Abstract:
A directional tap detection algorithm and a single tri-ax?s accelerometer (10) are employed to extend the number of unique button less input commands available for a small mobile electronic device (12) such as a cell phone or a MP3 player. The algorithm analyzes acceleration data from the tri-axis accelerometer (10) to detect the direction and number of taps imparted to any of the six sides (14) of a housing (13) of the device (12), yielding 12 unique inputs. The algorithm employs a parameter referred to as the performance index (Pl) to identify tap induced movements. The Pl is determined by calculating the time derivative of each acceleration signal for each axis and then calculating the sum of the absolute values of the calculated acceleration derivatives. A tap is determined to have occurred if the sum exceeds a threshold value for a predetermined amount of time.
Abstract:
A system (10) and method detect freefall associated with an object that i s spinning or tumbling as it falls. Two tri-axis accelerometers (14, 16) pro vide inputs to an algorithm (28) that detects the freefall of a spinning obj ect that would not otherwise be detected by a conventional freefall detectio n system, due to the centrifugal and centripetal forces being placed on the falling object as it spins. The system can be used to detect the freefall of portable devices with onboard memory or hard disk drives, allowing the devi ces to have time to park the read/write head and reduce the potential of los ing data that can be damaged by impact. This freefall detection system may b e applied to such portable devices as notebook computers, PDAs, MP3 players, digital cameras, mobile phones and even automobiles.
Abstract:
A system (10) and method detect freefall associated with an object that is spinning or tumbling as it falls. Two tri-axis accelerometers (14, 16) provide inputs to an algorithm (28) that detects the freefall of a spinning object that would not otherwise be detected by a conventional freefall detection system, due to the centrifugal and centripetal forces being placed on the falling object as it spins. The system can be used to detect the freefall of portable devices with onboard memory or hard disk drives, allowing the devices to have time to park the read/write head and reduce the potential of losing data that can be damaged by impact. This freefall detection system may be applied to such portable devices as notebook computers, PDAs, MP3 players, digital cameras, mobile phones and even automobiles.
Abstract:
A directional tap detection algorithm and a single tri-axis accelerometer are employed to extend the number of unique button less input commands available for a small mobile electronic device. The algorithm analyzes acceleration data from the tri-axis accelerometer to detect the direction and number of taps imparted to any of the six sides of a housing of the device, yielding 12 unique inputs. The algorithm employs a parameter referred to as the performance index (PI) to identify tap induced movements. The PI is determined by calculating the time derivative of each acceleration signal for each axis and then calculating the sum of the absolute values of the calculated acceleration derivatives. A tap is determined to have occurred if the sum exceeds a threshold value for a predetermined amount of time. If a second tap is detected within a predetermined time after the first tap, then a double tap is determined to have occurred.