Input system based on a three-dimensional inertial navigation system and trajectory estimation method thereof

• US 20040236500A1
• Filed: 03/17/2004
• Published: 11/25/2004
• Est. Priority Date: 03/18/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Chang, Wook, Bang, Won-chul, Choi, Eun-seok, Kim, Dong-yoon, Kang, Kyoung-ho
• Granted Patent: US 7,353,112 B2
• Time in Patent Office: Days
• US Class Current: 701/200
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects
• 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 3/03545 Pens or stylus
• CPC Class Codes: G06V 30/1423 the instrument generating sequences of position coordinates corresponding to handwriting preprocessing or recognising digital ink G06V30/32
• CPC Class Codes: G06V 30/228 of three-dimensional handwriting, e.g. writing in the air

Abstract

An input system based on a three-dimensional inertial navigation system and a trajectory estimation method thereof is disclosed. The input system based on the three-dimensional inertial navigation system according to the present invention has acceleration sensors for outputting acceleration information just before motions, acceleration information on the motions, and acceleration information just after the motions; a rotation angle information estimation-computing portion for estimating rotation angle information on the motions through a predetermined computing process based on the outputted acceleration information just before the motions and acceleration information just after the motions; a conversion-computing unit for calculating position information on the motions based on the estimated rotation angle information on the motions and the outputted acceleration information on the motions; and an optimal plane-computing unit for projecting the position information on the motions onto an optimal plane.

Claims

1. An input system based on a three-dimensional inertial navigation system and having an input part and a host device, and for detecting motion position information corresponding to three-dimensional motions of the input part and outputting the detected motion position information to the host device, comprising:

acceleration sensors for outputting pre-motion acceleration information, motion acceleration information, and post-motion acceleration information;

a rotation angle information estimation-computing portion for estimating motion rotation angle information Φ

, θ

, and Ψ

through a predetermined computing process based on the outputted pre-motion acceleration information and post-motion acceleration information;

a conversion-computing unit for calculating the motion position information based on the estimated motion rotation angle information and the outputted motion acceleration information; and

an optimal plane-computing unit for projecting the motion position information onto an optimal plane.

2. The input system as claimed in claim 1, wherein the rotation angle information estimation-computing portion includes:

a first computing unit for calculating pre-motion rotation angle information Φ

1, θ

1, and Ψ

1 and post-motion rotation angle information Φ

2, θ

2, and Ψ

2 through a predetermined computing process based on the outputted pre-motion acceleration information and post-motion acceleration information; and

a second computing unit for calculating the motion rotation angle information through a predetermined computing process based on the calculated pre-motion rotation angle information and post-motion rotation angle information.

3. The input system as claimed in claim 2, wherein the first computing unit calculates the pre-motion rotation angle information Φ

1 and the post-motion rotation angle information Φ

2 based on equations as follows;

4. The input system as claimed in claim 2, wherein the first computing unit calculates the pre-motion rotation angle information θ

1 and the post-motion rotation angle information θ

2 based on equations as follows;

5. The input system as claimed in claim 2, wherein the second computing unit calculates the motion rotation angle information Φ

by an equation as follows;

Φ

(t)=a*t+b

where, if t₁ denotes time just before the motions, t₂ denotes time just after the motions, a denotes [Φ

(t₂)−

Φ

(t₁)]/(t₂−

t₁), b denotes −

a*t, +Φ

(t₁), and coordinate axes for a navigation frame are denoted as X₀, Y₀, and Z₀, then the Ψ

denotes the rotation angle information for the Z₀ axis, the θ

denotes the rotation angle information for the Y₁ axis indicating an axis after the Y₀ axis is rotated as much Ψ

, and the Φ

denotes the rotation angle information for the X₂ axis indicating an axis after the X₀ axis is rotated as much as Ψ and

θ

, respectively.

6. The input system as claimed in claim 2, wherein the second computing unit calculates the motion rotation angle information 0 based on an equation as follows:

θ

(t)=c*t+d

where, if t₁ denotes time just before the motions, t₂ denotes time just after the motions, c denotes [θ

(t₂)−

θ

(t₁)]/(t₂−

t₁), d denotes −

c*t, +θ

(t₁), and coordinate axes are denoted as X₀, Y₀, and Z₀, then Ψ

denotes the rotation angle information for the Z₀ axis and the θ

denotes the rotation angle information for the Y₁ axis indicating an axis after the Y₀ axis is rotated as much as Ψ

.

7. An input system based on a three-dimensional inertial navigation system and having an input part and a host device, and for detecting motion position information corresponding to three-dimensional motions of the input part and outputting the detected motion position information to the host device, comprising:

acceleration sensors for outputting motion acceleration information;

a rotation angle information estimation-computing portion for estimating motion rotation angle information Φ

, θ

, and Ψ

based on acceleration information based on the gravitational acceleration separated from the outputted motion acceleration information;

a conversion-computing unit for calculating motion position information based on the estimated motion rotation angle information and the outputted motion acceleration information; and

an optimal plane-computing unit for projecting the motion position information onto an optimal plane.

8. The input system as claimed in claim 7, wherein the rotation angle information estimation-computing portion includes:

a separation unit for separating acceleration information based on the motions of the input part itself and acceleration information based on the gravitational acceleration from the outputted motion acceleration information based on a predetermined process; and

a computing unit for calculating the motion rotation angle information through a predetermined computing process based on the acceleration information based on the separated gravitational acceleration.

9. The input system as claimed in claim 8, wherein the predetermined process for separating the acceleration information based on the gravitational acceleration from the motion acceleration information is to pass the motion acceleration information through a low-pass filter.

10. The input system as claimed in claim 8, wherein the computing unit calculates the motion rotation angle information Φ

based on an equation as follows;

11. The input system as claimed in claim 8, wherein the computing unit calculates the motion rotation angle information θ

based on an equation as follows;

12. A trajectory estimation method for an input system based on a three-dimensional inertial navigation system and having an input part and a host device, and for detecting motion position information corresponding to three-dimensional motions of the input part and outputting the detected motion position information to the host device, comprising:

(a) outputting motion acceleration information, pre-motion acceleration information, and post-motion acceleration information just after the motions;

(b) estimating motion rotation angle information Ψ

, θ

, and Ψ

through a predetermined computing process based on the outputted pre-motion acceleration information and post-motion acceleration information;

(c) calculating the motion position information based on the estimated motion rotation angle information and the outputted motion acceleration information; and

(d) projecting the motion position information onto an optimal plane.

13. The trajectory estimation method as claimed in claim 12, wherein the step (b) includes:

(b1) calculating pre-motion rotation angle information Φ

1, θ

1, and Ψ

1 and post-motion rotation angle information Φ

2, θ

2, and Ψ

2 through a predetermined computing process based on the outputted pre-motion acceleration information and post-motion acceleration information; and

(b2) calculating the motion rotation angle information through a predetermined computing process based on the calculated pre-motion rotation angle information and post-motion rotation angle information.

14. The trajectory estimation method as claimed in claim 13, wherein the step (b1) calculates the pre-motion rotation angle information Φ

1 and the post-motion rotation angle information Φ

2 based on equations as follows;

15. The trajectory estimation method as claimed in claim 13, wherein the step (b1) calculates the pre-motion rotation angle information θ

1 and the post-motion rotation angle information θ

2 based on equations as follows;

16. The trajectory estimation method as claimed in claim 13, wherein the step (b2) calculates the motion rotation angle information Φ

by an equation as follows;

Φ

(t)=a*t+b

where, if t₁ denotes time just before the motions, t₂ denotes time just after the motions, a denotes [Φ

(t₂)−

Φ

(t₁)]/(t₂−

t₁), b denotes −

a*t, +Φ

(t₁), and coordinate axes are denoted as X₀, Y₀, and Z₀, then the Ψ

denotes the rotation angle information for the Z₀ axis, the θ

denotes the rotation angle information for the Y₁ axis indicating an axis after the Y₀ axis is rotated as much as Ψ

, and the Φ

denotes the rotation angle information for the X₂ axis indicating an axis after the X₀ axis is rotated as much as Ψ and

θ

, respectively.

17. The trajectory estimation method as claimed in claim 13, wherein the step (b2) calculates the motion rotation angle information θ

based on an equation as follows;

θ

(t)=c*t+d

where, if t₁ denotes time just before the motions, t₂ denotes time just after the motions, c denotes [θ

(t₂)−

θ

(t₁)]/(t₂−

t₁), d denotes −

c*t, +θ

(t₁), and coordinate axes are denoted as X₀, Y₀, and Z₀, then Ψ

denotes the rotation angle information for the Z₀ axis and the θ

denotes the rotation angle information for the Y₁ axis indicating an axis after the Y₀ axis is rotated as much as Ψ

.

18. A trajectory estimation method for an input system based on a three-dimensional inertial navigation system and having an input part and a host device, and for detecting motion position information corresponding to three-dimensional motions of the input part and outputting the detected motion position information to the host device, comprising:

(a) outputting motion acceleration information;

(b) estimating motion rotation angle information Φ

, θ

, and Ψ

based on acceleration information based on the gravitational acceleration separated from the outputted motion acceleration information;

(c) calculating motion position information based on the estimated motion rotation angle information and the outputted motion acceleration information; and

(d) projecting the motion position information onto an optimal plane.

19. The trajectory estimation method as claimed in claim 18, wherein the step (b) includes

(b1) separating acceleration information based on the motions of the input part itself and acceleration information based on the gravitational acceleration from the outputted motion acceleration information based on a predetermined process;

and

(b2) calculating the motion rotation angle information through a predetermined computing process based on the acceleration information based on the separated gravitational acceleration.

20. The trajectory estimation method as claimed in claim 19, wherein the predetermined process in the step (b1) is to pass the motion acceleration information through a low-pass filter.

21. The trajectory estimation method as claimed in claim 19, wherein the motion rotation angle information Φ

in the step (b2) is calculated based on an equation as follows;

22. The trajectory estimation method as claimed in claim 19, wherein the motion rotation angle information θ

in the step (b2) is calculated based on an equation as follows;