Autonomous Vehicle Trajectory Replanning for Emergency Obstacle Avoidance

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Solution Overview

Problem

Autonomous vehicles face challenges in emergency obstacle avoidance due to the limitations of existing trajectory replanning methods, which often result in instability and computational inefficiency, particularly when offline reference trajectories become infeasible or are influenced by changing environments.

Innovation Solution

A method for iterative trajectory replanning that updates reference trajectories in real-time, incorporating nonlinear vehicle dynamics, such as tire dynamics, to maintain stability and efficiency, using a combination of model predictive control (MPC) and spatial iterative replanning (SpIRe) to adapt to sudden obstacles and environmental changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If offline reference trajectories are used for trajectory planning, then computational efficiency is improved, but trajectory model fidelity deteriorates when environments change

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidtrajectory model fidelity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system dynamically switches between offline reference trajectories and online optimal sequences based on environmental conditions. When obstacles are detected, the system transitions from using pre-computed offline trajectories to generating real-time optimal sequences, ensuring both computational efficiency in normal conditions and trajectory fidelity in changing environments.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system continuously monitors environmental changes and vehicle state, using this feedback to determine when to abandon offline reference trajectories and switch to online optimal sequence generation. This feedback mechanism ensures trajectory model fidelity is maintained when environments change while preserving computational efficiency when conditions are stable.

Inventive Principle:
Principle #23Feedback

2Reliability

If completely new trajectories are computed in real-time, then trajectory model fidelity is improved, but computational efficiency deteriorates

Engineering Contradiction:
Improvetrajectory model fidelityVSAvoidcomputational efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Offline reference trajectories are pre-computed and stored before real-time operation. When environmental conditions permit, these pre-computed trajectories are used directly, avoiding the computational burden of real-time optimization. This preliminary action ensures trajectory model fidelity is available when needed while preserving computational efficiency during normal operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of computing completely new trajectories in all scenarios, the system computes optimal sequences only partially - specifically when environmental changes or obstacles require it. This partial action approach maintains trajectory fidelity in critical situations while avoiding the excessive computational cost of full real-time recomputation in all cases.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If offline reference trajectories are used, then computational efficiency is improved, but adaptability to changing environments deteriorates

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidadaptability to changing environments
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The system uses continuous feedback from environmental sensors to detect changes in the operating environment. When changes are detected, the feedback triggers a switch from offline reference trajectories to online optimal sequence generation, ensuring adaptability to changing environments while maintaining computational efficiency when conditions remain stable.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The trajectory planning system is dynamic, automatically adjusting its approach based on environmental conditions. It transitions from static offline reference trajectories to dynamic online optimal sequences when adaptability is required, providing both computational efficiency and environmental adaptability as needed.

Inventive Principle:
Principle #15Dynamics

4Adaptability or versatility

If online optimal sequences are computed in real-time, then adaptability to changing environments is improved, but computational efficiency deteriorates

Engineering Contradiction:
Improveadaptability to changing environmentsVSAvoidcomputational efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

Offline reference trajectories are pre-computed and stored as a foundation for real-time planning. This preliminary action provides a computationally efficient baseline that can be used directly when environments are stable, reducing the need for expensive real-time optimization and improving overall computational efficiency while maintaining adaptability when needed.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20240083457A1Iterative trajectory replanning for emergency obstacle avoidance
Publication Date: 2024.03.14 TOYOTA RESEARCH INSTITUTE INC
  • US20240083457A1 patent drawing
  • US20240083457A1 patent drawing
  • US20240083457A1 patent drawing

AI summary

Systems and methods of trajectory planning for an autonomous vehicle are disclosed. Exemplary implementations may: determine a first trajectory plan for the vehicle traveling along a first spatial location at a first point in time, the first trajectory plan being a reference trajectory plan; compute an optimal sequence for the vehicle traveling along a second spatial location at a second point in time subsequent the first point in time; and calculate a second trajectory plan for the vehicle by updating the first trajectory plan with information from the computed optimal sequence.