Our new motion capture system

At Vitrue we’re developing technology that tracks a patient’s movement, assesses that movement and uses it to generate clinically meaningful and actionable reports on the patient’s motor function.

The first part, technology capable of tracking human body movement, is not new. For example high fidelity optical motion capture has been used in biomechanics, entertainment and engineering applications for a couple of decades. However, finding a way to integrate that technology into existing patient pathways without substantial disruption is a different matter (which is a whole other blog post, watch this space).

There is always a usability vs accuracy trade off and quantifying or minimising that requires some hard work and access to several tracking technologies. To do all this we have invested in a state of the art optical motion capture system from Vicon Motion Systems. This post will show what was involved in getting it running!

Choosing a system:

There are two primary technology options - optical or inertial. Our team have worked with both in the past and know the pros and cons of each.

Inertial systems:

• Pro: No set volume so much more freedom to move around

• Con: Significantly less accuracy than optical (and drift in measurements is particularly high)

Markerless Optical:

• Pro: No need to put markers on (for example just to track your lower body it takes 16 markers!)

• Cons: Accuracy is still limited (though with some of the work going on right now, including at Google and Facebook often driven by VR needs, this might soon change!)

Markered Optical:

• Pro: Sub millimeter accuracy possible

• Cons: Time consuming setup (Calibration intense and lots of markers to put on)

The freedom of an inertial system from any set volume is attractive, but ultimately because we’re using this system as a ground truth we need the accuracy of an optical system. Similarly this rules out markerless optical systems leaving us with marker based optical tracking. Within this space there are multiple providers. I worked for the world leader Vicon Motion Systems for a few years helping to design the cameras so I know the quality of technology in both the Vicon hardware and software. That made Vicon easily the best choice.

The space:

Our office in Camden has a perfect space for a high spec motion capture volume. A 4x4 m volume is perfect for our application. A couple of trips to the hardware shop, about 40 holes drilled, and a divider wall donated from our Camden Collective neighbours accuRx and the cameras are up and ready to go.

System setup:

Our custom built PC from scan computers arrived and we installed Vicon Nexus (with some great responsive support from Vicon). We installed the hardware and software, calibrated and were capturing data in a few hours.

With our new capture volume we can develop, refine and validate new motor function tests in hours!

If you’re a clinician or engineer you’d like to come help, we’re hiring!!