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Bringing New Motion Capture Technology to Old Biomechanical Problems
A collaborative approach to gait analysis is shedding new light on how athletes’ joints work when they run through a bend.
In the 1980s, when the field of biomechanics was first getting to grips with the potential offered by motion capture, Professor Joe Hamill investigated the mechanics of running through a bend. 30 years on, he has been able to glean new insights on the matter thanks to Vicon’s most recent strides in tracking technology.
“I did a paper in 1988 running on a curve, but it was a flat curve,” says Hamill, Professor of Kinesiology at the University of Massachusetts. “And our results showed that the legs do two different things in the bend. So I wanted to know – is that true on the curve? So 30 years later, Gareth and I decided to do this particular study.”
To build on Hamill’s earlier work he, Professor Gareth Irwin, Head of Sports Biomechanics at Cardiff Metropolitan University, and a team of researchers set up a study at the National Indoor Athletics Centre (NIAC) in Cardiff. The centre features a curved but also banked running track, in contrast with the flat track used in 1988. The team set up an array of Vicon cameras around the track as well as fitting their athletes with Vicon’s IMU inertial sensors.
“That allows us to infer lots of other things,” said Irwin at the NIAC. “It develops on quite complex motor control theories, like dynamical systems, and some nonlinear dynamic approaches to understanding human movement.”
MORE MOVING PARTS
Using both optical and inertial capture methods enabled the team to build two complementary data sets. “So we’re going to have our Vicon motion capture system,” said Irwin, “we’re going to be looking at all the kinematics, the motions of the joints and the segments as they’re running around the bend [and] running in the straight.
“And we’re going to have the IMU information from the inertial measurement units – they’re going to measure the acceleration characteristics of those segments. So we’re going to be able to look, potentially, at the loading of those.”
Being able to capture the athletes’ full range of motion was crucial. “The Vicon system allows us to Capture three dimensional data, three planes of motion of each of the joints,” said Dr Gillian Weir, a biomechanics researcher from the University of Massachusetts. “So we can look at the hip, knee and ankle and it allows us to collect really high fidelity data and use that information to make certain comparisons with a really accurate set of equipment.
Hamill said that to capture data this complex you simply have to use a high-power system. “Vicon, actually, has become the world standard, because it’s a 3D system,” he said. “Your joints are not two simple hinge joints, they rotate. You’ve got flexion, extension, and you’ve got internal varus and valgus angulation. And you can’t get that unless you have a system like this.”
The flexibility of being able to incorporate inertial data into the modeling from within the same ecosystem was an important factor, too. “The great thing about the Vicon system is that it’s so mobile that we’re able to take it outdoors,” says Rachel. “We can use their IMU sensors and the Blue Tridents to capture data outside, away from a computer, which is fantastic.”
The end result of all this work will be to improve the health and performance of athletes. “Having this type of fine-grain research allows us to make objective decisions about health and wellbeing of athletes, about whether there are things we can change within sports to make it safer, healthier, and also at the elite end optimize performance,” said Irwin.
“That information can then drive the more recreational athletes and the wider population to get involved in sport and also improve their health and well being as well.”
Professor Irwin also praises the collaborative approach he has found working with Vicon. “An industrial partner like Vicon, being able to provide those essential methodologies to allow us to collect data, it’s fundamental,” he said.
“I think one of the advantages of working with a company like Vicon is that they’re big enough to respond to your needs.
“Certainly within sport it’s really important that you have a company that can identify the needs of the user and the need for not just applied research, but to be able to do that from a fundamental basic research level as well. I think that’s where Vicon kind of gives you the whole package.”