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A project log for Human Limb Tracking

A system that tracks limb movement of people who have movement disorders to assist in diagnosis and therapy

Jonathan KellyJonathan Kelly 04/08/2016 at 01:150 Comments

This is a bit of a ramble... sorry


Some background

My youngest child has a form of athetoid cerebral palsy that causes uncontrolled movement.

I am interested in ways I can use technology to help overcome some of the problems that condition causes.

I started this as a part time project over 18 months ago.

The original idea was to look at providing alternative ways of sensing exactly what your limbs are doing (particularly if they are not moving how you are intending to move them!) to help gain better control of your body.

One of the initial inspirations was how sometimes an unintentionally flexed muscle would relax if you stroked lightly the associated 'opposite' (or 'antagonist') muscle (eg if the bicep flexed, stroking the tricep at the back of the arm would seem to often help release the bicep) .

What I was initially interested in looking at:

1. ways of sensing when a muscle was unintentionally flexed and perhaps applying automatically some form of tactile feedback to the antagonist muscle (eg a vibration).

2. ways to provide additional proprioceptive feedback about limb movement (eg visual, tactile, auditory etc) in addition to the feedback our body gives normally.

3. ways to measure long term changes in the way the condition manifests itself, particularly when evaluating various therapies.

The first step in exploring these ideas, was to develop a system to accurately and unobtrusively measure limb motion.

So I started doing that.

That is this project.

It has been going about 2 years.

Where the project is now:

1. I have a working prototype. It is a bit rough and clunky but proves the system works.

2. it was used whilst trialing a drug treatment that can sometimes help people with dystonic movement disorders. (This was done in addition to the standard evaluation technique that involves experts taking before and after videos of various tasks that typically are used to diagnose dystonia). Unfortunately the drug trial was stopped part way through as it appeared subjectively to those involved to be causing more clumsiness and difficulty controlling movement rather than improving it.

The system did appear to also indicate more objectively a worsening of control that confirmed to me it was a potentially useful tool.

Where I am (personally) at now

After talking about what I was doing with friends and acquaintances over the last 2 years I started to wonder if something like this could be turned into a commercial product and what would be involved. I foolishly started to think of perhaps making a company that produced motion capturing systems.

Meanwhile, I hadn't done a lot of looking at what was out in the real world for some time - I was too engrossed in the nuts and bolts of getting it working.

I recently discovered that since I started playing with the technology, many people have been doing similar things (including several projects on this site) and I also saw that other's have recently come to market with commercial devices using IMUs for sensing of limb postion.

Which I should have realised was to be expected - IMUs and tracking your body are a pretty obvious match!

But to me this came as shock (silly me!) and was discouraging but then I thought - why am I doing this? To make a commercial product? or to explore how I can assist people with movement disorders?

It is the second - I had lost sight of the motivation - I am not trying to make a business. I want to see if I can make something that can assist the day to day life of people (like my son).


So where I am heading with it:

I now want to start looking at the other initial spurs that started me on the project: ie

1. sensing if a muscle is unintentionally flexed

2. providing feedback to the person (eg automatic tactile feedback to antagonist muscle pairs and alternative proprioceptive feedback to build better unconcious understanding of where your limbs actually are.

and integrate those ideas with the existing tracking system. I also need to refine the system to make it less physically clunky and more robust.

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