Analysis and algorithms for parametrization, optimization and customization of sled hockey equipment and other dynamical systems

Abstract

A dynamical system, an ensemble of particles, states of which evolve over time, can be described using a system of ordinary/partial differential equations (ODEs/PDEs). This dissertation presents fundamental investigations of the analysis and algorithms for the study of dynamical systems, by parametrizing, optimizing and customizing. We develop and/or implement numerical algorithms, for solving ODEs/PDEs, and statistical/machine-learning algorithms based on data, for physical inference and prediction. We further apply the methodologies on sled hockey, an adaptation of stand-up hockey, allows people with physical disabilities to participate in the game of ice hockey. First, we develop and implement numerical algorithms to study the nonlinear dynamics described by 4th-order nonlinear PDEs. The non-linear solvers apply multidimensional Newton's method with a Jacobian-free approach and a generalized conjugate residual (GCR) approach.

Applying the algorithms on the study of elastic systems, we investigate dynamics of hockey sticks as in a striking implement. We develop a mathematical model using an Euler-Lagrange equation to characterize the behavior of a hockey stick in the linear regime, and then apply this model to investigate the dynamic response of the stick throughout slap shots and wrist shots. We apply a modal decomposition method and decouple the resultant dynamics into kinetic and potential components. We further optimize the structures based on the dynamical analysis. Throughout testing with both elite and amateur sled hockey players, we find that final puck velocities with our prototype stick are on average over 10% higher compared to those achieved with commercially available sticks. Second, we investigate the dynamics of rigid system as in an over-constrained implement.

We propose two sets of dynamical modelling for the hockey sled using a trajectory-based modelling method and a state-space-based modelling method, which are used to study the dynamics of the propulsion for linear motion and of the tip-over and reset. We further propose a constrained optimization problem to optimize the Third, we develop and implement statistical and machine learning algorithms based on data, including algorithms of clustering for physical inference, algorithms of regression for Stribeck curve and algorithms of forecasting for wear rate. In the context of tribology of ice-metal contact, we design an experimental system to mimic the ice rink environment and to expand the experimental study of the friction coefficient in an extensive range of Hersey number from 10⁻¹³ to 10⁻⁴.

To build the understanding of the physics of friction, we perform a dimensional analysis and an asymptotic analysis for three regimes of friction - boundary friction regime, mixed friction regime, and hydrodynamic lubrication regime. We further develop a pipeline for creating the modified Stribeck curve based on data, after feature extraction, the regime of each experimental result is identified via clustering, followed by the regression constrained by the asymptotic analysis. Finally, we propose a methodology and algorithm to predict the wear rate subject to geometric constraints.