Method and apparatus for monitoring unintended vehicle motion
View Patent ↗A powertrain system is configured to transfer propulsion torque to a driveline of a vehicle. A method for controlling the powertrain system includes determining a magnitude of unintended vehicle motion based upon a difference between a change in actual vehicle acceleration and a change in an operator-intended vehicle acceleration. Propulsion torque to the driveline is limited when a fault associated with unintended vehicle motion is detected and the magnitude of unintended vehicle motion is less than a predetermined first threshold.
1. A method for controlling a powertrain system configured to transfer propulsion torque to a driveline of a vehicle, comprising:
determining a magnitude of unintended vehicle motion based upon a difference between a change in actual vehicle acceleration and a change in operator-intended vehicle acceleration; and
limiting propulsion torque to the driveline when a fault associated with unintended vehicle motion is detected and the magnitude of unintended vehicle motion is less than a predetermined first threshold.
2. The method of claim 1 , wherein the change in the actual vehicle acceleration is determined in relation to monitored vehicle motion.
3. The method of claim 1 , wherein the change in the operator-intended vehicle acceleration is determined based upon an operator torque request.
4. The method of claim 1 , wherein determining the magnitude of unintended vehicle motion comprises determining the magnitude of unintended vehicle motion in accordance with the following relationship:
δ
a
actual
-
δ
a
intended
=
[
a
^
actual
(
t
2
)
-
a
^
actual
(
t
1
)
]
-
1
m
·
r
tire
[
T
axle
_
int
(
t
2
)
-
T
axle
_
int
(
t
1
)
]
wherein
δa actual is the change in the actual vehicle acceleration,
δa intended is the change in the intended vehicle acceleration,
â actual (t 1 ) is an estimated actual acceleration at time t 1 ,
â actual (t 2 ) is estimated actual acceleration at time t 2 ,
T axle — int (t 1 ) is an operator-intended vehicle acceleration at time t 1 ,
T axle — int (t 2 ) is an operator-intended vehicle acceleration at time t 1 ,
m is vehicle mass,
r tire is a dynamic tire radius,
t 1 is a time at the beginning of a time period, and
t 2 is a time at the end of the time period.
5. The method of claim 4 , wherein the time period comprises a period of time wherein magnitudes of changes in vehicle operating conditions have a de minimis effect upon the change in the intended acceleration δa intended .
6. The method of claim 1 , further comprising removing propulsion torque from the driveline when the magnitude of unintended vehicle motion is greater than a predetermined second threshold that is greater than the predetermined first threshold.
7. The method of claim 1 , further comprising removing propulsion torque from the driveline when the fault associated with unintended vehicle motion comprises a fault originating from a torque control scheme.
8. The method of claim 1 , further comprising removing propulsion torque from the driveline when the fault associated with unintended vehicle motion comprises a fault originating from a torque monitoring scheme and the magnitude of unintended vehicle motion is greater than the predetermined first threshold.
9. A method for controlling a powertrain system configured to transfer propulsion torque to a driveline of a vehicle, comprising:
determining a magnitude of unintended vehicle motion for a time period based upon a difference between a change in actual vehicle acceleration and a change in operator-intended vehicle acceleration; and
operating the powertrain system to limit propulsion torque to the driveline when a fault associated with unintended vehicle motion is detected and the magnitude of unintended vehicle motion for the time period is less than a predetermined first threshold.
10. The method of claim 9 , wherein the change in the actual vehicle acceleration is determined based upon monitored vehicle motion for the time period.
11. The method of claim 9 , wherein the change in the operator-intended vehicle acceleration is determined based upon an operator torque request for the time period.
12. The method of claim 9 , wherein determining the magnitude of unintended vehicle motion comprises determining the magnitude of unintended vehicle motion in accordance with the following relationship:
δ
a
actual
-
δ
a
intended
=
[
a
^
actual
(
t
2
)
-
a
^
actual
(
t
1
)
]
-
1
m
·
r
tire
[
T
axle
_
int
(
t
2
)
-
T
axle
_
int
(
t
1
)
]
wherein
δa actual is the change in the actual vehicle acceleration,
δa intended is the change in the intended vehicle acceleration,
â actual (t 1 ) is an estimated actual acceleration at time t 1 ,
â actual (t 2 ) is estimated actual acceleration at time t 2 ,
T axle — int (t 1 ) is an operator-intended vehicle acceleration at time t 1 ,
T axle — int (t 2 ) is an operator-intended vehicle acceleration at time t 1 ,
m is vehicle mass,
r tire is a dynamic tire radius,
t 1 is a time at the beginning of the time period, and
t 2 is a time at the end of the time period.
13. The method of claim 12 , wherein the time period is less than 200 milliseconds.
14. The method of claim 9 , further comprising removing propulsion torque from the driveline when the magnitude of unintended vehicle motion is greater than a predetermined second threshold that is greater than the predetermined first threshold.
15. The method of claim 14 , further comprising removing propulsion torque from the driveline when the fault associated with unintended vehicle motion comprises a fault originating from a torque control scheme.
16. The method of claim 15 , further comprising removing propulsion torque from the driveline when the fault associated with unintended vehicle motion comprises a fault originating from a torque monitoring scheme and the magnitude of unintended vehicle motion is greater than the predetermined first threshold.
17. A method for controlling a powertrain system employing a plurality of torque-generative devices to transfer propulsion torque to a driveline of a vehicle, comprising:
determining a magnitude of unintended vehicle motion for a time period based upon a difference between a change in actual vehicle acceleration and a change in operator-intended vehicle acceleration; and
operating the powertrain system to limit transfer of propulsion torque to the driveline when a fault associated with unintended vehicle motion is detected and the magnitude of unintended vehicle motion for the time period is less than a predetermined first threshold.
18. The method of claim 17 , wherein determining the magnitude of unintended vehicle motion comprises determining the magnitude of unintended vehicle motion in accordance with the following relationship:
δ
a
actual
-
δ
a
intended
=
[
a
^
actual
(
t
2
)
-
a
^
actual
(
t
1
)
]
-
1
m
·
r
tire
[
T
axle
_
int
(
t
2
)
-
T
axle
_
int
(
t
1
)
]
wherein
δa actual is the change in the actual vehicle acceleration,
δa intended is the change in the intended vehicle acceleration,
â actual (t 1 ) is an estimated actual acceleration at time t 1 ,
â actual (t 2 ) is estimated actual acceleration at time t 2 ,
T axle — int (t 1 ) is an operator-intended vehicle acceleration at time t 1 ,
T axle — int (t 2 ) is an operator-intended vehicle acceleration at time t 1 ,
m is vehicle mass,
r tire is a dynamic tire radius,
t 1 is a time at the beginning of the time period, and
t 2 is a time at the end of the time period.
19. The method of claim 17 , wherein operating the powertrain system to limit transfer of propulsion torque to the driveline comprises derating torque outputs of the torque-generative devices.