WO2012044261A1

WO2012044261A1 - System and method for ssvep based control of electrical devices

Info

Publication number: WO2012044261A1
Application number: PCT/TH2010/000036
Authority: WO
Inventors: Yodchanan Wongsawat; Yunyong Punsawad
Original assignee: The Office Of National Telecommunications Commission
Priority date: 2010-09-29
Filing date: 2010-09-29
Publication date: 2012-04-05
Also published as: JP2013544546A; JP5688154B2

Abstract

In a system for SSVEP based electrical device control, a user state detection module can detect user behaviour such as an eyes closed state across a particular time interval. A system control unit can responsively activate a set of visual stimulus generators. Each visual stimulus generator can output visual signals at a unique presentation frequency. A user can selectively direct their visual attention to a particular visual stimulus generator associated with a specific electrical device or interface while an EEG acquisition unit captures EEG signals corresponding to SSVEPs generated by the user's brain. A device identification module generates EEG power spectral amplitude data corresponding to particular fundamental frequencies F _k, determines a dominant frequency F _D, and identifies a visual stimulus generator that output visual stimuli at a presentation frequency equal to F _D. The system control unit communicates an electrical device control command to a multi-device interface unit, which changes an operational state of an electrical device associated with the identified visual stimulus generator.

Description

SYSTEM AND METHOD FOR SSVEP BASED CONTROL OF ELECTRICAL

DEVICES

Technical Field

The present disclosure relates to brain - computer interface (BCI) techniques based upon steady state visual evoked potentials (SSVEPs). More particularly, aspects of the present disclosure relate to systems and methods for SSVEP based electrical device or appliance control that provide a simple electrode configuration for the capture of electroencephalographic (EEG) signals; a computationally efficient, accurate process by which EEG signals are analyzed and a visual stimulus generator associated with an appliance identified; a simple, reliable multi-device power interface unit; and a simple, robust, assistance-free system activation process that avoids or eliminates visual fatigue and/or user distraction.

Background

Aspects of brain waves measured from the human scalp have been intensely researched as a result of efforts to develop brain-computer interface (BCI) systems and devices. A BCI is a direct communication pathway between a brain and an external device. BCIs are often aimed at assisting, augmenting or repairing human cognitive or sensory-motor functions.

BCI techniques play a prominent role in the development of systems that utilize electromyogram (EMG), electrocorticogram (ECoG), or electroencephalogram (EEG) signals to facilitate a disabled user's control of a neuroprosthetic device. EEG is a common non-invasive modality that can be used with persons with serious disability. EEG signals arise from electrical activity that can be detected external to the human scalp. EEG signals are produced by neural firing within the brain, and reflect correlated synaptic activity caused by post-synaptic potentials generated by thousands or millions of cortical neurons having similar spatial orientation.

Acquisition of EEG signals involves scalp electrodes or leads, typically using locations specified by the International 10-20 system. In EEG, minute potentials evoked by sensory stimuli are of particular importance as these time-locked transient wavelets show how populations of cells behave in response to afferent volleys carried by primary sensory fibers. When a brief stimulus is presented to a subject, a transient brain response to that stimulation occurs. In general, EEG-based neuroprosthetic systems consist of a signal acquisition system, signal processing algorithms and application devices. Two modalities widely used in EEG-based neuroprosthetic systems are spontaneous EEG and event related potentials (ERPs) such as visual evoked potentials (VEPs). An evoked potential indicates the effect of a stimulus on the brain, and is sensitive to changes in sensory and perceptual processes. A primary advantage of the VEP technique is its temporal resolution, which is limited only by measurement device sampling rate.

VEPs can be categorized into transient visual evoked potentials (TVEPs) and steady state visual evoked potentials (SSVEPs). The SSVEP is a periodic response to a visual stimulus modulated at a frequency higher than 6 Hz, and can be recorded at scalp locations corresponding to the visual cortex. The visual stimulus can be generated by a light emitting diode (LED) or a checkerboard or other pattern displayed by a liquid crystal display (LCD) screen. The SSVEP has the same fundamental frequency as that of the visual stimulus as well as its harmonics. In SSVEP-based systems, several stimuli coded by different frequencies are presented in the field of vision and different SSVEP responses can be produced by shifting a user's interest or attention to one of a number of frequency-coded stimuli.

Prior techniques directed to stimulus selection fail to produce reliable SSVEP signals for accurate operation of EEG-based neuroprosthetic systems without incurring visual fatigue in the subject under consideration. Further, prior stimulus systems can require unnecessarily complex circuitry, leading to increased system overhead and/or cost.

Prior electrode configurations are also unnecessarily complex. For instance, in order to obtain reliable SSVEP signals, electrodes have been positioned at as many as 64 different scalp locations, resulting in increased cost and undesirably long signal processing times. Several attempts have been made to place fewer electrodes on the human scalp to obtain SSVEP signals, but such attempts have led to poor and inaccurate SSVEP signals, and hence poor, inaccurate, and unreliable neuroprosthectic device control.

Another problem arises from existing algorithms used to process the SSVEP signals. Current algorithms are complex and produce inaccurate or inconsistent results, and lack the capability to effectively discriminate similar stimuli which are near or next to each other. Yet another problem arises because current implementations of EEG-based neuroprosthetic systems lack an easy to use, flexible, reliable and cost effective way of controlling multiple devices in response to EEG signals. Because EEG-based neuroprosthetic systems offer the potential to provide a significant positive impact upon physically challenged individuals' lives, a need exists for improvement to existing EEG-based neuroprosthetic systems. It is therefore desirable to provide a solution to address at least one of the foregoing problems associated with EEG-based neuroprosthetic systems.

Summary

An aspect of the disclosure provides an automated process for controlling a set of devices based upon the EEG data generated by an individual's brain. The set of devices can include a set of visual stimulus generators and a set of electrical devices, where each electrical device is associated with a given visual stimulus generator. The process can include transitioning each visual stimulus generator to a first state (e.g., a quiescent or inactive state, or a state in which SSVEP generation at frequencies corresponding to device control operations is avoided) in which the output of visual stimuli by each visual stimulus generator in a distinct manner relative to each other visual stimulus generator is avoided; accessing first EEG data generated by the individual's brain; determining whether the first EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command; and transitioning each visual stimulus generator within the set of visual stimulus generators to a second state in which each visual stimulus generator outputs visual stimuli in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators in response to the visual stimulus generator activation command. In the absence of the detection of a visual stimulus generator activation command, the visual stimulus generators can be maintained in the first state. When in the second state, each visual stimulus generator can provide visual stimuli at a distinct presentation frequency relative to each other visual stimulus. Determining that the first EEG data corresponds to an unassisted behaviour that represents a visual stimulus generator activation command can involve analyzing the first EEG data to identify an awake individual eyes-closed condition and/or eye closure - eye opening sequence across or with respect to a particular time interval, such as an activation command interval.

A process according to the disclosure can further involve accessing second EEG data corresponding to SSVEPs generated by the individual's brain while the user directed their visual attention to a particular visual stimulus generator, and determining whether the second EEG data indicates the particular visual stimulus generator to which the user directed their visual attention. Each visual stimulus generator can be transitioned to the first state in the event that analysis of the second EEG data fails to indicate the particular visual stimulus generator within the set of visual stimulus generators to which the user directed their attention.

The process can additionally include identifying the particular visual stimulus generator to which the user directed their visual attention; and adjusting an operational state (e.g., by establishing, changing, or toggling a power state) of a particular electrical device associated with or corresponding to the particular visual stimulus generator. In association with (e.g., before, during, or after) adjusting the particular electrical device's operating state, each visual stimulus generator can be transitioned or returned to the first state. According to particular aspects of the disclosure, a system for controlling a set of electrical devices based upon SSVEP generation by a system user's brain includes a set of visual stimulus generators, each of which is configured to output visual stimuli; a visual stimulus generator controller coupled to each visual stimulus generator and configured to selectively enable each visual stimulus generator to output visual stimuli in a distinct manner relative to each other visual stimulus generator; an EEG system or unit configured to provide EEG data generated by the user's brain; and a device identification system. The device identification system includes a processing unit coupled to a memory in which portions of a user state detection module reside. The user state detection module includes a program instruction set that when executed determines whether EEG data generated in response to an unassisted user behaviour corresponds to a visual stimulus generator activation command such as an awake user eyes- closed condition and/or an eye closure - eye opening sequence across a particular time interval. The visual stimulus generator controller can maintain the stimulus generators in a first state in which in the output of visual stimuli by each visual stimulus generator in a distinct manner relative to each other visual stimulus generator is avoided until a visual stimulus generator activation command is detected, after which the visual stimulus generator controller can transition the visual stimulus generators to a second state in which each visual stimulus generator outputs visual stimuli in a distinct manner relative to each other visual stimulus generator. The memory further can further include a device identification module having a set of program instructions configured to identify a particular visual stimulus generator to which the user has directed their visual attention based upon captured EEG data, thereby facilitating the identification and selective control of an electrical device associated with the particular visual stimulus generator. Certain aspects of the disclosure provide an EEG acquisition system having a set of electrodes spatially organized in accordance with a standard EEG 10-20 montage and configured to detect at least one of a first EEG signal difference between 01 - Fz and a second EEG signal difference between 02 - Fz. The set of electrodes can include fewer than five electrodes configured to detect EEG signals at any given time.

In addition or as an alternative to the foregoing, an aspect of the present disclosure provides a process for controlling a set of devices based upon SSVEPs generated by an individual's brain, which can include providing first EEG data corresponding to EEG signals generated by the individual's brain while the individual directed their visual attention to a baseline scene; generating a plurality of baseline power spectral density amplitude values corresponding to the first EEG data, the plurality of baseline power spectral density amplitude values corresponding to a set of fundamental frequencies and a set of harmonic multiples n/_k of each fundamental frequency fa and generating a device identification threshold T_\ using the plurality of baseline power spectral density amplitude values.

The process can further include providing second EEG data corresponding to SSVEPs generated by the individual's brain while the individual directed their visual attention to a particular visual stimulus generator within a set of visual stimulus generators, each of which is configured to provide visual stimuli at a unique presentation frequency approximately equal to a corresponding fundamental frequency^ within the set of fundamental frequencies^; generating a plurality of active power spectral density values corresponding to the second EEG data, the plurality of active power spectral density values corresponding to the set of fundamental frequencies^ and the set of harmonic multiples n _k thereof; generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and the device identification threshold T_\; and determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

Such a process can also include identifying a dominant frequency f corresponding to a dominant active power spectral density amplitude value, the dominant frequency 7 equal to a particular fundamental frequency f_k within the set of fundamental frequencies identifying a particular visual stimulus generator configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency identifying an electrical device associated with the particular visual stimulus generator; and one of establishing and adjusting an operating state of the electrical device associated with the particular visual stimulus generator.

According to an aspect of the disclosure, a system for controlling a set of devices based upon SSVEPs generated by an individual's brain can include a set of visual stimulus generators, each of which is configured to output visual stimuli; a visual stimulus generator controller coupled to each visual stimulus generator and configured to selectively enable each visual stimulus generator to output visual stimuli in a distinct manner relative to each other visual stimulus; an EEG data provision or acquisition system configured to provide EEG data generated by the user's brain; and a device identification system. The device identification system can include a processing unit coupled to a memory in which portions of a device identification module reside. The device identification module includes a set of program instructions that when executed identifies a particular visual stimulus generator by way of device identification operations that include generating a plurality of active power spectral density values corresponding to EEG data acquired while the individual directed their visual attention to the particular visual stimulus generator, the plurality of active power spectral density values corresponding to a set of fundamental frequencies and a set of harmonic multiples n _k thereof; generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and a device identification threshold Tj; and determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

The device identification operations can further include determining a dominant frequency f corresponding to a dominant active power spectral density amplitude value, the dominant frequency fa equal to a particular fundamental frequency within the set of fundamental frequencies^; identifying a particualr visual stimulus generator within the set of visual stimulus generators that output visual stimuli at a frequency corresponding to the dominant frequency / ; identifying an electrical device associated with the particular visual stimulus generator; and outputting a set of identifiers corresponding to at least one from the group of the particular visual stimulus generator and the electrical device associated therewith.

According to an aspect of the disclosure, the system can further include a system control unit configured to facilitate changing an operating state of the electrical device associated with the particular visual stimulus generator in response to receipt of one or more identifiers, commands, or instructions. The system control unit can be configured to output an electrical device control command based upon an identifier. The system can further include a device control interface configured for signal communication with the system control unit and further configured to one of establish and adjust an operating state of the electrical device associated with the particular visual stimulus generator.

The memory can also include a calibration unit, which includes a set of program instructions configured to perform calibration operations that involve analyzing baseline EEG data corresponding to EEG signals generated by the individual's brain while the individual directed their visual attention to a baseline scene; generating a plurality of baseline power spectral density amplitude values corresponding to the baseline EEG data, the plurality of baseline power spectral density amplitude values corresponding to the set of fundamental frequencies and the set of harmonic multiples n _k of each fundamental frequency fa and generating the device identification threshold T_\ using the plurality of baseline power spectral density amplitude values.

Particular aspects of the present disclosure further provide one or more computer readable media storing program instructions that, when executed, facilitate or enable SSVEP based device control operations in accordance with embodiments of the disclosure, such as embodiments described herein.

Brief Description of the Drawings

Embodiments of the disclosure are described hereinafter with reference to the following drawings, in which:

FIG. 1 is a schematic illustration of an SSVEP based appliance control system according to an embodiment of the disclosure. FIG. 2 is a schematic illustration of an electrode configuration with respect to the International EEG 10 - 20 montage according to an embodiment of the disclosure.

FIG. 3 is a block diagram of a system control and communication unit according to an embodiment of the disclosure.

FIG. 4 is a block diagram of a device identification unit according to an embodiment of the disclosure.

FIG. 5 is a schematic illustration of a representative configuration GUI 500 in accordance with an embodiment of the disclosure.

FIG. 6 is a flow diagram of a representative SSVEP based electrical device or appliance control process according to an embodiment of the disclosure.

FIG. 7 is a flow diagram of a representative baseline parameter generation process according to an embodiment of the disclosure

FIG. 8 is a flow diagram of a representative device identification process according to an embodiment of the disclosure.

Detailed Description

Embodiments of the present disclosure are directed to systems, apparatuses, devices, and processes for selectively controlling the operation of one or more electrical devices such as appliances based upon the capture and analysis of EEG signals corresponding to SSVEPs. The SSVEPs are generated while a user selectively directs their visual attention to a visual stimulus generator. Various embodiments include multiple visual stimulus generators, each of which can be associated with a given electrical device or appliance. Each visual stimulus generator is configured to generate, output, display, or present visual or optical stimuli or signals to a user in a distinct or distinguishable manner relative to each other visual stimulus generator. For instance, depending upon embodiment details, each visual stimulus generator can be configured to output visual stimuli at a unique or distinct presentation frequency and/or a distinct spatial presentation pattern. The visual stimuli can trigger, evoke, or give rise to SSVEPs within a portion of the user's brain at SSVEP frequencies that correspond to the presentation frequency. A visual stimulus generator can be an LED array, or another type of optical signal presentation device.

An EEG acquisition system, subsystem, or unit facilitates the capture or acquisition of EEG signals generated by the user's brain. User wearable headgear can carry a set of electrodes at particular locations relative to a user's scalp, such that the electrodes can capture EEG signals corresponding to SSVEPs. In various embodiments, the set of electrodes includes a small or minimal number of electrodes. A system control and communication unit can capture EEG signals as sampled EEG data. A device identification unit can analyze captured EEG signals by way of a computationally efficient process, and determines which visual stimulus generator gave rise to the captured EEG signals, thereby identifying the electrical device or appliance associated with the visual stimulus generator to which the user directed their visual attention.

The device identification unit can communicate or transfer a device identifier (ID) and/or a power interface ID to the system control and communication unit, which issues a corresponding device control command and/or a corresponding power interface control command to a multi- device interface unit. In response, the multi-device interface unit can transition, adjust, or establish an operating state of the electrical device or appliance associated with the visual stimulus generator. For instance, a multi-device power interface unit can transition a power interface corresponding to an electrical device or appliance from an off-state to an on-state, or an on-state to an off-state, thereby transitioning the electrical device or appliance associated with the visual stimulus generator from an off-state to an on-state, or an on-state to an off-state. The EEG acquisition unit, the system control and configuration unit, the device identification unit, and the multi-device interface unit thus facilitate automatically changing an operating state of an electrical device associated with a visual stimulus generator to which the user directed their visual attention.

In various embodiments, the system control and communication unit transitions the visual stimulus generators to a state in which the generation of visual stimuli by each active visual stimulator in a distinct manner relative to each other active visual stimulus generator is avoided unless the device identification unit determines or detects that an unassisted or self directed user activity or behaviour corresponding to or representative of a visual stimulus activation command has occurred. In multiple embodiments, the unassisted user behaviour includes an awake user eyes closed state or condition that exists across a predetermined time interval. Upon detection or identification of a user generated visual stimulus generator activation command, the device identification unit can communicate an activation notification to the system control and commumcation unit, which can enable the generation of visual stimuli by each active visual stimulus generator in a manner that is distinct (e.g., temporally and/or spatially distinct) relative to each other active visual stimulus generator. In several embodiments, the device identification unit can determine whether captured EEG signals indicate or correspond to an eyes closed condition, and possibly whether an eyes closed condition corresponds to a user awake state or a user sleep state. In response to or following the detection of an eyes closed, awake user state across a predetermined period of time, the system control and communication unit transitions the set of visual stimulus generators to an active state, such that a user with eyes open can direct their visual attention to an active visual stimulus generator associated with an electrical device of interest. Thus, the system can be enabled, activated, or reset for electrical device identification and control operations in response to a user closing their eyes for a predetermined amount of time. In some embodiments, (re)activation of the set of visual stimulus generators can occur in response to the detection of an eyes closed, awake user state across a predetermined time interval has been detected, followed by the detection of an eyes open state (e.g, which immediately succeeds the eyes closed state).

Multiple embodiments of the present disclosure avoid continual, ongoing, or unnecessarily sustained or prolonged activation of visual stimulus generators during normal device or appliance operation (e.g., visual stimulus generators remain inactive unless a visual stimulus generator activation command corresponding to a particular awake user eye closure behaviour is detected), or while the user sleeps or attempts to sleep. As a result, embodiments of the disclosure can minimize or eliminate user distraction and/or visual fatigue.

After system (re)activation or reset in response to the detection of an eyes closed condition across a particular time interval, the device identification unit can analyze captured EEG signals and identify an electrical device of interest to the user in one or more manners described herein. The system control and communication unit can issue an appropriate control command to the multi-device interface unit, thereby toggling an operating state of the electrical device of interest. The system control and communication unit can subsequently transition the set of visual stimulus generators to a quiescent or off state, thereby reducing, minimizing, or eliminating user visual fatigue. In some embodiments, the system can additionally transition the set of visual stimulus generators to or maintain the set of visual stimulus generators in an inactive state in response to the detection of an eyes closed, user asleep state.

Embodiments of the present disclosure are configured to activate or deactivate electrical devices by way of an EEG based determination of which visual stimulus generator gave rise to a SSVEP signals correlated with the presentation frequency at which the visual stimulus generator is driven. Moreover, multiple embodiments of the present disclosure provide a system activation process that enables a user to selectively activate or deactivate electrical devices in an unassisted manner. As a result, embodiments of the present disclosure can be particularly helpful to or useful for a user that is physically challenged or disabled. Embodiments of the present disclosure can also be helpful to or convenient for a physically capable or normally functioning individual.

Representative embodiments of the disclosure for addressing one or more of the foregoing problems associated with existing SSVEP based BCI systems and techniques are described hereafter with reference to FIGs. 1 to 8. For purposes of brevity and clarity, the description herein is primarily directed to systems, devices, and techniques for electrical device or appliance control. This, however, does not preclude various embodiments of the disclosure from other applications in which fundamental principles described herein such as operational, functional, or performance characteristics are desired or required.

In the description that follows, like or analogous reference numerals indicate like or analogous elements. Additionally, the recitation of a given reference numeral shown in a particular FIG. can indicate the simultaneous consideration of another FIG. in which such reference numeral is also shown. Furthermore, the terms unit, module, and element can involve one or both of hardware and software in various embodiments described herein. In the context of the present disclosure, the term set is defined as a non-empty finite organization of elements that mathematically exhibits a cardinality of at least 1 (i.e., a set as defined herein can correspond to a singlet or single element set, or a multiple element set), in accordance with known mathematical definitions (for instance, in a manner corresponding to that described in An Introduction to Mathematical Reasoning: Numbers, Sets, and Functions, "Chapter 11: Properties of Finite Sets" (e.g., as indicated on p. 140), by Peter J. Eccles, Cambridge University Press (1998)). In general, an element of a set can include or be a device, a structure, a signal, a function or functional process, or a value depending upon the type of set under consideration.

Aspects of Representative System Embodiments

FIG. 1 is a schematic illustration of an SSVEP based appliance control system 10 according to an embodiment of the disclosure. In an embodiment, the system 10 includes a plurality of visual stimulus generators 20a-d; an EEG signal acquisition unit 100; a system control and communication unit 200; a device identification unit 300; and a multi-device interface unit such as a multi-device power interface unit 400 that is configured to selectively provide operating power to at least one electrical device or appliance 50a-d. In multiple embodiments, the EEG signal acquisition unit 100, the system control and communication unit 200, the device identification unit 300, and the multi-device power interface unit 400 can be coupled to a main or primary source of electrical power 80, for instance, by way of one or more electrical outlets coupled to a mains, household, or line power source. The visual stimulus generators 20a-d, the EEG signal acquisition unit 100, and the device identification unit 300 can be coupled to the system control and communication unit 200, as further described below. Additionally, the multi-device power interface unit 400 can be configured for wireless or wire-based communication with the system control and communication unit 200. The multi-device power interface 400 includes a control module 410; a plurality of power interfaces 420a-d such as electrical outlets to which each electrical device or appliance 50a-d can be coupled; a communication module 450 configured to receive commands or device control instructions from the system control and communication unit 200; and a relay module 460 configured to selectively provide power to particular power interfaces 420a-d in response to such commands, as further detailed below.

Each visual stimulus generator 20a-d is configured to provide, output, display, or present visual stimuli or optical signals. In multiple embodiments, at least one visual stimulus generator 20a-d includes an LED array, which in a representative implementation can be a 3 x 4 or other sized array of LEDs configured to output light of at least one central wavelength. Additionally or alternatively, a visual stimulus generator 20a-d can be another type of device, such as a portion of a fiat panel display screen.

The visual stimulus generators 20a-d can be selectively enabled, controlled, or driven by the system control and communication unit 200. In various embodiments, the system control and communication unit 200 is configured to selectively drive or apply signals to a set of visual stimulus generators 20a-d such that each active visual stimulus generator 20a-d can output visual stimuli in a distinct or distinguishable manner relative to each other active visual stimulus generator 20a-d. For instance, the system communication and control unit 200 can drive each visual stimulus generator 20a-d in accordance with a unique or distinct presentation pattern. In multiple embodiments, a presentation pattern can be a temporal pattern, such that a given visual stimulus generator 20a-d outputs visual stimuli at a unique or distinct presentation frequency. In some embodiments, a presentation pattern can additionally or alternatively include a spatial pattern, and/or an optical wavelength alternation or modulation scheme.

A visual stimulus generator 20a-d can be associated with each electrical device 50a-d that is coupled to the multi-device power interface 400. In multiple embodiments, the system control and communication unit 200 and/or the device identification unit 300 can establish an association, relationship, or mapping between a given visual stimulus generator 20a-d and/or electrical device 50a-d and a specific power interface 420a-d provided by the multi-device power interface unit 400. As a result, the particular electrical device or appliance 50a-d that is coupled to the specific power interface 420a-d is thereby associated with the given visual stimulus generator 20a-d.

For instance, a relationship between a particular visual stimulus generator 20a-d and a specific electrical device 0a-d or a specific power interface 420a-d can be established by associating an appropriate visual stimulus generator ID with an appropriate electrical device ID or an appropriate power interface ID. Such IDs can be stored in an associated set of memory addresses (e.g., within a data structure). In a representative implementation in which a first through a fourth electrical device 50a-d include a television 50a, an electrical fan 50b, a stereo system 50c, and a light 50d, a first visual stimulus generator 20a is associated with the television 50a; a second visual stimulus generator 20b is associated with the electrical fan 50b; a third visual stimulus generator 20c is associated with the stereo system 50c; and a fourth visual stimulus generator 20d is associated with the light 50d.

A visual or conceptual association between a given visual stimulus generator 20a-d and a particular electrical device 50a-d can be naturally conveyed to a user by way of the visual stimulus generator's placement or position with respect to the electrical device 50a-d. More particularly, a visual stimulus generator 20a-d can be conceptually or visually associated with a particular electrical device 50a-d by positioning or disposing the visual stimulus generator 20a-d upon or adjacent or proximate to the electrical device 50a-d. As a result, a given visual stimulus generator 20a-d and its associated electrical device 50a-d are both within the user's field of view when the user directs their visual attention to the visual stimulus generator 20a-d. In other embodiments, a given visual stimulus generator 20a-d need not be visually associated with a particular electrical device 50a-d by way of the visual stimulus generator's position relative to the electrical device 50a-d; rather, such conceptual association can be learned or memorized by a user.

In multiple embodiments, each visual stimulus generator 20a-d is configured to output visual or optical stimuli or signals in accordance with a distinct or distinguishable presentation frequency or periodicity that can trigger or give rise to a corresponding unique or distinct SSVEP generation frequency and/or SSVEP generation pattern within a portion of the user's brain. In a representative implementation, the first visual stimulus generator 20a is driven to output optical signals at a presentation frequency of approximately 6 Hz; the second visual stimulus generator 20b is driven to output optical signals at a presentation frequency of approximately 7 Hz; the third visual stimulus generator 20c is driven to output optical signals at a presentation frequency of approximately 8 Hz; and the fourth visual stimulus generator 20d is driven to output optical signals at a presentation frequency of approximately 13 Hz.

When user attention is directed to a given active visual stimulus generator 20a-d, the optical signals output by the visual stimulus generator can trigger SSVEP signals having a power spectrum that includes a fundamental frequency and a set of frequency harmonics that correspond to the presentation frequency at which the visual stimulus generator 20a-d is driven. Thus, a given visual stimulus generator 20a-d can evoke SSVEPs in a manner that is correlated with the presentation frequency at which the visual stimulus generator 20a-d is driven.

The EEG signal acquisition unit 100 is configured to detect EEG signals, including EEG signals corresponding to SSVEP signals. In an embodiment, the EEG signal acquisition unit 100 includes a signal amplification unit 110 that is configured to receive EEG signals from a plurality of electrodes 120a-d. The electrodes 120a-d can be carried by user wearable headgear 130, or the electrodes 120a-d can be directly carried by the user's scalp. Depending upon embodiment details, the electrodes 120a-d can be wet electrodes or dry electrodes. The electrodes 120a-d can be, for instance, wet electrodes or dry electrodes. The electrodes 120a-d can be carried or supported by or mounted to the headgear 130 at predetermined positions expected to correspond to particular scalp locations defined by the International EEG 10 - 20 montage. FIG. 2 is a schematic illustration of an electrode configuration with respect to a standard EEG 10 - 20 montage according to an embodiment of the disclosure. In several embodiments, a first and a second electrode 120a,b are carried by the headgear 130 at positions that correspond or are expected to correspond to Ol and 02, which are occipital scalp locations corresponding to portions of the visual cortex. A third electrode 120c is carried by the headgear 130 at a position expected to correspond to Fz; and a fourth electrode 120d is carried by the headgear 130 at a position expected to correspond to Cz. As further detailed below, in several embodiments, the capture of EEG information by way of an electrode configuration having electrodes 120a-c positioned at Ol, 02, and Fz facilitates the reliable, accurate, and computationally efficient identification of a particular electrical device 50a-d that a user intends to control.

In particular embodiments, a maximum number of electrodes 120a-d are configured to detect EEG signals at any given time. This maximum number of electrodes 120a-d can be, for instance, three (e.g., corresponding to the capture of EEG signals corresponding to at least one of Ol and 02, plus Fz and Cz) or four (e.g., corresponding to the capture of EEG signals corresponding to each of Ol, 02, Fz, and Cz). Other embodiments can provide for EEG signal capture by way of more than three or four electrodes 120a-d.

Referring again to FIG. 1, the signal amplification unit 110 is coupled to each electrode 120a-d, and receives a corresponding EEG signal therefrom. The signal amplification unit 110 provides amplified and possibly filtered (e.g., by way of a 50Hz notch filter, and possibly a 5 - 30 Hz bandpass filter) or otherwise processed EEG signals to the system control and communication unit 200. In several embodiments, the signal amplification unit 110 provides a first EEG signal and a second EEG signal to the system control and communication unit 200, where the first EEG signal is defined by a signal difference between the first and third electrodes 120a,c; and the second EEG signal is defined by a signal difference between the second and third electrodes 120b,c. That is, the signal amplification unit 110 outputs EEG signals on two channels, where a first channel carries an EEG signal defined by Ol - Fz, and a second channel carries an EEG signal defined by 02 - Fz. The signal amplification unit 110 can use an EEG signal provided by the fourth electrode 120d, corresponding to Cz, as a reference signal.

When the visual stimulus generators 20a-d are active, the system control and communication unit 200 captures or samples digital EEG data corresponding to EEG signals received from the signal amplification unit 110. The system control and communication unit 200 can store a) the first EEG signal as first EEG data corresponding to the signal difference 01 - Fz; and b) the second EEG signal as second EEG data corresponding to the signal difference 02 - Fz. The system control and communication unit 200 transfers such EEG data to the device identification unit 300 for analysis.

The device identification unit 300 receives, retrieves, or accesses EEG data captured by the signal control and communication unit 200, and analyzes or characterizes aspects of such data in accordance with visual stimulus generator and/or device identification operations. In various embodiments, the device identification unit 300 analyzes data corresponding to the EEG power spectrum. For instance, the device identification unit 300 can generate power spectral density data, and perform particular operations upon such data to facilitate the real time or near-real time determination or identification of a visual stimulus generator 20a-d that gave rise to the power spectral density data, as further described below. Prior to performing real time or near-real time device identification operations, the system 10 performs calibration operations involving the capture and analysis of one or more types of baseline EEG data from the user. Calibration operations can include eyes open calibration operations in which eyes open baseline EEG data is captured while the user directs their field of view to a portion of their surrounding environment that lacks visual stimuli corresponding to or correlated with the visual stimulus generators' presentation frequencies. More particularly, eyes open baseline EEG data can be captured while the user directs their visual attention to a baseline environment, scene, or image. A baseline environment or scene can be a portion of their surrounding environment that lacks or excludes optical signal sources that provide visual stimuli at frequencies at or near the visual stimulus generators' presentation frequencies, or harmonics of these presentation frequencies. For instance, eyes open baseline EEG data can be captured while the user looks at their normal surroundings under ambient lighting conditions and any visual stimulus generators 20a-d and associated electrical devices 50a-d that are within or proximate to the user's field of view are off. In certain embodiments, eyes open baseline EEG data can be captured while the user looks at a neutral baseline scene such as a wall having a uniform of substantially uniform colour scheme, and which is uniformly or substantially uniformly illuminated by a wide spectrum optical signal source (e.g., a white wall illuminated with ordinary room lighting). Calibration operations can further include eyes closed calibration operations in which eyes closed baseline EEG data is captured while the user maintains their eyes in a closed state for a given period of time. In various embodiments, as part of calibration operations, the device identification unit 300 can generate baseline power spectral density data, a set of baseline parameters or values, and a threshold parameter or value to facilitate a) the real time or near-real time identification of a visual stimulus generator 20a-d to which the user directed their visual attention; and b) the unassisted automatic activation or deactivation of visual stimulus presentation by the visual stimulus generators 20a-d, as described in greater detail below.

Aspects of Representative System Control and Communication Units

FIG. 3 is a block diagram of a system control and communication unit 200 according to an embodiment of the disclosure. In an embodiment, the system control and communication unit 200 includes a controller 210, a data acquisition or sampling unit 220, a memory 225, a first communication module 230, a set of visual stimulus drivers 240, and a second communication module 250. Certain embodiments additionally include a relay 255. Particular elements of the system control and communication unit 200 can be coupled by way of a set of shared or common signal pathways, such as a data bus 290 and/or a control bus 292, to facilitate data and/or control signal transfer.

The controller 210 can include an instruction processor, such as portion of a microcontroller or microprocessor. The controller 210 can operate in accordance with a set of program instructions that define and/or implement portions of an SSVEP based electrical device control process in accordance with embodiments of the present disclosure. Such program instructions can reside in the memory 225.

The data acquisition unit 220 is configured to sample EEG signals received from the signal amplification unit 110, and store sampled data in the memory 225. In some embodiments, the data acquisition unit 220 can be an on-chip element provided by a microcontroller. The memory 225 can include one or more types of volatile and/or non-volatile data storage elements, such as a buffer, a Random Access Memory (RAM), and a Read Only Memory (ROM). In microcontroller based embodiments, the memory 225 can include on-ship memory and/or off-chip memory. The first communication module 230 is configured for data transfer with the device identification unit 300. More particularly, the first communication module 230 is configured to transfer sampled EEG data to the device identification unit 300. The first communication module 230 can additionally receive data from the device identification unit 300, such as a power interface ID, a visual stimulator ID, and/or an electrical device or appliance ID. In general, the first communication module can include a standard data transfer interface, such as a serial interface (e.g., an RS-232 or Universal Serial Bus (USB) interface).

The second communication module 250 is configured for selective communication with the multi-device power interface unit 400. For instance, the second communication module 250 can be configured to transfer a power interface ID or an electrical device ID to the multi-device power interface unit 400. In various embodiments, the second communication module 250 is configured for wireless signal transfer. The second communication module 250 can be coupled to the relay 225, which the controller 210 can selectively activate to provide power to the second communication module 250 when signal transfer to the multi-device power interface unit 400 is desired.

Finally, the set of visual stimulus drivers 240 is configured to selectively provide a set of drive signals to the visual stimulus generators 20a-d. In a representative implementation, the set of drive signals can include square wave signals. A given square wave signal can drive a corresponding visual stimulus generator 20a-d such as an LED array.

Aspects of Representative Device Identification Units

FIG. 4 is a block diagram of a device identification unit 300 according to an embodiment of the disclosure. In an embodiment, the device identification unit 300 includes a processing unit 302; at least one data storage unit 304; a graphics unit 306 coupled to a display device 308; an I/O unit 310 coupled to a set of input devices 312; and a memory 320. In some embodiments, the device identification unit 300 additionally includes a network interface unit 314, which can be coupled to a network such as a Local Area Network (LAN), a Wide Area Network (WAN), or the Internet 316. Elements of the device identification unit 300 can be coupled by a common set of buses 390.

The processing unit 302 can include an instruction processor configured to execute stored program instructions. The I/O unit 310 can include one or more types of I/O interfaces, such as a serial interface (e.g., an RS-232 and/or a USB interface) that facilitate data transfer involving the system communication and control unit 200. For instance, the I/O unit 310 can receive sampled EEG data from the system communication and control unit 200, and store such data in the memory 320. The I/O unit 310 is further configured to receive input from the set of input devices 312, which can include one or more of a computer mouse, a keyboard, a touch screen, and/or another type of user input interface. The display device 308 can include a computer monitor. The data storage unit 304 can include a hard disk drive and/or other type of device(s) configured to read and/or store program instructions or data by way of fixed or removable computer readable media.

The memory 320 can include one or more types of computer readable media, such as volatile (e.g., RAM) and or non-volatile (e.g., ROM) memory, in which in which portions of an operating system 322 (e.g., a Microsoft Windows^® based operating system), a configuration module 330, a calibration module 332, a user state detection module 334, a device identification module 336, an EEG signal analysis library 338, a configuration memory 340, a sampled data memory 342, and an identification memory 344 reside. In various embodiments, the configuration module 330, the calibration module 332, the user state detection module 334, the device identification module 336, and the EEG signal analysis library 338 include program instruction sets that facilitate, define, and/or implement portions of an SSVEP based device control process in accordance with embodiments of the present disclosure. The configuration memory 340 can store configuration data, which can include data that defines or indicates associations or relationships between particular visual stimulus generators 20a-d and particular electrical devices 50a-d and/or power interfaces 420a-d. The configuration memory 340 can additionally store EEG data analysis parameters, such as a sampling rate and a number of samples to be considered during device identification operations. The sampled data memory 342 can store sampled EEG data received from the data acquisition unit 220, and the identification memory 344 can store processed data that facilitates the identification and control of an electrical device 50a-d in accordance with embodiments of the present disclosure. Such processed data can correspond, for instance, to power spectral data, as further detailed below. One or more of the configuration module 330, the calibration module 332, the user state detection module 334, and the device identification module 336 can access one or more of the configuration memory 340, the sampled data memory 342, the identification memory 344, and/or the EEG signal analysis library 338 to facilitate SSVEP based electrical device control operations in accordance with particular aspects of the present disclosure. In a representative implementation, the device identification unit 300 includes a personal computer such as a desktop or laptop computer system. One or more portions of the configuration module 330, the calibration module 332, the user state detection module 334, the device identification module 336, and the EEG signal analysis library 338 can be implemented by way of or in association with a visual programming, measurement, data analysis, test, and/or control environment such as LabVIEW (www.ni.com/labview/. National Instruments Corporation, Austin, TX USA). Additionally or alternatively, one or more portions of such modules 330 - 338 can be implemented by way of program instruction sets written in accordance with a programming language such as C, C++, C#, or Java.

Aspects of Representative SSVEP Based Device Control Processes

In general, an SSVEP based device control process in accordance with the present disclosure can involve a system configuration process; a calibration process; a user state detection process; and a device identification process. Portions of such processes can respectively occur in association with program instruction execution corresponding to the configuration module 330, the calibration module 332, the user state detection module 334, and the device identification module 336. In several embodiments, the EEG signal analysis library 338 includes program instruction sets corresponding to standard and/or custom EEG signal analysis routines or functions (e.g., based upon standard signal analysis routines, functions, or operations), which the calibration module 332, the user state detection module 334, and/or the device identification module 336 can access, call, or invoke during portions of an SSVEP based device control process. Aspects of representative SSVEP based device control processes are described in detail hereafter.

Aspects of Representative System Configuration and Device Association Processes

In several embodiments, system configuration or setup operations can involve establishing one or more associations or relationships between visual stimulus generators 20a-d and electrical devices 50a-d and/or power interfaces 420a-d to which the electrical devices 50a-d are coupled. System configuration or setup operations can additionally involve defining or specifying EEG data acquisition parameters, for instance, a sampling rate and/or a number of samples considered for device identification purposes (or correspondingly, a time interval considered). As indicated above, system configuration operations can be facilitated by a GUI. FIG. 5 is a schematic illustration of a representative configuration GUI 500 in accordance with an embodiment of the disclosure. In an embodiment, the configuration GUI 500 includes a graphical window 502 that facilitates the generation of configuration data or parameters in response to user input. The graphical window 502 can include a number of graphical controls. For instance, the graphical window 502 can include at least some of as a set of buttons 510a-d responsive to user input for defining a number of electrical devices 50a-d under consideration; a text box or list box 520 configured to receive user input identifying an EEG sampling rate; a text box or list box 522 configured to receive user input specifying a number of EEG samples to be analyzed during device identification operations; a text box or list box 524 configured to receive user input specifying an identification timeout interval; a text box or list box 526 configured to receive user input specifying an eyes closed activation interval; and a calibration initiation button 528. In some embodiments, the graphical window 502 can also include an EEG signal display window 530 and a power spectrum display window 532. In several embodiments, the graphical window 502 includes a visual stimulus generator icon or symbol 22a-d corresponding to each visual stimulus generator 20a-d; an electrical device or appliance icon 52a-d corresponding to each electrical device or appliance 50a-d; and possibly a power interface icon 422a-c corresponding to each power interface 420a-d controlled by the multi-device power interface unit 400. The visual stimulus generator icons 22a-d, the electrical device icons 52a-d, and the power interface icons 422a-d can be spatially displayed or oriented relative to each other to indicate a manner in which each visual stimulus generator 20a-d, each electrical device 50a-d, and each power interface 420a-d are physically and conceptually associated with each other. In certain embodiments, the aforementioned icons can be graphically (re)positioned or rearranged relative to each other to reflect a current physical and conceptual association.

In various embodiments, the configuration module 332 generates or manages the generation of the configuration GUI 500. The configuration module 332 further stores configuration data or parameters in the configuration memory 340 in response to user input received by way of the configuration GUI 500. For users that are disabled, system configuration operations can be initiated by an assistant, such as a caregiver or relative.

Aspects of Representative Calibration Processes Calibration operations involve calibration module's generation of calibration data or parameters (e.g., in response to user selection of the calibration button 528), which can be stored in the configuration memory 340. In various embodiments, calibration operations include eyes open calibration operations that facilitate the identification of a visual stimulus generator 20a-b, a device 50a-d, and/or a power interface 420a-d. In several embodiments, calibration operations additionally include eyes closed calibration operations that facilitate the selective, automatic transition of the visual stimulus generators 20a-d from an inactive state to an active state in response to user behaviour. In general, calibration operations can be performed on a one time basis (e.g., for a user whose neurological condition or brain function is stable or generally stable over time), or on an as needed basis in view of system performance.

A) Aspects of Representative Eyes Closed Calibration Processes

Eyes closed calibration operations involve the data acquisition unit's capture of eyes closed baseline EEG data during one or more eyes closed calibration intervals during or across which an awake user closes their eyes. An eyes closed calibration interval can be a predetermined or programmably specified interval, for instance, approximately 1 - 10 seconds (for instance, approximately 2 - 8 seconds, or about 2 - 6 seconds, or approximately 1 - 4 or 2 - 4 seconds), or another time period depending upon embodiment details. In some embodiments, the calibration module 332 can instruct the user to close their eyes, such as by way of text displayed on the calibration GUI 500 and/or a set of audible tones or an audio message. Following EEG data acquisition during the eyes closed calibration interval, the calibration module 332 can additionally instruct the user to re-open their eyes by way of one or more audible tones or an audio message. During or after eyes closed user-awake EEG data capture, the data acquisition unit 220 or the calibration module 332 can filter the captured eyes closed baseline EEG data with respect to a predetermined EEG frequency band. For instance, the calibration module 332 can bandpass filter eyes closed baseline EEG data to reject and/or significantly attenuate EEG data having frequencies outside a frequency range or band of approximately 8 - 12 Hz. In such an embodiment, the bandpass filtered EEG data includes alpha band data, but excludes or substantially excludes lower frequency (theta and delta) and higher frequency (beta and gamma) band data. In general, the amplitude of alpha band EEG signals significantly increases and the amplitude of beta band EEG signals significantly decreases when an individual closes their eyes. Correspondingly, when an individual's eyes are open, the amplitude of alpha band EEG signals significantly decreases relative to the amplitude of beta band signals. Thus, distinct or distinguishable alpha and/or beta band signal amplitudes, considered alone or relative to each other, can be used to determine whether a) an awake user has their eyes closed or open; and/or b) a user has transitioned into a state in which their eyes are likely to remain closed for a significant period of time. The calibration module 332 can determine or generate one or more baseline measures of EEG signal energy corresponding to one or more eyes closed user-awake states, for instance, an eyes closed user-awake state that exists or persists across a predetermined or programmably specified time interval. In particular embodiments, the calibration module 332 generates a baseline measure of eyes closed user-awake EEG signal energy corresponding to a minimum activation command interval of approximately 1 - 4 seconds (e.g., approximately 1, 2, or 3 seconds) as follows:

where X;² is the i^th sample of an averaged filtered eyes closed baseline EEG signal, and N_A is the total number of samples under consideration across the minimum activation command interval (e.g., N_A equals 250 when the EEG sampling rate is 125 Hz and the minimum activation command interval is 2 seconds). The calibration module 332 can define TA as an activation command threshold energy, which can facilitate the determination of whether the user has issued a visual stimulus generator activation command. As further detailed below, during post-calibration system operation, the user state detection module 334 can analyze captured EEG data relative to T_A on a real time, near-real time, or periodic basis to determine whether an awake user has issued a visual stimulus generator activation command. For instance, the user state detection module 334 can analyze captured EEG data relative to T_A to detect a transition from an eyes open state to an eyes closed state that persists across the minimum activation command interval (e.g., approximately 2 seconds), followed by a transition to an eyes open state prior to the expiration of a maximum activation command interval (e.g., approximately 3 - 5 seconds, or approximately 4 seconds). In several embodiments, the calibration module 332 can additionally or alternatively determine or generate a baseline measure of EEG signal energy that can indicate whether the user has transitioned to a state in which the user's eyes are likely to or will remain closed for a substantial or prolonged period of time, such as a sleep state. For instance, the calibration module 332 can determine or generate a baseline measure of eyes closed user-awake EEG signal energy corresponding to a predetermined or programmably specified sleep indication interval of approximately 5 - 30 seconds (e.g., approximately 6 - 20, or approximately 6, 8, or 10 seconds) as follows:

where Xj is the i sample of an averaged filtered eyes closed baseline EEG signal, and Ns is the total number of samples under consideration relative to the sleep indication interval (e.g., Ns equals 750 when the EEG sampling rate is 125 Hz and the sleep indication interval is 6 seconds. The calibration module 332 can define Ts as an awake state / sleep state threshold, which facilitates the determination of whether the user has entered into or intends to enter into a prolonged eyes closed state such as a sleep state. In some embodiments, Ts can be defined as a mathematical correlate of T_A, such as a particular multiple of T_A, depending upon the duration of the sleep indication interval relative to the minimum and/or maximum activation command interval. As further detailed below, during post-calibration system operation, the user state detection module 334 can analyze captured EEG data relative to Ts on a real time, near-real time, or periodic basis to determine a likelihood that the user is asleep, intends to fall asleep, or intends to keep their eyes closed for a prolonged period of time.

B) Aspects of Representative Eyes Open Calibration Processes

Eyes open calibration operations involve the data acquisition unit's capture of eyes open baseline EEG data from the user during an eyes open calibration interval. During the eyes open calibration interval, the user maintains their eyes in an open state while directing their visual attention to a portion of their environment in which visual stimuli or optical signals remain constant or essentially constant with respect to the rates at which the visual stimulus generators 20a-d are configured to periodically present visual stimuli. In various embodiments, during eyes open calibration operations, the system control and communication unit 200 disables or deactivates the visual stimulus generators 20a-d, and the user avoids looking at portions of their environment in which optical signals are cyclically or repetitively presented or displayed at frequencies approximately equal to the visual stimulus generators' presentation frequencies, as well as at least some harmonic multiples (e.g., the nearest 2 - 5 harmonics) thereof.

The eyes open calibration interval can be approximately 1 - 8 seconds (e.g., approximately 2 - 6 seconds, or about 2, 3, or 4 seconds), or another time period depending upon embodiment details. In some embodiments, the system 10 can instruct the user to direct their visual attention to a wall or surface that is blank or substantially optically uniform, and keep their eyes open for a given amount of time (e.g., at least approximately 2 - 4 seconds). Such user instruction can occur by way of text displayed on the calibration GUI 500 and/or a set of audible tones or an audio message. Following EEG data acquisition during the eyes open calibration interval, the system 10 can alert the user that eyes open calibration operations are complete by way of one or more audible tones or an audio message, thereby informing the user that the system 10 is ready to identify and/or control visual stimulus generators 20a-d, electrical devices 50a-d, and/or power interfaces 420a-d in accordance with particular embodiments of the disclosure. The system control and communication unit's first communication module 230 can transfer eyes open baseline EEG data to the sampled data memory 342, and the calibration module 332 can generate or determine a set of baseline identification values or parameters and a device identification threshold value or parameter corresponding to such EEG data, as described in detail hereafter.

In multiple embodiments, the calibration module 332 generates a plurality of baseline power spectral density amplitude values (hereafter baseline power spectral density amplitude primitives b) corresponding to each presentation frequency at which the visual stimulus generators 20a-d are configured to operate, in order to determine baseline power spectral amplitude parameters corresponding to such presentation frequencies.

To aid understanding, the description that follows considers four presentation frequencies f_\,f_∑, fi, and j. As indicated above, when a user directs their visual attention to a given visual stimulus generator 20a-d configured to output visual stimuli at a presentation frequency f_k, such visual stimuli give rise or are expected to give rise to SSVEPs exhibiting a substantially identical frequency. Hence, when the visual stimulus generators 20a-d are active, power spectral density amplitude data generated from captured EEG data includes or is expected to include components having a fundamental frequency of fa, as well as harmonics of _k.

For each fundamental frequency fa, baseline power spectral density amplitude primitives b can be generated foxfv. as well as particular harmonics of _k, for instance, a first harmonic of _k and a second harmonic of fa, respectively referred to herein as 2fa and 3fa. More particularly, in a representative implementation, the baseline power spectral density amplitude primitives b corresponding to each of f_\, fi, fi, and fa and their corresponding first and second harmonics include the following:

{δ(/1 - δ), 6( 0, 6(/1+δ)}

{6(2/, - δ), 6(2 i), 6(2 1+δ)}

{6(3 _! - δ), 6(3/i), ό(3/1+δ)}

{b(f₂ - o), b{fi), b(f₂+o)}

{b(2f₂ - 8), 6(2/₂), b{2f₂+b)}

{6(3/₂ - δ), 6(3/₂), 6(3/₂+δ)}

{b - δ), btf₃), b +δ)}

{ό(2/₃ - δ), 6(2/₃), 6(2/3+δ)}

{ό(3/₃ - δ), 6(3/₃), 6(3/₃+δ)}

{ό(/-₄ - δ), b(fa), δ( 4+δ)}

{b{2fa - o), 6(2/4), b{2fa+b)}

{6(3/4 - δ), 6(3/₄), 6(3/₄+δ)}

In the above equations, δ is a frequency offset, such as approximately 0.1 - 1.0 Hz (e.g., approximately 0.25Hz, or 0.5Hz). The frequency offset δ can be predetermined, and in certain embodiments can correspond to a ratio of a sampling rate to a sampling interval. For instance, if the EEG data sampling rate is approximately 125 Hz, and device identification operations consider EEG samples captured during a current or most recent device identification interval or epoch of approximately 2 seconds to provide 250 samples for analysis, then δ can be 125 / 250 or δ = 0.5.

The calibration module 332 can further generate a plurality of representative or average baseline power spectral density amplitude primitives Z>„_k corresponding to each fundamental frequency f . With respect to the notation b_nk, n = 1 corresponds to the fundamental frequency fa, n = 2 corresponds to the first harmonic of the fundamental frequency 2fa, and n = 3 corresponds to the second harmonic of the fundamental frequency 2>fa. In several embodiments, each representative baseline power spectral density primitive 6_nk can correspond to a normalization of particular baseline power spectral density amplitude primitives b. For instance, a plurality of average baseline power spectral density amplitude primitives 2>_nk can be generated as follows:

6,i = mean(6( i - δ), 6( 1+δ))

b_lx = mean(b(2/i - δ), 6(2/1), b(2f,+8))

b = mean(6(3./i - δ), 6(3/0, 63(/1+δ))

6₁₂ = mean(6½ - δ), b(f₂), b(f₂+S))

bn = mean(6(2/₂ - δ), b(2f₂), b(2f₂+5)) for/₂

b_n = mean(6(3/₂ - δ), b(3f₂), b3(f₂+S))

613 = meaner - δ), b(f₃), b +δ))

b₂₃ = mean(6(2/₃ - δ), 6(2/₃), 6(2/₃+δ)) for/₃

633 = mean(6(3/₃ - δ), 6(3/₃), b3(f≠6)) b_H = meanC^ - δ), b(f₄), 6(/^" ₄+δ))

6₂₄ = mean(b(2/₄ - δ), 6(2/₄), 6(2/₄+δ)) for/₄

b34 = mean(6(3/₄ - δ), 6(3/₄), b3(f₄+5))

The calibration unit 332 can additionally generate a composite baseline power spectral density amplitude value BL^ corresponding to each fundamental frequency The composite baseline spectral density amplitude values BL can be generated using the average baseline power spectral amplitude primitives b_nk, for instance, in accordance with the following equation: 51_k = max(b_lk, b_2k, b_3k)

Therefore, for fundamental frequencies f_\ through fc,

BL_\ = max(bi b₂₁, b₃₁) for/i

BL₂ = max(b₁₂, b₂₂, b₃₂) for/₂

BLi = max(bi₃, b₂₃, b₃₃) for/₃

BL₄ = max(b₁₄, b₂₄, b₃₄) for j

Finally, a device identification threshold T_\ can be generated as follows:

T_x = (1/ ) T BLi

where M= 1, 2, 3, 4 corresponding to each fundamental frequency f_\,fi,fi,

The calibration unit 332 can store the composite baseline power spectral density amplitudes BL^ and the device identification threshold T_\ in the configuration memory 340. As described in detail below, device identification operations can involve particular composite baseline power spectral density amplitude values BL^ and the device identification threshold T\.

Aspects of Representative User State Detection Processes

Following calibration operations, the system 10 is capable of performing device identification operations to identify a visual stimulus generator 20a-d, an electrical device 50a-d, and/or a power interface 420a-d in accordance with various embodiments of the disclosure. In various embodiments, upon completion of calibration operations, the system control and communication unit 200 transitions the visual stimulus generators 20a-d to an inactive or quiescent state. Additionally, upon completion of calibration operations, the data acquisition unit 220 continuously, essentially continuously, periodically, or regularly captures EEG data, and the first communication module 230 transfers such EEG data to the device identification unit's sampled data memory 342. The user state detection module 334 can analyze captured real time or near-real time EEG data to identify a set of unassisted or self-directed user behaviours that indicates, corresponds to, or conveys user issuance of a command to the system 10, such as a visual stimulus generator command or an electrical device control command. In various embodiments, the user state detection module 334 can analyze EEG data to determine whether the user a) is awake or has fallen asleep; and b) if awake, has issued a visual stimulus generator activation or an electrical device control command.

Detection of prolonged eyes closed state

In several embodiments, in order to determine whether the user has entered into a state in which the user's eyes are likely to or will remain closed for a prolonged period of time (e.g., the user intends to fall asleep, or has fallen asleep), the user state detection module 334 determines the normalized energy of bandpass filtered real time or near-real time sampled EEG data (e.g., EEG data bandpass filtered to correspond or approximately correspond to alpha band frequencies) on a periodic basis, for instance, approximately every 1 - 10 seconds (e.g., approximately every 4 - 8 seconds, or approximately every 6 seconds). If the normalized energy of such EEG data is greater than the awake state / sleep state threshold Ts, the user state detection module 334 determines that the user's eyes have been closed for at least the sleep indication interval, and are likely to remain closed for a prolonged period of time. If the user state detection unit 334 determines that the user's eyes are likely to or will remain closed for a prolonged period of time, the user state detection module 334 can issue a sleep notification to the system control and communication unit 200, in response to which the system control and communication unit 200 maintains the visual stimulus generators 20a-d in an inactive state. If the normalized energy of a current or most-recent EEG sample sequence is less than or equal to Ts, the user state detection module 334 determines that the user's eyes have not been closed for a prolonged period of time, which indicates that the user is awake.

User command detection

The user state detection module 334 can determine whether the user has issued a visual stimulus generator activation command or an electrical device control command by which the user can selectively direct the system 10 to activate the visual stimulus generators 20a-d and/or perform electrical device control operations as a result of one or more unassisted or self-directed user behaviours. In several embodiments, a visual stimulus generator activation command or an electrical device control command corresponds to an eyes closed user-awake condition across a predetermined or programmably specified time period, interval, or window. For instance, a visual stimulus generator activation command can correspond to an eyes closed user-awake condition across a first time interval, and which occurs within the span of a second time interval. In particular embodiments, a visual stimulus generator activation command can correspond to a transition to an eyes closed condition that exists across a predetermined time interval such as a minimum activation command interval (e.g., approximately 1 - 3 seconds), and which terminates within a particular time interval such as a maximum activation command interval (e.g., approximately 3 - 4 seconds) that is at least equal to, and typically at least slightly longer than, the minimum activation command interval Thus, the minimum activation command interval can be subsumed within the maximum activation command interval. Additionally, the maximum activation command interval is typically shorter or significantly shorter than the sleep indication interval. Termination of the eyes closed condition within the maximum activation command interval indicates that the user is awake or is likely to remain awake, and has not entered into a state in which the user's eyes are likely to or will remain closed for a prolonged period of time (e.g., a sleep related state).

In view of the foregoing description, the user state detection module 334 can analyze captured EEG data relative to T_A on an ongoing or recurring basis to identify the existence of a transition from an eyes open state to an eyes closed state, and the persistence of the eyes closed state across the minimum activation command interval. The user state detection module 334 can additionally analyze captured EEG data on an ongoing basis to identify a transition from the eyes closed state back to an eyes open state prior to the termination of the maximum activation command interval. If so, the user state detection module 334 determines that the user has issued a visual stimulus generator activation command.

Once the user state detection module 334 has determined that the user has issued a visual stimulus generator activation command, the user state detection module 334 communicates an activation notification to the system control and communication unit 200 and the device identification module 336. Until a visual stimulus generator activation command is detected, that is, until the system control and communication unit 200 receives an activation notification, the system control and communication unit 200 maintains the visual stimulus generators 20a-d in an inactive state. Aspects of Representative Device Identification Processes

In response to the system activation notification, the system control and communication unit 200 activates or drives the visual stimulus generators 20a-d such that each visual stimulus generator 20a-d presents or outputs optical signals a particular fundamental frequency fak. Additionally, the device identification module 336 analyzes real time, near-real time, or most recently captured EEG data in order to identify a particular visual stimulus generator 20a-d to which the user has directed their visual attention. More particularly, in various embodiments, the device identification module 336 generates a plurality of first, source, or primitive power spectral density amplitude values corresponding to EEG data captured during a current or most recent device identification interval or epoch such as approximately 1 - 8 seconds (e.g., approximately 2, 3, or 4 seconds) when the visual stimulus generators 20a-d were active. Such power spectral density amplitude values are referred to hereafter as active power spectral density amplitude primitives g.

For each fundamental frequency /_k, active power spectral density amplitude primitives g can be generated for fak as well as particular harmonics of fak, for instance, 2fa and 3fa. More particularly, in a representative implementation involving up to four fundamental frequencies fa, fa, fi, and fan, the active power spectral density amplitude primitives g corresponding to each fundamental frequency /_k and a first and second harmonic thereof include the following:

{i 3/i - 6), g(3/ , £(3/1+5)}

{g(fi - δ), g(f₂), g(f₂+5)}

{g 2fa - δ), g(2/₂), g(2f₂+6)}

{gm - δ), g(3f₂), g(3fa₂+b)}

{gVi - >), g(fi), g(f≠?>)} ^■

{£(2/3 - δ), £(2/3), £(2/3+δ)}

(£(3/3 - δ), £(3/3), £(3/3+δ)} {«0¾ - δ), g i), g( i+5)}

{£(2/₄ - δ), ί 2/4), £(2/₄+δ)} ∞f*

{^3/₄ - 6), g(3/₄), g(3/₄+8)}

As described above, δ corresponds to a frequency offset such as approximately 0.1 - 1.0 Hz (e.g., approximately 0.5 Hz).

The device identification module 336 can also generate a plurality of baseline referenced representative or average active power spectral density amplitude primitives g„_k corresponding to each fundamental frequency f^. In several embodiments, each baseline referenced representative active power spectral density primitive can correspond to a normalization of particular active power spectral density amplitude primitives g, which is selectively scaled, filtered, or weighted with respect to its value relative to BL^. In a representative embodiment, a plurality of baseline referenced average active power spectral density primitives g„_k can be generated as follows, where n = 1 corresponds to fundamental frequency fa (i.e., n = 2 corresponds to the first harmonic of the fundamental frequency 2/k, and n = 3 corresponds to the second harmonic of the fundamental frequency 3 k: A) Corresponding to fundamental frequency fx

mean(g( l - 0), g( i), ₍g( i+6)) if gn > BLx

0 if gx x < BL_x mean(g(2/i - δ), g(2 i), g(2fx+6)) ifg₂₁ > B

0 if g₂x < BL_x mean(g(3/i - δ), g(3/,), g(3/,+8)) if £31≥ BL

0 if g3i < BLx B) Corresponding to fundamental frequency^:

gn = mean(g(f₂ - δ), g(f₂), gtfi+fy) ifgx2≥ BL₂

gn = if gx₂ < BL₂ g₂₂ = mean(g(2^ - δ), g(2/₂), g(2/₂+5)) if g₂₂≥ BL₂

g22 = 0 if g₂₂ < BL₂ g₃₂ = mean(g(3/₂ - δ), g(3/₂), g(3/₂+5)) if g₃₂ > BL₂

gn = if g₃₂ < BL₂

C) Corresponding to fundamental frequency f .

gi3 = mean(g(/3 - δ), g(f{), C^+δ)) if g₁₃ > BU

gn = 0 if gn < BU g₂₃ = mean(g(2/₃ - δ), g(2/₃), g(2/₃+6)) if g₂₃ > BU

g₂₃ = 0 if g₂₃ < BU g₃₃ - mean(g(3/₃ - δ), g(3/₃), g(3/₃+5)) if g₃₃ > 5I₃

g₃₃ = 0 if g₃₃ < BL₃

D) Corresponding to fundamental frequency

g_H = mean(g(/4 - δ), gfa), g( ₄+5)) if g_H > BU

g₁₄ = 0 ifgi4 < 51 g₂₄ = mean(g(2/₄ - δ), g(2/₄), g(2/₄+5)) if g₂₄ > B g₂₄ = 0 if g₂₄ < 5Z₄ g₃₄ = mean(g(3/₄ - δ), g(3/₄), (3 ₄+δ)) if g₃₄ > B g34 = 0 if g₃ <

The device identification module 336 can additionally generate a composite active power spectral density amplitude value _k corresponding to each fundamental

In several embodiments, _k is generated using particular baseline referenced average active power spectral density amplitude primitives g„k, for instance, in accordance with the following equation: g_k = max(g_lk, g_2k, g_3k) Therefore, for fundamental frequencies f_\ through /, max(gn, g₂₁, g₃₁) for ! max(g₁₂, g₂₂, g₃₂) for/₂ max(g₁₃, g₂₃, g₃₃) for/3 max(g₁₄, g₂₄, g₃₄) for/

The device identification module 336 can further generate a thresholded active power spectral density amplitude value gi_k corresponding to each fundamental frequency f^. The thresholded active power spectral density amplitude values i_k can be determined relative to corresponding composite baseline spectral density amplitudes BL^ and the device identification threshold T_\, for instance, in accordance with the following equation: ifgk

gTk = 0 ifgk

Therefore, for fundamental frequencies / through /, gii - gi - BL\ if gi > Ά

g_T1 = 0 if gi < T]

gT2 = 0 ifg2 gT3 - g3 - BL\ if g3≥ Ά

gT3 = 0 if g3 < Ti gT4 - g4 - BL\

gT4 = 0 Next, the device identification module 336 can generate or determine a principal, dominant, or maximum active power spectral density amplitude value G based upon the thresholded active power spectral density amplitude values gi_k- For instance, a maximum active power spectral density amplitude value G can be defined in accordance with the following equation:

G = max(gTi, £τ2, gJ3, gw)

The maximum active power spectral density amplitude value G can correspond to or indicate a dominant frequency fo within the power spectral density data under consideration. Because each visual stimulus generator 20a-d is driven at a presentation frequency that equals or essentially equals one

or /¾, the dominant or maximum active power spectral density amplitude value G corresponds to or indicates which particular fundamental frequency

or fa is the dominant frequency fu, thereby indicating which particular visual stimulus generator 20a-d gave rise to, evoked, or dominated the generation of the EEG samples from which the active power spectral density amplitude primitives were generated.

After generating the maximum active power spectral density amplitude G, the device identification module 336 determines the dominant presentation frequency f , and determines at least one of a visual stimulus generator ID, an electrical device ID, and a power interface ID associated with the dominant presentation frequency f - The device identification module 336 subsequently communicates one or more of the visual stimulus generator ID, the electrical device ID, or the power interface ID to the system control and communication unit 200 to facilitate the control (e.g., activation or deactivation) of the device 50a-d associated with the visual stimulus generator 20a-d to which the user directed their visual attention.

To further aid understanding with respect to the above calibration and device identification processes, in a representative implementation in which the first through fourth visual stimulus presentation

respectively equal approximately 6 Hz, 7Hz, 8 Hz, and 13 Hz, the device identification unit 300 considers the fundamental frequencies and corresponding first and second harmonic frequencies shown below in Table. 1.

Fundamental frequency (Hz) First harmonic frequency (Hz) Second harmonic frequency (Hz)

6 12 18

7 14 21 8 16 24

13 26 39

Table 1 : Representative fundamental and harmonic frequencies

In view of the foregoing equations, in the event that each composite active power spectral density amplitude value g_k is less than the device identification threshold T_\, each corresponding thresholded active power spectral density amplitude value gj will be zero, and the maximum active power spectral density amplitude value G will correspondingly equal zero. In such a situation, a dominant presentation frequency fo and hence a specific visual stimulus generator 20a-d to which the user directed their visual attention cannot be accurately determined. When the device identification module 336 is unable to determine a dominant presentation frequency fo, the device identification module 336 can analyze a next sequence of EEG data samples (e.g., which overlaps with, immediately follows, or is otherwise subsequent to a most recently analyzed sequence of EEG data samples) to (re)attempt successful identification of a dominant presentation frequency _ j In various embodiments, if the device identification module 336 is unable to determine a dominant presentation frequency fo within a predetermined timeout interval or after a predetermined number of identification attempts, the device identification module 336 can communicate an unsuccessful identification notification to the system control and communication unit 200. The system control and communication unit 200 can then deactivate the visual stimulus generators 20a-d. After the user state detection unit's detection of another visual stimulus generator activation command (e.g., in response to an awake user closing their eyes for approximately 2 seconds), the system control and communication unit 200 can reactivate the visual stimulus generators 20a-d, and the device identification module 336 can (re)attempt to determine a dominant presentation frequency fo in a manner identical or analogous to that described above.

Aspects of Representative Device Control Processes

In response to receipt of one or more of a visual stimulus generator ID, a device ID, or a power interface ID, the system communication and control unit 200 can activate its second communication module 250, and communicate a corresponding device control command to the multi-device interface unit 400. For instance, the system communication and control unit 200 can communicate a device control command that includes an ID such as device ID and/or the power interface ID to the multi-device power interface unit 400. In response, the multi-device power interface unit 400 can establish or adjust the operational state (e.g., activate or deactivate, or toggle the power state of) a particular power interface 420a-d corresponding to the received power interface ID or device ID by way of issuing an appropriate power interface control command to its relay module 460. As a result, the electrical device 50a-d coupled to the identified power interface 420a-d can be controlled. If the electrical device 50a-d under consideration has been off, it can be transitioned to an on state. Otherwise, the electrical device 50a-d under consideration can be transitioned from an on state to an off state.

In several embodiments, after communicating a power interface ID to the multi-device power interface unit 400, the system control and communication unit 200 can deactivate the visual stimulus generators 20a-d. The visual stimulus generators 20a-d can be reactivated in response to the detection of a particular user behaviour, such as the detection of an awake user eyes- closed state corresponding to a visual stimulus generator activation command that can be detected by the user state detection module 334.

FIG. 6 is a flow diagram of a representative SSVEP based electrical device or appliance control process 600 according to an embodiment of the disclosure. In an embodiment, the process 600 includes a first process portion 602 that involves establishing system configuration parameters. The system configuration parameters can include a number of electrical devices 50a-d for consideration; EEG sampling parameters (e.g., a sample rate and/or a number of samples considered during a given device identification attempt); an identification timeout interval or number of identification attempts; an eyes closed activation interval that can indicate a visual stimulus generator activation command; and/or a set of associations between visual stimulus generator icons 22a-d or IDs and one or both of electrical device icons 52a-d or IDs and power interface icons 422a-d or IDs. In various embodiments, configuration parameters can be established by way of the configuration GUI 500. The configuration parameters can be stored in the device identification unit's configuration memory 340.

A second process portion 604 involves acquiring, generating, or retrieving calibration data or parameters corresponding to the user. The calibration data can include eyes closed calibration data and eyes open calibration data, which can be stored in the configuration memory 340. A third process portion 606 involves transitioning the visual stimulus generators 20a-d to an inactive state, and a fourth process portion 608 involves determining whether a visual stimulus generator activation command corresponding to an unassisted user behaviour has been detected. The activation command can correspond, for instance, to the detection of an awake user eyes- closed condition that exists or persists for a predetermined period of time, for instance, approximately 2 seconds. If an awake user eyes-closed condition across an appropriate time interval has not been detected, for instance, as a result of an awake user intentionally avoiding the generation of a visual stimulus generator activation command, or the user falling asleep, the process 600 can remain at the fourth process portion 608.

Following the detection of a user command directed to activating the visual stimulus generators, a fifth process portion 610 involves activating the visual stimulus generators 20a-d, and a sixth process portion 612 involves capturing EEG data corresponding to the generation of SSVEPs while the visual stimulus generators 20a-d are active. A seventh process portion 620 involves initiating a device identification attempt during which device identification operations occur such that a particular visual stimulus generator 20a-d, a particular electrical device 420, and/or a particular power interface 420a-d can be identified. An eighth process portion 630 involves determining whether a particular visual stimulus generator 20a-d, a particular electrical device 50a-d, and/or a particular power interface 420a-d has been successfully identified within the identification timeout interval. If so, a ninth process portion 632 involves issuing an appropriate command to control the operation of the electrical device 50a-d associated with an identified visual stimulus generator 20a-d. The ninth process portion 632 can involve establishing or transitioning an operating state (e.g., toggling a power state) of a particular electrical device 50a-d associated with a visual stimulus generator 20a-d that was automatically identified as the visual stimulus generator 20a-d to which the user directed their visual attention.

A tenth process portion 634 involves determining whether one or more visual stimulus generator deactivation conditions have been met. Such conditions can correspond to a most recent successful device identification attempt, or exceeding a timeout interval during which device identification attempts were unsuccessful. If a deactivation condition is met, or if the identification timeout interval has been exceed without successful device identification, an eleventh process portion 640 involves disabling the visual stimulus generators 20a-d, after which the process 600 can return to the third process portion 606 to determine whether a visual stimulus generator (re)activation condition has been met.

FIG. 7 is a flow diagram of a representative baseline parameter generation process 700 according to an embodiment of the disclosure. In an embodiment, the process 700 includes a first process portion 702 that involves capturing baseline eyes open EEG data, and generating a plurality of baseline power spectral density amplitude primitives b corresponding to a plurality of visual stimulus generator fundamental frequencies, a predetermined number of harmonics to such fundamental frequencies, and predetermined frequency offsets to the fundamental frequencies and harmonic frequencies under consideration. A second process portion 704 involves generating representative or average baseline power spectral density amplitude primitives corresponding to the fundamental frequencies and fundamental frequency harmonics under consideration, and a third process portion 706 involves generating a composite baseline power spectral density amplitude value BL^ corresponding to each fundamental frequency under consideration. A fourth process portion 708 involves generating a device identification threshold I using the composite baseline power spectral amplitude values BL^.

FIG. 8 is a flow diagram of a representative device identification process 800 according to an embodiment of the disclosure. In an embodiment, the process 800 includes a first process portion 802 involving capturing EEG data while a user directs their visual attention to a particular active visual stimulus generator 20a-d within a set of active visual stimulus generators 20a-d. Each active visual stimulus generator 20a-d is driven at a distinct presentation frequency fc. A second process portion 804 involves generating a plurality of active power spectral density amplitude primitives g corresponding to the fundamental frequencies associated with the active visual stimulus generators 20a-d, a predetermined number of harmonics (e.g., a first and a second harmonic) to such fundamental frequencies, and predetermined frequency offsets (e.g., corresponding to a frequency offset δ) to the fundamental frequencies and harmonic frequencies under consideration. A third process portion 806 involves generating baseline referenced representative or average active power spectral density amplitude primitives g„_k corresponding to the fundamental frequencies and fundamental frequency harmonics under consideration; and a fourth process portion 808 involves generating a composite active power spectral density amplitude value corresponding to each fundamental frequency using the representative or average active power spectral density amplitude primitives. A fifth process portion 810 involves generating a thresholded active power spectral density amplitude value

corresponding to each fundamental frequency. In particular embodiments, the fifth process portion 810 can involve comparing each composite active power spectral density amplitude value g_k with a device identification threshold T_\. If the composite active spectral density amplitude value g_k is greater than or equal to the device identification threshold T_\, the fifth process portion further includes referencing each such composite active power spectral density amplitude value g_k relative to a corresponding composite baseline power spectral density amplitude value BL^; and setting a thresholded active power spectral density amplitude value gr_k to a difference between the composite active power spectral density amplitude value g_k and the composite baseline power spectral density amplitude value BL^ in the event that the composite. If the composite active spectral density amplitude value g_k is less than the device identification threshold T\, the thresholded active power spectral density amplitude value gn. can be set to zero. A sixth process portion 812 involves determining whether a dominant or maximum active power spectral density amplitude value G can be determined from the thresholded active power spectral amplitude density values gn.. If so, seventh process portion 814 involves identifying a dominant fundamental frequency fr> corresponding to the dominant active power spectral density amplitude value G, and an eighth process portion 816 involves identifying a particular visual stimulus generator 20a-d that was driven at or essentially at the dominant fundamental frequency fa. Additionally, a ninth process portion 818 involves communicating at least one of a visual stimulus generator ID, an electrical device ID, and a power interface ID to the system communication and control unit 200 such that an operating state (e.g., a power state) of a particular electrical device 50a-d associated with the identified visual stimulus generator 20a-d can be established, adjusted, or toggled.

In the event that a dominant active power spectral density amplitude value does not exist, a tenth process portion 820 involves determining whether an identification timeout interval or a maximum number of device identification attempts has been exceeded. If not, the process 800 can return to the first process portion 800. Otherwise, an eleventh process portion 822 involves communicating an unsuccessful identification notification to the system control and communication unit 200, which can deactivate the visual stimulus generators 20a-d in response.

In the foregoing manner, various embodiments of the disclosure are described for addressing at least one of the foregoing disadvantages. Such embodiments are intended to be encompassed by the following claims, and are not to be limited to specific forms or arrangements of parts so described and it will be apparent to one skilled in the art in view of this disclosure that numerous changes and/or modification can be made, which are also intended to be encompassed by the following claims.

Claims

1. A method for controlling at least one from the group of a set of visual stimulus generators and a set of electrical devices based upon the generation of EEG data by an individual's brain, the method comprising:

automatically transitioning each visual stimulus generator within the set of visual stimulus generators to a first state in which the output of visual stimuli by each visual stimulus generator in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators is avoided;

automatically capturing first EEG data generated by the individual's brain;

automatically determining that the first EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command; and

automatically transitioning each visual stimulus generator within the set of visual stimulus generators to a second state in which each visual stimulus generator outputs visual stimuli in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators.

2. The method of claim 1, wherein transitioning each visual stimulus generator within the set of visual stimulus generators to the second state occurs in response to determining that the first EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command.

3. The method of claim 1, wherein capturing the first EEG data and determining that the first EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command occurs while each visual stimulus generator within the set of visual stimulus generators is maintained in the first state.

4. The method of claim 1 , wherein the unassisted user behaviour that represents a visual stimulus generator activation command comprises an eyes closed condition across a predetermined period of time while the individual is awake.

5. The method of claim 4, wherein the predetermined period of time is approximately 1 - 10 seconds.

6. The method of claim 4, wherein the predetermined period of time is approximately 1 - 4 seconds.

7. The method of claim 1, wherein transitioning each visual stimulus generator within the set of visual stimulus generator to the first state comprises transitioning each visual stimulus generator within the set of visual stimulus generators to an inactive state.

8. The method of claim 1, wherein transitioning each visual stimulus generator within the set of visual stimulus generators to the second state comprises operating each visual stimulus generator at a distinct visual stimulus presentation frequency relative to each other visual stimulus generator within the set of visual stimulus generators.

9. The method of claim 1 , further comprising:

capturing second EEG data corresponding to SSVEPs generated by the individual's brain while the user directed their visual attention to a particular visual stimulus generator within the set of visual stimulus generators; and

automatically determining whether the second EEG data indicates the particular visual stimulus generator within the set of visual stimulus generators to which the user directed their visual attention.

10. The method of claim 9, further comprising transitioning each visual stimulus generator to the first state in the event that automatically determining whether the second EEG data fails to indicate the particular visual stimulus generator within the set of visual stimulus generators to which the user directed their attention.

11. The method of claim 9, further comprising:

establishing an association between each electrical device within the set of electrical devices and each visual stimulus generator within the set of visual stimulus generators;

automatically identifying the particular visual stimulus generator within the set of visual stimulus generators to which the user directed their visual attention based upon the second EEG data; and automatically adjusting an operational state of a particular electrical device within the set of electrical devices , the particular electrical device corresponding to the automatically identified particular visual stimulus generator within the set of visual stimulus generators to which the user directed their visual attention.

12. The method of claim 11, wherein adjusting the operational state of the particular device within the set of electrical devices comprises toggling a power state of the particular device.

13. The method of claim 11, further comprising automatically transitioning each visual stimulus generator within the set of visual stimulus generators to the first state in association with automatically adjusting the operational state of the particular electrical device within the set of electrical devices.

14. The method of claim 13, further comprising:

capturing third EEG data;

automatically determining whether the third EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command; and

maintaining each visual stimulus generator within the set of visual stimulus generators in the first state unless the third EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command.

15. A system for controlling a set of electrical devices based upon the generation of SSVEPs by a system user's brain, the system comprising:

a set of visual stimulus generators, each visual stimulus generator within the set of visual stimulus generators configured to output visual stimuli;

a visual stimulus generator controller coupled to each visual stimulus generator, the visual stimulus controller configured to selectively enable each visual stimulus generator to output visual stimuli in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators;

an EEG data acquisition system configured to capture EEG data generated by the user's brain; and

a device identification system comprising:

a processing unit; and a memory coupled to the processing unit, the memory comprising a user state detection module including a set of program instructions that when executed determines whether EEG data generated in response to an unassisted user behaviour corresponds to a visual stimulus generator activation command.

16. The system of claim 15, wherein the unassisted user behaviour corresponds to an awake user eyes-closed state across a predetermined time interval.

17. The system of claim 16, wherein the predetermined time interval is approximately 1 - 10 seconds.

18. The system of claim 16, wherein the predetermined time interval is approximately 1 - 4 seconds. 19. The system of claim 15, wherein the user state detection module further comprises a set of program instructions that when executed communicates an activation notification to the visual stimulus generator controller in response to the detection of the visual stimulus generator activation command. 20. The system of claim 19, wherein the visual stimulus generator controller maintains each visual stimulus generator in a first state in which in the output of visual stimuli by each visual stimulus generator in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators is avoided until an activation notification is received. 21. The system of claim 19,

wherein in response to the receipt of the activation notification, the visual stimulus generator controller transitions each visual stimulus generator within the set of visual stimulus generators to a second state in which each visual stimulus generator outputs visual stimuli in a distinct manner relative to each other visual stimulus generator within the set of visual stimulus generators, and

wherein the memory further comprises a device identification module that includes a set of program instructions configured to identify a particular visual stimulus generator within the set of visual stimulus generators to which the user has directed their visual attention based upon captured EEG data.

22. The system of claim 15, wherein the EEG data acquisition system comprises a set of electrodes spatially organized in accordance with a standard EEG 10-20 montage and configured to detect at least one of a first EEG signal difference between 01 - Fz and a second EEG signal difference between 02 - Fz.

23. The system of claim 22, wherein the set of electrodes includes fewer than five electrodes configured to detect EEG signals at any given time. 24. A method for controlling a set of devices based upon SSVEPs generated by an individual's brain, the method comprising:

providing first EEG data corresponding to EEG signals generated by the individual's brain while the individual directed their visual attention to a baseline scene; generating a plurality of baseline power spectral density amplitude values corresponding to the first EEG data, the plurality of baseline power spectral density amplitude values corresponding to a set of fundamental frequencies and a set of harmonic multiples n _k of each fundamental frequency^;

generating a device identification threshold ι using the plurality of baseline power spectral density amplitude values;

providing second EEG data corresponding to SSVEPs generated by the individual's brain while the individual directed their visual attention to a particular visual stimulus generator within a set of visual stimulus generators, each visual stimulus generator within the set of visual stimulus generators configured to provide visual stimuli at a unique presentation frequency approximately equal to a corresponding fundamental frequency /_k within the set of fundamental frequencies _k;

generating a plurality of active power spectral density values corresponding to the second EEG data, the plurality of active power spectral density values corresponding to the set of fundamental frequencies ^ and the set of harmonic multiples n/_k thereof; generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and the device identification threshold T, and determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

The method of claim 24, further comprising:

determining a dominant frequency fu corresponding to a dominant active power spectral density amplitude value, the dominant frequency fu equal to a particular fundamental frequency^ within the set of fundamental frequencies^; and

identifying a visual stimulus generator within the set of visual stimulus generators that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency fu.

26. The method of claim 25, further comprising:

identifying an electrical device associated with the visual stimulus generator that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency f ; and

one of establishing and adjusting an operating state of the electrical device associated with the visual stimulus generator that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency fu-

27. The method of claim 26, wherein one of establishing and adjusting an operating state of the electrical device comprises issuing a device control command to a device interface unit configured to automatically control an operating state of the device in response to the device control command.

28. The method of claim 26, wherein the device interface unit is configured to toggle a power state of the device in response to the device control command.

29. The method of claim 26, wherein each visual stimulus generator within the set of visual stimulus generators is associated with a distinct electrical device.

30. The method of claim 24, wherein the baseline scene comprises one from the group of a scene and a portion of an environment that lacks visual stimuli having frequencies approximately equal to the fundamental frequencies fa within the set of fundamental frequencies

31. A system for controlling a set of devices based upon SSVEPs generated by an individual's brain, the system comprising:

a device identification system comprising:

a processing unit; and

a memory coupled to the processing unit, the memory comprising a device identification module including a set of program instructions that when executed identifies a particular visual stimulus generator within the set of visual stimulus generators by way of device identification operations comprising:

generating a plurality of active power spectral density values corresponding to EEG data acquired while the individual directed their visual attention to the particular visual stimulus generator within the set of visual stimulus generators, the plurality of active power spectral density values corresponding to a set of fundamental frequencies and a set of harmonic multiples n _k thereof;

generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and a device identification threshold T_\, and

determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

32. The system of claim 31 , wherein the device identification operations further comprise: determining a dominant frequency fo corresponding to a dominant active power spectral density amplitude value, the dominant frequency equal to a particular fundamental frequency ./_k within the set of fundamental

and

identifying a visual stimulus generator within the set of visual stimulus generators that output visual stimuli at a frequency corresponding to the dominant frequency fo.

33. The system of claim 32, wherein the device identification operations further comprise identifying an electrical device associated with the visual stimulus generator that output visual stimuli at a frequency corresponding to the dominant frequency D.

34. The system of claim 32, wherein the device identification operations further comprise outputting an identifier corresponding to one from the group of the visual stimulus generator that output visual stimuli at a frequency corresponding to the dominant frequency fo and an electrical device associated therewith.

35. The system of claim 34, wherein the system further comprises a system control unit configured to facilitate changing an operating state of the electrical device associated with the visual stimulus generator that output visual stimuli at a presentation frequency corresponding to the dominant frequency fo in response to receipt of the identifier.

36. The system of claim 35, wherein the system control unit is configured to output an electrical device control command based upon the identifier.

37. The system of claim 36, wherein the system further comprises a device control interface configured for signal communication with the system control unit and further configured to one of establish and adjust an operating state of the electrical device associated with the visual stimulus generator that output visual stimuli at a frequency corresponding to the dominant frequency fu in response to the electrical device control command.

38. The system of claim 37, wherein the device control interface is configured to toggle a power state of the electrical device associated with the visual stimulus generator that output visual stimuli at a frequency corresponding to the dominant frequency fo in response to the electrical device control command.

39. The system of claim 31, wherein the memory further comprises a calibration unit including program instructions that when executed perform calibration operations comprising: analyzing baseline EEG data corresponding to EEG signals generated by the individual's brain while the individual directed their visual attention to a baseline scene;

generating a plurality of baseline power spectral density amplitude values corresponding to the baseline EEG data, the plurality of baseline power spectral density amplitude values corresponding to the set of fundamental frequencies and the set of harmonic multiples n _k of each fundamental frequency^; and

generating the device identification threshold T_\ using the plurality of baseline power spectral density amplitude values.

40. The method of claim 39, wherein the baseline scene comprises one from the group of a scene and a portion of an environment that lacks visual stimuli having frequencies approximately equal to the fundamental frequencies _. within the set of fundamental frequencies

41. A computer readable medium storing program instructions directed to operating portions of a system for controlling a set of electrical devices based upon SSVEPs generated by an individual's brain, the system comprising an EEG acquisition unit, a set of visual stimulus generators in which each visual stimulus generator is configurable to output visual stimuli in a distinct manner relative to each other visual stimulus generator, a set of electrical devices associated with the set of visual stimulus generators, a device identification unit, and a system control unit, the program instructions when executed causing the system to perform control operations comprising:

automatically accessing first EEG data generated by the individual's brain; automatically determining that the first EEG data corresponds to an unassisted behaviour by the individual that represents a visual stimulus generator activation command; and

42. The computer readable medium of claim 41 , wherein determining that the first EEG data corresponds to an unassisted behaviour that represents a visual stimulus generator activation command comprises analyzing EEG data to identify an awake individual eyes closed condition across an activation command interval.

43. The computer readable medium of claim 41, wherein the computer readable medium further comprises program instructions that when executed cause the system to perform control operations further comprising:

accessing second EEG data corresponding to SSVEPs generated by the individual's brain while the user directed their visual attention to a particular visual stimulus generator within the set of visual stimulus generators;

automatically determining whether the second EEG data indicates the particular visual stimulus generator within the set of visual stimulus generators to which the user directed their visual attention;

identifying a particular electrical device within the set of electrical devices that is associated with the particular visual stimulus generator; and

automatically transitioning an operating state of the particular electrical device.

44. A computer readable medium storing program instructions directed to operating portions of a system for controlling a set of electrical devices based upon SSVEPs generated by an individual's brain , the system comprising an EEG acquisition unit, a set of visual stimulus generators in which each visual stimulus generator is configurable to output visual stimuli in a distinct manner relative to each other visual stimulus generator, a set of electrical devices associated with the set of visual stimulus generators, a device identification unit, and a system control unit, the program instructions when executed causing the system to perform control operations comprising: accessing first EEG data corresponding to EEG signals generated by the individual's brain while the individual directed their visual attention to a baseline scene; generating a plurality of baseline power spectral density amplitude values corresponding to the first EEG data, the plurality of baseline power spectral density amplitude values corresponding to a set of fundamental frequencies and a set of harmonic multiples n _k of each fundamental frequency^;

generating a device identification threshold T_\ using the plurality of baseline power spectral density amplitude values;

accessing second EEG data corresponding to SSVEPs generated by the individual's brain while the individual directed their visual attention to a particular visual stimulus generator within a set of visual stimulus generators, each visual stimulus generator within the set of visual stimulus generators configured to provide visual stimuli at a unique presentation frequency approximately equal to a corresponding fundamental frequency within the set of fundamental frequencies^;

generating a plurality of active power spectral density values corresponding to the second EEG data, the plurality of active power spectral density values corresponding to the set of fundamental frequencies and the set of harmonic multiples n _k thereof; generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and the device identification threshold

and determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

45. The computer readable medium of claim 44, wherein the computer readable medium further comprises program instructions that when executed cause the system to perform control operations further comprising:

generating a plurality of thresholded active power spectral density amplitude values by selectively scaling each active power spectral density value within the plurality of active power spectral density values based upon a comparison with at least one of a baseline power spectral density value and the device identification threshold T_\ and determining whether a dominant active power spectral density amplitude value exists corresponding to the plurality of thresholded active power spectral density amplitude values.

46. The computer readable medium of claim 45, wherein the computer readable medium further comprises program instructions that when executed cause the system to perform control operations further comprising:

determining a dominant frequency D corresponding to a dominant active power spectral density amplitude value, the dominant frequency f equal to a particular fundamental frequency f_k within the set of fundamental frequencies^; and

identifying a visual stimulus generator within the set of visual stimulus generators that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency f . 47. The computer readable medium of claim 46, wherein the computer readable medium further comprises program instructions that when executed cause the system to perform control operations further comprising:

identifying an electrical device associated with the visual stimulus generator that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency and

one of establishing and adjusting an operating state of the electrical device associated with the visual stimulus generator that is configured to provide visual stimuli at a presentation frequency corresponding to the dominant frequency D.