Realtà virtuale comandata dalle onde cerebrali

Transcription

1 Torino, 23 Settembre 2016 Realtà virtuale comandata dalle onde cerebrali Sebastiano

2 Sponsor

3 Brainwaves. Not thoughts. Measuring Electroencephalogram (EEG) activity has historically required complex, intimidating and immovable equipment costing thousands of dollars.

4 Brainwaves. Not thoughts. NeuroSky is unlock a new world of solutions for education and entertainment with their research-grade, mobile, embeddable EEG biosensor solutions. 4/8

5 Brainwaves. Not thoughts. 5/8

6 BrainWave Studio 6/8

7 Brainwaves reading 7/8

8 Fast Fourier Transform Reading analog raw data stream from EEG headset, the signal is transformed using Fast Fourier Transfom to get magnitudes of main frequencies. 8/8

9 Fast Fourier Transform The Fast Fourier Transform (FFT) transforms one function into another, which is called the frequency domain representation of the original function.

10 Fast Fourier Transform The DFT requires an input function that is discrete. Such inputs are often created by sampling a continuous function.

11 Fast Fourier Transform - Sampling The sampling rate, or sampling frequency defines the number of samples per unit of time (usually seconds) taken from a continuous signal to make a discrete signal. The choice of sampling frequency is arbitrary. A signal contains various frequency components that can be detected. The frequency equal to half of the sampling frequency is the highest detectable frequency. It's called the Nyquist or folding frequency. For a signal sampled with the sampling rate fs, due to the limitation imposed by the Shannon Theorem, components of the spectrum can only be extracted for frequencies between -fs/2 <= f <= fs/2, or between the negative and positive Nyquist frequency.

12 Fast Fourier Transform The FFT algorithm only applies to signals comprising a number of elements which is equal to 2n and returns a set of complex numbers, with the exception of the spectral components at f=0 and fs/2 ( the Nyquist frequency ), which are both real. The number of FFT elements is equal to the size of the time sample. The second half of these complex numbers corresponds to negative frequencies and contains complex conjugates of the first half for the positive frequencies, and does not carry any new information.

13 Fast Fourier Transform - Result interpretation Assuming that the number of samples k, being a power of 2, was sampled with a frequency fs, then The frequency resolution Δf = fs/k The maximun frequency of the spectrum is the Nyquist frequency = fs/2 FFT returns k complex numbers with spectral components as follows: The first item is for f=0. Since it has to be real, its imaginary component is 0. The maximun frequency of the spectrum is the Nyquist frequency = fs/2. The first k/2 items are for all positive frequencies in increasing order from Δf, 2Δf, 3Δf,..., (k/2-1)δf ( or fs/2 ) the next k/2-1 elements contains the negative frequency components and can be ignored.

14 Fast Fourier Transform - Spectrum

15 Brainwaves. Not thoughts.

16 Delta waves Frequency range: 0.1Hz to 3Hz Mental states and conditions Deep, dreamless sleep non-rem sleep unconscious

17 Theta waves Frequency range: 4Hz to 7Hz Mental states and conditions Intuitive Creative recall fantasy imaginary dream

18 Alpha waves Frequency range: 8Hz to 12Hz Mental states and conditions Relaxed, but not drowsy, tranquil, conscious Long term memory activated Visualization, meditation. Learning is easy and rapid

19 Beta waves Frequency range: 12Hz to 30Hz Mental states and conditions Low beta: 12Hz to 15 Hz Formerly SMR ( stronger you are idle, not moving), relaxed yet focused, integrated Mid beta: 15Hz to 20Hz Tinking, aware of self & surroundings Short term memory being used High beta: 21 Hz to 30 Hz Alertness, agitation

20 Gamma waves Frequency range: 30Hz to 100Hz Mental states and conditions Motor Functions Higher mental activity, which is great for learning

21 ThinkGear ThinkGear is the technology inside every NeuroSky product or partner product that enables a device to interface with the wearers brainwaves. It includes: the sensor that touches the forehead the contact and reference points located on the ear pad and the onboard chip that processes all of the data and provides this data to software and applications in digital form. Both the raw brainwaves and the esense Meters (Attention and Meditation) are calculated on the ThinkGear chip.

22 ThinkGear - esense(tm) Meters For all the different types of esenses (i.e. Attention, Meditation), the meter value is reported on a relative esense scale of 1 to 100. A value between 40 to 60 at any given moment in time is considered neutral A value from 60 to 80 is considered slightly elevated, and may be interpreted as levels being possibly higher than normal (levels of Attention or Meditation that may be higher than normal for a given person). Values from 80 to 100 are considered elevated, meaning they are strongly indicative of heightened levels of that esense.

23 Neurosky SDK 23/8

24 Snail Mind Race

25 Stereoscopic Vision

26 Eye calibration