Abstract:
A throttle control module comprises a primary throttle position module, a redundant throttle position module, and a remedial action module. The primary throttle position module transforms a primary throttle area signal indicating desired throttle area into a primary throttle position signal indicating a first desired throttle position of a throttle valve. The throttle valve is actuated based upon the primary throttle position signal. The redundant throttle position module transforms a redundant throttle area signal indicating desired throttle area into a redundant throttle position signal indicating a second desired throttle position of the throttle valve. The remedial action module selectively generates a remedial action signal based upon a comparison of the first and second desired throttle positions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/976,604, filed on Oct. 1, 2007. The disclosure of the above application is incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present disclosure relates to vehicle control systems and more particularly to electronic throttle control. 
       BACKGROUND 
       [0003]    Referring now to  FIG. 1 , a functional block diagram of a vehicle  100  is presented. The vehicle  100  includes an engine  102 , which generates torque to propel the vehicle  100 . Air is drawn into the engine  102  through an intake manifold  104 . A throttle valve  106  controls airflow into the engine  102 . The throttle valve  106  may include a throttle plate  108 , which may block all of or a portion of an opening in the throttle valve  106 . An electronic throttle control (ETC) motor  109  controls the throttle valve  106  and/or the throttle plate  108 . 
         [0004]    The air flowing through the throttle valve  106  is mixed with fuel from one or more fuel injectors  110  to form an air-fuel mixture. The air-fuel mixture is combusted within one or more cylinders  112  of the engine  102 . Combustion of the air-fuel mixture may be initiated by, for example, a spark delivered by a spark plug  114 . Although the spark plug  114  is depicted, the engine  102  may include a compression-combustion type engine that does not include the spark plug  114 . The combustion of the air-fuel mixture generates torque. Resulting exhaust gas is expelled from the cylinders  112  to an exhaust system  116 . 
         [0005]    An engine control module (ECM)  130  modulates torque output from the engine  102 . The ECM  130  may modulate torque by controlling the airflow through the throttle valve  106 , the fuel injected by the fuel injectors  110 , and/or the timing of the spark delivered by the spark plug  114 . The ECM  130  may modulate torque based upon, for example, a pedal position signal from a pedal position sensor  134  and/or signals from other sensors  136 . The pedal position sensor  134  generates the pedal position signal based upon actuation of an accelerator pedal  138  by a driver. The other sensors  136  may include, for example, a mass air flow (MAF) sensor, a manifold absolute pressure (MAP) sensor, an engine speed sensor, a transmission sensor, a cruise control system, and/or a traction control system. 
       SUMMARY 
       [0006]    A throttle control module comprises a primary throttle position module, a redundant throttle position module, and a remedial action module. The primary throttle position module transforms a primary throttle area signal indicating desired throttle area into a primary throttle position signal indicating a first desired throttle position of a throttle valve. The throttle valve is actuated based upon the primary throttle position signal. The redundant throttle position module transforms a redundant throttle area signal indicating desired throttle area into a redundant throttle position signal indicating a second desired throttle position of the throttle valve. The remedial action module selectively generates a remedial action signal based upon a comparison of the first and second desired throttle positions. 
         [0007]    A throttle control system comprises the throttle control module and a throttle actuation module. The throttle actuation module controls an electronic throttle control (ETC) motor that actuates the throttle valve. The throttle actuation module instructs the ETC motor to actuate the throttle valve to a predetermined throttle position after receiving the remedial action signal. In further features, the predetermined throttle position is a high-idle position. 
         [0008]    In other features, the throttle actuation module instructs the ETC motor to actuate the throttle valve to a lesser throttle position after receiving the remedial action signal. The lesser throttle position is one of the first and second desired throttle positions that corresponds to a lesser opening of the throttle valve. 
         [0009]    In further features, the throttle actuation module compares the first desired throttle position with an actual throttle position from a throttle position sensor and instructs the ETC motor to actuate the throttle valve to reach the first desired throttle position based upon the comparison. 
         [0010]    In still further features, the throttle control module further comprises nonvolatile memory that includes data for converting throttle area to throttle position. The primary and redundant throttle position modules determine the first and second desired throttle positions, respectively, based upon the data. The data comprises a first lookup table and a second lookup table. The first lookup table has a mapping from throttle area to segment value. The second lookup table has a mapping from segment value to throttle position. 
         [0011]    In still further features, the remedial action module suspends generating the remedial action signal when a service input signal is received. The remedial action module generates the remedial action signal when the first and second desired throttle positions differ by more than a predetermined percentage. The predetermined percentage corresponds to a maximum allowable calculation imprecision. 
         [0012]    A method comprises transforming a primary throttle area signal indicating desired throttle area into a primary throttle position signal indicating a first desired throttle position of a throttle valve, actuating the throttle valve based upon the primary throttle position signal, transforming a redundant throttle area signal indicating desired throttle area into a redundant throttle position signal indicating a second desired throttle position of the throttle valve, and selectively generating a remedial action signal based upon a comparison of the first and second desired throttle positions. 
         [0013]    In further features, the method further comprises actuating the throttle valve to a predetermined throttle position after receiving the remedial action signal. The predetermined throttle position is a high-idle position. The method further comprises actuating the throttle valve to a lesser throttle position after receiving the remedial action signal. The lesser throttle position is one of the first and second desired throttle positions that corresponds to a lesser opening of the throttle valve. 
         [0014]    In other features, the method further comprises comparing the first desired throttle position with an actual throttle position from a throttle position sensor and actuating the throttle valve to reach the first desired throttle position based upon the comparison. The method further comprises determining the first and second throttle positions based upon data for converting throttle area to throttle position. 
         [0015]    In still other features, the method further comprises determining the first and second throttle positions based upon a first lookup table and a second lookup table. The first lookup table has a mapping from throttle area to segment value. The second lookup table has a mapping from segment value to throttle position. 
         [0016]    The method further comprises suspending generating the remedial action signal when a service input signal is received. The method further comprises generating the remedial action signal when the first and second desired throttle positions differ by more than a predetermined percentage. 
         [0017]    Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0019]      FIG. 1  is a functional block diagram of a vehicle according to the prior art; 
           [0020]      FIG. 2  is a functional block diagram of an exemplary vehicle according to the principles of the present disclosure; 
           [0021]      FIG. 3A  is a functional block diagram of an exemplary throttle control module according to the principles of the present disclosure; 
           [0022]      FIG. 3B  is an exemplary tabular illustration of lookup tables used to convert a desired throttle area percentage into a desired throttle position according to the principles of the present disclosure; and 
           [0023]      FIG. 4  is a flowchart depicting exemplary steps performed by a throttle control module according to the principles of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure. 
         [0025]    As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
         [0026]    Referring now to  FIG. 2 , a functional block diagram of an exemplary vehicle  200  is presented. The vehicle  200  includes the engine  102 , which generates torque to propel the vehicle  200 . An engine control module (ECM)  230  modulates torque output from the engine  102 . The ECM  230  may modulate torque by controlling the airflow through the throttle valve  106 , the fuel injected by the fuel injectors  110 , and/or the timing of the spark delivered by the spark plug  114 . 
         [0027]    The ECM  230  includes a torque request module  232 , a fuel actuation module  246 , a spark actuation module  248 , a primary throttle area module  250 , and a redundant throttle area module  252 . The torque request module  232  generates a torque request based upon, for example, the pedal position signal from the pedal position sensor  134  and/or signals from the other sensors  136 . The torque request module  232  may also generate the torque request based upon data stored in memory, such as nonvolatile memory  240  and volatile memory  242 . For example only, the nonvolatile memory  240  may be read-only memory (ROM), flash memory, electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM) or any other suitable type of nonvolatile memory. 
         [0028]    Based on the torque request, the torque request module  232  transmits control signals to the fuel actuation module  246 , the spark actuation module  248 , and the primary throttle area module  250 . The control signal for the primary throttle area module  250  is also provided to the redundant throttle area module  252 . The fuel actuation module  246  controls the volume of fuel injected by the fuel injectors  110 . The spark actuation module  248  controls the timing of spark delivery of the spark plug  114 . 
         [0029]    The primary throttle area module  250  generates a primary throttle area signal based upon the control signal from the torque request module  232 . The primary throttle area signal may also be based upon data stored in memory, such as the nonvolatile memory  240  and the volatile memory  242 . The primary throttle area signal indicates the desired throttle area of the throttle valve  106 . The desired throttle area may be, for example, a desired percentage of the throttle valve opening that is unblocked by the throttle plate  108  or a desired physical area of the throttle valve opening. 
         [0030]    Independent of the primary throttle area signal, the redundant throttle area module  252  generates a redundant throttle area signal, which also indicates the desired throttle area of the throttle valve  106 . The redundant throttle area module  252  generates the redundant throttle area signal based upon the control signal from the torque request module  232 . The redundant throttle area module  252  may also generate the redundant throttle area signal based upon data stored in the nonvolatile memory  240  and the volatile memory  242 . 
         [0031]    The throttle area of the throttle valve  106  may be controlled by the position of the throttle plate  108 , which is referred to as throttle position. In various implementations, the throttle position represents an angular position of the throttle plate  108  on a rotational axis perpendicular to the direction of airflow through the throttle valve  106 . For example only, a throttle area opening percentage of 50% may correspond to a throttle position of 30°. 
         [0032]    A throttle control module  254  receives the primary throttle area signal and the redundant throttle area signal. Although the throttle control module  254  and other modules are depicted within the ECM  230 , one or more may be implemented separately from the ECM  230 . The throttle control module  254  transmits a throttle position signal to a throttle actuation module  256 . The throttle actuation module  256  drives the ETC motor  109  to actuate the throttle plate  108  to the position indicated by the throttle position signal. 
         [0033]    The throttle control module  254  generates a primary throttle position signal based upon the primary throttle area signal and a redundant throttle position signal based upon the redundant throttle area signal. The primary and redundant throttle position signals indicate desired throttle position. If the primary and redundant throttle position signals differ, the throttle control module  254  may take remedial action. 
         [0034]    To take remedial action, the throttle control module  254  may transmit a remedial action signal to the throttle actuation module  256 . When the throttle actuation module  256  receives the remedial action signal, the throttle actuation module  256  may, for example, instruct the ETC motor  109  to actuate the throttle plate  108  to a predetermined throttle position. The predetermined throttle position may be a high-idle position. Alternatively, the throttle actuation module  256  may instruct the ETC motor  109  to actuate the throttle plate  108  to the throttle position corresponding to the lesser of the primary and redundant throttle position signals. In this manner, the throttle control module  254  prevents an unexpected increase in torque in the event that one of the primary or redundant throttle position signals is corrupt. 
         [0035]    The throttle actuation module  256  may include an actuation diagnostic, which compares the desired throttle position with an actual throttle position. The actual throttle position may be measured by one or more throttle position sensors  260 . If the desired throttle position differs from the actual throttle position, the throttle actuation module  256  may attempt to control the ETC motor  109  to reach the desired throttle position. The throttle actuation module  256  may also signal an error and/or instruct the ETC motor  109  to actuate the throttle plate  108  to the high-idle throttle position. 
         [0036]    A service input signal may be transmitted to the primary throttle area module  250  and the throttle control module  254  by, for example, a service technician or a calibrator. The service input signal may instruct the primary throttle area module  250  to generate the primary throttle area signal based upon the service input signal. The primary throttle area signal will likely then differ from the redundant throttle area signal, which may cause the throttle control module  254  to incorrectly take remedial action. Accordingly, the throttle control module  254  may refrain from taking remedial action when the service input signal is received. 
         [0037]    Referring now to  FIG. 3A , a functional block diagram of an exemplary implementation of the throttle control module  254  is presented. The throttle control module  254  includes a primary throttle position module  302  and a redundant throttle position module  304 , which receive the primary throttle area signal and the redundant throttle area signal, respectively. 
         [0038]    The primary throttle position module  302  generates a primary throttle position signal based upon the primary throttle area signal. The redundant throttle position module  304  generates a redundant throttle position signal based upon the redundant throttle area signal. The primary throttle position signal and the redundant throttle position signal each indicate a desired throttle position. 
         [0039]    The desired throttle positions may be determined using throttle area to throttle position data stored in nonvolatile memory  306 . The nonvolatile memory  306  may be implemented in the nonvolatile memory  240  of  FIG. 2 . and may include, for example, a diagnostic or an error correcting code (ECC) to ensure data integrity. For example only, the nonvolatile memory  306  may be may be read-only memory (ROM), flash memory, electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM) or any other suitable type of nonvolatile memory. 
         [0040]    The nonvolatile memory  306  may include one or more lookup tables from which a desired throttle position (e.g., in degrees of throttle plate rotation) may be determined from a desired throttle area (e.g., in percentage of unrestricted throttle valve area). Referring to  FIG. 3B , an exemplary tabular illustration of lookup tables used to convert a desired throttle area percentage into a desired throttle position is presented. Numerical values and calculations in  FIG. 3B  are provided for exemplary purposes only, and the lookup tables may include any suitable values. 
         [0041]    In various implementations, the range of possible throttle areas (e.g., 0-100%) may be divided into a predetermined number of segments, such as 33 segments. These segments may be equally or unequally sized. When the range of possible throttle areas is divided into 33 equally sized segments, each segment includes approximately 3.3% of the range of throttle areas (i.e., 100%/33 segments). 
         [0042]    A first lookup table  308  may define each segment in terms of the maximum throttle area within the segment. A segment value for a desired throttle area may be determined based upon the first lookup table  308 . The segment value may include an integer part (IP) and a fractional part (FP), and may be represented as IP.FP. The first lookup table  308  may be used to determine in which segment the desired throttle area is located, IP, and where within segment IP the desired throttle area is located, FP. In various implementations, FP may not be determined. 
         [0043]    The desired throttle area may fall between a first and a second maximum throttle area MTA 1  and MTA 2 , respectfully. MTA 1  and MTA 2  correspond to upper and lower segments IP and IP-1, respectively. For example only, the FP may be calculated through interpolation, such as linear interpolation, using the equation: 
         [0000]    
       
         
           
             FP 
             = 
             
               ( 
               
                 
                   
                     Desired 
                      
                     
                         
                     
                      
                     Throttle 
                      
                     
                         
                     
                      
                     Area 
                   
                   - 
                   
                     MTA 
                     2 
                   
                 
                 
                   
                     MTA 
                     1 
                   
                   - 
                   
                     MTA 
                     2 
                   
                 
               
               ) 
             
           
         
       
     
         [0000]    where MTA 1  is the maximum throttle area corresponding to IP, and MTA 2  is the maximum throttle area corresponding to IP-1. 
         [0044]    For purposes of illustration and example only, in  FIG. 3B , a desired throttle area percentage of 8% falls between maximum throttle area percentages of 10% and 4%, which are MTA 1  and MTA 2 , respectively. MTA 1  and MTA 2  correspond to segment  2  (i.e. IP) and segment  1  (i.e., IP-1), respectively. Using the equation above and the exemplary values provided, FP can be determined and is 0.66 in  FIG. 3B . 
         [0045]    A second lookup table  310  is used to determine the desired throttle position that corresponds to the segment value IP.FP. The second lookup table  310  includes a mapping of segment to throttle position. IP and an upper segment IP+1 correspond to lower and upper throttle positions TP 1  and TP 2 , respectively. For example only, the desired throttle position that corresponds to the desired throttle area may be calculated through interpolation, such as linear interpolation, using FP and the equation: 
         [0000]      Desired Throttle Position= TP   1   +FP *( TP   2   −TP   1 ) 
         [0000]    where TP 1  is the throttle position corresponding to IP, TP 2  is the throttle position corresponding to IP+1, and FP is the fractional part of the segment value. 
         [0046]    For purposes of illustration and example only, in  FIG. 3B , the segment value 2.66 (from above) corresponds to IP (segment  2 ). IP and IP+1 (segment  3 ) correspond to throttle positions of 7° and 13°, respectively. Using the above equation and the exemplary values provided, the desired throttle position can be determined and is 11° in  FIG. 3B . Accordingly, using the exemplary values provided, a desired throttle area percentage of 8% may correspond to a desired throttle position of 11°. 
         [0047]    Referring back to  FIG. 3A , the desired throttle positions may be expressed as voltages within a voltage range. A lower limit of the voltage range may be learned upon starting the engine  102 . For example only, the lower limit may be learned based upon a minimum throttle position measured by the throttle position sensor  260 . An upper limit of the voltage range may be calibratable. For example only, the upper limit may be set to correspond to the greatest allowable throttle position. 
         [0048]    The primary throttle position module  302  transmits the primary throttle position signal to the throttle actuation module  256  and may transmit the primary throttle position signal to the throttle actuation diagnostic. A remedial action module  312  determines whether to take remedial action based upon a comparison of the primary and redundant throttle position signals and generates the remedial action signal accordingly. 
         [0049]    The remedial action module  312  may take remedial action when, for example, the desired throttle positions differ by more than a predetermined percentage. The predetermined percentage may allow for rounding errors, and may be, for example, 0.06%. Alternatively, taking remedial action may be limited to times when the desired throttle position of the primary throttle position signal is larger than that of the redundant throttle position signal by more than the predetermined percentage. 
         [0050]    The remedial action module  312  may also receive the service input signal. The remedial action module  312  may further limit taking remedial action to times when the service input signal is not received. This may prevent the incorrect taking of remedial action when the primary throttle area signal is being generated based upon the service input signal. 
         [0051]    The throttle actuation module  256  may, for example, instruct the ETC motor  109  to actuate the throttle plate  108  to the predetermined throttle position when the remedial action signal is received. In this manner, the throttle control module  254  prevents an unexpected increase in torque in the event that one of the primary or redundant throttle position signals is corrupt. The remedial action signal may also be transmitted to other components of the ECM  230  for diagnostic purposes. For example only, the ECM  230  may illuminate a “check engine” light and/or set an error code after receiving the remedial action signal. 
         [0052]    Referring now to  FIG. 4 , a flowchart depicting exemplary steps performed by the throttle control module  254  is presented. Control begins in step  404 , where control receives the primary throttle area signal and the redundant throttle area signal. The primary throttle area signal and the redundant throttle area signal each indicate the desired throttle area. 
         [0053]    Control continues in step  408 , where control determines the primary throttle position and generates the primary throttle position signal accordingly. Control continues in step  412 , where control determines the redundant throttle position and generates the redundant throttle position signal accordingly. Control may, for example, convert the desired throttle areas of the primary and redundant throttle area signals to the desired throttle positions using the lookup tables of the nonvolatile memory  306 . 
         [0054]    Control continues in step  416 , where control instructs the ETC motor  109  to actuate the throttle plate  108  to the throttle position indicated by the primary throttle position signal. In step  420 , control determines whether the throttle positions indicated by the primary and redundant throttle position signals differ by more than the predetermined percentage. If so, control transfers to step  424 ; otherwise, control returns to step  404 . In step  424 , control takes remedial action. For example only, control may take remedial action by instructing the ETC motor  109  to actuate the throttle plate  108  to a predetermined throttle position, such as the high-idle position. Control then returns to step  404 . 
         [0055]    Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.