Autonomous Vehicle Path Planning With Speed-Dependent Lateral Clearance
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Solution Overview
Problem
Autonomous vehicles face challenges in planning trajectories that allow for safe and smooth passage around objects without requiring complex joint space-time planning, particularly when objects are close to the path, as existing methods either stop or proceed without adjusting speed accordingly.
Innovation Solution
The method involves determining a speed-dependent minimum lateral clearance using a function that adjusts maximum speed based on actual clearance, allowing the vehicle to slow down or incrementally increase speed to maintain safe clearance, enabling continuous and safe reactions to dynamic and static objects without altering the path geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the vehicle maintains a predetermined minimum lateral clearance from objects, then safety is improved, but the vehicle cannot pass close objects efficiently and may require stopping
Solution Approach 1:
The patent applies dynamics by making the minimum lateral clearance speed-dependent rather than fixed. The system dynamically adjusts the required clearance based on the vehicle's speed: at lower speeds, smaller clearances are acceptable, while at higher speeds, larger clearances are maintained. This resolves the contradiction by allowing the vehicle to pass close objects efficiently at reduced speeds while maintaining safety through appropriate clearance adjustments.
Solution Approach 2:
The patent changes the parameter of lateral clearance from a fixed predetermined value to a variable value that depends on speed. By establishing a functional relationship between speed and minimum lateral clearance, the system can adapt the clearance requirement to match the vehicle's operational state, enabling both safe passage and efficient navigation through tight spaces.
2Reliability
If the vehicle stops to yield to objects when clearance is insufficient, then safety is improved, but travel time increases
Solution Approach 1:
The system dynamically determines whether stopping is necessary based on the relationship between speed, lateral clearance, and object characteristics. Rather than automatically stopping for all close objects, the system calculates whether a speed-adjusted clearance is sufficient, allowing continuous motion in many cases and reserving stopping only for situations where even reduced-speed passage would be unsafe.
Solution Approach 2:
The patent applies partial action by using stopping as a last resort rather than a default response. The system first attempts to pass with adjusted speed and speed-dependent clearance, applying the full stopping action only when partial measures (speed adjustment) are insufficient to ensure safety.
3Productivity
If the vehicle increases speed when clearance is sufficient, then productivity is improved, but safety margin decreases
Solution Approach 1:
The patent establishes a functional relationship where speed and lateral clearance are coupled parameters. When clearance is sufficient, the system can increase speed while the required clearance adjusts accordingly. This maintains safety margins because the clearance requirement scales with speed, ensuring that even at higher speeds, appropriate safety distances are preserved.
Solution Approach 2:
The system dynamically balances speed and clearance requirements based on real-time conditions. Rather than maintaining a fixed conservative clearance that limits speed, the system allows speed to increase when clearance conditions permit, with the safety margin adaptively adjusted through the speed-dependent clearance function.
Data Source
AI summary
The technology relates to controlling a vehicle in an autonomous driving mode. In one instance, sensor data identifying an object in an environment of the vehicle may be received. A first path of a first trajectory where the vehicle will pass the object may be determined. A function is used to determining a first maximum speed of the vehicle based on a predetermined minimum lateral clearance between the object and the vehicle. The first maximum speed may be used to determine whether an actual lateral clearance between the object and the vehicle will meet the predetermined minimum lateral clearance. The determination of whether the actual lateral clearance will meet the predetermined minimum lateral clearance may be used to generate a first speed plan for the first trajectory. The vehicle may be controlled in the autonomous driving mode according to the first trajectory including the first speed plan and the first path.