Real-Time Dynamic Tracking of Bias

• US 20130169539A1
• Filed: 02/28/2013
• Published: 07/04/2013
• Est. Priority Date: 06/28/2007
• Status: Active Grant

• Current Assignee: DRNC Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Hillcrest Laboratories Incorporated (CEVA Incorporated)
• Inventors: SHENG, Hua, LIBERTY, Matthew G., ROLLER, Christopher D., GRITTON, Charles W.K.
• Granted Patent: US 8,683,850 B2
• Time in Patent Office: Days
• US Class Current: 345/163
• CPC Class Codes: G01D 3/028 mitigating undesired influences, e.g. temperature, pressure
• CPC Class Codes: G01R 29/00 Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
• CPC Class Codes: G06F 3/033 Pointing devices displaced or positioned by the user , e.g. mice, trackballs, pens or joysticks; Accessories therefor digitisers characterised by the transducing means G06F3/041
• 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: G16Z 99/00 Subject matter not provided for in other main groups of this subclass
• CPC Class Codes: H04N 21/42204 User interfaces specially adapted for controlling a client device through a remote control device; Remote control devices therefor constructive details of casings for the remote control device H01H9/0235; user interfaces for controlling a tuning device of a television receiver through a remote control H03J9/00; remote control of peripheral devices connected to a television receiver through the remote control device of the television receiver H04B1/205
• CPC Class Codes: H04N 21/42222 Additional components integrated in the remote control device, e.g. timer, speaker, sensors for detecting position, direction or movement of the remote control, microphone or battery charging device

Abstract

A bias value associated with a sensor, e.g., a time-varying, non-zero value which is output from a sensor when it is motionless, is estimated using at least two, different bias estimating techniques. A resultant combined or selected bias estimate may then be used to compensate the biased output of the sensor in, e.g., a 3D pointing device.

Claims

1-65. -65. (canceled)

66. A device for estimating bias associated with a sensor comprising:

said sensor; and

a processor for estimating said bias associated with said sensor using at least a first bias estimating technique to generate a first bias estimate and a second bias estimating technique to generate a second bias estimate.

67. The device of claim 66, wherein said first bias estimate and said second bias estimate are associated with a non-zero value output from said sensor when said device to which said sensor is attached is stationary.

68. The device of claim 66, wherein said first bias estimate and said second bias estimate are combined to generate an output bias estimate.

69. The device of claim 66, wherein one of said first bias estimate and said second bias estimate are selected to generate an output bias estimate.

70. The device of claim 66, wherein said first bias estimating technique generates said first bias estimate based upon determining whether said device within which said sensor is located is stationary.

71. The device of claim 70, wherein said first bias estimating technique determines that said device is stationary when peak-to-peak values received from said sensor are less than a predetermined threshold.

72. The device of claim 66 wherein said first bias estimating technique generates said first bias estimate based upon detection of a pitch of said device within which said sensor is located.

73. The device of claim 66, wherein said first bias estimating technique generates said first bias estimate based upon detection of a change in angle of said device relative to one of a plurality of different axes.

74. The device of claim 72, wherein said first bias estimating technique calculates a difference between a first change of elevation angle determined using data output from said sensor and a second change of elevation angle determined using data output from another sensor.

75. The device of claim 74, wherein said sensor is an accelerometer and said another sensor is a sensor which measures rotation of said device about an axis.

76. The device of claim 72, wherein said first bias estimate is determined over a variable time window, said variable time window varying based upon measurement noise associated with data generated by said sensor.

77. The device of claim 72, wherein said first bias estimating technique operates in one mode to generate said first bias estimates as individual data points which converge over time.

78. The device of claim 72, wherein said first bias estimating technique operates in one mode to generate said first bias estimates using a line intersection technique associated with two individual bias estimates by combining two measurements of biases of pitch angular rates at two different roll angles.

79. The device of claim 72, wherein said first bias estimating technique operates in one mode to generate said first bias estimates by mapping averaged values output by said sensor into a bias of a yaw angular rate and a bias of a pitch angular rate defined in a user frame of reference.

80. The device of claim 72, wherein said first bias estimating technique operates in one of three modes to generate said first bias estimates including:

(a) a first mode for generating said first bias estimates as individual data points which converge over time;

(b) a second mode to generate said first bias estimates using a line intersection technique associated with two individual bias estimates; and

(c) a third mode for generating said first bias estimates by mapping averaged values output by said sensor into a bias of a yaw angular rate and a bias of a pitch angular rate defined in a user frame of reference.

81. The device of claim 80, wherein said first bias estimating technique operates in said third mode if (a) a measurement error variance associated with said first bias estimate is smaller than a first predetermined threshold, (b) a time window size over which said first bias estimate is calculated is smaller than a second predetermined threshold, and (c) a difference between a roll angle measured in a current time window and a roll angle measured in a previous time window is smaller than a third predetermined threshold.

82. The device of claim 80, wherein said first bias estimating technique operates in said second mode if (a) a difference between a roll angle measured in a current time window and a roll angle measured in a previous time window is greater than a first predetermined threshold and (b) a time gap between a current time window and a previous time window is shorter than a predetermined amount of time.

83. The device of claim 66, wherein said first bias estimating technique generates said first bias estimate based upon slew-rate filtering.

84. The device of claim 68, wherein said combining is performed by a Kalman filter to generate said output bias estimate.

85. The device of claim 66, wherein said sensor is a MEMS device.