POINTING AND CONTROL DEVICE AND METHOD FOR A COMPUTER SYSTEM

• US 20090058803A1
• Filed: 08/22/2008
• Published: 03/05/2009
• Est. Priority Date: 08/23/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Pasolini, Fabio, Bendiscioli, Paolo, Vocali, Francesco, Biganzoli, Fabio
• Granted Patent: US 8,411,030 B2
• Time in Patent Office: Days
• US Class Current: 345/157
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• 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 3/0383 Signal control means within the pointing device

Abstract

A pointing and control device for a computer system, the device having a body that can be maneuvered by a user; and an inertial sensor fixed to the body for supplying first signals correlated to the orientation of the body with respect to a gravitational field acting on the inertial sensor. The device moreover includes a magnetometer fixed to the body for supplying second signals correlated to the orientation of the body with respect to the Earth'"'"'s magnetic field acting on the magnetometer and processing modules for determining an orientation of the body in an absolute reference system, fixed with respect to the Earth'"'"'s magnetic field and gravitational field on the basis of the first signals and second signals.

Claims

1. A pointing and control device for a computer system, comprising:

a body, which can be maneuvered by a user; and

an inertial sensor fixed to the body for supplying first signals correlated to the orientation of the body with respect to a gravitational field acting on the inertial sensor;

a magnetometer, fixed to the body, for supplying second signals correlated to the orientation of the body with respect to the Earth'"'"'s magnetic field acting on the magnetometer; and

processing means for determining an orientation of the body in an absolute reference system, fixed with respect to the Earth'"'"'s magnetic field and to the gravitational field, on the basis of the first signals and of the second signals.

2. The device according to claim 1, wherein the processing means comprise a first processing module for determining in a relative reference system fixed with respect to the body relative gravitational-field components on the basis of the first signals and relative magnetic-field components on the basis of the second signals.

3. The device according to claim 2, wherein the first processing module comprises a low-pass filter for extracting d.c. components from the first signals and wherein the relative gravitational-field components are defined by respective d.c. components of the first signals.

4. The device according to claim 2, wherein the processing means comprise a second processing module for determining the orientation of the body in the absolute reference system, on the basis of the relative gravitational-field components and of the relative magnetic-field components.

5. The device according to claim 4, wherein the second processing module comprises a first processing stage for determining, in the relative reference system, relative co-ordinates of first three vectors parallel to respective axes of the absolute reference system.

6. The device according to claim 5, wherein the first processing stage is configured for determining the relative co-ordinates of the first three vectors on the basis of the relations

$U_1=\frac{-\underset{\_}{G}}{}$

- G _ 

$U_2=\frac{-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M})<br><br>}$ $U_3=\frac{-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)<br><br>}$

where U₁, U₂, U₃ are the first three vectors, G is the Earth'"'"'s gravitational field, and M is the Earth'"'"'s magnetic field.

7. The device according to claim 5, wherein the second processing module comprises a second processing stage for determining, on the basis of the first vectors, a transformation operator for transformation of co-ordinates from the relative reference system to the absolute reference system.

8. The device according to claim 7, wherein the second processing module comprises a third processing stage for determining, in the absolute reference system, absolute co-ordinates of three second vectors parallel to respective axes of the relative reference system.

9. The device according to claim 7, wherein the third processing stage is configured for determining a direction, in the absolute reference system, of a pointing vector, fixed with respect to the body.

10. The device according to claim 1, wherein the processing means are configured for determining a pitch angle, a roll angle, and a yaw angle of the body.

11. The device according to claim 10, wherein the pitch angle and the roll angle are correlated to the first signals, and the yaw angle is correlated to the second signals.

12. The device according to claim 1, wherein the processing means reside at least in part in a control unit housed within the body.

13. The device according to claim 1, wherein the processing means reside at least in part in a processing unit housed outside the body.

14. The device according to claim 1, wherein the magnetometer and the accelerometer are microelectromechanical devices.

15. A computer system comprising a computer and a pointing and control device coupled to the computer and made according to claim 1.

16. A pointing and control method for an electronic computer system comprising:

providing a body, which can be maneuvered by a user; and

determining an orientation of the body with respect to the Earth'"'"'s gravitational field,

determining an orientation of the body with respect to the Earth'"'"'s magnetic field; and

determining an orientation of the body in an absolute reference system, fixed with respect to the Earth'"'"'s magnetic field and gravitational field.

17. The method according to claim 16, wherein determining the orientation of the body in the absolute reference system comprises determining, in a relative reference system fixed with respect to the body, relative gravitational-field components and relative magnetic-field components.

18. The method according to claim 17, wherein the orientation of the body in the absolute reference system is determined on the basis of the relative gravitational-field components and of the relative magnetic-field components.

19. The method according to claim 17, wherein determining the orientation of the body in the absolute reference system comprises determining, in the relative reference system, relative co-ordinates of first three vectors parallel to respective axes of the absolute reference system.

20. The method according to claim 19, wherein the relative co-ordinates of the first three vectors are determined on the basis of the relations

$U_1=\frac{-\underset{\_}{G}}{}$

- G _ 

$U_2=\frac{-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}<br><br>}$ $U_3=\frac{-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)<br><br>}$

where U₁, U₂, U₃ are the first three vectors, G is the Earth'"'"'s gravitational field, and M is the Earth'"'"'s magnetic field.

21. The method according to claim 20, wherein determining the orientation of the body in the absolute reference system comprises determining, on the basis of the first vectors, a transformation operator for transformation of co-ordinates from the relative reference system to the absolute reference system.

22. The method according to claim 21, wherein determining the orientation of the body in the absolute reference system comprises determining, in the absolute reference system, absolute co-ordinates of three second vectors parallel to respective axes of the relative reference system.

23. The method according to claim 21, wherein determining the orientation of the body in the absolute reference system comprises determining a direction, in the absolute reference system, of a pointing vector that is fixed with respect to the body.

24. The method according to claim 16, wherein determining the orientation of the body in an absolute reference system comprises determining a pitch angle, a roll angle, and a yaw angle of the body.

25. The method according to claim 16, wherein determining the orientation of the body with respect to the gravitational field comprises using a microelectromechanical inertial sensor and determining an orientation of the body with respect to the Earth'"'"'s magnetic field comprises using a microelectromechanical magnetometer.

26. The method according to claim 16, comprising performing operations of control of a computer on the basis of the orientation of the body in the absolute reference system.

27. A controller for a computer, the controller comprising:

a hand-holdable body;

a first sensor mounted on the body and adapted to supply first signals correlated to the orientation of the body with respect to the gravitational field of the Earth;

a second sensor mounted on the body and adapted to supply second signals correlated to the orientation of the body with respect to the Earth'"'"'s magnetic field; and

a processor adapted to receive the first and second signals and to output a control signal to the computer, the processor comprising a first processing module adapted to determine in a relative reference system fixed with respect to the body a relative gravitational field component derived from the first signal and a relative magnetic field component derived from the second signal, and a second processing module adapted to determine the orientation of the body in an absolute reference system on the basis of the relative gravitational field components and the relative magnetic field components derived from the first processing module.

28. The device of claim 27, wherein the second processing module comprises a first processing stage for determining in the relative reference system relative coordinates of three vectors parallel to respective axes of the absolute reference system, and wherein the second processing module comprises a second processing stage adapted to determine on the basis of the three vectors parallel to the respective axes of the absolute reference system a transformation operator for transformation of coordinates from the relative reference system to the absolute reference system.

29. The device of claim 28, wherein the first processing stage is adapted to determine the relative coordinates of the three vectors on the basis of the following relations:

$U_1=\frac{-\underset{\_}{G}}{<br><br>-\underset{\_}{G}<br><br>}$ $U_2=\frac{-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M})<br><br>}$ $U_3=\frac{-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)}{<br><br>-\underset{\_}{G}\bigwedge <br><br>\left(-\underset{\_}{G}\bigwedge <br><br>\underset{\_}{M}\right)<br><br>}$

where U₁, U₂, U₃ are the first three vectors, G is the Earth'"'"'s gravitational field, and M is the Earth'"'"'s magnetic field.

30. The device of claim 29, wherein the second processing module comprises a third processing stage for determining in the absolute reference system the absolute coordinates of three second vectors parallel to respective axes of the relative reference system.

31. The device of claim 30, wherein the third processing stage is adapted to determine a direction in the absolute reference system of a pointing vector fixed with respect to the body.

32. The device of claim 27, wherein the processor is adapted to determine a pitch angle, a roll angle, and a yaw angle of the body, wherein the pitch angle and the roll angle are correlated to the first signals and the yaw angle is correlated to the second signals.