Autonomous Lane Change Trajectory Costing Across Speed-Limit Lanes
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Solution Overview
Problem
Autonomous driving vehicles face challenges in changing lanes when the source lane has a higher speed limit than the target lane, as they are incentivized to stay on the faster lane, leading to last-minute changes that may result in missed exits or turns due to the lack of efficient lane change algorithms.
Innovation Solution
A system that determines the source and target lane speed limits, generates trajectories for the autonomous vehicle to follow the target lane's speed limit, calculates costs for each trajectory using a cost function, and compares them to decide whether to change lanes, ensuring the vehicle follows the trajectory with the lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the autonomous vehicle stays on the source lane with higher speed limit, then the vehicle maintains higher speed and reduces travel time, but the vehicle cannot reach the destination or make required turns due to lane restrictions
Solution Approach 1:
The system performs preliminary action by calculating trajectories and comparing costs before the lane change is executed. It determines the target lane speed limit in advance, generates trajectories that account for the speed limit difference, and compares costs to make an informed decision about whether to change lanes, ensuring reliable route completion while minimizing speed reduction.
2Reliability
If the autonomous vehicle changes lanes to the target lane with lower speed limit, then the vehicle can reach the destination or make required turns, but the vehicle experiences speed reduction and increased travel time
Solution Approach 1:
The system applies parameter changes by modifying the trajectory speed parameter to match the target lane speed limit. When a lane change is determined to be necessary, the system generates a trajectory with speed corresponding to the lower target lane speed limit, allowing the vehicle to adapt its speed parameter to the new lane conditions while maintaining reliable route completion.
3Speed
If the autonomous vehicle delays lane change until the last minute, then the vehicle maintains higher speed on the preferred lane, but the vehicle risks missing exits or turns due to insufficient time for safe lane change
Solution Approach 1:
The system uses feedback by continuously monitoring the vehicle's position, the distance to the destination or turn point, and the calculated costs of different trajectories. This feedback mechanism allows the system to determine the optimal lane change timing, balancing the need to maintain speed with the requirement to allow sufficient time for safe lane change execution before reaching the destination or turn point.
Data Source
AI summary
Embodiments disclose a method and a system to operate an autonomous driving vehicle (ADV). In one embodiment, a system determines a source lane speed limit (SLSL) for a source lane (SL) and a target lane speed limit (TLSL) for a target lane (TL), where the SLSL is greater than the TLSL. The system generates a first trajectory for the ADV to follow the SL, the first trajectory having a modified speed corresponding to the TLSL instead of the SLSL. The system generates a second trajectory for the ADV to change from the SL to the TL, the second trajectory having a speed corresponding to the TLSL. The system determines a first cost and a second cost for the first trajectory and the second trajectory respectively based on a cost function for comparison. The system controls the ADV according to a trajectory with a lowest cost.