The Biomechanics Laboratory

About the Biomechanics Laboratory
Contacts
Equipment
Capture and Analysis
Application
Enquiries and Bookings

About the Biomechanics Laboratory

The Biomechanics Laboratory is concerned with the science of movement to understand the generation of muscular force, the transmission of these forces within the body, the body's interaction with external forces, and the movement that results.

The cutting-edge Motion Analysis [Motion Analysis Corporation, Santa Rosa, CA] system in the Biomechanics Laboratory provides clinicians, researchers, coaches and industry with an accurate description of how a person moves during sporting, workplace or everyday activities. Force plates provide information on external ground reaction forces while electromyography provides information in the temporal sequencing of muscle activity in the generation of movement.

The Biomechanics Laboratory also provides motion capture (MoCap) to the animation industry in applications such as computer games, advertising and television programs.

The application of biomechanics and the analysis of movement may be clinical, sports, work or everyday activities, providing:

Movement patterns for animation, Assessment of movement efficiency and performance, Measuring acquisition or learning of skill movements, Monitoring or predicting outcomes following training or clinical treatments, Undertaking fundamental research into how the body moves in normal and pathological conditions.

Contacts

For enquiries about the use of the Biomechanics Lab, bookings, or prices please contact:

Dr Allan Carman
Biomechanics Lab Manager,
School of Physiotherapy,
University of Otago,
325 Great King Street,
PO Box 56,
Dunedin.

Tel: (03) 479 3485
Fax: (03) 479 8414
Email: allan.carman@otago.ac.nz

Equipment

Motion Analysis System

The Biomechanics Laboratory features a 12-camera Motion Analysis [Motion Analysis Corporation, Santa Rosa, CA] system that can capture complex motion with extreme accuracy at up to 500 images per second. This is the animation industry's premier passive (no wires attached) 3D optical motion capture system. The system uses high resolution Eagle digital video cameras, infra-red illumination and retro-reflective markers place on the subject. Its real-time capability allow us to see captured results at the same instant as the subject is performing a specific task.

The motion capture system also includes a 64-channnel Analogue to Digital (AD) conversion card to collect simultaneous analogue data. Including force plates to record ground reaction forces, electromyography (muscle activity recording), electro-goniometers, load cells or foot switches to provide a comprehensive analysis of any movement.

Force Plates

The Biomechanics Laboratory has two AMTI [Advanced Mechanical Technology Inc., Watertown, MA] force plates that measure ground reaction forces. These measure the location of the centre of pressure and reaction forces in three dimensions (vertical plus two horizontal forces). The force plates are floor mounted and can be moved side by side (lifting, balance) or offset (walking) to measure the ground reaction forces under each foot.

Electromyography (EMG)

The Biomechanics Laboratory has a TeleMyo 2400T-G2 12 channel telemetric SEMG system [Noraxon, Scottsdale, Arizona]. Electromyography places electrodes on the skin surface to measure the electrical activity of underlying muscles. Electromyography gives insight into muscle recruitment and muscle temporal activity in the generation of movement.

Software

LabView [National Instruments Corporation, Austin, TX]: software for analogue data collection, signal conditioning and analysis. The Laboratory also has specific biomechanics software for clinical gait analysis or more generic motion analysis. Providing sophisticated 3D kinematic and kinetic movement analysis.

Foot Pressure

The Biomechanics Laboratory has a footscan® pressure sensing system, comprising a 1 meter / 500 Hz mat, a 3D interface box and associated software [RSscan International, Belgium]. The footscan® system uses a thin mat placed on the floor to measure the pressure distribution under the feet while standing and walking. Measurement of foot pressure distribution enables quantification of balance and stability to give insight into high pressure spots, foot contact area, impaired balance, normal and abnormal foot function, as well as the effects of different shoes, orthotics and prosthetics on foot function.

Acknowledgements

The School of Physiotherapy wishes to gratefully acknowledge the support of the New Zealand Lottery Grants Board whose funding has enabled the purchase of the electromyography [Noraxon TeleMyo 2400T] and pressure sensing [RSscan`] systems.

Capture and Analysis

The process of capturing movement with optical based systems involves the use of multiple video cameras and infra red illumination to reconstruct the 3D positions of reflective markers placed on the subject. With a model of the subject, underlying segment movements can then be reconstructed from the three dimensional marker locations.

Motion Capture:

Real time 3D motion capture is achieved using infrared illumination of reflective markers placed on the subject to identify bone landmarks and segment locations. Infrared illumination of the markers allows automatic digitization of 2D marker locations in each camera view. With accurate calibration of camera positions, the 2D coordinate data can be combined to reconstruct the 3D location of the markers.

Static Calibration:

Static calibration locates segment fixed axes with respect to each segment via calibration markers placed on specific bony landmarks and the subject in a known anatomical position. Segment fixed axes are defined from calibration markers using reference data and measured body dimensions. The main purpose of static calibration is to establish the local coordinates of segment markers with respect to a segment fixed axes. Segment markers are then used during movement trials to locate 3D segment position.

Movement Trials:

By reconstructing the global (or lab space) three dimensional coordinates of segment markers, and with known local coordinates of these markers with respect to a local body fixed axes, the three dimensional location of the body fixed axes can be determined. This can be achieved with a minimum of three markers per segment, however due to skin movement artefact and to a lesser extent photogrammetric errors four markers and a least squares approach is preferred to minimize errors in segment location.

Analysis:

Computer or mathematical modelling can then be used to either animate the character or calculate kinematics (position, velocity and accelerations) describing segment motion.

The measurement of ground reaction and other external forces allows segment kinetics (resultant forces, work and energy) to be calculated. With detailed modelling of individual muscle forces, bones contact forces can also be estimated in the generation of movement.

Applications

The flexibility of the motion capture and analysis system allows the Biomechanics Laboratory to be used for a variety of tasks including:

Motion capture for computer animation
3D modelling & visualisation
Clinical gait analysis, including:
- Cerebral palsy
- Prosthetics
- Diabetic gait
Injury prevention
Rehabilitation
Sports skill analysis
Motor learning and control
Occupational and work task assessment
Jaw function and visualisation
Forensic Science
Animal Locomotion

The laboratory’s highly-trained staff utilise state-of-the-art technology in computerised motion capture and analysis. As part of its commitment to providing cutting-edge services for education, research and industry, the School of Physiotherapy’s, Centre for Physiotherapy Research: Biomechanics Laboratory is able to offer flexible and specialised motion capture and analysis services.

Animals

Animal and human locomotion

School of Zoology University of Otago, Dunedin, New Zealand.

Canine locomotion

School of Zoology University of Otago, Dunedin, New Zealand.

Animation

The Motion Analysis System supports the major animation software packages including Alias' Maya, Discreet's 3ds max, Softimage's XSI and 3D, Lightwave's 3D, and Kaydara's FiLMBOX.

Used by: