Vehicle control based on eeg signals

Abstract

Computer-implemented control of a vehicle includes receiving an electroencephalography (EEG) signal 201 from one or more EEG sensors, associated with a driver of the vehicle. Processing the received EEG signal to determine a signal strength indicative of a brain activity level of the driver 202. Controlling adjustment of one or more operating parameters of the vehicle based on the determined signal strength 203. The EEG signals from the driver may control the different driving modes of the vehicle e.g., comfort or sport and control features of the vehicle such as seat adjustment, suspension stiffness, throttle response, ADAS settings, climate, lighting and in car entertainment.

Description

TECHNICAL FIELD The invention relates to controlling a vehicle based on electroencephalography (EEG) signals and, in particular, to automatically controlling operating parameters, e.g. driver seat recline level, suspension stiffness, of the vehicle based on a signal strength of an EEG signal associated with a driver of the vehicle. BACKGROUND It is known for vehicles, such as cars, to have a number of adjustable operating parameters or features that can be adjusted according to driver preference, driving conditions, etc. These can include features relating to the driveability of a vehicle, such a s a stiffness level of a vehicle suspension system or a response time / level of a vehicle throttle. These can also include features relating to driver comfort, such as the degree to which a vehicle driver seat is reclined or the driver seat ride height. Furthermore, these can also include features relating to vehicle cabin environment, such as cabin temperature or the vehicle audio device (radio) volume or specific playlist. It will be appreciated that it can be time consuming and a significant burden for a vehicle driver to need to manually adjust each of the various vehicle operating parameters in line with personal preference or what is appropriate for the prevailing driving conditions. Many vehicles are provided with a number of different driving modes. Switching between these different modes may automatically change a number of different vehicle operating parameters or features in line with predefined settings for a specific mode. For instance, selection of a sport mode of a vehicle may adjust the vehicle suspension to be stiffer, the driver seat to be more upright, and the throttle response to be more aggressive. On the other hand, selection of a comfort mode of a vehicle may soften the suspension, recline the driver seat, and smooth out the throttle response. Although selection of a particular vehicle driving mode may adjust a number of different operating parameters or features, manually selecting different driving modes can still be burdensome for a driver and a distraction from driving the vehicle. Also, a driver may not be aware of the most appropriate driving mode for a given set of driving conditions at a particular time. It is against this background to which the present invention is set. SUMMARY OF THE INVENTION According to an aspect of the invention there is provided a computer-implemented method of controlling a vehicle. The method comprises receiving an electroencephalography (EEG) signal, from one or more EEG sensors, associated with a driver of the vehicle. The method comprises processing the received EEG signal to determine a signal strength indicative of a brain activity level of the driver. The method comprises controlling adjustment of one or more operating parameters of the vehicle based on the determined signal strength. The method may comprise determining whether the signal strength is greater than a first threshold value. If the signal strength is greater than the first threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a first mode of vehicle operation. The first mode of vehicle operation may be a sport mode. The method may comprise determining whether the signal strength is less than a second threshold value less than or equal to the first threshold value. If the signal strength is less than the second threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a second mode of vehicle operation. The second mode of vehicle operation may be a comfort mode. The first threshold value may be greater than the second threshold value. If the signal strength is greater than the second threshold value and less than the first threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a neutral mode of vehicle operation. The method may comprise determining whether the signal strength is less than a third threshold value less than the second threshold value. If the signal strength is less than the third threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with the third mode of vehicle operation. The third mode may be the same as the first mode. Alternatively, in the third mode only some of the one or more vehicle operating parameters are adjusted in the same way as in the first mode. The one or more vehicle operating parameters may comprise a recline level of a driver seat of the vehicle. In the second mode of vehicle operation the recline level may be greater than in the first mode of vehicle operation. The one or more vehicle operating parameters may comprise a stiffness level of a suspension system of the vehicle. In the second mode of vehicle operation the stiffness level may be less than in the first mode of vehicle operation. The method may comprise processing the received EEG signal to filter signal content into one or more defined frequency ranges. The processing to determine the signal strength may comprise determining the signal strength of the filtered signal content in one or more of the defined frequency ranges. The controlling step may comprise controlling adjustment of the one or more vehicle operating parameters based on the determined signal strength of the filtered signal content in the one or more defined frequency ranges. The one or more defined frequency ranges may include a gamma wave frequency range. If the signal strength of the filtered signal content in the gamma wave frequency range is greater than a first threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a sport mode of vehicle operation. The one or more defined frequency ranges may include an alpha wave frequency range. If the signal strength of the filtered signal content in the alpha wave frequency range is greater than a second threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a comfort mode of vehicle operation. The one or more defined frequency ranges may include a beta wave frequency range. If the signal strength of the filtered signal content in the beta wave frequency range is greater than a third threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with a neutral mode of vehicle operation. The one or more defined frequency ranges may include a theta wave frequency range. If the signal strength of the filtered signal content in the theta wave frequency range is greater than a fourth threshold value then the controlling step may comprise controlling the one or more vehicle operating parameters to be adjusted in accordance with an alert mode of vehicle operation. The alert mode may be the same as the sport mode. Alternatively, in the alert mode only some of the one or more vehicle operating parameters are adjusted in the same manner as in the sport mode. The one or more vehicle operating parameters may comprise a recline level of a driver seat of the vehicle. In the comfort mode of vehicle operation the recline level may be greater than in the sport mode of vehicle operation. In the alert mode of vehicle operation the recline level may be less than in the comfort mode of vehicle operation. The one or more vehicle operating parameters may comprise a stiffness level of a suspension system of the vehicle. In the comfort mode of vehicle operation the stiffness level may be less than in the sport mode of vehicle operation. In the alert mode of vehicle operation the stiffness level may be greater than in the comfort mode of vehicle operation. Each of the one or more operating parameters of the vehicle may be adjustable between a sport setting and a comfort setting. If it is determined that the signal strength has increased relative to a previous iteration, then the method may comprise controlling adjustment of the one or more operating parameters towards the respective sport setting. If it is determined that the signal strength has decreased relative to a previous iteration, then the method may comprise controlling adjustment of the one or more operating parameters towards the respective comfort setting. Each of the one or more operating parameters of the vehicle are adjustable between a sport setting and a comfort setting, the method comprising determining whether the determined signal strength corresponds to an optimal signal strength associated with a current setting of each of the one or more vehicle operating parameters, wherein if the determined signal strength is less than the optimal signal strength then the method comprises controlling adjustment of the one or more operating parameters towards the respective sport setting, and wherein if the determined signal strength is greater than the optimal signal strength then the method comprises controlling adjustment of the one or more operating parameters towards the respective comfort setting. In some examples, controlling adjustment of the one or more operating parameters towards the respective sport setting may comprise one or more of: increasing a stiffness level of a suspension system of the vehicle; and, reducing a recline level of the driver seat. In some examples, controlling adjustment of the one or more operating parameters towards the respective comfort setting may comprise one or more of: decreasing the stiffness level of the suspension system; increasing the recline level of the driver seat; smoothening a response of a throttle of the vehicle. The first threshold value, second threshold value, third threshold value and / or fourth threshold value may be dependent on the individual driver of the vehicle. It will be understood that any suitable number of threshold values of signal strength may be defined, and each interval or range of signal strengths defined by the thresholds may be associated with different settings for the one or more vehicle parameters. It will also be understood that the settings of one or more of the vehicle parameters may be adjusted without reference to threshold values of signal strength. Instead, the values of such vehicle parameters may be adjusted gradually based on signal strength. For instance, a firmness of a suspension system of the vehicle may be adjusted based on the signal strength, where the adjustment is relatively gradual and occurs substantially constantly. The first threshold value, second threshold value, third threshold value and / or fourth threshold value may be set based on historical EEG signals associated with the individual driver acquired when the individual driver is operating the vehicle in one or more specific modes of vehicle operation as part of a training process. For instance, the vehicle may initially be provided with default values for the threshold values, e.g. based on an average user, and then the threshold values are adapted from the default values during the training process to be specific to a specific user of the vehicle. The one or more vehicle operating parameters may comprise one or more of: a recline level of a driver seat of the vehicle; a stiffness level of a suspension system of the vehicle; a response setting of a throttle of the vehicle; an advanced driver assistance system (ADAS) setting of the vehicle; an interior climate setting in a cabin of the vehicle; an interior lighting setting in the cabin; a seat massage setting of the driver seat; and, a playlist or radio station setting in the cabin. According to another aspect of the invention there is provided a non-transitory, computer readable storage medium storing instructions thereon that when executed by one or more processors cause the one or more processors to perform the method defined above. According to another aspect of the invention there is provided a controller for controlling a vehicle. The controller is configured to receive an electroencephalography (EEG) signal, from one or more EEG sensors, associated with a driver of the vehicle. The controller is configured to process the received EEG signal to determine a signal strength indicative of a brain activity level of the driver. The controller is configured to output a control signal to adjust one or more operating parameters of the vehicle based on the determined signal strength. According to another aspect of the invention there is provided a control system for a vehicle. The control system comprises a controller as defined above. The control system comprises a device comprising at least one EEG sensor for acquiring the EEG signal, the device being configured to be wearable on a head of the driver. According to another aspect of the invention there is provided a vehicle comprising a controller as defined above. BRIEF DESCRIPTION OF THE DRAWINGS Examples of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a vehicle in accordance with an example of the invention; Figure 2 shows the steps of a method performed by a controller of the vehicle of Figure 1, in accordance with examples of the invention; Figure 3 shows sub-steps of steps of the method of Figure 2 in an example of the invention; and, Figure 4 shows sub-steps of steps of the method of Figure 2 in another example of the invention. DETAILED DESCRIPTION The present invention advantageously provides for automatically controlling adjustment of one or more vehicle operating parameters in an appropriate manner without the need for a vehicle driver to manually adjust such operating parameters. This can involve adjustment of individual operating parameters of the vehicle, e.g. driver seat recline level, suspension stiffness, etc., or it can involve switching between different defined driving modes of the vehicle, e.g. sport mode, comfort mode, etc., which can include adjusting a set of operating parameters in a defined manner. The invention particularly involves automatically determining what vehicle operating parameter values / settings are desired or appropriate at a given time and then providing for automatic control to adjust the operating parameters accordingly. The determination is based on measurements or recognition of the driver emotional state or mood, specifically the excitement levels of the driver or other vehicle occupant under consideration. This is achieved by monitoring brain activity of the driver or other occupant. The invention associates different driver emotional states to different driving modes or operating parameter settings of the vehicle, and provides for automatic control to adjust / switch the driving mode or operating parameters as appropriate based on monitored driver emotional state. The operating parameters can therefore be adjusted in a binary manner, e.g. by switching between different defined driving modes, or incrementally, by adjusting values / settings of different operating parameters. The invention in particular bases the automatic adjustment / personalisation of driving modes or operating parameters on feedback from electroencephalogram (EEG) sensors / data associated with a vehicle driver. EEG sensors can be used to monitor the brain and the acquired sensor signals can be used to determine or estimate (perceived) emotional states of a human, e.g. a vehicle driver. For instance, an emotional state of a human may be recognised based on activity levels in EEG sensor signals. That is, brainwave activity may be correlated to levels of emotional arousal, which in some cases can be conveniently labelled as or referred to as excitement levels, with high levels of activity being associated with excitement and low levels of activity being associated with relaxation or calm. The invention advantageously associates specific emotional states of a vehicle driver with the most appropriate driving modes or individual operational parameter settings of the vehicle, and automatically adjusts the driving modes or operational parameter settings based on the emotional state of the vehicle driver, determined based on monitored EEG sensor signals from the driver. Beneficially, there is a reduced burden on the driver as the driver needs to make fewer (or zero) manual interventions to adjust various vehicle operating parameters. This means that the driver is freer to concentrate on driving the vehicle with fewer distractions. An important benefit of the invention is that the automatic adjustment of vehicle driving mode or operating parameters is performed subconsciously on the part of the driver. That is, there is no need for the driver to consciously think about how the vehicle operating parameters should be adjusted in order for the adjustment to be performed, i.e. there is no need to determine an intention on the part of the driver. The invention instead acts on monitored brainwave activity levels to determine the most appropriate driving mode or operating parameter settings. Indeed, by not determining and acting on a driver intention the driving mode or operating parameters of the vehicle can be automatically adjusted in a manner that is most appropriate to the driver’s emotional state, whether the driver realises that such an adjustment is appropriate or not. Further advantages associated with the invention will become apparent in the description of examples of the invention below. Figure 1 schematically illustrates a vehicle 10 in the form of a car or automobile. The vehicle 10 is to be driven by a (human) driver 12. The vehicle 10 has a number of operating parameters, features or functions that may be adjusted in line with driver preference or in line with what is most suitable for particular driving conditions, e.g. time of day, weather, traffic levels, terrain, etc. In the described example, the operating parameters include parameters relating to the driveability of the vehicle 10. These include a stiffness level of a suspension system of the vehicle 10, a response time / level of a throttle (pedal) of the vehicle 10, and a tightness level of a steering wheel of the vehicle 10. In the described example, the operating parameters also include parameters relating to driver comfort. These include the positioning of a driver’s seat of the vehicle 10. The driver seat positioning can refer to the degree to which the driver seat - in particular, the back of the seat - is reclined. The driver seat positioning can also refer to the ride height of the driver seat. Furthermore, in the described example the operating parameters also include parameters relating to vehicle cabin environment. These can include cabin temperature and / or a heat setting of a heated driver seat. These can also include settings relating to the vehicle radio (or other audio device), such as volume, specific radio station, specific playlist, etc. It will be appreciated that an exhaustive list of vehicle operating parameters, features or functions is not provided here, and that the skilled person will be aware of further such parameters, features or functions that are provided in vehicles and could be included in examples of the invention. The vehicle 10 includes one or more electronic control units (ECUs) 101 for controlling one or more electrical systems or subsystems of the vehicle 10. In particular, each ECU 101 may be configured to control adjustment of one or more operating parameters of the vehicle 10, such as one or more of the operating parameters outlined above. The vehicle 10 also includes a central processing unit (CPU) 102 (or processing means or, simply, a processor). The CPU 102 may be referred to as a (vehicle) controller, or the CPU 102 and ECU(s) 101 may collectively be referred to as a controller. The CPU 102 is communicatively coupled to each of the ECUs 101, e.g. via a wired connection such as a CAN bus connection. The CPU 102 is configured to determine how one or more of the vehicle operating parameters are to be controlled or adjusted, and configured to transmit output signals to the ECUs 101 to instruct adjustment of the vehicle operating parameters appropriately. The CPU 102 in particular determines how to adjust the operating parameters based on input signals received by the CPU 102. It is known for a vehicle driver - or other vehicle occupant - to provide such input signals manually by adjusting or actuating various settings or controls in the vehicle cabin to effect adjustment of operating parameters in a desired manner. For instance, cabin temperature may be adjusted by the driver via a human machine interface (HMI) in the cabin or by actuating mechanical or electronic controls in the cabin. In another example, the degree to which the driver seat is reclined may be adjusted by the driver via a mechanical or electrical actuator located at a side of the driver seat. In examples of the present invention, the CPU 102 receives sensor data from one or more electroencephalography (EEG) sensors associated with the vehicle driver 12. In the described example, the driver 12 is provided with a wearable device 14 that is to be mounted to, or worn on, the head of the driver 12. The wearable device 14 may for instance be in the form of a headband or visor. The wearable device 14 is provided with one or more EEG sensors 141 that are configured to monitor brain activity or brainwaves of the driver 12. The device 14 may be provided with any appropriate number or set of sensors such as those typically used to acquire EEG signals. These may include single or multiple electrodes positioned around the driver’s scalp. Typically, a number of electrodes or receptors are positioned to sense electrical activity levels at different parts of the driver’s brain. Any suitable number of electrodes may be used to obtain a sufficiently accurate signal. For instance, in one example about 5-7 electrodes may be provided. Such a number may provide good signal strength and fidelity, where a greater number of electrodes typically provides a greater level of accuracy. One or more of the electrodes may be configured to measure background electrical activity, which can then be compared to the measurements from the other electrodes to determine the difference between background activity and brain activity, thereby removing noise from the monitored brain signals. The EEG signals obtained from the EEG sensors 141 may for instance be voltage and / or current measurements indicative of electrical activity of the driver’s brain. EEG signals from the EEG sensor(s) 141 are received by the CPU 102. The wearable device 14 and EEG sensor 141 may be wirelessly connected to the CPU 102. The CPU 102 may receive EEG signals directly from the EEG sensor 141. Alternatively, the EEG signals from the sensor 141 may be received by a mobile device, e.g. a mobile phone, which then transmits the EEG signals to the CPU 102. Figure 2 shows the steps of a method 20 implemented by a controller (CPU 102 and / or ECUs 101) of the vehicle 10 to control the vehicle in accordance with examples of the invention. The method 20 is therefore a computer-implemented method. At step 201, the method 20 involves receiving the EEG signals, from the one or more EEG sensors 141, associated with the driver 12 of the vehicle 10. The EEG signals may be processed to remove noise and other artifacts in a known manner to provide a consistent and reliable measurement of brain activity. This processing may be performed at the sensor 141 prior to transmittal to the CPU 102, or may be performed at the CPU 12. Typical output from the EEG sensor 141 at the scalp of the driver 12 may be in a range of approximately 10 microvolts to 100 microvolts. This can be amplified, normalised, etc. in a known manner, again at the device 12 or at the CPU 102 (or indeed at a further device such as a mobile device that receives the EEG signals). Known techniques such as power spectrum analysis, wavelet analysis or feature analysis may be performed to determine signal strength I power density of a received EEG signal. The measurements acquired by the sensor 141 may be real-time measurements, they may be acquired at a certain sampling rate, and / or they may be integrated over time depending on the particular sensor 141 being used. The or each potential from each individual sensor can be used or combined with other electrode potentials. At step 202, the method 20 involves processing the received EEG signal to determine a signal strength indicative of a brain activity level of the driver 12. This may be performed at the CPU 102. The signal strength may be based on a power density of the received (and optionally, processed) signal. The signal strength may be based on the received EEG signal ata given moment in time, in a given time range (e.g. the average in a given time range), an integrated value over time, or any other suitable method. At step 203, the method 20 involves controlling adjustment of one or more operating parameters of the vehicle 10 based on the determined signal strength. The operating parameters may include one or more of the operating parameters outlined above. A defined set of operating parameters may be adjusted based on the determined signal strength. The defined set may be associated with one of defined plurality of driving modes of the vehicle 10. These driving modes can include, for instance, a sport mode, comfort mode (relaxed mode), neutral mode, alert / focussed mode, eco mode, etc. Each of the defined driving modes may be associated with defined values / settings of one or more operating parameters of the vehicle 10. As an example, in a sport mode the driver seat may be adjusted to be in a relatively upright position, in a comfort mode the driver seat may be adjusted to be in a relatively reclined position, and in a neutral mode the driver seat may be adjusted to be in a position between the recline levels of the sport and comfort modes. Step 203 may therefore involve automatic adjustment of one or more individual operating parameters of the vehicle 10, or may involve automatic adjustment / switching between defined driving modes of the vehicle (each associated with particular values / settings of certain operating parameters). There are various ways in which the determined signal strength may be used to control the operating parameters, examples of which are described in greater detail below. In one example, adjustment of the operating parameters or switching between driving modes is based on the determined signal strength relative to one or more threshold values. Broadly, higher levels of signal strength are associated with a more excited emotional state, whereas lower levels are associated with a more relaxed / calm emotional state. As such, in one example a first threshold value is defined such that values of signal strength above the first threshold value are associated with an excited emotional state. In this example, the method 20 includes a step of determining whether the signal strength is greater than the first threshold value. If it is, then it is determined that the driver 12 is in an excited emotional state, and the method 20 involves effecting automatic adjustment of the operating parameters in a manner appropriate for an excited emotional state. In an example, this can involve automatically switching the driving mode of the vehicle 10 to a sport mode. The sport mode may include one or more of the following settings of possible operating parameters: a relatively upright driver seat (back) position; a relatively stiff setting of a suspension system of the vehicle; a relatively sensitive response of a throttle of the vehicle 10; relatively close shift points of a transmission of the vehicle 10; a relatively low ride height of the driver seat; disabling a driver seat massage feature; disabling traction control of the vehicle; a relatively cool cabin temperature; a relatively loud audio / radio volume setting; and, a relatively upbeat radio station or playlist setting. Alternatively, the automatic adjustment may involve effecting adjustment of one or more of the individual operating parameters. Some operating parameters may instead be selected by the user / occupant to be adjusted manually rather than automatically according to specific user preference. For instance, a specific user may prefer that traction control is not enabled / disabled automatically according to measured brain signal strength, e.g. to maintain consistency and predictability when driving the vehicle. On the other hand, in this example if the signal strength is less than a certain threshold value, then it is determined that the driver 12 is in a relaxed or calm emotional state, and the method 20 involves effecting automatic adjustment of the operating parameters in a manner appropriate for a relaxed emotional state. In an example, this can involve automatically switching the driving mode of the vehicle 10 to a comfort mode (relaxed mode, calm mode). The comfort mode may include one or more of the following settings of possible operating parameters: a relatively reclined driver seat (back) position; a relatively soft setting of a suspension system of the vehicle 10; a relatively insensitive response of a throttle of the vehicle 10; relatively distant shift points of a transmission of the vehicle 10; a relatively high ride height of the driver seat; enabling a driver seat massage feature; enabling traction control of the vehicle; a relatively soft / dark lighting level in the vehicle cabin; a relatively warm cabin temperature; a relatively quiet audio / radio volume setting; and, a relatively downbeat radio station or playlist setting. Alternatively, the automatic adjustment may involve effecting adjustment of one or more of the individual operating parameters. The certain threshold may be the first threshold value. Alternatively, the certain threshold may be a second threshold value less than the first threshold value. In the latter case, if the determined signal strength is between the first and second threshold values then it may be determined that the driver 12 is in a neutral emotional state, and the method 20 may involve switching the driving mode to a neutral mode. This may include operational parameter settings between those of the sport and comfort modes, as appropriate. In an example, a third threshold value is defined that is less than the second threshold value (and first threshold value), or just less than the first threshold example if a second threshold value is not defined. Values of signal strength below the third threshold value may be associated with an emotional state that is sleepy, overly relaxed or not sufficiently focussed for driving the vehicle 10. If the determined signal strength is less than the third threshold value, then the method 20 may involve switching the driving mode to an alert mode. The alert mode may be associated with operating parameter values / settings that promote driver alertness more than the comfort mode. For instance, the alert mode may be the same as - or have operating parameter settings similar to - the sport mode. In an example, the alert mode may include adjusting operating parameters to encourage an increase in alertness of the driver 12, e.g. vibrating the driver seat or steering wheel, outputting audio or visual signals in the vehicle cabin, etc. Consider a case in which the driver seat inclination level is adjusted based on the received EEG signals. High levels of signal strength in the received EEG signal may result in the driver seat being adjusted to be relatively upright as the driver is in an excited emotional state and so a ‘sport’ setting is appropriate. Slightly lower signal strength levels may result in the driver seat being adjusted to be less upright (more reclined) as the driver is in a more neutral emotional state. Slightly lower still signal strength levels may then result in the driver seat being adjusted to be even less upright (even more reclined) as the driver is in a more relaxed emotional state. However, if the signal strength decreases even further then the driver seat may be adjusted to be more upright (less reclined) than in the relaxed emotional state as the driver 12 may be becoming more sleepy or less concentrated, and so a more ‘alert’ setting for the driver seat is needed. It will be appreciated that various vehicle operating parameters can be adjusted in a corresponding manner. The various threshold values may be specific to a specific individual driver. For instance, the threshold values may be determined or set based on historical data obtained from the specific driver under consideration. In one example, an initial training process may be performed in which EEG sensor signals are acquired from the driver, from which baseline levels of EEG signal strength (i.e. levels of excitement or emotional states) may be determined. The determined signal strengths may be compared against the particular driving mode or particular operating parameter settings selected by the driver as being appropriate (matching) their current emotional state, with the thresholds being set based on, or to reflect, these manually selected settings. The threshold values may be determined using various feedback strategies, e.g. monitoring the driver while in different driving modes and examining the acquired EEG signal strengths in the respective driving modes. Alternatively, various machine learning strategies may be used to assign levels of signal strength to each region representing a different driving mode. Further alternatively, the threshold values may be derived from EEG data obtained from a number of different users, which may be held locally or be cloud-based, held in lookup tables, etc. The received EEG data may be compared against threshold values stored in a memory device accessible by the CPU 102 and / or against reference EEG data stored in the memory device. In one example of the invention, the step 202 of processing the received EEG signal involves filtering the received signal into one or more defined frequency ranges prior to determining the signal strength. EEG signals of different frequencies are associated with different emotional states, and this can be leveraged to determine the driver emotional state, and so determine a most appropriate adjustment of vehicle operating parameters. EEG signals can in particular include so-called gamma waves, beta waves, alpha waves, theta waves and delta waves. Each of these different types of brainwave are associated with a different signal frequency range and associated with a different emotional state. Gamma waves have a frequency of about 30-100 Hz, and are associated with higher mental activity, excitement and motor functions. Beta waves have a frequency of about 12-30 Hz, and are associated with a normal waking state and concentration. Alpha waves have a frequency of about 7.5-12 Hz, and are associated with relaxation and light meditation. Theta waves have a frequency of about 4-7.5 Hz, and are associated with light sleep or deep meditation. Delta waves have a frequency of about 0.1-4 Hz, and are associated with deep, dreamless sleep. The step of filtering the received EEG signal may involve isolating frequency content in the signal corresponding to one or more of the different types of brainwaves. The step of determining the signal strength may then involve determining the strength of the signal in a particular frequency range, i.e. the strength of the signal of certain types of brainwave. Each of the different types of brainwave may have a threshold value associated therewith, and determining the signal strength may involve comparison of the signal strength against one or more thresholds of the respective different types of brainwave. If the signal strength of a specific type of brainwave exceeds the respective threshold, then this may correspond to automatic adjustment of vehicle operating parameters in a defined and appropriate manner. For instance, if the strength of gamma waves in the received signal is greater than a gamma wave threshold then the method 20 may involve automatically controlling the vehicle 10 to switch the driving mode to the sport mode (or equivalent operating parameter settings). If the strength of beta waves in the received signal is greater than a beta wave threshold then the method 20 may involve automatically controlling the vehicle 10 to switch the driving mode to the neutral mode. If the strength of alpha waves in the received signal is greater than an alpha wave threshold then the method 20 may involve automatically controlling the vehicle 10 to switch the driving mode to the comfort mode. If the strength of beta waves in the received signal is greater than a theta wave threshold then the method 20 may involve automatically controlling the vehicle 10 to switch the driving mode to the alert mode (or sport mode). Consider a case in which the driver seat inclination level is adjusted based on the received EEG signals. High levels of gamma waves in the received EEG signal may result in the driver seat being adjusted to be relatively upright as the driver is in an excited emotional state and so a ‘sport’ setting is appropriate. High levels of beta waves may result in the driver seat being adjusted to be less upright (more reclined) as the driver is in a more neutral emotional state. High levels of alpha waves may then result in the driver seat being adjusted to be even less upright (even more reclined) as the driver is in a more relaxed emotional state. However, high levels of theta waves may result in the driver seat being adjusted to be more upright (less reclined) than in the case of high alpha waves as the driver 12 may be becoming more sleepy or less concentrated, and so a more ‘alert’ setting for the driver seat is needed. It will be appreciated that various vehicle operating parameters can be adjusted in a corresponding manner. In examples of the invention, the step 202 of processing the received EEG signal involves monitoring a temporal change in the brainwave activity (signal strength), with the step 203 of controlling adjustment of the vehicle parameters being based on said change. Figure 3 illustrates sub-steps of steps 202, 203 of the method 20 in an example in which temporal change of the received signal strength is monitored. The method 20 may be repeated substantially continuously, at a sampling rate of the EEG signal or a defined time intervals. At sub-step 31, the method 20 may involve (at step 202) determining whether the signal strength of the (currently) received EEG sensor signal is different from the signal strength of an EEG signal previously received by the CPU 102, e.g. a previous sample or a previous execution of the method 20. If the signal strength remains the same, e.g. within a certain tolerance, then no action is taken. This may mean that current settings / values of the operating parameters or a current driving mode, e.g. as determined and adjusted at a previous iteration of the method 20, remain unchanged. On the other hand, if the signal strength has changed, then at sub-step 32 the CPU 102 determines whether the signal strength has increased or decreased. If the signal strength has decreased, then it is determined to increase the comfort level / feel of the operating parameter settings / values from their current level. The amount by which the comfort level is increased may depend on the magnitude of the decrease in EEG signal strength. Then at sub-step 33 (of step 203), the method involves automatically adjusting one or more vehicle operating parameters to effect this change of increasing the comfort level. This could be in the form of incrementally adjusting parameters, e.g. by a set amount. For instance, this could involve incrementally increasing the recline level of the driver seat or incrementally reducing a stiffness level of the vehicle suspension system. In a corresponding manner, if the signal strength has increased, then it is determined to increase the ‘sport’ level / feel of the operating parameter settings / values from their current level. The amount by which the sport level is increased may depend on the magnitude of the increase in EEG signal strength. Then at sub-step 34 (of step 203), the method involves automatically adjusting one or more vehicle operating parameters to effect this change of increasing the sport level. Again, this could be in the form of incrementally adjusting parameters. For instance, this could involve incrementally decreasing the recline level of the driver seat or incrementally increasing the stiffness level of the vehicle suspension system. Figure 4 illustrates sub-steps of steps 202, 203 of the method 20 in an example in which the received signal strength is monitored to determine whether current settings / values of vehicle operating parameters are appropriate for a current emotional state of the driver. At sub-step 41, the method 20 may involve (at step 202) determining whether signal strength determined from the received EEG signal corresponds to an emotional state for which the current operating parameter settings are appropriate. That is, it is determined whether the current operating parameter values are optimal, e.g. within a defined tolerance, for the current emotional state of the driver 12. If the current setup is optimal then no action is taken, i.e. no adjustment of parameter values is initiated by the CPU 102. On the other hand, if the current EEG signal strength is not at an optimal level for the current operating parameter values, then at step 42 it is determined whether the current EEG signal strength is above or below an optimal level. If the signal strength is too low for the current operating parameter settings then it is determined to increase the comfort level / feel of the operating parameter settings / values from their current level. The amount by which the comfort level is increased may depend on the amount that the current EEG signal strength is below the optimal level for the current parameter settings. Then at substep 43 (of step 203), the method involves automatically adjusting one or more vehicle operating parameters to effect this change of increasing the comfort level. In a corresponding manner, if the signal strength is too high for the current operating parameter settings, then it is determined to increase the ‘sport’ level / feel of the operating parameter settings / values from their current level. The amount by which the sport level is increased may depend on the amount that the current EEG signal strength is above the optimal level for the current parameter settings. Then at sub-step 44 (of step 203), the method involves automatically adjusting one or more vehicle operating parameters to effect this change of increasing the sport level. Many modifications may be made to the described examples without departing from the scope of the appended claims. In the described example, the device including the EEG sensors is a wearable device, specifically to be worn on a head of a user. In different examples, the device may be located differently relative to the user and / or vehicle. For instance, in some examples the device comprising the EEG sensors may be located in a headrest of a vehicle seat in which the user is sitting. More generally, the EEG sensors may be positioned in any suitable location on the user or vehicle that allows for a sufficiently accurate measurement of brain activity to be performed.

Claims

1. A computer-implemented method of controlling a vehicle, the method comprising: receiving an electroencephalography (EEG) signal, from one or more EEG sensors, associated with a driver of the vehicle;processing the received EEG signal to determine a signal strength indicative of a brain activity level of the driver; and,controlling adjustment of one or more operating parameters of the vehicle based on the determined signal strength.

2. A method according to Claim 1, the method comprising determining whether the signal strength is greater than a first threshold value, wherein if the signal strength is greater than the first threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with a first mode of vehicle operation.

3. A method according to Claim 2, wherein the first mode of vehicle operation is a sport mode.

4. A method according to Claim 2 or Claim 3, the method comprising determining whether the signal strength is less than a second threshold value less than or equal to the first threshold value, wherein if the signal strength is less than the second threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with a second mode of vehicle operation.

5. A method according to Claim 4, wherein the second mode of vehicle operation is a comfort mode.

6. A method according to Claim 4 or Claim 5, wherein the first threshold value is greater than the second threshold value.

7. A method according to any of Claims 4 to 6, wherein if the signal strength is greater than the second threshold value and less than the first threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with a neutral mode of vehicle operation.

8. A method according to any of Claims 4 to 7, the method comprising determining whether the signal strength is less than a third threshold value less than the second threshold value, wherein if the signal strength is less than the third threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with the third mode of vehicle operation.

9. A method according to Claim 8, wherein the third mode is the same as the first mode.

10. A method according to any of Claims 4 to 9, wherein the one or more vehicle operating parameters comprises a recline level of a driver seat of the vehicle, wherein in the second mode of vehicle operation the recline level is greater than in the first mode of vehicle operation.

11. A method according to any of Claims 4 to 10, wherein the one or more vehicle operating parameters comprises a stiffness level of a suspension system of the vehicle, wherein in the second mode of vehicle operation the stiffness level is less than in the first mode of vehicle operation.

12. A method according to any previous claim, the method comprising processing the received EEG signal to filter signal content into one or more defined frequency ranges, wherein the processing to determine the signal strength comprises determining the signal strength of the filtered signal content in one or more of the defined frequency ranges, and wherein the controlling step comprises controlling adjustment of the one or more vehicle operating parameters based on the determined signal strength of the filtered signal content in the one or more defined frequency ranges.

13. A method according to Claim 12, wherein the one or more defined frequency ranges includes a gamma wave frequency range, wherein if the signal strength of the filtered signal content in the gamma wave frequency range is greater than a first threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with a sport mode of vehicle operation.

14. A method according to Claim 12 or Claim 13, wherein the one or more defined frequency ranges includes an alpha wave frequency range, wherein if the signal strength of the filtered signal content in the alpha wave frequency range is greater than a second threshold value then the controlling step comprises controlling the one or more vehicleoperating parameters to be adjusted in accordance with a comfort mode of vehicle operation.

15. A method according to any of Claims 12 to 14, wherein the one or more defined frequency ranges includes a beta wave frequency range, wherein if the signal strength of the filtered signal content in the beta wave frequency range is greater than a third threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with a neutral mode of vehicle operation.

16. A method according to any of Claims 12 to 15, wherein the one or more defined frequency ranges includes a theta wave frequency range, wherein if the signal strength of the filtered signal content in the theta wave frequency range is greater than a fourth threshold value then the controlling step comprises controlling the one or more vehicle operating parameters to be adjusted in accordance with an alert mode of vehicle operation.

17. A method according to Claim 16, wherein the alert mode is the same as the sport mode.

18. A method according to any of Claims 14 to 17, wherein the one or more vehicle operating parameters comprises a recline level of a driver seat of the vehicle, wherein in the comfort mode of vehicle operation the recline level is greater than in the sport mode of vehicle operation, and wherein in the alert mode of vehicle operation the recline level is less than in the comfort mode of vehicle operation.

19. A method according to any of Claims 14 to 18, wherein the one or more vehicle operating parameters comprises a stiffness level of a suspension system of the vehicle, wherein in the comfort mode of vehicle operation the stiffness level is less than in the sport mode of vehicle operation, and wherein in the alert mode of vehicle operation the stiffness level is greater than in the comfort mode of vehicle operation.

20. A method according to any previous claim, wherein each of the one or more operating parameters of the vehicle are adjustable between a sport setting and a comfort setting, wherein if it is determined that the signal strength has increased relative to a previous iteration, then the method comprises controlling adjustment of the one or more operating parameters towards the respective sport setting, and wherein if it is determined that the signal strength has decreased relative to a previous iteration, then the method comprisescontrolling adjustment of the one or more operating parameters towards the respective comfort setting.

21. A method according to any previous claim, wherein each of the one or more operating parameters of the vehicle are adjustable between a sport setting and a comfort setting, the method comprising determining whether the determined signal strength corresponds to an optimal signal strength associated with a current setting of each of the one or more vehicle operating parameters, wherein if the determined signal strength is less than the optimal signal strength then the method comprises controlling adjustment of the one or more operating parameters towards the respective sport setting, and wherein if the determined signal strength is greater than the optimal signal strength then the method comprises controlling adjustment of the one or more operating parameters towards the respective comfort setting.

22. A method according to Claim 20 or Claim 21, wherein:controlling adjustment of the one or more operating parameters towards the respective sport setting comprises one or more of: increasing a stiffness level of a suspension system of the vehicle; and, reducing a recline level of the driver seat,controlling adjustment of the one or more operating parameters towards the respective comfort setting comprises one or more of: decreasing the stiffness level of the suspension system; increasing the recline level of the driver seat; smoothening a response of a throttle of the vehicle.

23. A method according to any of Claims 2 to 22, wherein the first threshold value, second threshold value, third threshold value and / or fourth threshold value is dependent on the individual driver of the vehicle.

24. A method according to Claim 23, wherein the first threshold value, second threshold value, third threshold value and / or fourth threshold value is set based on historical EEG signals associated with the individual driver acquired when the individual driver is operating the vehicle in one or more specific modes of vehicle operation as part of a training process.

25. A method according to any previous claim, wherein the one or more vehicle operating parameters comprises one or more of:a recline level of a driver seat of the vehicle;a stiffness level of a suspension system of the vehicle;a response setting of a throttle of the vehicle;an advanced driver assistance system (ADAS) setting of the vehicle;an interior climate setting in a cabin of the vehicle;an interior lighting setting in the cabin;a seat massage setting of the driver seat; and,a playlist or radio station setting in the cabin.

26. A controller for controlling a vehicle, the controller being configured to:receive an electroencephalography (EEG) signal, from one or more EEG sensors, associated with a driver of the vehicle;process the received EEG signal to determine a signal strength indicative of a brain activity level of the driver; and,output a control signal to adjust one or more operating parameters of the vehicle based on the determined signal strength.

27. A control system for a vehicle, the control system comprising:a controller according to Claim 26; and,a device comprising at least one EEG sensor for acquiring the EEG signal, the device being configured to be wearable on a head of the driver.

28. A vehicle comprising a controller according to Claim 26.

Images