Motion capture system

Tracking of markers, rigid bodies and skeletons

The laboratory is equipped with a state-of-the-art motion capture system by OptiTrack. It uses 18 Felx13 cameras, and is capable of recording at 120 fps.

Camera images are synced, and 3D information is extracted using OptiTrack’s Motive software. Data can be recorded, exported into numeric data. Real time streaming is also available through the NatNet protocol.

The system uses passive markers, which are reflective to infrared light. The system is capable of tracking single markers, as well as rigid clusters of markers, and complete skeletons using a motion capture suit.

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Balancing measurements

The assessment of balancing abilities is an integral part of orthopaedic and physiotherapeutic evaluation. The use of static balance assessment, such as posturography is widespread in clinical practice.

Dynamic balance tests are aimed at assessing complex coordination such as stabilizing posture and recovery of balance after a sudden perturbation. A widely used therapeutic and diagnostic method is to apply a sudden unidirectional perturbation on a free oscillating platform. In our laboratory, we use a Posturomed© platform (Haider Bioswing, Germany).

The participants stands on the platform that is locked outside of its resting position. Release of the lock triggers the platform perturbation. Following the perturbation, the participant instinctively attempts to regain postural balance. This balancing acts as a damping agent to decrease and eventually stop the oscillation. We are analysing the effectiveness of damping and the path and strategy of balance recovery as well.

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Motion analysing softwares

We use a custom developed motion analysis platform nicknamed MUBMA. This program can receive motion capture data from any NatNet based server. This program implements virtual marker tracking feature, meaning points can be tracked without actual markers, as long as an object is tracked, that the point id rigidly attached to.

This makes it possible to track motion below the surface of skin, making motion analysis more accurate. Custom “biomechanical models” can be implemented in this program, meaning every user can create the measurement setup best used for their goals, and the evaluation algorithms to go with it.

This means that with the right model, the program can be used in a wide variety of applications ranging from academic research, to use in clinical applications, and analysis and development of atheletes motions.

We also use the open source biomechanical simulation software OpenSim. This program is capable of processing exported motion capture data, to calculate joint angles, and a wide variety of other biomechanical parameters.

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Sports biomechanics

We study the effect of various sports on the human motion, especially movement coordination and motion repetition. We develop and perform measurements in the laboratory with the aim to arrive at practical results as well.

We are currently working on a project with basketball players to identify important movement patterns that may lead to injury with time.

In another, student-led project, we are analysing Hungarian folk dancer's balancing abilities and motion performance.

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Gait analysis

Gait analysis is the measurement of forward motion, walking and running

We use these measurements to understand how the highly complex biomechanical system of humans and animals work, as well as to diagnose musculoskeletal disorders, and track the progress of rehabilitation.

Gait analysis is subject to many measurement errors. The overlying skin and soft tissues make it difficult to track the skeletal movements. We us a state-of-the-art motion capture system in conjunction with rigid body tracking.

Bony anatomical landmarks are tracked virtually, based on their relative position to the rigidbody tracking the movement of the appropriate body segment. This helps reduce the artefacts related to skin-bone relative movements, and makes highly accurate gait analysis measurements possible.

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Additional devices of the MotionLab

There are several high-tech devices that we aim to incorporate into our education and projects.

These devices include wireless EEG-headsets, clinical-rate EMG-devices and Virtual Reality headsets.

Some projects involve Virtual Reality (VR). Pairing a VR headset with our Motion Capture system, users are able to see their virtual bodies which is not possible in current systems.

More on these later...

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