Human interface device and method
A method for detecting a continuous circular gesture performed by an object, may have the steps of: detecting a movement of an object performing a circular movement by scanning the movement and determining subsequent position points of the object, wherein a reference position of a virtual circular movement is adapted depending on the history of scanned position points.
1. A method for detecting a continuous circular gesture performed by an object, the method comprising
detecting a movement of an object performing a circular movement by scanning the movement and determining subsequent position points of the object, wherein a reference position of a virtual circular movement is determined and adapted depending on fee a history of scanned position points, wherein the reference position is a circle center position and the circle center position is used to determine a current output angle of a circular movement, wherein the circle center position is updated when the distance between a new position point and a current center position is smaller than the distance between a previous position point and the current center position.
2. The method according to claim 1 , wherein the subsequent position points are transformed into positions in a two-dimensional plane and extrema of a plurality of subsequent position points are stored in a buffer.
3. The method according to claim 2 , wherein the extrema comprise a most left, a most right, a most top and a most bottom position in said two-dimensional plane and wherein said circle center position is determined from said stored extrema.
4. The method according to claim 1 , wherein a circular movement is detected by computing an angle between a current velocity vector and a low passed filtered version of the current velocity vector.
5. The method according to claim 1 , wherein updating is performed by adding a fraction of a distance between a new circle center position and a current circle center position to the current circle center position.
6. The method according to claim 1 , wherein updating is performed by low pass filtering a circle center position change.
7. The method according to claim 1 , wherein a current position is buffered in a buffer and wherein the buffer is only updated when a movement is determined to be part of a circular movement and when a velocity vector is higher than a predetermined velocity threshold.
8. The method according to claim 1 , wherein a gesture is determined between a start event and a stop event.
9. The method according to claim 8 , wherein the start event is defined by a circular trajectory and a predefined threshold angle.
10. The method according to claim 9 , wherein a current angle measurement is accumulated over multiple measurements to determine the start event.
11. The method according to claim 8 , wherein the stop event is determined when no circular movement is detected for a predetermined time period.
12. The method according to claim 8 , wherein the stop event is determined when no movement is detected for a predetermined time period.
13. The method according to claim 1 , wherein the object is a finger, a hand, or a pen.
14. The method according to claim 1 , wherein scanning the movement and determining subsequent position points of the object is performed by a sensor system generating a quasi-static electric field through a transmission electrode and wherein the sensor system comprises at least two receiving electrodes.
15. A method for detecting a continuous circular gesture performed by an object, the method comprising
detecting a movement of an object performing a circular movement by scanning the movement and determining subsequent position points of the object, wherein a reference position of a virtual circular movement is adapted depending on fee a history of scanned position points, wherein the current output angle is determined using an inverse tangent of (p new−p c), wherein p new is a current position point and p c is a current circle center position.
16. The method according to claim 15 , wherein a circular movement is determined by analyzing a segmented movement in each quadrant of a circular movement.
17. The method according to claim 16 , further comprising using a look-up table storing pre-computed threshold values for segments of a quarter of a circular movement.
18. A method for detecting a continuous circular gesture performed by an object the method comprising
detecting a movement of an object performing a circular movement by scanning the movement and determining subsequent position points of the object wherein a reference position of a virtual circular movement is determined and adapted depending on a history of scanned position points, wherein the reference position is a circle center position and the circle center position is used to determine a current output angle of a circular movement, wherein the subsequent position points are transformed into positions in a two-dimensional plane and extrema of a plurality of subsequent position points are stored in a buffer wherein the extrema comprise a set of positions on the trajectory wherein, for each comprised position p, there are two associated velocity vectors, the current velocity vector, starting at p, and the previous velocity vector, ending at p; and an angle of one of the said vectors is greater than or equal to a defined angle where an angle of the other said vector is less than the defined angle, or an angle of one of the said vectors is greater than a defined angle where an angle of the other said vector is less than or equal to the defined angle; and wherein said circle center position is determined from said stored extrema.
19. The method according to claim 18 , wherein a circular movement is detected by computing an angle between a current velocity vector and a low passed filtered version of the current velocity vector.
20. A method for detecting a continuous circular gesture performed by an object, the method comprising:
detecting a movement of an object performing a circular movement by scanning the movement and determining subsequent position points of the object,
detecting a decrease of a radius of a circular movement, wherein the decrease of the radius is detected when a sector line of a velocity vector between two successive position points intersects with a line through a center point and an older position point of the two successive position points;
updating a center point when a decrease of the radius has been detected.
21. The method according to claim 20 , wherein updating is performed by adding a fraction of a distance between an intersection point and the center point to the center point.
22. The method according to claim 20 , wherein updating is performed by low pass filtering a center point change.
23. The method according to claim 20 , wherein the sector line is a perpendicular bisector of the line between new and old position.
24. The method according to claim 20 , wherein the sector line has an angle unequal 90 degrees with respect to the velocity vector.
25. The method according to claim 24 , wherein two different lines are considered, for clockwise and counter-clockwise movement.
26. The method according to claim 20 , further comprising outputting an angle of a position point relative to the reference position of the virtual circular movement.