Mateusz Bocian

Biomechanically inspired modeling of pedestrian-induced vertical self-excited forces

AbstractAlthough many models of pedestrian dynamic loading have been proposed, possible bidirectional interactions between the walker and the excited structure are generally ignored, particularly for vertical vibrations. This shortcoming has arisen from scarcity of data on gait-adaptation strategies used in the presence of structural motion and, as a consequence, the absence of a credible fundamental pedestrian model capable of capturing the underlying relations between the two dynamic systems. To address this inadequacy of current approaches, a biomechanically inspired inverted-pendulum pedestrian model has been applied to the human-structure interaction problem. The behavior of the model is studied when subjected to vertical motion of the supporting structure, in particular, in relation to potential self-excited forces that can be generated. A mechanism has been identified by which the timing of pedestrian footsteps can be altered subtly, giving a net damping effect on the structure, without necessarily...

Experimental identification of the behaviour of and lateral forces from freely-walking pedestrians on laterally oscillating structures in a virtual reality environment

Highlights • A novel setup for investigating pedestrian–structure interaction is presented.• Foot-placement is the main balance control mechanism on laterally vibrating ground.• All components of pedestrian force are uncovered, including self-excited forces.• Inverted pendulum pedestrian model qualitatively captures the nature of forces.• The ground and visual conditions cause significant changes in pedestrian loading.

Real-Life Measurement of Tri-Axial Walking Ground Reaction Forces Using Optimal Network of Wearable Inertial Measurement Units

Monitoring natural human gait in real-life environment is essential in many applications including the quantification of disease progression, and monitoring the effects of treatment and alteration of performance biomarkers in professional sports. Nevertheless, reliable and practical techniques and technologies necessary for continuous real-life monitoring of gait is still not available. This paper explores in detail the correlations between the acceleration of different body segments and walking ground reaction forces GRF(t) in three dimensions and proposes three sensory systems, with one, two, and three inertial measurement units (IMUs), to estimate GRF(t) in the vertical (V), medial-lateral (ML), and anterior–posterior (AP) directions. The nonlinear autoregressive moving average model with exogenous inputs (NARMAX) non-linear system identification method was utilized to identify the optimal location for IMUs on the body for each system. A simple linear model was then proposed to estimate GRF(t) based on the correlation of segmental accelerations with each other. It was found that, for the three-IMU system, the proposed model estimated GRF(t) with average peak-to-peak normalized root mean square error (NRMSE) of 7%, 16%, and 18% in V, AP, and ML directions, respectively. With a simple subject-specific training at the beginning, these errors were reduced to 7%, 13%, and 13% in V, AP, and ML directions, respectively. These results were found favorably comparable with the results of the benchmark NARMAX model, with subject-specific training, with 0% (V), 4% (AP), and 1% (ML) NRMSE difference.

Characterisation of transient actions induced by spectators on sport stadia

In a wake of Hillsborough disaster of 1989, all stadia hosting major sport championships in the UK were converted from terraced to all-seated. Driven by spectators’ demands for improving the quality of their experience and organisers’ interest in increasing the capacity of their venues, a debate has arisen recently about the possible introduction of safe standing areas. Some issues have been already highlighted, mainly related to security aspects and comfort. This study investigates how the introduction of safe standing areas and the expected increase of the density of a crowd could impact the dynamic loading induced by the spectators and the resulting structural response. To this end an experimental campaign has been conducted in a laboratory delving into the effects of common actions performed by seated and standing cheering spectators. The data on dynamic behaviour of a lively test structure in both conditions have been collected, simultaneously with data on behaviour of the spectators. The forces applied by the spectators have been inferred using inverse dynamics, by analysing the structural response. The results are presented in the context of human-to-structure interaction and human-to-human coordination.