Vehicle display assembly and method for reducing motion sickness of a vehicle passenger

The present invention relates to a vehicle display assembly and a method for reducing motion sickness of a vehicle passenger.

Motion sickness is also known as kinetosis or travel sickness. Motion sickness can occur to passengers of any vehicle. Depending on the specific kind of vehicle, motion sickness is sometimes referred to as car sickness, seasickness or air sickness.

Symptoms of motion sickness can include dizziness, fatigue and nausea. It is believed that one cause for motion sickness is a disagreement between visually perceived movement and the vestibular system's sense of movement.

For example, motion sickness can occur when a passenger reads a book during car travel. Looking at the book, the passenger's eyes do hardly sense any motion, whereas the vestibular system senses the motion, in particular any acceleration, that the passenger's body, in particular the passenger's head, is exposed to. Modern vehicles often exhibit displays on which the vehicles' passengers can watch films or other information during travel. Keeping the eyes on such a display can cause kinetosis in a similar way as reading a book.

DE 10 2006 009 566 A1 proposes a method for reducing kinetosis, whereby images from the vehicle's environment are recorded and shown on a vehicle display. In this way, kinetosis of passengers whose outside view is partly or entirely obstructed can be reduced.

DE 10 2007 037 852 A1 proposes a similar method for reducing kinetosis, whereby various visual effects can be shown on the vehicle display. The visual effects are chosen in such a way that they convey an impression corresponding to the current movement of the vehicle. DE 101 56 219 C1 proposes another method for reducing kinetosis, whereby the visual content of a display of a vehicle is adapted according to measured driving parameters such as direction and magnitude of acceleration, velocity or inclination of the vehicle. The visual content can be enlarged, reduced, moved or rotated. However, this method requires the display to be significantly larger than the actual displayed image.

It is an objective of the present invention to provide an improved display assembly and method for reducing motion sickness.

The objective is achieved by a vehicle display assembly and a method for reducing motion sickness of a vehicle passenger according to the independent claims. Preferred embodiments of the invention are defined in the dependent claims.

According to the invention, a vehicle display assembly for reducing motion sickness of a vehicle passenger is provided. The assembly comprises a display device and at least one mounting element for mounting the display device to an interior portion of the vehicle. For example, a display device for passengers travelling in a rear seat of an automobile can be mounted to a back rest of a front seat of the automobile. In another example, a display device could be mounted to a ceiling of the automobile. In yet another example, a display device for a front-seat passenger could be mounted to a dashboard of the automobile. The at least one mounting element is configured to hold the display device in a resting position when the vehicle is not accelerating.

Acceleration of the vehicle should be understood in a broad sense as any change of a magnitude and / or a direction of a velocity of the vehicle. In particular, the term acceleration includes positive, negative, radial (tangential), lateral and longitudinal acceleration. The vehicle does not exhibit any acceleration (i.e., the acceleration vector has zero magnitude) when the vehicle stands still. The vehicle also does not exhibit any acceleration when the vehicle is in constant motion. For example, an automobile travelling along a straight road at constant velocity does not exhibit acceleration. In practice, however, a vehicle that is in motion constantly experiences at least small magnitudes of acceleration due to frequent changes in velocity and / or direction. According to the invention, at least one of the at least one mounting element is a transformable mounting element, wherein the at least one transformable mounting element is configured to be transformed when the vehicle is accelerating such that the display is moved to an accelerating position when the vehicle is accelerating. In other words, the display can be held in at least two positions. One is the resting position, which the display assumes when the vehicle is not accelerating. The at least one other position is the accelerating position, which the vehicle assumes when it is accelerating. There must be at least one accelerating position. However, preferred embodiments of the invention provide a multitude of accelerating positions. The accelerating position is different from the resting position in at least one degree of freedom.

The inventors have observed that moving the display itself (rather than moving the image depicted on the display) can result in an increased reduction of motion sickness of the passenger observing the screen. The inventors have further observed that motion sickness is in fact not caused by motion, but rather by acceleration. By moving the display from the resting position to the accelerating position upon acceleration, the passenger visually perceives a dynamic action. This visual perception is congruent with the passenger's vestibular perception, which reduces the cause for motion sickness.

In a preferred embodiment of the invention, a movement of the display from the resting position to the accelerating position comprises a linear movement and / or a rotational movement. A linear movement is also known as translation. A linear movement can be any shift along one or more of the space axes. Hence, a linear movement can comprise

- a shifting along the x-axis (forward or backward) and / or

- a shifting along the y-axis (left or right) and / or

- a shifting along the z-axis (up or down).

A rotational movement can be any rotation about the display's center of mass. Hence, a rotational movement can comprise

- a pitching (tilting) forward or backward and / or

- a swiveling (yawing) left or right and / or

- a pivoting (rolling) to the left side or to the right side.

Preferably, the movement of the display from the resting position to the accelerating position can comprise any combination of the above-mentioned movements, so that the display device preferably has six degrees of freedom. Further preferred, the movement of the display from the resting position to the

accelerating position comprises a movement against a direction of acceleration.

Acceleration causes a fictitious force or inertial force whose direction is opposed to the direction of acceleration. For example, when a vehicle accelerates in the driving direction, an inertial force directed against the driving direction appears to act on items in the vehicle (caused by the items' inertia). The inventors have observed that motion sickness can be remedied when the display moves as expected by human intuition, i.e. when the display moves in the direction of the inertial force. In particular, the movement of the display from the resting position to the accelerating position can comprise any single one or any combination of the following movements.

A shifting against the driving direction of the vehicle when the vehicle performs a positive longitudinal acceleration. In other words, the display may move towards the passenger when the vehicle increases its velocity.

A shifting in the driving direction of the vehicle when the vehicle performs a negative longitudinal acceleration. In other words, the display may move away from the passenger when the vehicle decreases its velocity, i.e., when the vehicle brakes.

A shifting to the right when the vehicle performs a lateral acceleration to the left. In other words, the display may move to the right when the vehicle turns left.

A shifting to the left when the vehicle performs a lateral acceleration to the right. In other words, the display may move to the left when the vehicle turns right.

A positive pitching when the vehicle performs a positive longitudinal acceleration. In other words, the display may tilt such that an upper edge of the display move towards the passenger and / or a lower edge of the display moves away from the passenger when the vehicle increases its velocity.

A negative pitching when the vehicle performs a negative longitudinal acceleration. In other words, the display may tilt such that an upper edge of the display move away from the passenger and / or a lower edge of the display moves towards the passenger when the vehicle decreases its velocity.

A positive rolling when the vehicle performs a lateral acceleration to the left. In other words, the display may pivot in a clockwise direction (from the passenger's point of view) when the vehicle turns left.

A negative rolling when the vehicle performs a lateral acceleration to the right. In other words, the display may pivot in a counterclockwise direction (from the passenger's point of view) when the vehicle turns right.

A positive yawing when the vehicle performs a lateral acceleration to the left. In other words, the display may swivel in a clockwise direction (seen from above the display) when the vehicle turns left.

A negative yawing when the vehicle performs a lateral acceleration to the right. In other words, the display may swivel in a counterclockwise direction (seen from above the display) when the vehicle turns right.

In a preferred embodiment, the at least one transformable mounting element comprises a spring, wherein the at least one transformable mounting element is transformed by an inertial force of the display. An advantage of using one or several springs in the at least one transformable mounting element is that the display assembly can be particularly cost-effective and require only little maintenance. The spring constants of the springs and the mounting positions of the springs can be chosen such that the display moves as desired upon acceleration. In one particular embodiment, all mounting elements comprise springs. For example, the display device can be mounted to the interior portion of the vehicle by four springs, whereby the springs are each mounted on one of the corners of the display. All springs can be identical. In particular, all springs can have identical spring constants. Alternatively, the upper springs' spring constants can differ from the lower springs' spring constants to achieve a pitching movement. Alternatively, the left springs' spring constants can differ from the right springs' spring constants to achieve a yawing movement. In an advantageous embodiment, the assembly comprises at least two mounting elements, whereby at least one of the at least two mounting elements is a non- transformable mounting element. Particularly advantageous, first mounting elements can be mounted on a first edge or corner of the display, and second mounting elements can be mounted on a second edge or corner of the display opposite to the first edge or corner. The first mounting elements can be non-transformable mounting elements and the second mounting elements can be transformable mounting elements. In particular, the first mounting elements can comprise a hinge.

In a further embodiment, the vehicle display assembly comprises a control unit, wherein the at least one transformable mounting element comprises an electric motor, wherein the at least one electric motor is controllable by the control unit, wherein the

transformable mounting element is transformed by the at least one electric motor. This embodiment may be combined with the previously described embodiments. In other words, an assembly according to the invention may comprise transformable mounting elements comprising an electric motor and transformable mounting elements

comprising a spring. Using transformable mounting elements comprising an electric motor rather than only mounting elements comprising springs increases the technical complexity of the assembly, but also provides means for more versatile movements of the display. In a particularly preferred embodiment, the display is mounted by

transformable mounting elements each comprising an electric motor in such a way that the display is moveable in all six degrees of freedom.

Further preferred, the assembly comprises an inertial measurement unit configured to measure the inertial force of the vehicle, wherein the inertial measurement unit is connected to the control unit, wherein the control unit is configured to control the at least one electric motor such that the movement of the display from the resting position to the accelerating position comprises a movement in the direction of the inertial force of the vehicle. Many modern vehicle do already exhibit an inertial measurement unit (IMU) able to measure a direction and a magnitude of acceleration. The IMU can be used to supply the control unit with the acceleration measurement data. The control unit can be configured to control the electric motors such that the display device is moved in a "natural" way. This means that the electric motors can be controlled to move the display device as if it was mounted by passive transformable mounting elements (e.g., springs) or as if it were held by other elastic mounting elements (such as rubber bands).

The invention can be further refined when the assembly comprises a tracking device configured to measure a movement of the head of the vehicle passenger. The tracking device is connected to the control unit, and the control unit is configured to control the at least one electric motor such that the movement of the display from the resting position to the accelerating position comprises a movement in the direction of the movement of the head. The inventors have observed that kinetosis can be most effectively mitigated when the acceleration that acts on the passenger's head equals the acceleration exerted on the display the passenger is looking at. A potential reason for this

observation is that the inner ear (which, of course, is located in the passenger's head) constitutes a major element of the passenger's vestibular system. The passenger's head is not necessarily exposed to the same acceleration (or inertial) forces as the vehicle or the display. This is because damping elements such as the seat or the passenger's spine located between the vehicle and the passenger can absorb part of the acceleration forces exerted upon the vehicle. In addition, the movement of the head in response to an acceleration of the vehicle also depends on whether and how prepared the passenger is for the acceleration. For example, if a passenger is focused on the display and does not observe the environment of the vehicle, the passenger's head may be moved relatively strongly when the vehicle drives along a curve. In contrast, if the passenger is observing the road ahead of the vehicle, the passenger will be prepared for the upcoming curve. By tensing the neck muscles, the passenger can hold his head in a relatively constant position despite the acceleration forces exerted upon his head. The control unit can be configured to control the electric motors such that the display device's movement mimics the passenger's head's movement, whereby a proportionality constant may be applied. Alternatively, the control unit can control the electric motors such that the display device's movement mimics the difference between the vehicle movement and the passenger's head's movement, whereby a proportionality constant may be applied.

Advantageously, the tracking device comprises a camera. Video cameras directed at the passenger's (in particular the driver's) head are already frequently used in modern vehicles for various purposes. Using such a camera for the present invention is therefore possible at limited cost.

It is understood that the described embodiments may be advantageously combined. In particular, a very useful embodiment of the invention uses measurements from both an IMU and a camera to control the accelerating position of the display device to take into account both the actual acceleration of the vehicle and the passenger's reaction to this acceleration force.

The invention also comprises a method for reducing motion sickness of a vehicle passenger in a vehicle comprising a vehicle display assembly as described herein. The method steps are laid out in the method claims.

It is understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following detailed description of the invention, which describes exemplary embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a schematic illustration of a first exemplary embodiment of the invention from three viewing directions (Figs. 1 a, 1 b and 1 c),

Fig. 2 is a schematic illustration of a second exemplary embodiment of the invention from three viewing directions (Figs. 2 a, 2 b and 2 c),

Fig. 3 depicts an exemplary control scheme for use with the second exemplary

embodiment of the invention.

Identical reference signs designate identical or similar elements of the invention. It is emphasized that the depicted embodiments are exemplary embodiments of the invention. Combinations of features in these examples are not to be understood in a limiting sense. Other embodiments of the invention may exhibit less, more or other features. The extent of the protection and the disclosed subject-matter are determined by the claims and the entire description. It is further noted that the figures depict schematic and abstract illustrations of the exemplary embodiments. The arrangement of the depicted elements is exemplary and may be different for different embodiments. Furthermore, the illustration is not necessarily drawn to scale. Some elements may be shown increased or decreased in size for illustration purposes.

Figs. 1 a, 1 b and 1 c depict a first exemplary embodiment of the invention from three viewing directions. Each figure bears a Cartesian coordinate cross to indicate the respective viewing direction. In the Cartesian coordinate system used, x is the vehicle's longitudinal axis (back to front), y is the vehicle's transverse axis (right to left) and z is the vehicle's height axis (bottom to top). In Fig. 1 a, a side view of a passenger 5 and a vehicle display assembly according to a first embodiment of the invention are shown. The viewing direction of Fig. 1 a is the y-direction. Fig. 1 b shows the view into x- direction onto the display device 1 , which is the view the passenger 5 has onto the display device 1 from his seating position. Fig. 1 c shows a top view (minus-z-direction) onto the display assembly. The passenger 5 is located on a rear seat 6 of a vehicle. A front seat having a backrest 4 is located in front of the passenger 5. A display device 1 is mounted to the backrest 4 of the front seat. The passenger 5 looks onto the display's front side, which is illustrated in Fig. 1 a with a dashed arrow. The display device assembly comprises a total of six mounting elements 2, 3, with which the display device 1 is mounted to the backrest 4. As can be seen from Figs. 1 a and 1 b, two mounting elements are connected to an upper part of the display device 1 , two mounting elements are connected to a middle part of the display device 1 and two mounting elements are connected to a lower part of the display device 1 . All six mounting elements comprise springs 2. A respective first end of each of the springs 2 is connected to the display device 1 . A respective second end of the springs 2 of the upper and middle mounting elements is connected to the backrest 4. The two lower mounting elements comprise bearings 3. A respective second end of the springs 2 of the lower mounting elements is connected to a first end of the respective bearing 3. A respective second end of the bearings 3 is connected to the backrest 4. The bearings 3 compensate the inclination angle of the backrest 4. When the vehicle is not

accelerating, the display 1 is held in a resting position (shown in Fig. 1 a) by the mounting elements 2, 3. All springs 2 could be identical, i.e., all springs 2 could have identical lengths and spring constants. When the vehicle is exposed to any kind of acceleration, the inertia of the display device 1 causes a force to be exerted upon each spring 2. In response, each spring 2 is displaced from its respective equilibrium state (depicted in Fig. 1 ) according to Hooke's law. The display device 1 is hence moved from its resting position to an accelerating position. For a given acceleration vector (i.e., for a given magnitude and direction of the acceleration), the display device 1 is moved to a particular accelerating position. The display device 1 may be moved to a different accelerating position when the acceleration changes, i.e., when the magnitude and / or direction of the acceleration change or changes. When the vehicle stops accelerating (i.e., when the magnitude of the acceleration is zero), the display device 1 returns to its resting position.

It is understood that the number and mounting positions of the mounting elements as well as the characteristics of the springs 2 are parameters that can be adapted by a skilled person in order to achieve a desired response of the display device 1 to a certain acceleration. For example, the spring constant of the upper springs 2 could be smaller than the spring constant of the lower springs 2 in order to achieve a pronounced positive pitching when the vehicle performs a positive longitudinal acceleration. In some embodiments of the invention, the degrees of freedom of the display device 1 can be restricted. For example, the display device 1 can be mounted by two non-transformable mounting elements mounted to the two lower corners of the display device 1 (e.g. two bearings 3 directly mounted to the display device 1 ) and by two transformable mounting elements (e.g. springs 2) mounted to the two upper corners of the display device 1 . In this example, a movement of the display device 1 would be limited to a pitching movement.

Figs. 2 a, 2 b and 2 c depict a second exemplary embodiment of the invention from three viewing directions. Each figure bears a Cartesian coordinate cross to indicate the respective viewing direction. In the Cartesian coordinate system used, x is the vehicle's longitudinal axis (back to front), y is the vehicle's transverse axis (right to left) and z is the vehicle's height axis (bottom to top). In Fig. 2 a, a side view of a passenger 5 and a vehicle display assembly according to a second embodiment of the invention is shown. The viewing direction of Fig. 2 a is the y-direction. Fig. 2 b shows the view into x- direction onto the display 1 , which is the view the passenger 5 has onto the display device 1 from his seating position. Fig. 2 c shows a top view (minus-z-direction) onto the display assembly. The passenger 5 is located on a rear seat 6 of a vehicle. A front seat having a backrest 4 is located in front of the passenger 5. A display device 1 is mounted to the backrest 4 of the front seat. The passenger 5 looks onto the display's front side, which is illustrated in Fig. 2 a with a dashed arrow. The display device assembly comprises a total of four mounting elements 7, with which the display device 1 is mounted to the backrest 4. As can be seen from Figs. 2 a and 2 b, two mounting elements are connected to the upper corners of the display device 1 and two mounting elements are connected to the lower corners of the display device 1 . All mounting elements comprise electric motors 7, which can be controlled to change the length of the respective mounting elements. When the vehicle is not accelerating, the display device 1 is held in a resting position (shown in Fig. 2 a) by the mounting elements 7. Also shown in Fig. 2 a is a tracking device comprising a camera 8. The camera 8 is directed at the head of the passenger 5. The tracking device 8 is configured to measure a movement of the passenger's head 5.

An advantage of the vehicle display assembly depicted in Fig. 2 over the vehicle display assembly depicted in Fig. 1 is that the movement of the display device 1 can be controlled by a control unit 10 (shown in Fig. 3, but not shown in Fig. 2). The control unit 10 can be a programmable control unit 10. To achieve a different movement, it suffices to change the programming of the control unit 10. The vehicle display assembly can thus be adapted to the needs of different passengers.

Fig. 3 depicts an exemplary control scheme for use with the second exemplary embodiment of the invention shown in Fig. 2 and explained above. An acceleration force 1 1 is exerted upon an inertial measurement unit (IMU) 9, the display device 1 and the passenger 5. The acceleration force is schematically illustrated in Fig. 3 by dashed arrows. The electric motors 7 of the mounting elements are separately controlled by a control unit 10. The control unit 10 receives the measurement data from the IMU 9. The control unit 10 further receives information from the tracking system 8. The information from the tracking system 8 can comprise information about a current position of the passenger's head 5, from which information the control unit 10 can derive information about a movement of the head 5 by comparison of the information about the current position of the passenger's head 5 with information about a previous position of the passenger's head 5. Alternatively, the tracking system 8 can be configured to determine the movement of the head 5 upon acceleration and transmit this information to the control unit 10.

As mentioned previously, the passenger's head 5 is not necessarily exposed to the same acceleration (or inertial) forces as the vehicle or the display 1 . In addition, the passenger 5 may compensate the acceleration forces partly using his or her neck muscles. Using the information supplied from the IMU 9 and the tracking system 8, the control unit 10 may be configured to determine a differential acceleration effectively acting on the head 5. The differential acceleration may be determined by subtracting from the actual acceleration (as measured by the IMU 9) the acceleration force compensated by damping elements (e.g., seat 6) and / or by the passenger 5 (e.g., using his neck muscles). The acceleration force compensated by damping elements and / or by the passenger may be determined by the tracking unit 8 and / or by the control unit 10.

List of reference signs

Display device

Spring

Bearing

Front seat

Passenger

Passenger seat

Electric motor

Camera / tracking system

Inertial measurement unit

Control unit

Acceleration