Method for adjusting a control signal of an electronic sensor
A method of adjusting a control signal generated by a sensor ( 16 ) is provided. The control signal varies as a pedal lever ( 14 ) rotates between an idle position and a wide-open throttle (WOT) position. The method comprises comparing target values (P IdleT ,P WotT ) for the control signal at the idle position and the WOT position with initial values (P IdleNT , P WotNT ) at the idle position and the WOT position to determine if the control signal needs to be adjusted. To adjust the control signal, first ( 26 ) and second ( 28 ) trim resistors are laser trimmed. An intermediate target value (P IdleInt ) is determined prior to laser trimming and the first trim resistor ( 26 ) is laser trimmed until the value of the control signal at the idle position is substantially equal to the intermediate target value (P IdleInt ). As a result, when the second trim resistor ( 28 ) is laser trimmed, the value of the control signal at the idle position drifts to the corresponding target value (P IdleT ), thus eliminating the need to re-trim the first trim resistor ( 26 ).
1 . A method for adjusting a control signal generated by an electronic sensor ( 16 ) using first ( 26 ) and second ( 28 ) trim resistors electrically connected to the sensor ( 16 ) wherein the sensor ( 16 ) is fitted to a pedal assembly ( 10 ) having a pedal lever ( 14 ) and the control signal generated by the sensor ( 16 ) varies in value as the pedal lever ( 14 ) rotates between an idle position and a wide-open throttle position, said method comprising the steps of:
selecting a target value (P IdleT ) for the control signal to be generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the idle position,
selecting a target value (P WotT ) for the control signal to be generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the wide-open throttle position,
measuring an initial value (P IdleNT ) of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the idle position,
measuring an initial value (P WotNT ) of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the wide-open throttle position,
comparing the initial values (P IdleNT , P WotNT ) of the control signal and the corresponding target values (P IdleT , P WotT ), and
trimming both the first ( 26 ) and second ( 28 ) trim resistors until values of the control signal at the idle position and the wide-open throttle position are substantially equal to the corresponding target values (P IdleT , P WotT ),
said method characterized by determining an intermediate target value (P IdleInt ) for the control signal based on the initial (P IdleNT , P WotNT ) and target (P IdleT , P WotT ) values prior to trimming the first ( 26 ) and second ( 28 ) trim resistors and trimming one of the trim resistors ( 26 , 28 ) until the value of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the idle position is substantially equal to the intermediate target value (P IdleInt ).
2 . The method as set forth in claim 1 wherein trimming one of the trim resistors ( 26 , 28 ) is further defined as trinming the first trim resistor ( 26 ) until the value of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the idle position is substantially equal to the intermediate target value (P IdleInt ).
3 . The method as set forth in claim 2 wherein trimming both the first ( 26 ) and second ( 28 ) trim resistors further includes trinmming the second trim resistor ( 28 ) after trimming the first trim resistor ( 26 ) and until the value of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the wide-open throttle position is substantially equal to the corresponding target value (P WotT ) whereby trimming the second trim resistor ( 28 ) automatically shifts the value of the control signal generated by the sensor ( 16 ) when the pedal lever ( 14 ) is at the idle position to the corresponding target value thereby eliminating any need to re-trim the first trim resistor ( 26 ).
4 . The method as set forth in claim 2 wherein determining the intermediate target value (P IdleInt ) for the control signal is further defined as determining the intermediate target value (P IdleInt ) for the control signal based on the equation:
P
IdleInt
=
K
*
P
IdleT
1
+
K
*
P
IdleT
-
P
IdleNT
where
,
K
=
P
WotNT
-
P
IdleNT
P
WotT
-
P
IdleT
and
P IdleInt is the intermediate target value,
P IdleT is the target value for the control signal at the idle position,
P WotT is the target value for the control signal at the wide-open throttle position,
P IdleNT is the initial value of the control signal at the idle position, and
P WotNT is the initial value of the control signal at the wide-open throttle position.
5 . The method as set forth in claim 2 wherein determining the intermediate target value (P IdIelnt ) for the control signal is further defined as determining the intermediate target value (P IdleInt ) for the control signal based on the equation:
P
IdleInt
=
P
IdleNT
P
IdleNT
+
K
*
(
1
-
P
IdleT
)
where
,
K
=
P
IdleNT
-
P
WotNT
P
IdleT
-
P
WotT
and
P IdleInt is the intermediate target value,
P IdleT is the target value for the control signal at the idle position,
P WotNT is the target value for the control signal at the wide-open throttle position,
P IdleNT is the initial value of the control signal at the idle position, and
P WotNT is the initial value of the control signal at the wide-open throttle position.
6 . The method as set forth in claim 1 wherein the steps of selecting the target values (P IdleT , P WotT ) for the control signal at the idle position and the wide-open throttle position are further defined as selecting target ratios based on a reference voltage (V ref ) and an output voltage (V out ) when the pedal lever ( 14 ) is at the idle position and the wide-open throttle position.
7 . The method as set forth in claim 6 wherein the steps of measuring the initial values (P IdleNT , P WotNT ) of the control signal when the pedal lever ( 14 ) is at the idle position and the wide-open throttle position are further defmed as measuring the reference voltage (V ref ) and the output voltage (V out ) when the pedal lever ( 14 ) is at the idle position, cycling the pedal lever ( 14 ) from the idle position to the wide-open throttle position, and measuring the reference voltage (V ref ) and the output voltage (V out ) when the pedal lever ( 14 ) is at the wide-open throttle position.
8 . The method as set forth in claim 2 including cycling the pedal lever ( 14 ) to the wide-open throttle position after trimming the first trim resistor ( 26 ).