Moving beyond traditional GPS data analysis, Catapult has progressively encompassed athlete analytics as a whole to tell you everything about a player’s movement. Just like a Formula 1 car is meticulously monitored at every stage of production and competition, a team’s athletes are its greatest asset and an area that has gone lacking prior to Catapult’s inception.
Just using GPS data to measure athlete performance would be like Ferrari just monitoring speed and distance. It is the complex information provided by the inertial sensors inside a Catapult device that mean the difference between measuring the impact force of a tackle and confusing a tackle with a device being dropped on the ground.
This complex information is a result of accelerometers, magnetometers and gyroscopes and is processed with an advanced algorithm to provide Inertial Movement Analysis (IMA) – a simple way of expressing the most complex athlete movements.
IMA was developed by Glenn McIntosh, a Firmware Engineer who worked with eventual Catapult founders in the Cooperative Research Centres (CRC), with the aim to put acceleration data in to a real world reference frame that wasn’t relative. Because of the chaotic and unpredictable nature of sports, monitoring the movement of a small unit is dependent on many factors, and removing these individual variables to provide real references ensures measurements will be the same for every athlete.
By combining the data provided by the accelerometers, magnetometers and gyroscopes, and running it through a Kalman filter (a linear filter for multiple sensors), you can optimise how much noise is on the filters and determine the best parameters. This removes the variability between athletes, or between how the unit is worn – because it is set to a reference frame, it doesn’t matter how the unit is worn – which means you can derive parameters that can be compared between different people’s measurements, providing testability.
Accelerometers are vital in this process as they measure gravity and give you both a measure of your orientation and a measure of acceleration. But in order to accurately measure an athlete’s acceleration, you need to remove gravity from the equation. This is done by utilising information from the gyroscopes, which determine orientation and explain the direction of the gravity.
Over the long term accelerometers tell you the absolute orientation, while gyroscopes tell you how much it has changed. From that you can work out your orientation, and absolute information regarding directional analytics.
As a whole, IMA tells you your actual orientation and then you can work out which direction gravity is and subtract it from the accelerometers. What you’re left with is pure acceleration data.
Catapult is the only system in the world with activated gyroscopes, can provide directional analytics (forwards, backwards, sideways), and accurate acceleration information. Without IMA, all references to accelerations are relative to the player, sport and environment.