Inertial input apparatus with six-axial detection ability and the operating method thereof

• US 7,843,430 B2
• Filed: 02/15/2007
• Issued: 11/30/2010
• Est. Priority Date: 12/12/2006
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Liou, Shun-Nan, Tsai, Ming-Jye, Huang, Shih-Ching, Jeng, Sheng-Wen
• Primary Examiner(s): Shankar; Vijay
• Application Number:
  US11/675,104
• Publication Number:
  US 20080134784A1
• Time in Patent Office: 1,384 Days
• Field of Search: 345156-172
• US Class Current: 345/158
• CPC Class Codes: G01P 15/18 in two or more dimensions
• 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 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/0485 Scrolling or panning

Abstract

An inertial input apparatus with six-axial detection ability, structured with a gyroscope and an acceleration module capable of detecting accelerations of X, Y, Z axes defined by a 3-D Cartesian coordinates, which is operable either being held to move on a planar surface or in a free space. When the inertial input apparatus is being held to move and operate on a planar surface by a user, a two-dimensional detection mode is adopted thereby that the gyroscope is used for detection rotations of the inertial input apparatus caused by unconscious rolling motions of the user and thus compensating the erroneous rotations, by which the technical disadvantages of prior-art inertial input apparatuses equipped with only accelerometer can be overcame and thus control smoothness of using the input apparatus is enhanced.

Claims

1. A method for switching an inertial input apparatus with six-axial detection ability between a two-dimensional detection mode and a three-dimensional detection mode, comprising the steps of:

recording three initial accelerations (g_xs, g_ys,g_zs) measured along three perpendicular directions with respect to a Cartesian coordinate system of X-, Y- and Z-axes respectively by an acceleration module of the inertial input apparatus while the inertial input apparatus is at rest on a planar surface along with an initial angular velocity ω

_zs gyroscope and setting an initial angle θ

_p of the inertial input apparatus to be zero and enabling the inertial input apparatus to enter the two-dimensional detection mode;

double-integrating the difference between the initial acceleration g_zs and current accelerations detected by a Z-axis accelerometer of the acceleration module for obtaining a mode-change value S_z, i.e. S_z=∫

∫

(g_z−

g_zs);

comparing S_z with a threshold value thr;

maintaining the inertial input apparatus at the two-dimensional detection mode when S_z<

thr; and

enabling the inertial input apparatus to enter the three-dimensional detection mode when S_z>

thr.

2. The method of claim 1, wherein the inertial input apparatus is enabled to enter the three-dimensional detection mode when a plurality of mode-change values S_z detected within a specific time interval are all larger than the threshold value thr.

3. The method of claim 1, wherein the inertial input apparatus is enabled to enter the two-dimensional detection mode when the mode-change values S_z is smaller than the threshold value thr and the absolute differences between the inertial acceleration g_ys and a plurality of Y-axis accelerations g_Y detected by a Y axis accelerometer of the acceleration module within a specific time interval, i.e. |g_y−

g_ys|, are all smaller than a specific value or almost equal to zero.

4. An operating method for an inertial input apparatus with six-axial detection ability being held to move in a free space, comprising the steps of:

recording two accelerations (g_xs, g_ys) measured along two perpendicular directions with respect to a Cartesian coordinate system of X-, and Y-axes at an initial operating stage of the inertial input apparatus along with an initial angular velocity ω

_zs of a gyroscope while setting an initial angle θ

_p of the inertial input apparatus to be zero;

calculating a yawing angle θ

_z with respect to a Z-axis of the Cartesian coordinate system and a pitch angle θ

_y with respect to the Y-axis, further comprises the steps of;

calculating the yawing angle θ

_z with respect to the Z-axis;

compensating a Y-axis acceleration detected by a Y-axis accelerometer of an acceleration module; and

calculating the pitch angle θ

_y; and

using two angles (θ

_z, θ

_y) to define a position coordinate (M_x, M_y) for an object displayed on a screen of an interactive computer; and

detecting a page-change, comprising the steps of;

defining a threshold value thr;

calculating a rolling angle θ

_x with respect the Y-axis; and

comparing the rolling angle θ

_x with thr so as to use the comparison to determine whether to perform a page-up operation or a page-down operation.

5. The method of claim 4, wherein the step of calculating the yawing angle θ

_z with respect to the Z-axis is performed by the following formulas;

θ

_z=θ

_p+(ω

_z−

ω

_zs)×

Δ

t, while |ω

_z−

ω

_zs| is larger than a threshold value,

wherein Δ

t is the sampling interval, preferably every 10 mini-sec,

the threshold value is preferably being set to be 0.1 so as to eliminate noise correspondingly,

and then let θ

_p=θ

_z.

6. The method of claim 4, wherein the step of compensating a Y-axis acceleration detected by a Y-axis accelerometer of an acceleration module is perform by subtracting a centripetal force g_r from an actual acceleration g_a detected by the Y-axis accelerometer, as illustrated in the following formulas:

g_a=g_r+g_s;

g_r=R×

(ω

<sub>z−

ω

zs</sub>)²;

g_y=g_a−

g_r;

wherein R is the distance between a rotation center and the accelerometer;

g_s is acceleration caused by other electrical noises;

g_y is the compensated Y-axis acceleration.

7. The method of claim 4, wherein the step of calculating the pitch angle θ

_y with respect to the Y-axis using the compensated Y-axis acceleration g_y is performed by the following formulas;

10. The method of claim 4, detecting the page-change, further comprising the steps of:

comparing (g_x−

g_xs) with thr so as to use the comparison to determine whether to perform a page-up operation or a page-down operation, whereas g_x is an X-axis acceleration at the end of an abrupt change occur, and g_xs is an X-axis acceleration at the beginning of an abrupt change occur.

11. The method of claim 10, wherein the page-change detection step further comprises the steps of:

paging up if (g_x−

g_xs)>

thr; and

paging down if (g_x−

g_xs)<

−

thr.

12. The method of claim 11, further comprising the step of:

maintaining without page change if −

thr≦

(g_x−

g_xs)≦

thr.

13. The method of claim 10, wherein the page-change detection step further comprises the steps of:

paging down if (g_x−

g_xs)>

thr; and

paging up if (g<sub>x−

gxs</sub>)<

−

thr.

14. The method of claim 13, wherein further comprising the step of:

maintaining without page change if −

thr≦

(g_x−

g_xs)≦

thr.

15. The method of claim 10, wherein the threshold value thr is adjustable according to actual requirement.

16. The method of claim 4, wherein the page-change detection step further comprises the steps of:

paging down if θ

hd x>

thr; and

paging up if θ

_x<

−

thr.

17. The method of claim 16, wherein further comprising the step of:

maintaining without page change if −

thr≦

θ

_x≦

thr.

18. The method of claim 4, wherein the page-change detection step further comprises the steps of:

paging up if θ

_x>

thr; and

paging down if θ

_x<

−

thr.

19. The method of claim 18, wherein further comprising the step of:

maintaining without page change if −

thr≦

θ

hd x≦

thr.

8. An operating method for an inertial input apparatus with six-axial detection ability being held to move in a free space, comprising the steps of:

recording two accelerations (g_xs, g_ys) measured along two perpendicular directions with respect to a Cartesian coordinate system of X-, and Y-axes at an initial operating stage of the inertial input apparatus along with an initial angular velocity ω

_zs of a gyroscope while setting an initial angle θ

_p of the inertial input apparatus to be zero;

calculating a yawing angle θ

_z with respect to a Z-axis of the Cartesian coordinate system and a pitch angle θ

_y with respect to the Y-axis; and

using two angles (θ

_z, θ

_y) to define a position coordinate (M_x, M_y) for an object displayed on a screen of an interactive computer;

wherein the two angles (θ

_z, θ

_y) are amplified by specific ratios S_x, S_y in respective so as to be used for defining a position coordinate (M_x, M_y) for an object displayed on a screen of an interactive computer, according to the following formulas;

M_s=S_x×

θ

_z, M_y=S_y×

θ

_y

wherein S_x is the amplifying ratio with respect to the X-axis, and S_y is the amplifying ratio with respect to the Y-axis.

9. The method of claim 8, wherein the specific ratios S_x, S_y are adjustable.