Moving trajectory generation method

• US 9,098,123 B2
• Filed: 08/03/2012
• Issued: 08/04/2015
• Est. Priority Date: 08/04/2011
• Status: Active Grant

• Current Assignee: National Cheng KUNG University (Government of The Republic of China)
• Original Assignee: National Cheng KUNG University (Government of The Republic of China)
• Inventors: Wang, Jeen-Shing, Hsu, Yu-Liang
• Primary Examiner(s): Xavier, Antonio
• Application Number:
  US13/566,620
• Publication Number:
  US 20130069917A1
• Time in Patent Office: 1,096 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 3/03 Arrangements for converting the position or the displacement of a member into a coded form
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/0354 with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
• CPC Class Codes: G06V 30/1423 the instrument generating sequences of position coordinates corresponding to handwriting preprocessing or recognising digital ink G06V30/32

Abstract

A moving trajectory generation method includes the following steps of: sensing a movement of a writing device in the air by a moving trajectory sensing module so as to generate a moving trajectory and then generate a moving trajectory signal; generating a virtual projection plane and a trajectory projection plane by a trajectory reconstruction unit of a trajectory reconstruction module according to the moving trajectory signal; calculating an angle between the virtual projection plane and the trajectory projection plane, and generating a transformation matrix according to the angle; transforming the virtual projection plane to the trajectory projection plane according to the transformation matrix; and projecting the moving trajectory to the trajectory projection plane so as to obtain a two-dimensional trajectory signal.

Claims

1. A moving trajectory generation method, comprising the steps of:

sensing a movement of a writing device in the air by a moving trajectory sensing module so as to generate a moving trajectory and then generate a moving trajectory signal, wherein the moving trajectory signal includes a first axial signal, a second axial signal, and a third axial signal, and a first axis, a second axis, and a third axis are perpendicular to each other;

generating a virtual projection plane and a trajectory projection plane by a trajectory reconstruction unit of a trajectory reconstruction module according to the moving trajectory signal, wherein the weakest signal magnitude of the first axial signal, the second axial signal, and the third axial signal is determined by comparing the first, second and third axial signals, and the axis of the weakest axial signal is used as the normal vector axis to generate the virtual projection plane;

calculating an angle between the virtual projection plane and the trajectory projection plane, and generating a transformation matrix according to the angle;

transforming the virtual projection plane to the trajectory projection plane according to the transformation matrix; and

projecting the moving trajectory signal to the trajectory projection plane so as to obtain a two-dimensional trajectory signal.

2. The moving trajectory generation method of claim 1, wherein the moving trajectory signal comprises an angular velocity signal, an acceleration signal, a magnetic-field intensity signal, a geomagnetic orientation signal, or their combinations in three axes with respect to the moving trajectory at different time points.

3. The moving trajectory generation method of claim 2, further comprising a step of:

transforming the acceleration signals according to the angular velocity signals by an orientation calculation module so as to transform the acceleration signals from a body frame of the writing device to a local level frame.

4. The moving trajectory generation method of claim 1, wherein in the step of generating the virtual projection plane and the trajectory projection plane when the axis of the weakest axial signal is used as the normal vector axis, the other axes are used as two basis vector axes.

5. The moving trajectory generation method of claim 4, wherein the basis vector axes define the virtual projection plane.

6. The moving trajectory generation method of claim 4, wherein the angle is obtained according to the second axial signal and the third axial signal.

7. The moving trajectory generation method of claim 4, further comprising, before projecting the moving trajectory signal on the trajectory projection plane, a step of:

calibrating the first axial signal and the second axial signal according to the third axial signal by a detecting-calibration unit of the trajectory reconstruction module, so as to generate a first axial trajectory signal and a second axial trajectory signal.

8. The moving trajectory generation method of claim 7, wherein the step of calibrating the first axial signal comprises:

when a variation of the third axial signal within a time interval exceeds a preset signal value, the detecting-calibration unit zeros the first axial signal within the time interval.

9. The moving trajectory generation method of claim 7, wherein the step of calibrating the second axial signal comprises:

when a variation of the third axial signal within a time interval exceeds a preset signal value, the detecting-calibration unit zeros the second axial signal within the time interval.

10. The moving trajectory generation method of claim 1, wherein the moving trajectory represents a trajectory of the writing device projected on the trajectory projection plane as the writing device moves in the air.

11. The moving trajectory generation method of claim 1, further comprising a step of:

performing a calculation to the two-dimensional trajectory signal by a trajectory calculation unit of the trajectory reconstruction module.

12. The moving trajectory generation method of claim 11, further comprising a step of:

displaying the two-dimensional moving trajectory by a display module according to the calculated two-dimensional trajectory signal.