Department of Engineering / News / Meet James Cozens – the Guinness World Record-holding juggling engineer

Department of Engineering

Meet James Cozens – the Guinness World Record-holding juggling engineer

Meet James Cozens – the Guinness World Record-holding juggling engineer

When first-year Cambridge PhD student James Cozens took up juggling seven years ago, little did he know he would go on to become a Guinness World Record holder. He currently holds the Guinness World Record for ‘the most objects juggled while riding a unicycle’ – a total of seven balls for a period of 16.77 seconds. 

Ultimately, my hope is that the software will be used as a valuable training and visualisation tool for beginner and advanced jugglers alike, and most importantly, a source of inspiration for the next generation of aspiring jugglers.

PhD student James Cozens

While competitive juggling is a rapidly emerging sport with thousands of athletes worldwide, for James, there has been one thing missing: a lack of tracking software for performance analysis. So, he set out to find a solution.

Similar to rhythmic gymnastics, juggling competitions, such as those within the World Juggling Federation, involve the performance of a routine (often with seven or more balls), which is then ranked by difficulty and execution. The routines are typically formulated from a notation system called ‘Siteswap’. ‘Siteswaps’ are sequences of numbers that represent the relative durations of throws in a juggling pattern. 

Over the past year, James, who is studying for a PhD in Statistical Signal Processing and Machine Learning, has been busy developing software that provides insight into jugglers’ technique through tracking, visualisation and simulation of Siteswap routines – similar to the performance analysis tools employed in sports such as golf and tennis.  

James said: “I first noticed the lack of training software available for athletes during my attendance at the juggling conventions. Despite almost all ball sports having some form of tracking software for analysis, none existed for this sport.

“So, I set out to develop a prototype for this software. Its development began as a personal research project, before becoming a dissertation module as part of my fourth-year while studying for my Master of Engineering (MEng) in Information and Computer Engineering, under the supervision of Professor Hugh Hunt.”

The module, which focused on the inference of the relative difficulty of Siteswap routines, was also supervised by one of the founders of the Siteswap system, Colin Wright. 

The tracking and visualisation software meanwhile, originally developed as part of James’s personal ongoing research project, has now been integrated into James’s PhD work, which also includes research into Generative Music (AI), under the supervision of Professor Simon Godsill.

The prototype tracking software was first tested at the 2022 European Juggling Convention, with numerous world-renowned jugglers contributing to the testing of James’s software, including juggler Tom Whitfield, who is currently the 10 ball and 11 ball juggling world record holder. For instance, Tom has used the software to help recognise irregularities in endurance runs. 

James has since followed up with the first official prototype application of the software, based on feedback from the Convention. He is also planning on competing in the World Juggling Federation’s (WJF) 2023 Champions for Team GB, as well as trialling the tracking software live in competition.

The software aims to provide athletes with a method for analysing their technique and suggests potential solutions and training routines to improve technical efficiency. This is in addition to providing a system for recognising Siteswap routines in real time for adjudicators (from the WJF and the International Jugglers’ Association), as an aid for evaluating performances during competitions. 

“This is increasingly important, given that those in the juggling industry are hopeful that the sport can make its Olympic debut in the next couple of decades,” said James. 

“The reason why limited software currently exists for generalised juggling tracking is due to the complexity and variability of conditions. Object segmentation and assignment are especially difficult, given the unpredictable nature of juggling trajectories in a competitive environment (with accelerations approaching 120 metres per second squared), and the variety of props and background conditions. 

“Excitingly, the new algorithms that have been devised have been shown to track effectively, even under some especially difficult conditions when tested in events such as the European Juggling Convention.

“Ultimately, my hope is that the software will be used as a valuable training and visualisation tool for beginner and advanced jugglers alike, and most importantly, a source of inspiration for the next generation of aspiring jugglers.”

Additionally, James organises welfare juggling workshops at the University of Cambridge, offering students the chance to learn a new skill, socialise and enjoy a break from the academic grind. 

“I have a firm belief in the potential of juggling to support mental health, as it can alleviate stress and anxiety,” he said.

As a composer and pianist, James is also captivated by the dynamic interplay between juggling and music. It is a fascination that provided James with a unique opportunity to compose a juggling concerto, featuring a solo juggler as the central performer, and accompanied by a symphonic orchestra.

“My top juggling tips are to have fun and explore the wide-ranging art form through YouTube,” he said. “There are a wealth of amazing tutorials online, from beginner to advanced, that introduce aspiring jugglers to concepts like Siteswap. With juggling, you never stop learning!” 

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