Digitally controlled sensor system

• US 20060107746A1
• Filed: 12/29/2005
• Published: 05/25/2006
• Est. Priority Date: 05/31/2002
• Status: Active Grant

• Current Assignee: Brooks Instrument LLC (Illinois Tool Works Inc.)
• Original Assignee: Brooks Instrument LLC (Illinois Tool Works Inc.)
• Inventors: Edwards, Marvin B., Arrant, Edwin K., Albert, David M.
• Granted Patent: US 7,720,628 B2
• Time in Patent Office: Days
• US Class Current: 73/714
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14
• CPC Class Codes: G01L 19/04 Means for compensating for effects of changes of temperature , i.e. other than electric compensation
• CPC Class Codes: G01L 27/002 Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
• CPC Class Codes: G01L 9/125 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

Systems and methods for digitally controlling sensors. In one embodiment, a digital controller for a capacitance diaphragm gauge is embedded in a digital signal processor (DSP). The controller receives digitized input from a sensor AFE via a variable gain module, a zero offset module and an analog-to-digital converter. The controller automatically calibrates the received input by adjusting the variable gain and zero offset modules. The controller also monitors and adjusts a heater assembly to maintain an appropriate temperature at the sensor. The controller utilizes a kernel module that allocates processing resources to the various tasks of a gauge controller module. The kernel module repetitively executes iterations of a loop, wherein in each iteration, all of a set of high priority tasks are performed and one of a set of lower priority tasks are performed. The controller module thereby provides sensor measurement output at precisely periodic intervals, while performing ancillary functions as well.

Claims

1-55. -55. (canceled)

56. A digital pressure sensing system, comprising:

a sensor for measuring a pressure-related variable;

an analog front end (AFE) to convert the measured variable into an analog signal;

a processing stage to receive the analog signal;

a digital controller to provide a digital control signal to control the processing stage,

wherein the processing stage processes the analog signal based on the digital control signal; and

an analog to digital converter to convert the processed analog signal into a digital signal.

57. The system of claim 56, wherein the sensor is a strain gauge or a capacitance manometer.

58. The system of claim 56, wherein the sensor measures capacitance and the AFE converts the capacitance measurement to an analog voltage signal.

59. The system of claim 56, wherein the processing stage comprises:

a variable gain stage, wherein the variable gain stage is operable to amplify the analog signal; and

a zero offset stage, wherein the zero offset stage is operable to compensate for a zero offset drift.

60. The system of claim 59, wherein the variable gain stage and zero offset stages are separate from the analog to digital converter.

61. The system of claim 56, further comprising a digital processing stage, wherein the digital processing stage processes the digital signal.

62. The system of claim 61, wherein the processing of the digital stage comprises linearization.

63. The system of claim 59, wherein a digital control signal is provided to the processing stage in response to a manually input zero adjust command.

64. The system of claim 56, further comprising a digitally controlled sensor heating assembly to control a temperature of the sensor based on a received digital control signal.

65. The system of claim 56, further comprising an ambient temperature sensor for measuring an ambient temperature, wherein the processing of the digital stage comprises compensating for the ambient temperature.

66. The system of claim 56, wherein the digital controller is a DSP or a microcontroller.

67. The system of claim 56, wherein the processed digital signal is provided to a controller area network or a DeviceNet communications link.

68. A method for digitally controlling the processing of a pressure signal, comprising:

receiving an analog pressure signal;

processing the analog pressure signal, wherein the processing is digitally controlled; and

converting the processed analog signal into a digital signal.

69. The method of claim 68, further comprising:

measuring a pressure related variable; and

converting the pressure related variable to the analog pressure signal.

70. The method of claim 69, wherein the pressure related variable is measured by a sensor.

71. The method of claim 70, wherein the sensor is a strain gauge or a capacitance manometer.

72. The method of claim 70, further comprising controlling a temperature of the sensor based on a received digital control signal.

73. The method of claim 68, wherein processing the analog pressure signal comprises amplifying the analog pressure signal or compensating for a zero offset drift.

74. The method of claim 73, further comprising providing a digital control signal in response to a manually input zero adjust command.

75. The method of claim 68, further comprising processing the digital signal.

76. The method of claim 75, wherein processing of the digital signal comprises linearization.

77. The method of claim 75, wherein the processing of the digital signal comprises compensating for a measured ambient temperature.

78. The method of claim 68, wherein the processed digital signal is provided to a controller area network or a DeviceNet communications link.