Autonomous Vehicle Trajectory Optimization Fallback Mechanism

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Solution Overview

Problem

Autonomous driving vehicles face challenges in path and speed optimization due to numerical issues, such as quadratic programming problems not converging within a finite number of iterations, necessitating a robust fallback mechanism to ensure reliable operation.

Innovation Solution

A computer-implemented method for generating a driving trajectory for autonomous driving vehicles, which includes calculating an initial trajectory based on a map and route information, performing spline curve-based path optimization, determining if the result satisfies a predetermined condition, and if not, performing finite element-based path optimization, followed by speed optimization to generate a controlled trajectory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If spline curve based path optimization is performed, then path smoothness and continuity are improved, but numerical convergence reliability deteriorates due to QP problem failures

Engineering Contradiction:
Improvepath optimization precisionVSAvoidoptimization solver reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements a fallback mechanism that prepares an alternative finite element based optimization method in advance. When the spline curve based QP optimization fails to converge, the system automatically switches to the finite element method, which uses a different mathematical formulation that is more numerically stable. This beforehand preparation of an alternative solution cushiones against the reliability issues of the primary optimization method.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the mathematical parameters and formulation of the optimization problem by offering two different approaches: spline curve based QP optimization and finite element based optimization. When numerical issues arise in one parameterization, the system switches to different parameters in the alternative formulation, maintaining optimization precision while avoiding convergence failures.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a fallback mechanism is implemented, then optimization solver reliability is improved, but system complexity increases

Engineering Contradiction:
Improveoptimization solver reliabilityVSAvoidoptimization system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic optimization system that can switch between different optimization methods based on real-time convergence status. The system starts with the spline curve based method and dynamically transitions to the finite element method only when needed. This dynamic approach improves reliability while minimizing the actual complexity introduced, as the alternative method remains dormant until required.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent introduces a convergence check mechanism as an intermediary that monitors the optimization process and decides when to switch methods. This intermediary layer manages the complexity by providing a clear decision boundary: if convergence is achieved, use the primary method; if not, switch to the fallback method. This structured approach to complexity management makes the system more tractable.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If multiple optimization methods are prepared, then robustness against numerical failures is improved, but computational time increases

Engineering Contradiction:
ImproverobustnessVSAvoidcomputational time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary action by establishing the finite element based optimization method and convergence checking mechanisms in advance. However, the actual computational work is only performed by the primary spline curve based method unless convergence fails. This preliminary preparation ensures robustness while minimizing computational time, as the fallback method is ready but not executed unless absolutely necessary.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a skipping strategy where the system rushes through the primary optimization method first, checking for convergence at each iteration. Only when convergence failure is detected does the system skip to the alternative finite element method. This approach minimizes computational time by avoiding unnecessary execution of the fallback method while maintaining robustness through the ability to switch.

Inventive Principle:
Principle #21Skipping (Rushing through)

Data Source

PatentEP3517893B1Path and speed optimization fallback mechanism for autonomous vehicles
Publication Date: 2020.11.18 BAIDU USA LLC
  • EP3517893B1 patent drawingFigure 1
  • EP3517893B1 patent drawingFigure 2
  • EP3517893B1 patent drawingFigure 3A

AI summary

According to some embodiments, a system calculates (901) a first trajectory based on a map and a route information. The system performs (902) a path optimization based on the first trajectory, traffic rules, and an obstacle information describing obstacles perceived by the ADV. The path optimization is performed by performing (903) a spline curve based path optimization on the first trajectory, determining (904) whether a result of the spline curve based path optimization satisfies a first predetermined condition, performing (905) a finite element based path optimization on the first trajectory in response to determining that the result of the spline curve based path optimization does not satisfy the first predetermined condition, performing (906) a speed optimization based on a result of the path optimization, and generating (907) a second trajectory based on the path optimization and the speed optimization to control the ADV.