First steps

[Jr Franklin]

Dear friends,

after exchanging ideas with a PhD about robotics, he recommended me to purchase Emotiv BCI device below.

Insight – 5 Channel Wireless EEG Headset

I seriously consider purchasing it but, before purchasing, there are some questions I’d like to ask as I’m totally new to the concept of BCI interface.

How does this BCI differentiate each signal for raising left/right arm, moving each finger, etc., while sending signals to computer interface? Which data captured by this BCI specifically says, “this is end user thinking of raising this arm” and “this is end user thinking of moving this finger with this arm”?

Other questions will follow but I’d like to have these questions answered first.

Regards,

Franklin

[Orozco Malachy]

Hi, Franklin,

First – these forums are something of a ghost town. I hope more people show up. Most posts are several months old, and there doesn’t seem to be much activity from anyone who works for Emotiv. I’m happy to be corrected, but this is what I’m seeing so far.

To your question:

There might be a simpler way to do this, but this is the method that I’m working on at the moment:

It feels like you’re asking: how does the device differentiate between ‘participant is thinking of moving left / right arm or hand or finger?’

I’m assuming that your experiment involves getting a robot arm to mimic the movement of a human arm.

I think it depends on the participant, but the general process seems to be:

1. Ask participant to think of nothing.
2. Note their ‘baseline’ measurements.
3. Ask particpant to do something (move their arm, limb, finger, hand, et cetera).
4. Note the new measurements.
5. You would then translate the difference between those measurements to the movement that your robotic device is meant to carry out.
6. The more times you repeat this ‘tuning’ process, the more likely you are to establish the numerical ranges within which ‘baseline’ will sit, and within which ‘move their arm, limb, finger, hand, et cetera’ will sit.

(Note that ‘baseline’ and ‘doing an action’ will vary from participant to participant.)

So, for example: if the difference between baseline and ‘arm raised’ is 0-100 for each sensor’s input, then you would map out the limits of the robotic device’s range of movement based on the mathematical difference.

You say: ‘think of nothing’ – sensor 1 reads ‘0’; sensor 2 reads ’40’; sensor 3 reads ’20’.

You say: ‘raise your right arm’ – sensor 1 reads ’30’; sensor 2 reads ’80’; sensor 3 reads ‘100’

To establish ‘gradient’ – so, the action of raising the arm is partially completed / the arm is half-raised – if sensor 1 reads ’15’; sensor 2 reads ’40’; sensor 3 reads ’50’ the arm would then be half-raised.

Therefore – the robot arm should be fully raised when the readouts from the sensors are landing within the ranges that you establish.

I hope this helps.

My Best,

Mal

 

[Orozco Malachy]

Sorry – I should have mentioned:

I’m assuming that the robotic arm will be able to move along the x, y, and z axes.

So:

You say: ‘think of nothing’ – sensor 1 reads ‘0’; sensor 2 reads ’40’; sensor 3 reads ’20’: robot arm x position is 0; y is 0; z is 0.

You say: ‘raise your right arm’ – sensor 1 reads ’30’; sensor 2 reads ’80’; sensor 3 reads ‘100’: robot arm x is 100; y is 100; z is 100.

To establish ‘gradient’ – so, the action of raising the arm is partially completed / the arm is half-raised – if sensor 1 reads ’15’; sensor 2 reads ’40’; sensor 3 reads ’50’ the arm would then be half-raised: robot arm x is 50; y is 50; z is 50.

[Jr Franklin]

Thanks for your answers Orozco, I saved them in my mailbox for further reference. And here comes the reason why I purchased an Emotiv BCI.

A friend of mine became paralyzed after having encephalitis, and my idea is to create a prosthetic device that will be used by quadriplegic people like her. The concept is of a 3D-printed glove for her hands and fingers, arms and eventually shoulders. While the idea behind the device is neither “cure” her quadriplegy (which depends of other factors far from my knowledge) nor allow 100% precision and dexterity, it’ll grant her some degree of freedom and autonomy with her upper limbs, and act as a therapy as well.

BCI receives brain signals such as “move right hand”, send these signals to a mobile app or a computer, and these signals are sent to the prosthetic limbs in order to perform the desired movements which are currently not possible due to her palsy.

I’d like to talk with people involved in prosthetics to get things started; I already have some contacts, but the more people involved, the better it’ll be.

Regards,

Franklin

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