Researchers work on new generation of bike fitting for cyclists

19 February 2013

The next generation of bike fitting for cyclists may rely on inertial sensors developed at the Auckland Bioengineering Institute.

Researchers are working on a project to determine if inertial sensors can give reliable and accurate estimates of three-dimensional cycling motion.

Three researchers from The University of Auckland are performing research with a Dunedin-based software company, ‘Siliconcoach’, that creates video analysis solutions for sporting companies and institutions. Siliconcoach develops bike-fit software for more than 350 bicycle stores worldwide.  One of the co-investigators on the project is Professor Poul Nielsen who is based at ABI, but is also from the Department of Engineering Science at the Faculty of Engineering.

The ABI biomechanics team has been researching applications for an Inertial Measurement Unit (IMU) designed by bioinstrumentation engineer Mark Finch. The inertial sensors will be fitted to a cyclist with the orientation from the sensors linked to a computer model of the subject. This will ultimately remove the need for video to obtain motion data.

“The IMU is small, light and waterproof so it’s ideal for the next generation of bike fitting and athletic motion software,” says the principal investigator on the project, Thor Besier. “It will enable athletes to measure motion on the road.”

“It’s a fantastic opportunity for Siliconcoach to value-add with some really interesting technology within the University. The Auckland Bioengineering Institute has some great ideas and tools, and Siliconcoach has a great path to market, providing a really good synergy,” says Thor.

He says the Australian Institute of Sport in Canberra are already interested in using the IMU with their swimmers as it will enable them to measure motion under water.

Prosthetics and orthotics is another area of interest for Siliconcoach. At present, a prosthetist can film the client and give feedback to improve their function with the prosthetic limb. In future, they could be using IMU’s to measure the motion of the limbs, and feed it back to the new system, says Thor.

“The Siliconcoach project aims at coupling the IMU with a computational model of the musculoskeletal system, and to use that model to perform gait and movement analysis by estimating muscle joint forces,” he says.

“I am working on a computer-based model of bones, muscles and joints using OpenSim, a software programme developed at Stanford University,” says Thor. “The purpose is to create models which will be animated by the IMU system. An individual would strap the IMUs onto various positions on the limbs, perform a motion, and you would see the motion personalised via the computer software.”

The programme could receive individual measurements, so that the figure presented on screen would be a model of the individual wearing the IMUs. This subject-specific modelling would enable forces in muscles and joints to be assessed, he says.

“We are investigating how to optimise individual performance such as power in cycling and perform different simulations in OpenSim,” says Thor. “We also have experiments to capture the data of cyclists using IMU’s alongside video motion capture to validate the accuracy of using the sensor.”

“The next step is to be able to explain how you got this position or orientation through the joint and muscular forces,” he says. “We are looking at questions like ‘What are the joint forces and loads that an individual has to change or facilitate to create a performance gain or reduce risk of injury?’ This is the objective of the computer model we are working on.”

“Some core elements of an IMU are found in a smart phone and this points to a potential for integration with smartphone technology in the future,” says Thor.

Thor and his team have been granted funds jointly by Siliconcoach and TechNZ through the Ministry of Business, Innovation and Employment (former MSI) for contract research.