Normalized process dynamics
AssigneeRosemount Inc.
InventorsJohn Philip Miller, Robert Carl Hedtke
Life of this patent
Estimating the term…
Abstract
A sensing system includes a filter construction module that constructs a high pass filter for filtering sensor values indicative of a process variable, the filter construction module setting values for parameters of the filter based on a temperature value indicative of a temperature of the sensor that produced the sensor values.
Claims24
A process field device comprising:
- a sensor providing a signal indicative of a process variable;
- a temperature sensor providing a signal indicative of a temperature of the sensor;
- converter circuitry for converting the sensor signal into sensor values and the temperature sensor signal into temperature values;
- a processor implementing a digital filter that filters the sensor values to produce filtered sensor values and executing statistical process monitoring instructions that compute a statistical value from the filtered sensor values, wherein the digital filter is temperature-dependent such that the filter changes as the temperature values change.
A sensing system comprising a filter construction module constructing a filter for filtering sensor values indicative of a process variable, the filter construction module setting values for parameters of the filter based on a temperature value indicative of a temperature of the sensor that produced the sensor values.
A control system comprising:
- a filter that filters a series of sensor values to produce filtered values;
- and
- a statistical process monitoring unit that determines a statistical value from the filtered values and that issues an alert when the statistical value crosses a threshold, wherein the filter filters the sensor values to achieve a desired frequency response in the statistical value that matches a frequency response in the statistical value produced from sensor values generated by a sensor operating in a selected range.
A method comprising:
- training coefficients for temperature-dependent filter parameters;
- receiving a sensor signal and a temperature signal;
- constructing a filter using the temperature-dependent filter parameters and the temperature signal;
- applying the sensor signal to the filter to produce a filtered signal;
- generating a statistical value from the filtered signal;
- and
- activating an alarm when the statistical value crosses a threshold.
Dependencies are inferred from the claim text.