OLGA

OLGA is a procedure which will increase the accuracy and repeatability of trials that have been captured with the Newington/Helen Hayes marker set and processed with the Conventional Gait Model (CGM), also known as the Davis/Kadaba model (as implemented by Vicon first in VCM and later in Plug-in Gait).

The basic idea is to take the output of the CGM and try to improve on the locations of the joint centers and the orientations of the segments by looking at the measured movement across the entire trial. If the movement around a particular axis is significant, it is possible to use a method known as Global Optimization [Lu and O'Connor, 1999. Journal of Biomechanics, 32, p. 129-134.] to try and optimize the locations of the coordinate systems so that they more closely match the measured movement. This is an iterative procedure which will converge towards the optimal solution - which is the solution that minimizes the distances between where the markers "should have been" according to their local segment attachments and where they have actually been measured.

This results in a calibrated model, which describes kinematic skeleton in terms of the optimal relationships between the segments and markers. OLGA users have three choices when choosing which trials to use for the calibration:

An active range of motion trial where the patient moves the joints over the lower body through their full range as far as possible.
A passive range of motion trial where the patient is assisted in moving the joints through their range of motion.
A typical walking trial.

If a calibration has converged successfully, it can be used to kinematic fit several walking trials. This procedure will use a fast least-square based algorithm to find the best fit for the calibrated skeleton given any set of measured marker positions.

Furthermore, the kinematic fit procedure includes an intelligent filter which smoothes the marker data by applying a dynamical model Kalman filtering technique, giving much smoother data without the need for filtering raw marker data.

In addition, OLGA locates the main axis of flexion of the knee joints, resulting in much more reliable and meaningful interpretation of the lower limb kinematics and kinetics.

REFERENCE MATERIAL
(1) Roren, L. and Tate, P. (2002) A new lower body model using global optimisation techniques. Proc.VII Meeting of GCMAS, Gait & Posture, 16 (S1), p S14-S15.

(2) Charlton, I.W., Tate, P., Smyth, P. and Roren, L. (2002) Calibration of kinematic models for motion capture. Proc. IV World Congress of Biomechanics, August 2002, Calgary, Canada.

(3) Charlton, I.W., Tate, P. and Roren, L. (2002) Repeatability of an optimised lower body model. Proc. XI Meeting of ESMAC, Gait & Posture, 16 (S1), p S127.

(4) Charlton, I.W., Tate, P. and Roren, L. (2002) Repeatability of an optimised lower body model. Gait & Posture, 20, p 213-221.

Downloads

Click here to download the OLGA Explained White Paper.

Screens

Tracker

Vicon Tracker is a specifically configured 3D optical tracking system designed for users of virtual environments, simulators and visualisation systems who currently use cumbersome magnetic or inertial tracking systems.

Vicon Tracker is a specifically configured Vicon 3D optical tracking system designed for Virtual and Immersive environments. It combines Vicon expertise and technology in a package suitable for your VR application.

Precise motion tracking and accurate latency free tracking is key to creating a realistic sense of immersion in Visualisations and Simulations. Vicon Tracker delivers six degrees-of-freedom (6DOF) data for the full range of targets using reflective markers and high speed, high-resolution cameras.

Vicon Tracker outclasses obsolescent electromagnetic, inertial and ultrasonic technologies in speed, latency and precision, yet is the simplest to set up and calibrate. Optical technology provides interference free performance and is not susceptible to motion errors, which effect other systems.

Highest positional and angular accuracy
6 DOF multiple targets
Low latency
Wireless
Scalable
Fast setup
Zero interference

	TRACKER BROCHURE - LOW RESOLUTION Click on the pdf icon to download. This file is 492Kb.

	TRACKER BROCHURE - HIGH RESOLUTION Click on the pdf icon to download. This file is 6Mb.

PECS

Vicon PECS represents a new, powerful way of integrating with 3rd party software. Instead of exchanging data between applications using a data file, the PECS plug-in allows data to be directly accessed and modified by popular 3rd party applications, as part of the Workstation pipeline.

ULTIMATE IN FLEXIBILITY
The PECS plug-in works as a data server, to which 3rd party applications can communicate via Microsoft’s Automation interface technology. As long as the 3rd party application supports this interface, data can be exported, imported and manipulated. Popular applications that already support these interfaces include Microsoft Excel, Visual Basic, MatLab and LabView. This enables you to write scripts in, for example, Excel, that directly access the data inside Workstation.

NO NEED FOR FILE IMPORTERS AND EXPORTERS
Because the data transfer happens using objects rather than files, there’s no need to worry about what file formats Vicon uses with respect to what file formats the 3rd party application uses. All you need to do is to hook the 3rd party application up to the PECS server, access the data and, optionally, process and put the results back into Workstation.

ACCESS THIRD-PARTY SCRIPTING LANGUAGES
Although Vicon BodyBuilder provides a powerful scripting language, Vicon acknowledge that other, more powerful languages are sometimes needed. MatLab, for example, is such a language and PECS enables you to fully exploit MatLab’s capabilities to process motion data. It could not be simpler: when you run PECS in the Workstation pipeline, MatLab (or whatever other 3rd party application) will be automatically launched in the background and execute a MatLab script.

THERE’S EVEN A DEBUG MODE
To make the development of the script that access the data via PECS even simpler, PECS has a debug mode that allows you to start the 3rd party application, hook it dynamically to PECS and access the data in Workstation via PECS as you are typing and executing the script inside the 3rd party application. Thus, you can easily develop and debug the script in PECS debug mode and then switch to ordinary mode for routine processing.

SEAMLESS INTEGRATION INTO THE VICON WORKSTATION PIPELINE
Since PECS looks like an ordinary plug-in to Workstation, you are able to via PECS execute any 3rd party script seamlessly – just as you would use the “ordinary” plug-ins such as Plug-in Gait or Plug-in Modeler. Thus, once a script has been developed and is ready for routine processing, the actual processing will simply happen in the background and the operator will not have to know how to use the third-party application.

PECS BROCHURE
Click on the pdf icon to download. This file is 133Kb

Vicon Analysis Toolkit

The Analysis Toolkit is a collection of plug-ins that integrate with the Vicon Workstation pipeline to offer you a range of useful functions, including customized yet automatic generation of events, calculation of temporal-spatial parameters and Butterworth filtering.

The Toolkit has been developed in close cooperation with users, and offer intuitive, user friendly interfaces allowing you to set up your customized calculations quickly and easily. The toolkit can be used for many applications, including Sport, Animal Science, Neuroscience and Clinical Gait.

ANALYSIS TOOLKIT KEY BENEFITS
• Simplify your workflow by automatically generating and auto-correlating events
• Calculate extra temporal-spatial parameters to incorporate into later analysis
• User interaction based on simple dialogs – no need to learn a scripting language
• Seamlessly integrated with the Vicon Workstation one-click processing pipeline
• Add useful, time-saving automated features to your workflow

FULLY INTEGRATED
The Analysis Toolkit fits seamlessly into the Vicon Workstation pipeline, allowing you to pick and choose which functions you need to use for particular applications. The Workstation Trial Type customization utility allows you to set up pre-defined workflows where you simply select the plug-ins you need for a particular application. Added to the standard plug-ins available, the Toolkit offers you an extremely powerful set of functionality designed to save time and automate tasks that would otherwise require tedious manual work.

GENERATE EVENTS
Two of the plug-ins, the Event Correlator and the Event Generator plug-ins automatically generate events based on certain pre-defined criteria. The Event Correlator uses a pre-recorded snippet of motion data to compare with the current data and automatically determine where new events need to be added. The Event Generator uses thresholds or percentage calculations to add new events based on other recorded data such as marker trajectories (for example, an event can be generated when a marker’s vertical coordinate crosses a pre-defined threshold). Whether you need to automatically identify the time when a horse’s hoof strikes the ground or when a subject’s finger touches a button, one of these two plug-ins will solve the problem.

CALCULATE NEW PARAMETERS
The Parameter Calculator plug-in allows you to calculate new parameters based on a large range of functions such as minima, maxima, averages, distances and velocities. It is very simple – just bring up the user-friendly dialog interface, choose the data on which to base the calculations and select the function. You can calculate any number of independent parameters which will be added to your data file, and which can later be viewed in Vicon Polygon or other analysis or reporting software. So, if you would like to know the maximum knee flexion during swing or the maximum speed of a golf club’s head during downswing, this plug-in calculates the answer and adds it to the data set.

BUTTERWORTH FILTER
If you’ve ever wanted to use a standard Butterworth filter on trajectories or analog data, this plug-in allows you to do just that. The Butterworth filter is a standard, publicized smoothing algorithm which is commonly used in a wide range of applications.

IMPORT DATA FROM ASCII FILES
The ASCII importer is the ideal tool for transferring data from text-based file formats to Workstation. Instead of having to go via the C3D file format, you can read files which, for example, have been saved in Microsoft Excel as text files. Using the plug-in, data in such files is seamlessly added to the Workstation data store – and merged with data captured by the Vicon system. You can then choose to do further processing or exporting to a range of file formats. The plug-in is a great tool if you need to merge data from 3rd party measurement equipment or if you want to add reference data from earlier experiments to your current processing.

CONVERT THOSE PELVIS ANGLES
The format of the Euler angle output for the Pelvis angles has been widely discussed. The normal way of decomposing the pelvis orientation to the 3 Euler components is to extract Tilt first, then Obliquity and finally Rotation (the so-called TOR sequence). However, several authorities have proposed that extracting Rotation, then Obliquity and finally Tilt (the ROT sequence) yields data that is much more intuitive and logical for clinical interpretation. This plug-in lets you choose: either keep the default TOR, or convert to ROT by adding the Pelvis Angle Converter to your pipeline.

LINK TO OTHER APPLICATIONS
Ever wished you could start another application from within the Workstation pipeline and pass parameters such as the filename of the currently open trial along? The Application Linker plug-in allows you to do this seamlessly and automatically. You could, for example, open a 3rd party application such as MatLab and then have it automatically import the data and run a script.

Screens

Oxford Foot Model

The Oxford Foot Model is a clnically tested and validated model which can quickly add a valuable dimension to your studies. The model is available as a plug-in that seamlessley integrates with Vicon Nexus and Vicon Workstation.

The Oxford Foot model has been developed by the Nuffield Orthopaedic Centre (NOC) and Oxford University.

CLINICALLY VALIDATED
The NOC has used the Oxford Foot Model clinically for several years, and has published many clinical papers on the validation of the model during this time. Based on two main foot segments – hindfoot and forefoot – plus a separate hallux segment, the model outputs adjusted kinematics for the ankle as well as the added inter-segment angles.

SEAMLESS
The Oxford Foot Model has been implemented to run seamlessly in the one click processing pipeline of Vicon Nexus, where it appears alongside standard plug-ins such as Plug-in Gait and Plug-in Modeler. You can start using the foot model simply by adding one more processing step to the pipeline, which is automatically executed without complicating your existing workflow.

COMPATIBLE
The marker set for the Oxford Foot Model is an extension to the Conventional Gait Model, implemented in Vicon Plug-in Gait. This means you can conduct a detailed foot analysis at the same time as you work through the standard gait data acquisition. There is no need to remove one marker set and attach another, and you get results from both models for the same gait cycle. Easier for the patient, and easier for you.

Output from the foot model appears as extra data next to the standard plug-in Gait kinematics and kinetics, allowing you to choose what added information you wish to use.

USE IT AT NO EXTRA COST
The Oxford Foot Model is available to all Vicon Nexus and Vicon Workstation users at no extra cost. Try it out and see how it can quickly add a valuable dimension to your clinical studies.

HOW TO DOWNLOAD
To download the Oxford Foot Model login in to your Vicon Online Support account and click on downloads. When in downloads navigate to the plug-ins folder or type Oxford Foot Model in to the search facility.