Vehicle rollover detection and mitigation using rollover index
First Claim
1. Method for determining likelihood of rollover of a vehicle comprising the steps:
- measuring vehicle lateral acceleration;
measuring one of vehicle roll rate and vehicle suspension displacements;
from the measured lateral acceleration and the measured one of the vehicle roll rate and the vehicle suspension displacements, deriving a first estimate of roll angle and a first estimate of roll rate;
storing a dynamic, closed loop observer equation comprising a model of the vehicle in a first roll mode for roll angles small compared to a reference value indicating two wheel lift-off and a second roll mode for roll angles at least near the reference value indicating two wheel lift-off, the observer equation having a plurality of terms with coefficients;
deriving a roll angle index from at least the measured lateral acceleration and the measured one of vehicle roll rate and vehicle suspension displacements;
storing values of the coefficients of selected ones of the plurality of terms of the observer equation as functions of the roll angle index, the stored coefficients for each of the selected ones of the plurality of terms having at least a first value corresponding to the first roll mode and a second value corresponding to the second roll mode;
deriving a second estimate of roll angle from the observer equation using one of the first values of the stored coefficients and the second values of the stored coefficients based on the derived roll angle index; and
determining the likelihood of vehicle roll-over at least in response to the second estimate of roll angle.
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Accused Products
Abstract
A method and apparatus for determining likelihood of rollover of a vehicle and/or mitigating rollover of the vehicle is responsive to measured vehicle lateral acceleration and a measured one of vehicle roll rate and vehicle suspension displacements to derive estimates of roll angle and roll rate. First, preliminary, estimates of roll angle and roll rate are derived and used as pseudo-measurements in a dynamic, closed loop observer equation which represents a model of the vehicle in a first roll mode for roll angles small compared to a reference value indicating two wheel lift-off and a second roll mode for roll angles at least near a reference value indicating two wheel lift-off. The observer equation has parameters and gains with values for each mode stored as a function of roll angle index derived from measurements and pseudo-measured values. The observer equation produces second, improved values or roll angle and roll rate together indicating the likelihood of vehicle rollover. Rollover mitigating controls for brakes, active front steer, and/or active rear steer are also disclosed.
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Citations
24 Claims
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1. Method for determining likelihood of rollover of a vehicle comprising the steps:
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measuring vehicle lateral acceleration;
measuring one of vehicle roll rate and vehicle suspension displacements;
from the measured lateral acceleration and the measured one of the vehicle roll rate and the vehicle suspension displacements, deriving a first estimate of roll angle and a first estimate of roll rate;
storing a dynamic, closed loop observer equation comprising a model of the vehicle in a first roll mode for roll angles small compared to a reference value indicating two wheel lift-off and a second roll mode for roll angles at least near the reference value indicating two wheel lift-off, the observer equation having a plurality of terms with coefficients;
deriving a roll angle index from at least the measured lateral acceleration and the measured one of vehicle roll rate and vehicle suspension displacements;
storing values of the coefficients of selected ones of the plurality of terms of the observer equation as functions of the roll angle index, the stored coefficients for each of the selected ones of the plurality of terms having at least a first value corresponding to the first roll mode and a second value corresponding to the second roll mode;
deriving a second estimate of roll angle from the observer equation using one of the first values of the stored coefficients and the second values of the stored coefficients based on the derived roll angle index; and
determining the likelihood of vehicle roll-over at least in response to the second estimate of roll angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Apparatus for determining likelihood of rollover of a vehicle comprising:
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means for measuring vehicle lateral acceleration;
means for measuring one of vehicle roll rate and vehicle suspension displacements;
means responsive to the measured lateral acceleration and the measured one of the vehicle roll rate and the vehicle suspension displacements for deriving a first estimate of roll angle and a first estimate of roll rate;
means for storing a dynamic, closed loop observer equation comprising a model of the vehicle in a first roll mode for roll angles small compared to a reference value indicating two wheel lift-off and a second roll mode for roll angles at least near the reference value indicating two wheel lift-off, the observer equation having a plurality of terms with coefficients;
means for deriving a roll angle index from at least the measured lateral acceleration and the measured one of vehicle roll rate and vehicle suspension displacements;
means for storing values of the coefficients of selected ones of the plurality of terms of the observer equation as functions of the roll angle index, the stored coefficients for each of the selected ones of the plurality of terms having at least a first value corresponding to the first roll mode and a second value corresponding to the second roll mode;
means for deriving, a second estimate of roll angle from the observer equation using one of the first values of the stored coefficients and the second values of the stored coefficients based on the derived roll angle index; and
means for determining the likelihood of vehicle roll-over at least in response to the second estimate of roll angle. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification