Emergency Steering Trajectory Control Using Polynomial Functions
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Solution Overview
Problem
Existing emergency steering systems for land vehicles face challenges in calculating stable avoidance trajectories during evasive maneuvers, leading to discomfort and difficulty in controlling the vehicle, especially at high speeds, due to the computational effort required and discontinuities in trajectory calculations using sigmoid functions.
Innovation Solution
A control device and method that calculates a preliminary avoidance trajectory using sensor signals to generate an environmental model, determining the object's position relative to the vehicle, and optimizing the trajectory parameters to ensure smooth lateral offsets and accelerations, allowing for easy control and reduced lateral speeds and accelerations, with the option to extend the trajectory iteratively to maintain a safe distance from obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sigmoid function is used to calculate the avoidance trajectory, then the trajectory can be determined, but discontinuities occur in the trajectory course that impair driver comfort and control
Solution Approach 1:
The patent changes the mathematical parameters from sigmoid functions to piecewise polynomial functions (quadratic, cubic, or quartic polynomials) that are continuously differentiable. This parameter change eliminates discontinuities in the trajectory and its derivatives, ensuring smooth transitions and continuous lateral acceleration while maintaining reliable avoidance trajectory calculation.
2Reliability
If complex trajectory calculations are performed to ensure stability, then the avoidance trajectory can be determined, but the computational effort increases
Solution Approach 1:
The patent segments the avoidance trajectory into multiple sections, each described by simple polynomial equations rather than complex sigmoid functions. This segmentation allows each section to be calculated independently with minimal computational effort while ensuring overall trajectory stability through continuous differentiability at the segment boundaries.
Solution Approach 2:
The patent uses simple polynomial equations that are computationally inexpensive and can be quickly recalculated if needed. These lightweight mathematical models replace heavy computational algorithms, enabling fast recalculation of avoidance trajectories without requiring significant processing power or time.
3Reliability
If the avoidance trajectory is extended iteratively, then the safe distance from obstacles is maintained, but the calculation complexity increases
Solution Approach 1:
The patent performs preliminary calculations to determine the end point of the avoidance trajectory before iterative extension is needed. By pre-calculating the trajectory parameters and using simple polynomial equations, the system reduces the complexity of subsequent iterative extensions, as each extension can be achieved by adjusting polynomial coefficients rather than recalculating the entire trajectory.
Data Source
AI summary
A control device for a land vehicle is described. The control device is set up to control at least one actuator of the land vehicle on the basis of an avoidance trajectory calculated by the control device in order to support a driver of the land vehicle during an evasive maneuver. The control device is also set up to receive sensor signals of at least one sensor; to generate an environmental model from the received sensor signals; to determine the position of an object relative to a current position of the land vehicle in the generated environmental model; and to calculate a preliminary avoidance trajectory. In the calculation of the preliminary avoidance trajectory, the current position of the land vehicle in the generated environmental model constitutes the starting point of the preliminary avoidance trajectory. A preliminary end point of the preliminary avoidance trajectory is determined on the basis of the determined position of the object. To determine the parameters of the preliminary avoidance trajectory, at least the coordinates of the starting point and of the preliminary end point are used.