GB2626796A - Apparatus and method for vibration control - Google Patents

Abstract

A vehicle seat vibration control system for controlling vibrations of an unoccupied vehicle seat comprises: a vibration sensor 11 such as an accelerometer to detect the frequency and phase and/or amplitude of the seat vibrations, an occupancy detector 15, a vibration generator 13, and a controller (17,fig.3). The controller 17 comprises input means (19,fig.3) for receiving vibration sensor 11 data, input means (25,fig.3) for receiving occupancy detector 15 data, processing means (21,fig.3) for generating a driving signal for the vibration generator 13, and output means (23,fig.3) for outputting the signal to the vibration generator 13 to generate seat vibrations. The phase of the generated vibrations may be in anti-phase with that of the detected vibrations. The vibration generator 13 may comprise a haptic motor or speaker system. The method for seat vibration control may be stored on a computer program or readable storage medium to be executed by a computer.

Description

APPARATUS AND METHOD FOR VIBRATION CONTROL

TECHNICAL FIELD

The present disclosure relates to vibration control in vehicle seats and particularly but not exclusively to vibration control in seats of automobiles. Aspects of the invention relate to a vehicle seat vibration system, a vehicle, a method of vehicle seat vibration control, a computer program and a non-transitory computer readable storage medium.

BACKGROUND

Unoccupied vehicle seats, because they are not damped by an occupant, may be prone to vibration, caused for instance by vibration of a vehicle structure to which the vehicle seat is secured. Such vibrations may include resonant vibrations where the vibration of the vehicle structure excites a natural frequency of the vehicle seat, which may tend to exacerbate the vibration. Vibrations of a vehicle seat may be visible to human observers, and so may be distracting for other occupants of the vehicle and/or may give rise to a perception of low quality.

Taking for instance a car, an unoccupied passenger seat may be seen to vibrate by occupants of the vehicle as the vehicle body is vibrated by an uneven road surface. Given the potential implications in terms of apparent quality, this may be particularly (though not exclusively) undesirable in vehicles likely to be used as chauffeur driven cars or in vehicles with automated driving capability.

Conventional solutions to this problem include the designing for increased stiffness and/or the provision of a vibration damper in the form of a sprung mass (weighing for instance 800g) within the vehicle seat. Such solutions however tend to add cost and weight. Additionally, they are tuned to a specific vibration frequency and may therefore be of limited effect where additional or alternative frequency vibrations are present.

It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a vehicle seat vibration system, a vehicle, a method of vehicle seat vibration control, a computer program and a non-transitory computer readable storage medium as claimed in the appended claims.

Any controllers or control systems described herein may suitably comprise a control unit or computational device having one or more electronic processors. Thus the system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term "controller", "control unit" or "control system" will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller or control system, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors.

Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. A first controller may be implemented in software run on one or more processors. One or more other controllers may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

According to an aspect of the invention there is provided a vehicle seat vibration system configured to reduce vibration of a vehicle seat when a vehicle is in use and the vehicle seat is unoccupied, the vehicle seat vibration system comprising: a vibration detector configured to detect vibrations in the vehicle seat; an occupancy detector configured to detect occupancy of the vehicle seat; a vehicle seat vibration generator configured to generate vibrations in the vehicle seat; and a control system in communication with the vibration detector, occupancy detector and vehicle seat vibration generator, and wherein the control system is configured to: determine occupancy of the vehicle seat; analyse vibration data received from the vibration detector to determine vibration modes of the vehicle seat; and, activate the vehicle seat vibration generator to generate vibrations in the vehicle seat in antiphase to at least a lowest frequency mode of the vibrations detected, whereby said vibrations of the vehicle seat are at least partially cancelled.

The control system may be configured to activate the vehicle seat vibration generator to generate hapfic signals for the occupant of the seat.

According to another aspect of the invention there is provided a vehicle seat vibration system comprising a control system, the control system comprising: input means for receiving first signal data indicative of a vibration of a vehicle seat (optionally when unoccupied); processing means arranged to generate, in dependence on the signal data, a driving signal for a vehicle seat vibration generator (optionally to control the vibration of the vehicle seat when unoccupied); and output means for outputting the driving signal to cause driving of the vehicle seat vibration generator.

Vibration in a vehicle seat may be excited by displacement and/or vibration of the vehicle body to which the vehicle seat is attached e.g. as a result of the vehicle traveling on an uneven surface or movement of occupants within the vehicle. Such vibrations of the vehicle seat may be considered unwanted. Vibration in the vehicle seat may be directly detected in the vehicle seat itself or inferred by other means, e.g. detection of vibration in the vehicle body. Whatever the method of detection/inference, the first signal data may be consequently issued. Where such a vibration is indicated, there is an opportunity to at least partially counteract it (e.g. control it by reducing it), by generating another vibration by means of the vehicle seat vibration generator which may then interfere destructively with the vibration. The vibration generated by the vehicle seat vibration generator may be of a pre-determined frequency and/or phase and/or amplitude as previously determined to be likely effective in reducing a common or expected or particular vibration. In such cases the first signal data could for instance be data provided by a signal simply indicating the existence of a vibration. Alternatively, where for instance the first signal data is indicative of properties of the vibration e.g. its frequency and/or phase and/or amplitude, the driving signal may be determined to counteract (e.g. cancel or otherwise destructively interfere with) the vibration by reference to its properties.

In some embodiments the first signal data is indicative of the frequency and phase of the vibration and the processing means generates the driving signal to drive the seat vibration generator substantially in anti-phase to the vibration of the vehicle seat when unoccupied. This approach may increase the effectiveness of the controlling of the vibration because destructive interference may be more likely and/or completely achieved. In particular, the phase of the vibration generated by the vehicle seat vibration generator may be selected to be substantially in anti-phase with that of the vibration. Further, the frequency of the vibration generated by the vehicle seat vibration generator may be selected to substantially match that of the vibration.

In some embodiments the first signal data is indicative of the amplitude of the vibration and the processing means generates the driving signal to drive the seat vibration generator at an amplitude dependent on the vibration amplitude of the vehicle seat when unoccupied. This approach may allow for an increase in the effectiveness of the controlling of the vibration.

Specifically, destructive interference may be more completely achieved where the amplitude of the vibration generated by the vehicle seat vibration generator is substantially matched to the amplitude of the vibration. Thus, the driving signal may be generated to demand that the vehicle seat vibration generator is driven to vibrate at an amplitude that correspondingly increases and decreases in magnitude with the amplitude of the vibration. The driving signal may be generated to demand that the vehicle seat vibration generator is driven to vibrate at an amplitude that is proportional to and/or substantially equal to the amplitude of the vibration.

In some embodiments the processing means generates the driving signal to control vibration of the vehicle seat when unoccupied at a known natural frequency thereof. The vibration of the vehicle body may excite a natural frequency of the vehicle seat and thereby generate a resonant vibration. By generating the driving signal to control this vibration (e.g. reduce it) a significant vibration of the vehicle seat may be reduced or prevented. As will be appreciated, there may be multiple natural frequencies of the vehicle seat when unoccupied. It may be that the lowest frequency instance of a natural frequency vibration occurring within the vibration is exclusively targeted or prioritised for control, because it may be the most noticeable. It has been found that vibrations which may be excited in vehicle seats as a result of vehicle body vibrations might typically fall in the range 10Hz-30Hz and vibrations in the order of 12.5Hz are particularly common. Relevant natural frequencies of vehicle seats might for instance fall in the range 12Hz-14Hz. The first natural mode of a seat back will normally be under 20Hz, and the mode shape will typically be a fore-aft cantilever movement of the seat back pivoting about the seat base, or pivoting about the floor of the vehicle to which the seat is attached. For such a mode of vibration the highest amplitude of movement (i.e. the anti-node) will be towards the top of the seat back such as the head rest The vibration frequency and amplitude are determined by the mass and stiffness of the seat, the vehicle body structure and the attachment between the vehicle body structure and the seat. Specifically, the measure of mass that is relevant at the particular modal frequency is the modal mass, and the measure of stiffness that is relevant at the particular modal frequency is the dynamic stiffness.

In some embodiments the control system is arranged to perform the generating and outputting in real time in response to real time changes to the first signal data. In this way the control system may provide more timely and potentially accurate adaptations to the vibration of the vehicle seat when unoccupied.

In some embodiments the vehicle seat is a seat among those of the vehicle which can be unoccupied whilst the vehicle is being operated to provide transport. It may be for instance that the vehicle seat is a passenger seat. It may be that the vehicle seat is a non-driver/non-operator seat. It may be that the vehicle seat is a front seat of the vehicle and the vehicle may have at least one rear seat. In this case it may be more likely that there is a passenger who would note vibration of the front seat when unoccupied.

In some embodiments the control system is arranged to receive second signal data indicative of whether or not the vehicle seat has become occupied and causing operation of the vehicle seat vibration generator to control the vibration only whilst the second signal data indicates that the vehicle seat is unoccupied. The second signal data could for instance be data provided by a signal from a weight detector indicating weight present on the vehicle seat. Additionally or alternatively it could be data provided by a signal indicating the presence of a seatbelt plate in a seat belt buckle associated with the vehicle seat. Additionally or alternatively it could be data provided by a signal from a camera system indicative of a visible change consistent with the vehicle seat being occupied. The control system being operative only where the vehicle seat is unoccupied may be appropriate, because occupation of the seat may naturally damp vibrations and so reduce or prevent the problem of visible vehicle seat vibrations. The second signal data may be received via the input means or alternatively via an additional input means.

The control system may be operable to control vibrations at all times while the vehicle is operating and the vehicle seat is unoccupied.

In some embodiments the vehicle seat vibration system comprises a vibration sensor arranged to generate the first signal data and send it to the input means. The vibration sensor may be located on the body of the vehicle adjacent a mounting between the body and the vehicle seat. This may make the provision of associated wiring/connections easier and better facilitate ease of installation and removal of the vehicle seat with regard to the body of the vehicle. The vibration sensor may alternatively be in the base, back or headrest of the seat. Such arrangements may offer improved signal to noise ratio.

In some embodiments the vehicle seat vibration system comprises the vehicle seat vibration generator.

In some embodiments, the vehicle seat vibration generator is a hapfic system.

In some embodiments the vehicle seat vibration generator comprises a haptic motor. This could for example be an eccentric mass on a rotor driven by a motor.

In some embodiments the vehicle seat vibration generator is a speaker system. A speaker may be capable of serving as the vehicle seat vibration generator. This may be convenient, especially where it is desired for other reasons to place at least one speaker within the vehicle seat (e.g. for reasons of selective audio playback such as noise, music, verbal communication and/or noise cancellation). In this case the vibration control and audio-playback functionalities may be performed by the same speaker system (and indeed speaker). Audio playback might typically be at higher frequencies than would be used for the vibration control functionality.

In some embodiments the vehicle seat vibration generator is located in/or on a seat back or headrest of the vehicle seat. This may be more effective in terms of vibration control than locating the seat vibration generator in or on the seat base where the seat base is rigidly mounted to the vehicle body. Further, the seat vibration generator may be located proximate an anti-node location for a resonant vibration of the vehicle seat. This may improve the effectiveness of the anti-vibration functionality. Additionally or alternatively it may be that the seat vibration generator is located within the top half, third or quarter of the seat back. Such locations may mean that the seat vibration generator is nearer to a free end (i.e. the top) of the vehicle seat, where the amplitude of the vibration is likely to be largest.

In some embodiments the vehicle seat vibration system is arranged to provide additional functionality comprising seat occupant haptic interaction. It may be for example that the vehicle seat vibration generator is part of a driver-assistance system which uses it to provide one or more alerts, feedback or information by haptic interaction with a human occupant of the vehicle seat when it becomes so occupied. Additionally or alternatively, the vehicle seat vibration generator may selectively provide a massage functionality and/or selective audio generation. Thus, it may be for instance that the vehicle seat vibration generator is arranged to selectively provide at least one haptic effect when the vehicle seat becomes occupied. Additionally, the haptic effect may be distinct from the vibration control described previously. Despite this, the haptic effect may be generated using the same mechanism as that used to perform vibration control.

According to yet another aspect of the invention there is provided a vehicle seat comprising the vehicle seat vibration system according to any of the previous aspects.

According to a further aspect of the invention there is provided a vehicle comprising the vehicle seat vibration system according to any of the previous aspects. The vehicle may be a land vehicle, road vehicle and/or passenger vehicle.

The vehicle may comprise no other system provided to damp the vehicle seat. It may not for instance comprise a weight or spring system provided to damp vibration of the vehicle seat.

In some embodiments the vehicle comprises the vehicle seat.

According to a still further aspect of the invention there is provided a method of vehicle seat vibration control comprising: receiving first signal data indicative of a vibration of a vehicle seat when unoccupied; generating, in dependence on the first signal data, a driving signal for a vehicle seat vibration generator to control the vibration of the vehicle seat when unoccupied; and outputting the driving signal to cause driving of the vehicle seat vibration generator.

In some embodiments the first signal data is indicative of the frequency and phase of the vibration and the processing means generates the driving signal to drive the seat vibration generator substantially in anti-phase to the vibration of the vehicle seat.

In some embodiments the method comprises receiving second signal data indicative of whether or not the vehicle seat is occupied and causing operation of the vehicle seat vibration generator to control the vibration only whilst the second signal data indicates that the vehicle seat is unoccupied.

According to a still further aspect of the invention there is provided a computer program that, 30 when read by a computer, causes performance of the method as described above.

According to a still further aspect of the invention there is provided a non-transitory computer readable storage medium comprising computer readable instructions that, when read by a computer, cause performance of the method as described above.

According to a still further aspect of the invention there is provided a signal comprising computer readable instructions that, when read by a computer, cause performance of the method as described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention are now described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a side view of vehicle according to an embodiment of the invention; Figure 2 shows a side view of a vehicle seat according to an embodiment of the invention; Figure 3 shows a schematic view of a control system according to an embodiment of the invention; Figure 4 shows a flow chart of method steps in accordance with an embodiment of the invention; and Figure 5 is a graph indicative of the effect of the vibration control according to an embodiment of the invention.

DETAILED DESCRIPTION

Referring first to Figures 1 and 2, a vehicle (in this case a car) is generally shown at 1. The vehicle 1 has various vehicle seats including a driver seat, a front passenger seat 3 and two rear passenger seats. It should be noted that the invention is also applicable to self-driving vehicles, in which case there may not be a driver's seat, but rather simply a plurality of passenger seats. The invention is also applicable to embodiments where there is a driver (and driver's seat) but where at least some driving control is exercised by an autonomous/automated system under particular operating conditions or in particular operating modes.

The front passenger seat 3 has a seat base 5 and a seat back 7. The front passenger seat 3 is mounted to a body 9 (i.e. a frame) of the vehicle 1 via mounting brackets attached to its seat base 5. A vibration sensor 11 (in this case an accelerometer) is provided on the body 9 at a location proximate the front passenger seat. Specifically, the location of the vibration sensor 11 is selected to facilitate detection of vibrations which may be transmitted from the body 9 to the front passenger seat 3 and in this case is adjacent an attachment point between one of the mounting brackets and the body 9. As will be appreciated, in other embodiments, the vibration sensor 11 may be located elsewhere e.g. within or on the front passenger seat 3 itself. For instance, the vibration sensor 11 may be located in the seat back 7 so as to detect the vibration of the seat back 7, particularly a first mode of vibration. A vehicle seat vibration generator 13 On this case a speaker of a speaker system) is provided in the seat back 7. In other embodiments an alternative form of vehicle seat vibration generator 13 may be used (e.g. a haptic motor driving a rotor having an eccentric mass). The location of the vehicle seat vibration generator 13 is selected so as to substantially coincide with an anti-node of a lowest frequency resonant vibration (for instance the first mode) of the front passenger seat 3 as installed in the vehicle 1. A weight detector 15 is provided in the seat base 5 (though in other embodiments this may be replaced by an alternative sensor capable of at least inferring seat occupation e.g. a camera or seat belt plate detector).

The vibration sensor 11, vehicle seat vibration generator 13 and weight detector 15 form part of a vehicle seat vibration system arranged to control vibrations of the front passenger seat 3 when it is unoccupied. Referring to Figure 3, the vehicle seat vibration system also has a control system On this case a controller 17) arranged to operate the vehicle seat vibration system. The controller 17 has a first input means 19 which is connected (in this case via a wired connection, but a wireless connection is also possible) to the vibration sensor 11. The first input means 19 is for receiving first signal data transmitted to it by the vibration sensor 11 and indicative of a vibration of the front passenger seat 3. The controller 17 also has a processing means 21 arranged to generate, in dependence on the signal data, a driving signal for the vehicle seat vibration generator 13. The controller 17 has an output means 23 which is connected (in this case via a wired connection, but a wireless connection is also possible) to the vehicle seat vibration generator 13. The output means 23 is for outputting the driving signal to cause driving of the vehicle seat vibration generator 13. The controller 17 also has a second input means 25 which is connected (in this case via a wired connection, but a wireless connection is also possible) to the weight detector, or other seated occupant detector,15. The second input means 25 is for receiving second signal data indicating whether a weight above a pre-determined level is present on the front passenger seat 3. As will be appreciated, in other embodiments, the first 19 and second 25 input means may be combined.

The front passenger seat 3 may, when unoccupied and in use of the vehicle 1, be prone to vibrate. Such vibrations may be caused by an uneven road surface and/or by engine vibration and/or by movement of passengers within the vehicle and/or by closure of vehicle doors. The vibrations of the front passenger seat 3 may be exacerbated because it is mounted only at its seat base 5 and so it has effectively a free end at the top of the seat back 7. The front passenger seat 3 (and in particular its seat back 7) may have at least one natural frequency of vibration, the lowest frequency natural frequency (or first mode) of vibration potentially being the most visibly noticeable when excited by vibration of the vehicle body 9 via the mounting brackets of the front passenger seat 3. Specifically, a resonant vibration may occur.

The vibration, resonant and otherwise, may give rise to visible vibration of the front passenger seat 3. Thus if not controlled (i.e. by prevention/reduction), the vibration may give rise to distraction for passengers and even the driver, and/or a perception of lack of quality for occupants of the vehicle observing the vibration of the seat.

Consequently the vehicle seat vibration system is used to control the vibration. An example of use of the vehicle seat vibration system is provided below with reference to Figure 4, summarising the method employed, and Figure 5 which shows the effect of the vehicle seat vibration system on a resonant vibration of the vehicle seat caused by vibration of the vehicle body as it travels over uneven ground.

The vehicle seat vibration system is active in monitoring for and controlling any vibrations at all times while the vehicle 1 is turned on and the front passenger seat 3 is unoccupied. The first step 27 of the method illustrated in Figure 4 comprises the occupation state of the front passenger seat 3 being determined by the controller 17, in accordance with the second signal data delivered via the second input means 25. Where the second signal data indicates that a weight above the predetermined level is detected, it is determined that the front passenger seat 3 is occupied, and otherwise that it is unoccupied. This second signal data is updated in real time, allowing for dynamic changes to the determination as to whether or not the front passenger seat 3 is occupied. This process is ongoing throughout the remainder of the process and at all times, though alternatives are also envisaged, e.g. checking occupancy at the start of a journey and assuming that the determined status does not change. Where it is determined that the front passenger seat 3 has become occupied, the vehicle seat vibration system discontinues the process for controlling vibrations, but nevertheless continues to monitor for the front passenger seat 3 once again becoming unoccupied, whereupon vibration control is resumed. As stated previously, an alternative means of occupancy detection, other than weight detection, is envisaged.

The controller 17 also receives the first signal data from the vibration sensor 11 via the first input means 19 in step 29. In this embodiment the first signal data indicates the frequency and phase of the vibration in the area of the body 9 to which the front passenger seat 3 is mounted and thereby vibration which is delivered from the body 9 to the front passenger seat 3. In other embodiments the vibration at the anti-node of the first mode of the seat back 7 is measured by a vibration sensor 11, which in this event is positioned towards the top of the seat back 7, or in the head rest. Thus, such an arrangement may directly indicate amplitude, frequency and phase of the vibration of the seat back 7 that is to be controlled by the vehicle seat vibration system.

The graph of Figure 5 shows in solid trace 29 an example of an instantaneous amplitude of vibration at different frequencies. Two natural frequencies of vibration that are being excited to cause resonant vibration are visible as amplitude peaks. The lower frequency of the two resonant frequency vibrations is at a frequency labelled WI and has an amplitude labelled Al'. The higher frequency of the two resonant frequency vibrations is at a frequency labelled w2'. The lower frequency resonant vibration will normally be the more noticeable, visually, because it may be associated with the lowest dynamic stiffness and/or highest modal mass of the vibrating system. The frequency and phase of this lower resonant vibration is identified by the processing means 21 from the first signal data. The processing means 21 then generates a driving signal at substantially the same frequency as the lower resonant frequency vibration and substantially in anti-phase with it in step 31. This first signal data is updated in real time, allowing for dynamic changes to the driving signal in response to changes in the vibration e.g. changes to the frequency and/or phasing of the lower frequency resonant vibration. This updating of the first signal data in real time may be useful because the cancellation of the vibration by the vehicle seat vibration system may impact the frequency and/or phase and/or amplitude of vibration of the seat back 7.

The processing means 21 outputs the driving signal to the vehicle seat vibration generator 13 via the output means 23 in step 33. At the vehicle seat vibration generator 13, the driving signal gives rise to the generation of vibration which counters the vibration (i.e. the vibration identified and reported in the first signal data). Specifically, because the vibration generated by the vibration generator 13 corresponds to the driving signal, and is therefore substantially of the same frequency as the resonant vibration of lower frequency and substantially in anti-phase with it, it gives rise to destructive interference between the vibrations. This controls the vibration of the seat by reducing its amplitude. The vibration generator 13 is assisted in its effect by its location substantially coinciding with an anti-node of the lower frequency resonant vibration of the front passenger seat 3. The effect of the control can be seen in Figure 5 where a hashed trace 35 shows the vibration in the front passenger seat 3 as modified by the vehicle seat vibration system operating to control the vibration. As can be seen, there remains an amplitude peak at a frequency wl" which is substantially consistent with the frequency of the lower resonant vibration, but this amplitude peak is at a significantly reduced amplitude of Al". Normally w1' = wt, but minor changes in frequency as the resonance is cancelled are possible due to system non-linearities, such as a variation in dynamic stiffness due to reduced amplitude of vibration. The controller 17 may also act to cancel or reduce other resonances of the seat, such as the second resonance labelled w2', by the same means of applying an anti-phase signal at other resonance peaks.

The vibration generator 13 may also be used for other haptic and audio functionalities.

Specifically, it may form part of a driver-assistance system, and use the same mechanism as used to control the vibration (i.e. vibration as generated by a speaker cone of the vibration generator) to selectively provides alerts, feedback and/or information to any occupant of the front passenger seat 3. This functionality is controlled via the controller 17, although in other embodiments it may be controlled by a separate controller.

In this embodiment the driver seat is equipped in the same manner as the front passenger seat 3 as described above, but with the vibration control functionality permanently disabled/non-activated. This approach may be efficient in terms of fitting a standardised vehicle seat system for both the driver and front passenger seats despite the lack of a need for a vibration control system in the driver's seat, but where it is nonetheless desired that the driver seat be equipped with the driver-assistance system elements of the integrated system.

It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine-readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 15 The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims. For instance, it may be that in other embodiments the first signal data additionally provides the amplitude of the vibration and the driving signal generated substantially matches this amplitude such that the vibration is better cancelled. Further, in addition or alternatively to the vibration generator 13 being used for the haptic and audio functionalities mentioned, it may be used for other functionalities, such as noise cancelling and/or massage.

Claims (15)

1. CLAIMS1. A vehicle seat vibration system comprising a control system, where the control system comprises: input means for receiving first signal data indicative of a vibration of a vehicle seat when unoccupied; processing means arranged to generate, in dependence on the signal data, a driving signal for a vehicle seat vibration generator to control the vibration of the vehicle seat when unoccupied; and output means for outputting the driving signal to cause driving of the vehicle seat vibration generator.
2. 2. A vehicle seat vibration system according to claim 1 where the first signal data is indicative of the frequency and phase of the vibration and the processing means generates the driving signal to drive the seat vibration generator substantially in anti-phase to the vibration of the vehicle seat when unoccupied.
3. 3. A vehicle seat vibration system according to claim 2 where the first signal data is indicative of the amplitude of the vibration and the processing means generates the driving signal to drive the seat vibration generator at an amplitude dependent on the vibration amplitude of the vehicle seat when unoccupied.
4. 4. A vehicle seat vibration system according to any preceding claim where the processing means generates the driving signal to control vibration of the vehicle seat when unoccupied at a known natural frequency thereof.
5. 5. A vehicle seat vibration system according to any preceding claim arranged to receive second signal data indicative of whether or not the vehicle seat has become occupied and causing operation of the vehicle seat vibration generator to control the vibration only whilst the second signal data indicates that the vehicle seat is unoccupied.
6. 6. A vehicle seat vibration system according to any preceding claim comprising a vibration sensor arranged in the vehicle seat to generate the first signal data
7. 7. A vehicle seat vibration system according to claim 6 where the vehicle seat vibration generator comprises a haptic motor or a speaker system.
8. 8. A vehicle seat vibration system according to any preceding claim arranged to provide additional functionality comprising, when the seat is occupied by an occupant, the control system outputting a driving signal to the vehicle seat vibration generator to provide the occupant with haptic interaction with vehicle systems.
9. 9. A vehicle seat vibration system configured to reduce vibration of a vehicle seat when a vehicle is in use and the vehicle seat is unoccupied, the vehicle seat vibration system comprising: a vibration detector configured to detect vibrations in the vehicle seat; an occupancy detector configured to detect occupancy of the vehicle seat; a vehicle seat vibration generator configured to generate vibrations in the vehicle seat; and a control system in communication with the vibration detector, occupancy detector and vehicle seat vibration generator, and wherein the control system is configured to: determine occupancy of the vehicle seat; analyse vibration data received from the vibration detector to determine vibration modes of the vehicle seat; and, activate the vehicle seat vibration generator to generate vibrations in the vehicle seat in antiphase to at least a lowest frequency mode of the vibrations detected, whereby said vibrations of the vehicle seat are at least partially cancelled.
10. 10. A vehicle seat vibration system as claimed in claim 9, wherein the control system is configured to activate the vehicle seat vibration generator to generate haptic signals for the occupant of the seat.
11. 11. A vehicle comprising the vehicle seat vibration system according to any of claims 1 to 10.
12. 12. A Method of vehicle seat vibration control comprising: receiving first signal data indicative of a vibration of a vehicle seat when unoccupied; generating, in dependence on the first signal data, a driving signal for a vehicle seat vibration generator to control the vibration of the vehicle seat when unoccupied; and outputting the driving signal to cause driving of the vehicle seat vibration generator.
13. 13. A method according to claim 12 where the first signal data is indicative of the frequency and phase of the vibration and the processing means generates the driving signal to drive the seat vibration generator substantially in anti-phase to the vibration of the vehicle seat when unoccupied.
14. 14. A method according to claim 12 or claim 13 comprising receiving second signal data indicative of whether or not the vehicle seat is occupied and causing operation of the vehicle seat vibration generator to control the vibration only whilst the second signal data indicates that the vehicle seat is unoccupied.
15. 15. A computer program or a non-transitory computer readable storage medium comprising computer readable instructions, that, when read by a computer, causes performance of the method as claimed in any of claims 12 to 14.