Compensating Drift of a Sensor System for Measuring a Motion Direction of a User During Usage of a VR System

Abstract

A method for compensating drift of a motion direction sensor system for measuring a motion direction of a user in a VR system includes receiving a measured viewing direction of the user from a viewing direction sensor system for measuring a viewing direction at a measurement time, receiving a measured motion direction of the user from the motion direction sensor system for measuring a motion direction at the same measurement time, and calculating a drift compensation from the difference between the measured viewing direction of the user and the measured motion direction of the user so that a drift compensated motion direction of the user can be determined by adding the calculated drift compensation to a subsequently measured motion direction of the user. One embodiment includes a computer program product and a device configured to perform the method.

Claims

1. A method for iteratively compensating drift of a motion direction sensor system for measuring a motion direction of a user during usage of a VR system (100), the method comprising: receiving a measured viewing direction of the user from a viewing direction sensor system for measuring an angular position indicative of the user's head orientation in the user's transverse ane at a measurement time; receiving a measured motion direction of the user from the motion direction sensor system for measuring an angular position indicative of a direction of the user's walking or running movements in the user's transverse plane at the same measurement time; and calculating a drift compensation from the difference between the measured viewing direction of the user and the measured motion direction of the user, such that a drift compensated motion direction of the user can be determined by adding the calculated drift compensation to a subsequently measured motion direction of the user; wherein the drift compensation is only calculated provided that the viewing direction of the user at the measurement time does not deviate from a previously determined motion direction of the user by more than a viewing angle threshold.

2. The method according to claim 1, further comprising: receiving a measured motion velocity of the user from a motion velocity sensor system for measuring a motion velocity; wherein the drift compensation is only calculated provided that the measured motion velocity of the user is greater than or equal to a velocity threshold.

3. The method according to claim 1, wherein the drift compensation is only calculated provided that the measured motion direction of the user is indicative of the user's walking or running movements in a forward direction in the user's transverse plane.

4. The method according to claim 1, executed iteratively within a compensation time interval, wherein calculating the drift compensation comprises averaging over the values of drift compensation calculated in the iterations within the compensation time interval.

5. The method according to claim 1, further comprising: calculating a current drift compensated motion direction by adding the last calculated drift compensation to a currently measured motion direction of the user.

6. The method according to claim 5, further comprising: receiving a measured second motion direction of the user from a second motion direction sensor system for measuring a second motion direction at the same measurement time; calculating a second drift compensation for the second sensor system; calculating a current drift compensated second motion direction by adding the calculated second drift compensation to a currently measured second motion direction of the user; and calculating a current drift compensated average motion direction by averaging the current drift compensated motion direction and the current drift compensated second motion direction.

7. The method according to claim 1, further comprising: resetting the calculated drift compensation after having aligned, by user request, the viewing direction of the user with the motion direction of the user to a defined direction in order to calibrate the motion direction with the viewing direction.

8. The method according to claim 1, wherein receiving a measured viewing direction of the user comprises: measuring an angular position indicative of an orientation of VR glasses (14) in the user's transverse plane, wherein the VR glasses (14) are worn by the user.

9. The method according to claim 1, wherein receiving a measured motion direction of the user comprises: measuring an angular position indicative of an orientation of one or more motion direction sensors in the user's transverse plane, wherein the one or more motion direction sensors are arranged on a user's foot or leg.

10. A computer program product with instructions stored thereon which, when executed by one or more processors, cause the one or more processors to perform the method according to claim 1.

11. A device (10) for iteratively compensating drift of a motion direction sensor system for measuring a motion direction of a user during usage of a VR system (100), the device comprising: a viewing direction sensor system configured for measuring an angular position indicative of the user's head orientation in the user's transverse plane; the motion direction sensor system configured for measuring an angular position indicative of a direction of the user's walking or running movements in the user's transverse plane; and one or more processors configured to perform the steps of: receiving a measured viewing direction of the user from the viewing direction sensor system at a measurement time; receiving a measured motion direction of the user from the motion direction sensor system at the same measurement time; and calculating a drift compensation from the difference between the measured viewing direction of the user and the measured motion direction of the user, such that a drift compensated motion direction of the user can be determined by adding the calculated drift compensation to a subsequently measured motion direction of the user; wherein the drift compensation is only calculated provided that the viewing direction of the user at the measurement time does not deviate from a previously determined motion direction of the user by more than a viewing angle threshold.

12. (canceled)

13. The device according to claim 11, wherein the one or more processors are configured to perform the step of: receiving a measured motion velocity of the user from a motion velocity sensor system for measuring a motion velocity; wherein the drift compensation is only calculated provided that the measured motion velocity of the user is greater than or equal to a velocity threshold.

14. The device according to claim 11, wherein the one or more processors are configured to calculate the drift compensation only provided that the measured motion direction of the user is indicative of the user's walking or running movements in a forward direction in the user's transverse plane.

15. The device according to claim 11, wherein the one or more processors execute the steps iteratively within a compensation time interval, wherein calculating the drift compensation comprises averaging over the values of drift compensation calculated in the iterations within the compensation time interval.

16. The device according to claim 11, wherein the one or more processors are configured to perform the step of: calculating a current drift compensated motion direction by adding the last calculated drift compensation to a currently measured motion direction of the user.

17. The device according to claim 16, wherein the one or more processors are configured to perform the steps of: receiving a measured second motion direction of the user from a second motion direction sensor system for measuring a second motion direction at the same measurement time; calculating a second drift compensation for the second motion direction sensor system; calculating a current drift compensated second motion direction by adding the calculated second drift compensation to a currently measured second motion direction of the user; and calculating a current drift compensated average motion direction by averaging the current drift compensated motion direction and the current drift compensated second motion direction.

18. The device according to claim 11, wherein the one or more processors are configured to perform the step of: resetting the calculated drift compensation after having aligned, by user request, the viewing direction of the user with the motion direction of the user to a defined direction in order to calibrate the motion direction with the viewing direction.

19. The device according to claim 11, wherein the viewing direction sensing system is configured to: measure an angular position indicative of an orientation of VR glasses (14) in the user's transverse plane, wherein the VR glasses (14) are worn by the user.

20. The device according to claim 11, wherein the motion direction sensing system is configured to: measure an angular position indicative of an orientation of one or more motion direction sensors in the user's transverse plane, wherein the one or more motion direction sensors are arranged on a user's foot or leg.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Further advantageous embodiments of the inventive method and the inventive device are explained in more detail in the following figures:

[0055] FIG. 1 shows a perspective view of a VR system in which the inventive method of determining a motion direction of a user may be implemented;

[0056] FIG. 2 shows the problem underlying the invention in the form of an angular difference between the viewing direction and the measured motion direction, which results from the actual angular difference between the motion direction and the viewing direction plus the drift of the measured motion direction; and

[0057] FIG. 3 shows the steps of the inventive method according to a preferred example embodiment of the invention.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0058] FIG. 1 shows a perspective view of a VR system 100 in operating mode during use by a user who has assumed a slightly elevated sitting position on a seat element 105 of a seat 110 of VR system 100 that allows the legs to be moved. VR system 100 also includes a tread surface 104 on the ground, Cybershoes formed by sandals 50b, and a central control means 10 for controlling a display means indicating a virtual space. The display means can be implemented by 3D glasses 14 which comprises a sensor system for measuring a viewing direction of the user.

[0059] VR system 100 may further comprise a central control means 10 implemented by a computer or a game console, the central control means 10 comprising an input unit 11 as shown in FIG. 1 in simplified form. The method in accordance with the invention may be carried out in the central control means 10. The input unit 11 may, for example, be implemented by a touch display, a mouse, at least one joystick, at least one controller and/or a keyboard. The central control means 10 is arranged at VR system 100 externally to a display means displaying a virtual space and to the Cybershoes. However, it is also possible that the central control means 10 is implemented in at least one of the Cybershoes and/or in the display means. The display means is preferably implemented as 3D glasses 14.

[0060] Non-shown sensors of a sensor system are arranged in sandals 50b for measuring a motion direction of the user, wherein signals from the sensors are transmitted to central control means 10 via a radio network 13 by means of non-shown microcontrollers arranged in sandals 50b. The central control means 10 converts the received signals into a virtual space and changes a display in 3D glasses 14 accordingly. 3D glasses 14 and central control means 10 are connected via the radio network 13 for communication.

[0061] FIG. 2 shows the problem underlying the invention. The viewing direction determined by the sensor system for measuring the viewing direction of the user and the motion direction determined by the sensor system for measuring the motion direction of the user will show an angular difference due to the drift of the sensors even if the user is looking exactly in the same direction in which he is moving. According to some embodiments of the invention, the angular difference is measured at those points in time at which it can be assumed that the user is looking in the direction in which he is moving, so that the calculated angular difference for drift compensation can be taken into account in subsequent measurements of the motion direction.

[0062] FIG. 3 shows a preferred example embodiment of the invention, according to which the conditions for improving the precision of drift compensation are checked, so that the calculation of drift compensation is performed only at those times when it is highly likely that the user is looking in the direction in which he is moving. The drift compensation is calculated from the angle difference between the viewing direction and the motion direction; however, this calculation leads to errors if the viewing direction and the motion direction are decoupled from each other and do not coincide.

[0063] The first step is to check whether the user is actually walking or running in any forward direction. It can only be assumed with a significantly high probability that the user looks in the motion direction when the user is moving and moves forward. When standing still (e.g. standing or sitting without moving the legs), when moving sideways or backwards at any angle, it is not guaranteed, if not impossible, that the user looks in the direction in which he is moving. For this reason, such motion states of the user are not taken into account in the calculation of drift compensation.

[0064] If the user moves in a forward direction, it is nevertheless possible that the user will look around in any direction. This state can be checked via a calculated angle difference between the current viewing direction and the last determined motion direction, preferably taking into account the last calculated drift compensation. If the calculated angle difference is greater than a viewing angle threshold, e.g. 20°, it can be assumed that the user is currently looking around, so that this case also does not contribute to the calculation of the drift compensation.

[0065] A further criterion for evaluating whether the user is looking in the direction in which he is moving may be the motion velocity. With increasing motion velocity, the probability increases that the user looks in the direction in which he is moving.

[0066] The invention also includes all components mentioned in the example embodiments which are required for the realization of a respective device for calculating a drift compensation or a correspondingly equipped VR system. The distribution of tasks between the individual components of the VR system described in the aforementioned embodiments is to be understood as an example. Other divisions between the components of the VR system are also conceivable, which realize the described characteristics of the invention in equivalent form.

[0067] The details contained in the above description of embodiments should not be understood as a limitation of the scope of protection of the invention, but as an exemplary representation of some of its embodiments. Many variants are possible and immediately obvious to the specialist. In particular, this concerns variations which include a combination of features of the different embodiments disclosed in this specification. Therefore, the scope of the invention should not be determined by the example embodiments presented, but by the attached claims and their legal equivalents.