF-VBFsquare and noVBF-VBFsmile. Each condition was repeated three times. The effect of the two VBFs was studied by four parameters extracted directly from CoP coordinates (sway area, sway path, mean amplitude and mean frequency). The comparison between the two VBFs showed significant difference in sway path and mean frequency. The decrease of the parameters' values in VBFsmile opens the possibility of using it as a tool to facilitate postural control in upright stance.