Electrodermal activity acquisition

The measurement of electrodermal activity (EDA) can be facilitated by a sensing surface. The sensing surface can have a plurality of electrode pairs. An electrode pair can include a first electrode and a second electrode that are electrically isolated from each other. The plurality of electrode pairs can be electrically isolated from each other. A distance between neighboring electrode pairs can be larger than a distance between the first electrode and a second electrode of each electrode pair. One or more sensors can be configured to detect contact with the sensing surface. In response to the one or more sensors detecting contact with the sensing surface, one or more electrode pairs can be selected to be activated. In response to the one or more electrode pairs being selected to be activated, the selected one or more electrode pairs can be activated.

FIELD

The subject matter described herein relates in general to electrodermal activity (EDA) and, more particularly, to acquiring EDA.

BACKGROUND

Electrodermal activity (EDA) is a biosensing technique used in psychology and medicine to detect emotional arousal, measure distress levels, and/or predict seizures, among other things. EDA is the measurement of skin transpiration in the palm and/or fingers of a user. An emotional state of the user can be identified based on the determined EDA.

SUMMARY

In one respect, the subject matter presented herein relates to a method for measuring electrodermal activity (EDA). The method can include detecting, using one or more sensors, contact with a sensing surface. The sensing surface can have a plurality of electrode pairs. Each electrode pair can include a first electrode and a second electrode. The first electrode and the second electrode can be electrically isolated from each other. The plurality of electrode pairs can be electrically isolated from each other. A distance between neighboring electrode pairs can be larger than a distance between the first electrode and a second electrode of each electrode pair. The method can include, in response to detecting the contact with the sensing surface, selecting one or more electrode pairs to activate. The method can include, in response to selecting one or more electrode pairs to activate, causing the selected one or more electrode pairs to be activated.

In another respect, the subject matter presented herein relates to a system for measuring electrodermal activity. The system can include a sensing surface. The sensing surface can have a plurality of electrode pairs. Each electrode pair can include a first electrode and a second electrode. The first electrode and the second electrode can be electrically isolated from each other. The plurality of electrode pairs can be electrically isolated from each other. A distance between neighboring electrode pairs can be larger than a distance between the first electrode and a second electrode of each electrode pair. The system can include one or more sensors. The one or more sensors can be configured to detect contact with the sensing surface. The system can include one or more processors. The one or more processors can be operatively connected to the plurality of electrode pairs. The one or more processors can be operatively connected to the one or more sensors. The one or more processors can be programmed to initiate executable operations that include, responsive to detecting contact with the sensing surface, selecting one or more electrode pairs to activate, and, responsive to selecting one or more electrode pairs to activate, causing the selected one or more electrode pairs to be activated.

DETAILED DESCRIPTION

Electrodermal Activity (EDA) can be used to determine a user's emotional state. Electronic devices and vehicles that can access the EDA of the user can adapt their functions to accommodate the user's emotional state. However, in order to accurately capture EDA and reduce the occurrence of noise in the measured EDA, electrodes are glued (or otherwise attached) to and/or hardly pressed against the user's skin. Electrodes that are neither glued nor hardly pressed against the skin may result in friction as the user moves, which, in turn, can generate significant noise in the measurements. As such, the user may experience discomfort with the electrodes being glued to the user's skin, and may find the technique invasive.

Arrangements presented herein are directed to acquisition systems and methods for capturing EDA. The EDA acquisition system can include a sensing surface, which can be rigid or compliant. EDA data can be captured when the user touches the sensing surface. More particularly, EDA data can be captured when a portion of the user's hand (e.g., fingers or palm) or other portion of the body is in contact with the sensing surface.

As an example, the sensing surface can include a plurality of electrodes. The electrodes can capture EDA without being glued or pressed into the skin of the user. In some arrangements, the EDA acquisition system can apply a noise-cancelling algorithm to the captured EDA to achieve a high signal-to-noise ratio. The sensing surface can be incorporated into one or more vehicle structures, such as a steering wheel, a touchscreen, and/or a touchpad. The electrodes of the sensing surface can be exposed on the surface, or they can be located under the surface of the vehicle structure. The resulting EDA measurement can be transmitted to any interested entity (e.g., a vehicle system, a mobile device, and/or a server).

Referring toFIG.1, an example of electrodermal activity (EDA) acquisition system100is shown. The EDA acquisition system100can include various elements, which can be communicatively linked in any suitable form. As an example, the elements can be connected as shown inFIG.1. Some of the possible elements of the EDA acquisition system100are shown inFIG.1and will now be described. It will be understood that it is not necessary for the EDA acquisition system100to have all of the elements shown inFIG.1or described herein. The EDA acquisition system100can have any combination of the various elements shown inFIG.1. Further, the EDA acquisition system100can have additional elements to those shown inFIG.1. In some arrangements, the EDA acquisition system100may not include one or more of the elements shown inFIG.1. Further, it will be understood that one or more of these elements can be physically separated by large distances.

The EDA acquisition system can include one or more sensing surfaces102. The sensing surface102can include a plurality of electrode pairs104, and one or more skin conductance sensors118. The sensing surface102can include an electrically insulating material. The sensing surface102can include a rigid surface, which is a surface that can maintain its shape when a pressure is exerted on it (e.g., polymer). Alternatively, the sensing surface102can be a compliant surface, which is a surface that deviate from its original shape in response to a pressure being exerted on it (e.g., Polydimethylsiloxane (PDMS) or rubber). The sensing surface102can be of any material that does not conduct electricity and can be suitable for at least partially embedding the electrode pairs104. The one or more sensing surfaces102can be integrated into any suitable vehicle component, such as human interface devices, steering wheels, touchpads, track pads, and/or touch screens.

The sensing surface(s)102can be formed using any suitable method, e.g., conventional printed circuit board (PCB) manufacturing technology, flex circuit manufacturing technology where thin electrodes are embedded in a flexible KAPTON® substrate, screen printing or multi-material additive manufacturing.

Each electrode pair104can include a first electrode106and a second electrode108. The first and second electrodes106,108can be at least partially embedded in the sensing surface102. In some arrangements, a portion of the first electrode106and a portion of the second electrode108can be embedded in the sensing surface102and a portion of the first electrode106and a portion of the second electrode108can be exposed on the sensing surface102. In some arrangements, the exposed portions of the first and second electrodes106,108can be substantially flush with the rest of the sensing surface102. In some arrangements, the first electrode106and the second electrode108can be embedded in the sensing surface102such that the first electrode106and the second electrode108are not exposed to the sensing surface102. In such case, the first electrode106and the second electrode108can be located just under the outer surface of the sensing surface102. The first electrode106and the second electrode108can be electrically isolated from each other within the sensing surface102. When the first electrode106and the second electrode108are activated, there can be substantially low electric current travelling through the sensing surface102between the first electrode106and the second electrode108. The current can be at a biocompatible level that is undetectable when the sensing surface102is touched by a portion of a human's body.

The first and second electrodes106,108can be of any material suitable for permitting skin conductance and acquiring electrodermal activity. As an example, the first and second electrodes106,108can be standard silver-silver chloride (Ag/AgCl) electrodes. As another example, the first and second electrodes106,108can be stainless steel electrodes.

The electrode pairs104can be arranged in any suitable manner. As an example, the electrode pairs104can be arranged in a grid-like pattern as shown inFIG.2. In some arrangements, the electrode pairs104can be arranged in an interdigitated or non-interdigitated matrix configuration. The sensing surface102can be mapped such that the exact location of each electrode and each electrode pair is known. For instance, the sensing surface102can be mapped using Cartesian coordinates (x, y) or other coordinates such that each electrode106,108and/or electrode pair104can be identified by their coordinates of the sensing surface102proximate to the electrode's and/or electrode pair's location respectively.

The electrode pairs104can be electrically isolated from each other. In such a case, there is substantially no electric current travelling through the sensing surface102from one electrode pair104to another electrode pair104. In one or more arrangements, the first electrode106can be a negative electrode, and the second electrode108can be the positive electrode. In such cases, the negative electrode of the electrode pairs104can be electrically connected to each other and the positive electrode of the electrode pairs104can be electrically connected. Thus, the negative electrode from the electrode pairs104can share an electric potential value and can behave like a single negative electrode. The positive electrode from the electrode pairs104can share an electric potential value and can behave like a single positive electrode. As an alternative, the negative electrodes of the electrode pairs104may not be electrically connected and/or the positive electrodes of the electrode pairs104may not be electrically connected. The electrode pairs104can be activated and/or deactivated using any suitable means such as one or more control switches. The electrode pairs104can be activated and/or deactivated individually or as a group. As an example of such a case, a single control switch can activate or deactivate a single electrode pair104or a group of two or more electrode pairs104.

In one or more arrangements, distance between the first electrode106and the second electrode108of the plurality of electrode pairs104can be substantially equal. The first electrode106and the second electrode108of the electrode pairs104can be substantially equidistant. The distance between two neighboring electrode pairs104can be larger than the distance between the first electrode106and a second electrode108of the electrode pairs104. The larger the difference between the distance between neighboring electrode pairs104and the distance between the first and the second electrodes106,108, the more negligible the parasitic voltage drop and/or parasitic resistance between the neighboring electrode pairs104. Parasitic resistance between activated electrode pairs104can cause a parasitic voltage drop between the electrode pairs104, which can lead to false or inaccurate EDA measurements.

The EDA acquisition system100can include one or more processors120. “Processor” means any component or group of components that are configured to execute any of the processes described herein or any form of instructions to carry out such processes or cause such processes to be performed. The processor(s)120can be implemented with one or more general-purpose and/or one or more special-purpose processors. Examples of suitable processors include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Further examples of suitable processors include, but are not limited to, a central processing unit (CPU), an array processor, a vector processor, a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic array (PLA), an application specific integrated circuit (ASIC), programmable logic circuitry, and a controller. The processor(s)120can include at least one hardware circuit (e.g., an integrated circuit) configured to carry out instructions contained in program code. In arrangements in which there is a plurality of processors120, such processor(s)120can work independently from each other or one or more processor(s)120can work in combination with each other. In one or more arrangements, one or more processor(s)120can be a main processor(s) of a vehicle. For instance, one or more processor(s)120can be electronic control unit(s) (ECU).

The EDA acquisition system100can include one or more data stores122for storing one or more types of data. The data store(s)122can include volatile and/or non-volatile memory. Examples of suitable data store(s)122include RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The data store(s)122can be a component of the processor(s)120, or the data store(s)122can be operatively connected to the processor(s)120for use thereby. The term “operatively connected,” as used throughout this description, can include direct or indirect connections, including connections without direct physical contact.

In one or more arrangements, the data store(s)122can include historical data for the electrode pairs104. The historical data can be provided in any suitable form. As an example, the historical data can be in a tabulated format with each electrode pair104identified using any suitable identifier such as a unique number. Non-limiting examples of the historical data can include previously measured signal strengths or quality of the electrode pair104, value of parasitic resistance between the electrode pair104and its neighboring electrode pairs104, the number of times the electrode pair104has been used within a certain time period, and/or a percentage value indicating the frequency of use of the electrode pair104in relation to an overall use of the EDA acquisition system100.

Parasitic resistance can occur between two or more electrode pairs104that are activated. The value of the parasitic resistance can be determined based on the distance and material between the two activated electrode pairs104. Additionally and/or alternatively, the value of the parasitic resistance can be determined at the time of manufacture and can be stored in the historical data for the electrode pairs104. In one or more arrangements, the data store(s)122can include user data, such as a fingerprint and/or a handprint of one or more users. In some instances, the user data can include information about the size and/or shape of the hand of one or more users. User data can include information relating to hand, finger and/or palm placement in relation to the sensing surface. Such user data can be based on average human data, user specific data, learned user data, and/or any combination thereof.

In arrangements in which there is a plurality of sensors110, the sensors110can work independently from each other. Alternatively, two or more of the sensors110can work in combination with each other. In such case, the two or more sensors110can form a sensor network. The sensors110can be attached to or embedded into the sensing surface102. The one or more sensors110can be operatively connected to the processor(s)120, the data store(s)122, and/or other element of the EDA acquisition system100(including any of the elements shown inFIG.1).

The sensor(s)110can be any suitable type of sensor. Various examples of different types of sensors will be described herein. However, it will be understood that the embodiments are not limited to the particular sensors described.

The sensors110can include one or more capacitive touch sensors112. The capacitive touch sensor(s)112can detect and measure anything that is conductive or has a dielectric different from air based on capacitive coupling. The capacitive touch sensor(s)112can detect and measure proximity, pressure, position and displacement, force, humidity, and/or acceleration. The capacitive touch sensor(s)112can be used in connection with the sensing surface102. In one or more arrangements and as an example, the capacitive touch sensor(s)112can be embedded into the sensing surface102and the capacitive touch sensor(s)112can detect contact with the sensing surface102. The capacitive touch sensor(s)112can detect how much surface area of the sensing surface102is in contact with an object (e.g., a hand or a finger).

The sensors110can include one or more force touch sensors114. In one or more arrangements and as an example, the force touch sensor(s)114can distinguish between various levels of force applied to the sensing surface102. The force touch sensor(s)114can measure the pressure and/or the weight of a finger and/or a hand and determine that there is contact with an object.

The sensors110can include one or more optical sensors116. The optical sensor(s)116can detect contact based on the presence and/or absence of light. As an example, the optical sensor(s)116can include infrared emitters that emit infrared light and infrared image sensors that detect infrared light. The infrared image sensors can detect when an object touches the sensing surface102and blocks a portion of the infrared light from being received by the infrared image sensors. In one or more arrangements and as another example, the optical sensor(s)116can detect contact with the sensing surface102based on an object touching the surface and the optical sensor(s)116detecting an absence of light. The location of the contact and the size of the contact area can be calculated by using information from the optical sensor(s)116and mathematical triangulation. In one or more arrangements, the optical sensors116can include one or more cameras.

The sensors110can include one or more skin conductance sensor(s)118. The skin conductance sensor(s)118can acquire EDA by measuring the conductivity of skin and/or sweat on the user's fingers and/or palm. In one or more arrangements, the skin conductance sensor(s)118can apply a constant voltage (e.g., 0.5V) to the first and second electrodes106,108that are in contact with the skin, creating a circuit. The skin conductance sensor(s)118can calculate the conductivity of the skin and/or sweat by measuring the current flowing through the first and second electrodes106,108. As an example, each electrode pair104can include a skin conductance sensor(s)118for measuring the skin conductance at that respective electrode pair104. Skin conductance can be expressed in micro-siemens. As an example, the skin conductance sensor(s)118can be designed to measure minute ( 1/1000) micro-siemens relative changes in sweat activity.

The EDA acquisition system100can include one or more modules, which will be described herein. The modules can be implemented as computer readable program code that, when executed by a processor, implement one or more of the various processes described herein. One or more of the modules can be a component of the processor(s)120, or one or more of the modules can be executed on and/or distributed among other processing systems to which the processor(s)120is operatively connected. The modules can include instructions (e.g., program logic) executable by one or more processor(s)120. Alternatively or in addition, one or more data store122may contain such instructions.

The EDA acquisition system100can include one or more electrode pair selection (EPS) modules130. The EPS module(s)130can be configured to select one or more electrode pairs104to activate in response to contact with the sensing surface102being detected. The EPS module130can receive information from the sensors110indicating which portions (if any) of sensing surface102are in contact with an object. The information can include, as an example, Cartesian coordinates of the portions in contact with an object. The EPS module130can identify the electrode pair(s)104proximate to the Cartesian coordinates. Upon identifying the electrode pair(s)104proximate to the Cartesian coordinates, the EPS module130can select one or more electrode pairs104to activate. In some arrangements, the selection of the electrode pair(s)104to activate can be based on additional or alternative factors, including at least one of signal quality and historical data. The EPS module130can select the electrode pairs104to activate based on any other suitable criteria such as to maximize the distance between the selected electrode pairs104, which can reduce parasitic voltage drop.

To select the electrode pairs104to activate based on signal strength, the EPS module130can measure the skin conductance level for the electrode pairs104that are in contact with an object and select the electrode pairs104with a strong signal. To determine the electrode pairs104with strong signals, the EPS module130can determine a threshold value that the measured skin conductance can meet or exceed.

In some arrangements, the EPS module130can activate the electrode pairs104that have been identified as being in contact with an object. To activate an electrode pair104, electrical energy can be supplied to the electrode pair104. The first and second electrodes106,108can be made active with opposite polarities. As an example, the first electrode106can have a negative polarity, and the second electrode108can have a positive polarity. Alternatively, the first electrode106can have a positive polarity, and the second electrode108can have a negative polarity. The EPS module130can measure the skin conductance through the activated electrode pairs104. If the measured skin conductance level meets or exceeds the threshold value, the EPS module130can determine that the electrode pair104has a strong signal and select the electrode pair104to be activated for measuring electrodermal activity. If the measured skin conductance level does not meet the threshold value, the EPS module130can determine that the electrode pair104does not have a strong signal and can determine not to select the electrode pair104for measuring electrodermal activity. The EPS module130can update signal strength of the electrode pair104in the historical data.

To select the electrode pairs104to activate based on historical data, the EPS module130can, as an example, determine the frequency with which the electrode pairs104in contact with an object are selected for measuring electrodermal activity. As another example, the EPS module130can determine the previously measured signal strength of the electrode pairs. In some arrangements, the EPS module130can select the electrode pairs104that are most frequently used to measure electrodermal activity. In some other arrangements, the EPS module130can select the electrode pairs104that are least frequently used to measure the electrodermal activity. In some other arrangements, the EPS module130can select the electrode pairs104that were used in a preceding session of measuring the electrodermal activity.

As an example, the EPS module130can receive the historical data from the data store122. The EPS module130can determine, based on the received historical data, the frequency of use of the electrode pairs104in contact with an object and/or the previously measured signal strength of the electrode pair104. The EPS module130can sort the electrode pairs104in contact from most frequently used to least frequently used, and/or from the electrode pair104with the highest previously measured signal strength to the electrode pair104with the lowest previously measured signal strength. The EPS module130can use any suitable algorithm to select the electrode pairs104to be activated. As an example, the EPS module130can select a certain number (e.g., one, more than one, or all) of electrode pairs104that meet a criteria, e.g., a frequency of use level or a signal strength level, to be activated for measuring electrodermal activity.

The EDA acquisition system100can include one or more finger/palm determination (FPD) module(s)132. The FPD module(s)132can be configured to determine whether a user's finger and/or palm is in contact with the sensing surface102. The FPD module(s)132can determine the area of contact with the sensing surface102based on the perimeter of the contact area. The FPD module(s)132can determine the size and/or the shape of the contact area based on, as an example, the x-, y-coordinates of the contact area. The FPD module(s)132can determine and/or distinguish between a finger and a palm based on size and shape as fingers tend to be narrower and longer than palms which tend to be wider and shorter.

In some arrangements, the FPD module(s)132can receive a finger print and/or handprint from a suitable sensor (e.g., fingerprint scanner, hand scanner, camera, etc.). In such arrangements, the FPD module(s)132can compare the fingerprint and/or handprint received from the sensor with fingerprint and/or handprint data in the user data stored in the data store(s)122. If the FPD module(s)132detects a match with the fingerprint, the FPD module(s)132can determine that the object in contact with the sensing surface102is a finger. If the FPD module(s)132detects a match with the handprint in the user data, the FPD module(s)132can determine that the object in contact with the sensing surface102is a palm.

In addition to the above examples, the FPD module(s)132can include any suitable object recognition software to detect whether the contact is being made by a user's finger, palm, both, or neither. The FPD module(s)132can use any suitable technique, including, for example, template matching and other kinds of computer vision and/or image processing techniques and/or other artificial or computational intelligence algorithms or machine learning methods. In some arrangements, the FPD module(s)132can tag the selected electrode pairs104that are in contact with the user's palm as being in contact with the user's palm. Additionally and/or alternatively, the FPD module(s)132can tag the selected electrode pairs104that are in contact with the user's finger(s) as being in contact with the user's finger(s).

The EDA acquisition system100can include one or more electrode pair activation (EPA) module(s)134. The EPA module(s)134can be configured to cause the one or more electrode pairs104to be activated or remain in an activated condition in response to the one or more electrode pairs104being selected. In some arrangements, the EPA module(s)134can be configured to deactivate or keep in a deactivated condition one or more non-selected electrode pairs. In some arrangements, the EPA module(s)134can be configured to cause the electrode pairs104tagged as being in contact with the user's palm and/or the electrode pairs104tagged as being in contact with the user's finger(s) to be activated. In cases where each of the electrode pairs104is operatively connected to an individualized control switch, the EPA module(s)134can power up the control switch(es) for the selected electrode pairs104. Upon being powered up, the control switch(es) can activate the electrode pair(s)104. In such cases and as previously mentioned, the first and second electrodes106,108can be set to opposite polarities and a small voltage can be applied between the first and second electrodes106,108.

The EDA acquisition system100can include one or more electrodermal activity acquisition (EAA) module(s)135. The EAA module(s)135can be configured to acquire EDA data from a user based on the contact with the sensing surface102, using the activated electrode pairs104. In one or more arrangements, the EAA module(s)135can cause the skin conductance sensor(s)118associated with the activated electrode pairs104to be activated. The skin conductance sensor(s)118can measure the skin conductance across the activated electrode pairs104, and the EAA module(s)135can receive the EDA data and the related electrode pairs104associated with the EDA data. Acquiring EDA data from the user can include measuring EDA using at least one of skin potential, resistance, conductance, admittance, and impedance. Skin potential can be the voltage measured between the first and second electrodes106,108of an activated electrode pair104. Skin resistance can be the resistance measured between the first and second electrodes106,108of the activated electrode pair104. Skin conductance can be the measurement of the electrical conductivity of the skin between the first and second electrodes106,108of the activated electrode pair104. Skin admittance is determined by measuring relative permittivity and the resistivity of the skin, and by contact ratio between dry electrodes and skin. Skin impedance can be the measurement of the impedance of the skin to alternating current of low frequency.

The EDA acquisition system100can include one or more parasitic resistance determination (PRD) modules136. The PRD module(s)136can be configured to determine the parasitic resistance between two or more activated electrode pairs104. The PRD module(s)136can receive information indicating the electrode pairs104selected to be activated. In one or more arrangements, the PRD module(s)136can calculate the parasitic resistance between two electrode pairs104based on the distance and/or the material between the electrode pairs104. Alternatively or additionally, the PRD module(s)136can access the historical data of the electrode pair104and retrieve from the historical data, the parasitic resistance for the electrode pair104based on whether any of the neighboring electrode pairs104have been selected to be activated. The PRD module(s)136can use any suitable method to calculate the parasitic resistance.

The EDA acquisition system100can include one or more electrodermal activity evaluation (EAE) module(s)138. In one or more arrangements, the EAE module(s)138can be configured to evaluate the EDA data based on one or more factors. As an example, the EAE module(s)138can be configured to evaluate the EDA data based on the determination of whether the user's finger or palm is in contact with the sensing surface102. The range of EDA data acquired from the fingers can differ significantly from the range of EDA data acquired from the palm such that evaluating the EDA data from the fingers and palm together can lead to inaccuracies. As such the EAE module(s)138can evaluate the EDA data for the palms or the EDA data for the fingers. In cases where the EAE module(s)138evaluates EDA data for the palms and the fingers, the EAE module(s)138can evaluate the EDA for the palm(s) separate from EDA data for the finger(s).

In cases when there are activated electrode pairs104in contact with the user's palm or the user's finger(s) but not both, the EAE module(s)138can conduct further analyses with the activated electrode pairs104. In the case where the activated electrode pairs104include electrode pairs104in contact with the user's palm and electrode pairs104in contact with the user's finger(s), the EAE module(s)138can group the EDA data into a first group, where the electrode pairs104are in contact with a finger and a second group, where the electrode pairs104are in contact with a palm. The EAE module(s)138can determine which one of the two groups to select for further analysis. Alternatively, the EAE module can continue with the two groups for further analysis.

The EAE module(s)138can be configured to evaluate the EDA data based on the determined parasitic resistance. The parasitic resistance can affect the EDA data, leading to inaccuracies. As such, the EAE module(s)138can adjust the EDA data so as to take the parasitic resistance into account. As an example, the EAE module(s)138can subtract the parasitic resistance from the EDA calculations.

The EAE module(s)138can use any suitable calculations and/or algorithms to evaluate and determine accurate EDA data. The EAE module(s)138can identify and reduce noise in the EDA data measurement. The EAE module(s)138can compare EDA data received from two or more activated electrode pairs104to identify noise. The EAE module(s)138can apply any suitable machine learning techniques to learn how to receive noisy EDA data from the electrode pairs104and reconstruct the noisy EDA data into one or more EDA measurements with low signal-to-noise ratio. The EAE module(s)138can evaluate the one or more EDA measurements to determine the emotional state of the user. Alternatively or additionally, the single resulting EDA measurement can be transmitted to any interested entity.

The EDA acquisition system100can include one or more communication modules140. A “communication module” refers to a component designed to transmit and/or receive information from one source to another. The communication module(s)140can transmit and/or receive information via one or more communication networks. The communication network(s) can include an internal communication network as well as an external communication network.

The internal communication network can include a bus and/or other wired and/or wireless mechanisms. The elements of the EDA acquisition system100such as the data store122, the sensors110, and the processor(s)120can be communicatively linked to each other through the internal communication network. Each of the elements of the EDA acquisition system100can include and/or execute suitable communication software, which enables the various elements to communicate with each other through the communication network and perform the functions disclosed herein.

The external communication network represents one or more mechanisms by which the EDA acquisition system100can communicate with other entities, e.g., a mobile device, a vehicle system, and/or a server. For instance, the EDA acquisition system100can send EDA data to a mobile device, a vehicle safety system, and/or a server. The external communication network can include any suitable communication mechanism such as a Wi-Fi hotspot.

Referring toFIG.2, an example of a sensing surface102is shown. As an example and as shown inFIG.2, the sensing surface102can include the plurality of electrode pairs104. The electrode pairs104can be arranged in any suitable manner. For example, as shown, the electrode pairs104can be arranged in a grid format.

The distance D1between the first and second electrode106,108of each electrode pair104can be substantially equal. The distance A1, D2between neighboring electrode pairs104can be significantly larger (e.g., 2, 3, 4, 5 or more times larger) than the distance D1between the first and second electrodes106,108. In some arrangements, the distance A1, D2between neighboring electrode pairs104can be substantially equal across the sensing surface102.

With the distance D1between the first and second electrode106,108of the electrode pairs104being substantially equal, the resistance between the first and second electrodes106,108of the electrode pairs104can be substantially equal. Having the voltages, resistances, and currents of the electrode pairs104be substantially equal to the voltage, resistance, and current of other electrode pairs104respectively can reduce the processing power required for evaluating the EDA data.

Now that the various potential systems, devices, elements and/or components of the EDA acquisition system100have been described, various methods will now be described. Various possible steps of such methods will now be described. The methods described may be applicable to the arrangements described above in relation toFIGS.1-2, but it is understood that the methods can be carried out with other suitable systems and arrangements. Moreover, the methods may include other steps that are not shown here, and in fact, the methods are not limited to including every step shown. The blocks that are illustrated here as part of the methods are not limited to the particular chronological order. Indeed, some of the blocks may be performed in a different order than what is shown and/or at least some of the blocks shown can occur simultaneously.

Referring now toFIG.3, an example of an EDA measuring method300is shown. The method300can be directed to actions being performed by one or more of the elements of the EDA acquisition system100.

At block310, contact with a sensing surface102can be detected. The contact can be detected by the one or more sensors110. In some arrangements, it can be determined whether a user's finger or a user's palm is in contact with the sensing surface102. The FPD module(s)132can determine whether the user's finger or the user's palm is in contact with the sensing surface102. The method300can continue to block320.

At block320, in response to detecting contact with the sensing surface102, one or more electrode pairs104can be selected to be activated. The selection of the one or more electrode pairs104to activate can be performed by the EPS module(s)130. As an example and as previously mentioned, the EPS module(s)130can select the electrode pairs104to activate based on at least one of signal quality and historical data. The method300can continue to block330.

At block330, in response to selecting one or more electrode pairs104to activate, the selected one or more electrode pairs104can be activated. The EPA module(s)134can cause the electrode pairs104to be activated.

The method300can end. Alternatively, the method300can return to block310or to some other block. The method300can be repeated at any suitable point, such as at a suitable time or upon the occurrence of any suitable event or condition (e.g., a change in hand position or contact area).

The method300can include additional and/or alternative blocks to those described above. For instance, in some arrangements, the parasitic resistance for the activated electrode pairs104can be determined. In some arrangements, the EAE module(s)138can acquire EDA data from the user using the activated electrode pairs104. In some arrangements, the EDA data can be evaluated and/or transmitted to any interested entity.

A non-limiting example of the operation of the EDA acquisition system100and/or one or more of the methods will now be described in relation toFIGS.4A-4B.FIGS.4A-4Bshow an example of an EDA acquisition and measuring scenario. Referring toFIGS.4A-4B, a user can rest his or her palm on a handrest400while operating a vehicle user interface402.

As shown inFIG.4A, the user places his or her palm on top of the handrest400, which includes the sensing surface102. The sensors110can detect contact with the sensing surface102. Based on the detected contact with the sensing surface102, the FPD module(s)132can determine whether the user's finger(s) or palm is in contact with the sensing surface102. In this case, the FPD module(s)132can receive information from the sensors110such as the force touch sensor(s)114indicating that a relatively even force is being applied to the sensing surface102. The FPD module(s)132can determine that the surface area corresponding to the applied force on the sensing surface102is significantly wider than the width of a human finger, and as such can determine that the user's palm is in contact with the sensing surface102.

The EPS module(s)130can select the electrode pairs404to activate based on current conditions such as signal quality. Alternatively or additionally, the EPS module(s)130can select the electrode pairs404based on historical data such as signal quality and the frequency of use of the electrode pairs404in contact with the user's palm. In this example, the EPS module(s)130can select three electrode pairs404A,404B,404C. The EPA module(s)134can activate the selected electrode pairs404A,404B,404C. Activating the electrode pairs404A,404B,404C can causes the first electrodes406A,406B,406C to have a negative polarity, the second electrodes408A,408B,408C to have a positive polarity. A low voltage can travel through the skin of the user from the second electrode408A,408B,408C to the first electrode406A,406B,406C, respectively.

The parasitic resistance between the activated electrode pairs404can be determined based on the material of the sensing surface102and the distance between the activated electrode pairs404A,404B,404C. The skin conductance sensor(s)118can measure the conductivity of the skin on the user's palm. The EAE module(s)138can determine the EDA data based on the conductivity measured by the skin conductance sensor(s)118and the parasitic resistance. Upon calculating the EDA data, the EAE module(s)138can transmit the resulting EDA data through the communication module(s)140to the user's mobile device and/or to one or more vehicle components and/or systems, such as the processor(s)120.

As shown inFIG.4B, the user has moved his or her hand from the position shown inFIG.4A. The sensor(s)110can detect there is no longer contact between the previously selected electrode pairs404and the user's palm. The sensors110can also detect contact at another portion of the sensing surface102. The EPA module(s)134can deactivate the previously selected electrode pairs404A,404B,404C by, as an example, powering down the control switch(es) associated with the previously selected electrode pairs404A,404B,404C. The EPS module(s)130can select one or more electrode pairs404D,404E,404F to be activated based on the electrode pairs404D,404E,404F in contact with the user's hand and historical data. The EPA module(s)134can activate the selected electrode pairs404D,404E,404F. The selected electrode pair404D includes a first electrode406D and a second electrode408D. The selected electrode pair404E includes a first electrode406E and a second electrode408E. The selected electrode pair404F includes a first electrode406F and a second electrode408F. The skin conductance sensor(s)118can measure the conductivity across the selected electrode pairs404D,404E,404F. The parasitic resistance can be determined. The EDA data can be evaluated based on the parasitic resistance. The resulting EDA data can be transmitted, as mentioned in the example above, through the communication module(s)140to the user's mobile device and/or one or more vehicle components and/or systems, such as the processor(s)120.

It will be appreciated that arrangements described herein can provide numerous benefits, including one or more of the benefits mentioned herein. For example, arrangements described herein facilitate acquiring and measuring the electrodermal activity of a user. Arrangements described herein can acquire the electrodermal activity of the user in a non-invasive manner. Arrangements described herein can acquire EDA measurements without a continuous connection to the user's skin. Arrangements described herein can acquire EDA measurements without the use of glued electrodes or electrodes hardly pressed against the skin. Arrangements described herein can provide accurate electrodermal activity measurements. Arrangements described herein can result in reduced computing and processing power requirements. Arrangements described herein can result in identifying the emotional state of a user.

As used herein, the term “substantially” or “about” includes exactly the term it modifies and slight variations therefrom. Thus, the term “substantially equal” means exactly equal and slight variations therefrom. “Slight variations therefrom” can include within 15 percent/units or less, within 14 percent/units or less, within 13 percent/units or less, within 12 percent/units or less, within 11 percent/units or less, within 10 percent/units or less, within 9 percent/units or less, within 8 percent/units or less, within 7 percent/units or less, within 6 percent/units or less, within 5 percent/units or less, within 4 percent/units or less, within 3 percent/units or less, within 2 percent/units or less, or within 1 percent/unit or less. In some instances, “substantially” can include being within normal manufacturing tolerances.