Method and device for sensing orientation of an object in space in a fixed frame of reference

A handheld device for controlling a cursor on a display, comprising:

• a first sensor for sensing one of angular velocity and position of the handheld device with at least two active sensing axes;
• a second sensor for sensing acceleration of the handheld device with three sensing axes;
• said first and second sensors being in communication with a processing module configured to convert the handheld device orientation data from a Sensing Reference Frame to a Working Reference Frame by fusing a motion vector Vm composed from some or all of the outputs from the first sensor and a synthetic vector Vsyn representative of the gravity components of the acceleration of the object, said synthetic vector Vsyn being calculated as a weighted average of a corrected vector Vcor with weight K composed from the outputs of at least one of the first and the second sensors, and an acceleration vector Vac with weight (1−K) composed from some of the outputs of the second sensor;
• wherein the calculation of the corrected vector Vcor depends on the number of active sensing axes of the first sensor and K is a function of a dynamicity variable D of the movement of the object, and the results of the fusion control a movement of the cursor on the display independently of the roll movement of the handheld device.

A method for controlling a cursor on a display with a handheld device, comprising the steps of:

• acquiring signals from a first sensor for sensing one of angular velocity and angular position of the handheld device with at least two active sensing axes;
• acquiring signals from a second sensor for sensing acceleration of the handheld device with three sensing axes;
• processing the signals from said first and second sensors with a processing module configured to convert handheld device orientation data from a Sensing Reference Frame to a Working Reference Frame by fusing a motion vector Vm composed from some or all of the outputs from the first sensor and a synthetic vector Vsyn representative of the gravity components of the acceleration of the object, said synthetic vector Vsyn being calculated as a weighted average of a corrected vector Vcor with weight K composed from the outputs of at least one of the first and the second sensors, and an acceleration vector Vac with weight (1−K) composed from some of the outputs of the second sensor;
• wherein the calculation of the corrected vector Vcor depends on the number of active sensing axes of the first sensor and K is a function of a dynamicity variable D of the movement of the object, and the result of the fusion controls a movement of the cursor of the display independently of the roll movement of the handheld device.

A computer program configured for controlling a cursor on a display with a handheld device when executed on computer, said computer program comprising modules fit for:

• acquiring signals from a first sensor for sensing angular velocity of the object with at least two active sensing;
• acquiring a second sensor for sensing linear acceleration of the object with three sensing;
• processing the signals from said first and second sensors with a processing module configured to convert handheld device orientation data from a Sensing Reference Frame to a Working Reference Frame by fusing a motion vector Vm composed from some or all of the outputs from the first sensor and a synthetic vector Vsyn representative of the gravity components of the acceleration of the object, said synthetic vector Vsyn being calculated as a weighted average of a corrected vector Vcor with weight K composed from the outputs of at least one of the first and the second sensors, and an acceleration vector Vac with weight (1−K) composed from some of the outputs of the second sensor;
• wherein the calculation of the corrected vector Vcor depends on the number of active sensing axes of the first sensor and K is a function of a dynamicity variable D of the movement of the object, and the result of the fusion controls a movement of the cursor on the display independently of the roll movement of the handheld device.