Algorithm for steering angle command to torque command conversion
First Claim
1. A method for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle, said method comprising:
- estimating a self-aligning torque that defines the torque that maintains a vehicle steering wheel at an initial steering angle;
applying known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque;
measuring, using a steering angle sensor, a vehicle steering angle at each time step; and
modeling the steering system of the vehicle using the torque commands, the measured steering angles, a system delay and a plurality of steering system parameters for a plurality of different vehicle speeds, wherein modeling the steering system includes performing an off-line process to determine an off-line steering model and an on-line process to correct the off-line steering model in real time during vehicle operation.
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Abstract
A system and method for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle. The method estimates a self-aligning torque that defines the torque that maintains a vehicle steering wheel at a neutral steering position or to a position that makes no slip angle at the road wheel, applies known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque, and measures a vehicle steering angle at each time step. The method then models the steering system of the vehicle using the torque commands, the measured steering angles, a system delay and a plurality of unknown parameters.
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Citations
20 Claims
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1. A method for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle, said method comprising:
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estimating a self-aligning torque that defines the torque that maintains a vehicle steering wheel at an initial steering angle; applying known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque; measuring, using a steering angle sensor, a vehicle steering angle at each time step; and modeling the steering system of the vehicle using the torque commands, the measured steering angles, a system delay and a plurality of steering system parameters for a plurality of different vehicle speeds, wherein modeling the steering system includes performing an off-line process to determine an off-line steering model and an on-line process to correct the off-line steering model in real time during vehicle operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle, said method comprising:
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estimating a self-aligning torque that defines the torque that maintains a vehicle steering wheel at an initial steering angle using dynamic equations or an empirical data set that models the self-aligning torque as a multi-dimensional look-up table based on vehicle speed, steering angle and other vehicle parameters; applying known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque; measuring, using a steering angle sensor, a vehicle steering angle at each time step; modeling the steering system of the vehicle off-line at a plurality of vehicle speeds using the torque commands, the measured steering angles, a system delay and a plurality of steering system parameters, wherein modeling the steering system includes using the equation; - View Dependent Claims (13, 14, 15, 16, 17)
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18. A conversion system for converting a vehicle steering angle command to a vehicle steering torque command for a vehicle steering system in a vehicle, said conversion system comprising:
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means for estimating a self-aligning torque that defines the torque that maintains a vehicle steering wheel at an initial steering angle; means for applying known total steering torque commands to the steering system at a plurality of sample time steps where the known steering torque commands include the self-aligning torque; means for measuring a vehicle steering angle at each time step; and means for modeling the steering system of the vehicle using the torque commands, the measured steering angles, a system delay and a plurality of steering system parameters for a plurality of different vehicle speeds, wherein the means for modeling the steering system performs an off-line process to determine an off-line steering model and an on-line process to correct the off-line steering model in real time during vehicle operation. - View Dependent Claims (19, 20)
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Specification