Jonathan Shepherd

A Novel AHRS Inertial Sensor-Based Algorithm for Wheelchair Propulsion Performance Analysis

With the increasing rise of professionalism in sport, athletes, teams, and coaches are looking to technology to monitor performance in both games and training in order to find a competitive advantage. The use of inertial sensors has been proposed as a cost effective and adaptable measurement device for monitoring wheelchair kinematics; however, the outcomes are dependent on the reliability of the processing algorithms. Though there are a variety of algorithms that have been proposed to monitor wheelchair propulsion in court sports, they all have limitations. Through experimental testing, we have shown the Attitude and Heading Reference System (AHRS)-based algorithm to be a suitable and reliable candidate algorithm for estimating velocity, distance, and approximating trajectory. The proposed algorithm is computationally inexpensive, agnostic of wheel camber, not sensitive to sensor placement, and can be embedded for real-time implementations. The research is conducted under Griffith University Ethics (GU Ref No: 2016/294).

Evaluating the Use of Inertial-Magnetic Sensors to Assess Fatigue in Boxing During Intensive Training

Automating measures of performance can allow for heightened understanding of how an athlete is performing, not only during a session but over time. Physical and mental performance degrades in high-intensity skilled sports like boxing as the athlete fatigues. Although the use of low cost, ubiquitous inertial sensors have been reported effective for performance classification in boxing, no assessment of a boxers efficacy has been reported under fatigue conditions. This letter evaluates the use of inertial sensors for automatic classification of fatigue by assessing the punch consistency in terms of pitch angle, punch force through acceleration, and hand speed, using the inverse time between punches. To achieve this, bespoke software was created in MATLAB, aided by the use of an attitude and heading reference system orientation filter. Six right-handed male elite boxers from the Pacific Nations, in preparation for the 2018 Gold Coast Commonwealth Games, Australia, consented to participate in the study. A noticeable decrease in performance for both hand speed (inverse time between punches) and force production (acceleration) was observed over time during intensive training, resulting in a Pearsons correlation coefficient of r 0.97 for the acceleration component and r 0.89 for the timing component. Inertial-magnetic sensors, with bespoke software, were experimentally found to be an effective tool for the automatic classification of boxing fatigue performance metrics. This study was conducted under ethical approval (ENG1413HREC).

A Literature Review Informing an Operational Guideline for Inertial Sensor Propulsion Measurement in Wheelchair Court Sports

With the increasing rise of professionalism in sport, teams and coaches are looking to technology to monitor performance in both games and training to find a competitive advantage. Wheelchair court sports (wheelchair rugby, wheelchair tennis, and wheelchair basketball) are no exception, and the use of microelectromechanical systems (MEMS)-based inertial measurement unit (IMU) within this domain is one innovation researchers have employed to monitor aspects of performance. A systematic literature review was conducted which, after the exclusion criteria was applied, comprised of 16 records. These records highlighted the efficacy of IMUs in terms of device validity and accuracy. IMUs are ubiquitous, low-cost, and non-invasive. The implementation in terms of algorithms and hardware choices was evidenced as a barrier to widespread adoption. This paper, through the information collected from the systematic review, proposes a set of implementation guidelines for using IMUs for wheelchair data capture. These guidelines, through the use of flow-charts and data tables, will aid researchers in reducing the barriers to IMU implementation for propulsion assessment.

Development and Validation of a Single Wrist Mounted Inertial Sensor for Biomechanical Performance Analysis of an Elite Netball Shot

The primary objective of the game netball is to score more goals than the opposition. Subsequently, there is impetus on improving shooting accuracy to maximize scoring. Understanding the kinematic factors of shooting that lead to scoring success allows for iterative adjustment and optimization of technique. Three-dimensional retro-reflective motion capture has been used to assess kinematics; however, these systems are expensive, require substantial setup and postprocessing time, and cannot be used in game-such as environments. With modern advancements in wearable microelectromechanical systems based technology, the ability to monitor shooting kinematics in the performance environment has become possible. This article evaluates the efficacy of a single wireless inertial measurement unit (IMU) sensor to monitor shooting kinematics, in terms of forearm angle at ball release. Four elite female shooters shot a total of 30 shots each (totaling 120 shots) from three different distances wearing both reference retroreflective motion capture (Vicon) markers and an IMU. To assess whether wearing the IMU had adverse effects on the kinematic shooting chain, a further ten shots each were taken without wearing the IMU. When contrasted with the gold standard reference of retro-reflective motion capture, the IMU sensor overestimated the forearm angle at ball release established by a mean percentage error of 4.03 1.58. Shots with and without the IMU indicated that the IMU did not biomechanically alter the shooting action. Important advantages of using IMUs over motion-capture solutions include that they are ubiquitous, low cost, require minimal user intervention, and can be used in representative training environments under defensive pressure. This information can enhance the understanding of the athletes distal segment coordination patterns, providing actionable insights to enable performance to athletes and coaching staff.