Patent Number: 
Section: claims

1. A method of determining a segment-specific estimate of a parameter associated with a process control loop, the method comprising:measuring a signal within the process control loop when the process control loop is connected on-line within a process control environment, including:measuring an input signal indicative of an input parameter; andmeasuring an output signal indicative of an output parameter;storing the measured signal as a series of data points, each data point having a first component derived from the input signal and a second component derived from the output signal;partitioning the stored signal data into a plurality of data segments, wherein:each of the plurality of data segments corresponds to a respective range of travel of the output signal, andat least two of the plurality of data segments correspond to adjacent ranges of travel of the output signal;performing a statistical analysis on at least some of the plurality of data segments; andgenerating a set of segment-specific estimates based on the performed statistical analysis. 2. The method of claim 1, wherein partitioning the stored signal data into a plurality of data segments includes defining non-overlapping segments of equal size. 3. The method of claim 2, further comprising:comparing each of the segment-specific friction estimates to a threshold value;generating a problem indication in response to detecting that a particular segment-specific friction estimate exceeds the threshold value. 4. The method of claim 2, further comprising:calculating an average of the set of segment-specific estimates;comparing each of the set of segment-specific estimates to the average of the set of segment-specific estimates; andgenerating a problem indication in response to detecting that at least one of the set of segment-specific estimates differs from the average of the set of segment-specific estimates by more than a certain amount. 5. The method of claim 2, wherein the parameter associated with a process control loop is one of a friction, a dead time, a dead band, or shaft windup associated with a portion of the range of travel of the actuator. 6. The method of claim 2, further comprising repeating the acts of measuring a signal within the process control loop, storing the signal data, partitioning the stored signal data, and performing a statistical analysis at a later point in time to generate a second set of segment-specific estimates; andgenerating trend data by comparing the set of segment-specific estimates to the second set of segment-specific estimates. 7. The method of claim 6, wherein comparing the first subset to the second subset to generate trend data includes generating segment-specific trend data. 8. A method of determining a segment-specific estimate of a parameter associated with a valve operating in a process control loop, the method comprising:receiving signal data corresponding to an output signal from a process control loop, wherein the output signal is indicative of a response of the valve operating in the process control loop to an input command signal;storing the signal data;partitioning the stored signal data into a plurality of data segments, so that each of the plurality of data segments corresponds to a respective range of travel of the output signal;performing a statistical analysis on a first one of the plurality of data segments selected from the plurality of data segments;andgenerating a first segment-specific parameter estimate based on the performed statistical analysis of the first one of the plurality of data segments. 9. The method of claim 8, wherein partitioning the stored signal data into a plurality of data segments includes partitioning the stored signal data into a plurality of non-overlapping segments of substantially equal size. 10. The method of claim 8, further comprising performing a statistical analysis on a second one of the plurality of data segments to generate a second segment-specific parameter estimate. 11. The method of 10, further comprising providing the first and second segment-specific parameter estimates to a user via a display unit. 12. The method of claim 11, wherein the first and second segment-specific parameter estimates to a user via a display unit includes displaying a histogram, wherein each bar in the histogram is associated with one of the segment-specific parameters. 13. The method of claim 8, wherein receiving signal data corresponding to a signal from a process control loop includes measuring the signal within the process control loop when the process control loop is connected on-line within a process control environment. 14. The method of claim 8, wherein receiving signal data corresponding to a signal from a process control loop includes receiving signal data corresponding to the signal generated at a first point in time and a second point in time; andwherein performing a statistical analysis on a first one of the plurality of data segments includes:generating a first value corresponding to the first segment-specific parameter estimate at the first point in time;generating a second value corresponding to the first segment-specific parameter estimate at the second point in time; andcomparing the first and the second values to determine a first trend in the segment-specific parameter. 15. The method of claim 14, further comprising:performing a statistical analysis on a second one of the plurality of data segments to generate a second segment-specific parameter estimate;generating a third value corresponding to the second segment-specific parameter estimate at the first point in time;generating a fourth value corresponding to the second segment-specific parameter estimate at the second point in time;comparing the first and the second values to determine a second trend in the second-specific parameter. 16. A method of determining a segment-specific estimate of a parameter associated with a process control loop, the method comprising:receiving signal data corresponding to a signal from a process control loop, including receiving measurements of an actuator pressure signal and an actuator position signal of a device having an actuator that moves in response to actuator pressure and has a range of travel; andstoring the signal data, including storing a series of tuples, each tuple including an actuator pressure value derived from the actuator pressure signal and an actuator position value derived from the actuator position signal;partitioning the stored signal data into a plurality of data segments;performing a statistical analysis on a first one of the plurality of data segments selected from the plurality of data segments; andgenerating a first segment-specific parameter estimate based on the performed statistical analysis of the first one of the plurality of data segments. 17. The method of claim 16, wherein the first segment-specific estimate is one of a friction, a dead time, a dead band, or shaft windup associated with a portion of the range of travel of the actuator. 18. The method of claim 17, further comprising comparing the first segment-specific estimate to a threshold value to conditionally generate a problem indication, wherein the problem indication is generated if the first segment-specific estimate is substantially higher or substantially lower than the threshold value. 19. A method of determining a segment-specific estimate of a parameter associated with a process control loop, the method comprising:receiving signal data corresponding to a signal from a process control loop; including receiving signal data corresponding to the signal generated at a first point in time and a second point in time; wherein the first and the second points in time are selected in accordance with a maintenance cycle associated with the process control loop;storing the signal datapartitioning the stored signal data into a plurality of data segments;performing a statistical analysis on a first one of the plurality of data segments selected from the plurality of data segments, including:generating a first value corresponding to the first segment-specific parameter estimate at the first point in time;generating a second value corresponding to the first segment-specific parameter estimate at the second point in time; andcomparing the first and the second values to determine a first trend in the segment-specific parameter; the method further comprising:generating a first segment-specific parameter estimate based on the performed statistical analysis of the first one of the plurality of data segments. 20. The method of claim 19, wherein the maintenance cycle is 30 days or less. 21. A computer program stored on a computer readable medium for use in controlling a processor based on data stored in a memory associated with the processor, the program performing the steps of:reading from a memory a data net indicative of a signal associated with a process control loop operating within a process control environment;dividing the data set into a plurality of sections, wherein each of the plurality of sections corresponds to a segment of a range of operation of a device operating in the process control loop, and wherein at least two sections correspond to adjacent segments of the range of operation of the device; andperforming a statistical analysis on data associated with a first one of the plurality of sections to produce a first segment-specific estimate of a parameter associated with the process control loop. 22. The computer program of claim 21, further comprising the step of performing a statistical analysis on a second one of the plurality of sections to generate a second segment-specific estimate of the parameter. 23. The computer program of claim 22, further comprising the step of comparing the first segment-specific estimate of the parameter and the second segment-specific estimate of the parameter to a threshold value. 24. The computer program of claim 22, further comprising the step of comparing the first segment-specific estimate of the parameter and the second segment-specific estimate of the parameter to an average value of the parameter associated with the complete data set. 25. The computer program of claim 21, wherein the step of performing a statistical analysis on a first one of the plurality of sections includes:generating a first value corresponding to the segment-specific parameter estimate at a first point in time;generating a second value corresponding to the first segment-specific parameter estimate at a second point in time; andcomparing the first and the second values to determine a trend in the segment-specific parameter. 26. The computer program of claim 21, wherein the process control loop includes a valve having a moveable actuator and wherein the parameter is one of a friction, a dead time, a dead band, or shaft windup.