Data processing: measuring – calibrating – or testing – Measurement system – Measured signal processing
Reexamination Certificate
2002-03-25
2004-10-26
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Measured signal processing
C702S189000
Reexamination Certificate
active
06810366
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to signal processing, and more particularly, to low pass filtering using a deadband.
BACKGROUND
Conventional low pass filters using resistors and capacitors work quite well in many, but not all, applications. In some instances, the inherent phase shift of the input signal causes a delay that is significant enough to cause problems.
For example, in many engine applications, a sensor detects the rotational speed or position of the engine and transmits a signal indicative thereof.
FIG. 1
is a graph showing one example of an engine speed signal
10
transmitted from such a sensor. The engine was set to run at 2140 revolutions per minute (rpm) plus or minus 4 rpm. Thus, the portion of the engine speed signal
10
outside this range is noise, which may be filtered out to some extent by a conventional low pass filter.
FIG. 2
shows a graph of a modeled engine speed signal
12
of 2149 rpm plus or minus 3 rpm (generated by a frequency generator) transmitted from the engine speed sensor, along with a filtered version (an output signal
14
) created by filtering the modeled engine speed signal
12
with a conventional (5 Hz) resistor/capacitor type low pass filter. As you can see, the modeled engine speed signal
12
contains portions having an amplitude outside of the 2149 plus or minus 3 rpm, which is noise. While the conventional low pass filter reduces the noise so that the amplitude of the output signal
14
is within the expected parameters (2149 plus or minus 3 rpm), the output signal
14
is delayed (phase shifted) by approximately 50 msec from the input signal.
In engine applications, it is not unusual for the conventional low pass filter to cause a phase shift of 100 msec. This is problematic in that, depending on the application, the engine speed signal may be read every 20 msec. Thus, the conventional low pass filter may process the input signal more slowly than is desired.
SUMMARY OF THE INVENTION
The present invention provides apparatuses and methods for filtering a signal. A first processing device receives a first control signal and a first feedback signal. The first processing device transmits a first error signal as a function of the first control signal and the first feedback signal. A second processing device is coupled with the first processing device to receive the first error signal. The second processing device transmits a second control signal as a function of the first error signal, the second control signal being substantially indicative of zero when the absolute value of the first error signal is less than or equal to a first predetermined value, substantially indicative of the first error signal value minus the first predetermined value, multiplied by a second predetermined value, when the absolute value of the first error signal is greater than the first predetermined value, and the first error signal is greater than the first predetermined value, and substantially indicative of the first error signal value plus the first predetermined value, multiplied by the second predetermined value, when the absolute value of the first error signal is greater than the first predetermined value, and the first error signal is not greater than the first predetermined value.
A third processing device is coupled with the second processing device to receive the second control signal and the first feedback signal. The third processing device transmits an output signal as a function of the second control signal and the first feedback signal. A fourth processing device is coupled with the third processing device to receive the output signal. The fourth processing device transmits the first feedback signal as a function of the output signal to the first processing device and the third processing device, the first feedback signal being substantially equal to the output signal delayed by a first predetermined duration of time.
REFERENCES:
patent: 3571578 (1971-03-01), Fry
patent: 3803357 (1974-04-01), Sacks
patent: 3857104 (1974-12-01), Sacks
patent: 4375599 (1983-03-01), Bleckmann et al.
patent: 4478068 (1984-10-01), Bonitz et al.
patent: 4485649 (1984-12-01), Martin et al.
patent: 4556956 (1985-12-01), Dickenson et al.
patent: 4637247 (1987-01-01), Dreyer et al.
patent: 4730499 (1988-03-01), Gianella et al.
patent: 4852657 (1989-08-01), Hardy et al.
patent: 4935682 (1990-06-01), McCuen
patent: 4940929 (1990-07-01), Williams
patent: 4954732 (1990-09-01), Surauer et al.
patent: 5029118 (1991-07-01), Nakajima et al.
patent: 5040119 (1991-08-01), Hardy et al.
patent: 5343843 (1994-09-01), Hamren
patent: 5400644 (1995-03-01), Remboski, Jr. et al.
patent: 5444579 (1995-08-01), Kline et al.
patent: 5576962 (1996-11-01), Ferguson et al.
patent: 5747681 (1998-05-01), Kuroka et al.
patent: 5781048 (1998-07-01), Nakao et al.
patent: 5838599 (1998-11-01), Tao et al.
patent: 5873427 (1999-02-01), Ferguson et al.
patent: 5901059 (1999-05-01), Tao et al.
patent: 5939881 (1999-08-01), Slater et al.
patent: 5949677 (1999-09-01), Ho
patent: 5966684 (1999-10-01), Richardson et al.
patent: 5978084 (1999-11-01), Blake
patent: 6006153 (1999-12-01), Stander et al.
patent: 6055016 (2000-04-01), Darden et al.
patent: 6120663 (2000-09-01), Kato et al.
patent: 6278914 (2001-08-01), Gaudreau et al.
patent: 6317676 (2001-11-01), Gengler et al.
patent: 6540148 (2003-04-01), Salsbury et al.
Hui, K; Chan, C; “Stabilization of Systems with Deadzone Nonlinearity”; IEEE Int'l Conference on Control Applications;Vol 2; Sep. 1-4, 1998; pp 1036-1040.*
Cranshaw, S; Vinnicombe, G; “Local Stability Properties of Systems with Saturation and Deadzone Nonlinearities”; IEEE Conference on Decision and Control; Vol 1; Dec. 16-18, 1998; pp 897-902.*
Corrandini, M; Leo, T; Orlando, G; “Robust Stabilization of Systems with Actuator Nonlinearities”;IEEE Int'l Symposium on Industrial Electronics; Vol 1; Jul. 12-16, 1999; pp 327-330.*
Bu, F; Yao, B; “Nonlinear Adaptive Robust Control of Hydraulic Actuators Regulated by Proportional Directional Control Valves with Deadband and Nonlinear Flow Gains”; Proce dings of American Control Conference 2000; Vol 6; Jun. 2000; pp 4129-4133.*
Recker, D; Kokotovic, P; Rhode, D; Winkelman, J; “Adaptive Nonlinear Control of Systems Containing a Deadzone”; 30thIEEE Conference on Decision and Control; Dec. 1991; pp 2111-2115.*
Tao, G; Kokotovic, P; “Continuous-Time Adaptive Control of Systems with Unknown Backlash”;IEEE Transactions on Automatic Control; Vol 40, Issue 6; Jun. 1995; pp 1083-1087.*
Tao, G; Kokotovic, P; “Adaptive Control of System with Unknown Output Backlash”; IEEE Transactions on Automatic Control; vol 40, Issue 2; Feb. 1995; pp 326-330.*
Ezai, K; Tao, G; Kokotovic, P; “Optimal Control of Tracking Systems with Backlash and Flexibility”; 36thIEEE Conferenc on Decision and Control; Vol 2; Dec. 1997; pp 1749-1754.
Kendrick Larry E.
Kherat Samir Med
Were Muhammed
Barlow John
Caterpillar Inc
Green Clifton
Washburn Douglas N
LandOfFree
Method and apparatus for filtering a signal using a deadband does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for filtering a signal using a deadband, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for filtering a signal using a deadband will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3286022