A method for driving speed optimization of autonomous vehicles under lateral saturation constraints
A driving speed, automatic driving technology, applied in the registration/indication of vehicle operation, registration/indication, instruments, etc., can solve the problem of excessive experimental data, ignoring the lateral force of the rear wheel, and the friction force cannot be equivalent to the centripetal force, etc. problem, to achieve the effect of optimizing the driving speed and driving safely
Active Publication Date: 2020-12-04
JILIN UNIV
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Problems solved by technology
First. In the high-speed steering process, only the friction force of the front wheel is used as the centripetal force provided by the vehicle turning, ignoring the lateral force generated by the rear wheel, and the friction force cannot be equivalent to the centripetal force
Second. Through a large number of experiments, the optimal driving speed is repeatedly measured, and the road curvature and the optimal driving speed are made into a map. The disadvantage of this method is that the amount of experimental data is too large
Method used
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[0043] The present invention will be described in detail below in conjunction with the accompanying drawings and implementation.
[0044] Such as figure 1 As shown, the present invention proposes a driving speed optimization method under the lateral saturation constraint of an automatic driving vehicle, comprising the following steps:
[0045] Step 1: Establish a vehicle model, and solve the lateral force and corresponding slip angle under the condition of lateral saturation of the front tires.
[0046] According to the vehicle parameters (including the mass of the vehicle, the distance from the center of mass to the front wheels, and the distance from the center of mass to the rear wheels), through the load distribution formula, that is
[0047]
[0048] Solve for the front wheel vertical load force for the vehicle model.
[0049] Bring the tire parameters into the magic tire formula:
[0050] F(α)=D·sin{C·arctan[B·α-E(B·α-arctan(B·α))]} (2)
[0051] Calculate the maxi...
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The invention discloses a travelling speed optimization method for a self-driving car by considering lateral saturation constraint. The travelling speed optimization method aims to achieve the effectsthat in the turning work condition, the speed optimization interval is determined and used for optimizing the travelling speed, and quick, stable and safe curve travelling of the car is ensured. Thetravelling speed optimization method comprises the steps that firstly, a tire lateral force limit value is solved through a tire model; then tire lateral force is substituted into a car monorail model, and rear wheel lateral force is solved; the relationship among the front wheel rotating angle of the car, the speed and the road curvature when the tire force is exactly saturated is derived througha centripetal force formula; and the relationship among the car speed, the front wheel rotating angle and the road curvature in the turning process is derived by combining a car two-degree-of-freedommodel with a linear tire lateral force model, and the optimization intervals of the speed and the front wheel rotating angle under a path with certain curvature are solved on the basis. According toa current planned track, the minimum curvature radius of the track is obtained, and then the optimization speed under a road with the certain curvature radius is obtained.
Description
technical field [0001] The invention relates to the field of vehicles. In particular, it relates to a method for optimizing the driving speed of an autonomous vehicle under lateral saturation constraints. Background technique [0002] In unmanned vehicles, the control strategy of trajectory tracking is becoming more and more mature. However, how fast the vehicle is in reality, it is a long way to go to stably track the upper trajectory. When the vehicle follows the trajectory with a relatively small longitudinal velocity, although it will improve the accuracy of trajectory tracking, it will increase the turning time and reduce the utilization of the lane. If there is no basis to increase the longitudinal speed of the vehicle, understeer may occur. [0003] Currently, unmanned driving speed optimization methods include the following two. First. In the high-speed steering process, only the friction force of the front wheels is used as the centripetal force provided by the v...
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IPC IPC(8): B60W40/00B60W40/072B60W40/10B60W40/13G07C5/08
CPCB60W40/00B60W40/072B60W40/10B60W40/13G07C5/0808G07C5/0841
Inventor 王德军徐鹏史德伟王丽华
Owner JILIN UNIV