Control-Dominated Three-Point Turn Planning for Autonomous Vehicles
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Solution Overview
Problem
There is a lack of efficient methods for planning and controlling autonomous driving vehicles to perform a three-point turn, which is complex due to the need for precise navigation and coordination of forward and backward turning paths.
Innovation Solution
A control-dominated three-point turn system generates forward and backward turning paths based on maximum turning angles, using full steering commands and perception information to calculate speed profiles, allowing the vehicle to make a smooth and accurate turn without considering lane shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional path planning methods are used for three-point turns, then the vehicle can complete the turn, but the planning process is complicated and inefficient
Solution Approach 1:
The three-point turn path is divided into three distinct segments: forward turning path, backward turning path, and final forward move. Each segment is planned independently with specific curvature and speed parameters, simplifying the overall complex maneuver into manageable parts that can be executed sequentially
Solution Approach 2:
The system dynamically adjusts curvature radius and speed parameters for each path segment based on vehicle characteristics and environmental conditions. By changing these parameters optimally for each phase of the turn, the system achieves efficient three-point turns while adapting to different road widths and traffic situations
2Measurement precision
If precise navigation is required for three-point turns, then turning accuracy is improved, but the control requirements become more stringent
Solution Approach 1:
The system continuously monitors actual vehicle position and orientation during the three-point turn maneuver and compares it with the planned trajectory. Real-time feedback allows dynamic adjustments to steering and speed commands, ensuring the vehicle stays on the optimal path without requiring overly complex control mechanisms
Solution Approach 2:
The complete three-point turn path is planned in advance with all curvature and speed parameters determined before execution. This preliminary path generation includes prediction of the vehicle's motion trajectory, allowing the control system to follow a pre-calculated optimal path rather than requiring complex real-time decision-making
Data Source
AI summary
In response to a request for a three-point turn, a forward turning path from a current location and heading direction of the ADV is generated. In generating the forward turning path, a forward curvature is determined based on the maximum forward turning angle of the ADV by applying a full steering command. The forward turning path is determined based on the forward curvature from the current location of the ADV. A forward speed profile is calculated for the forward turning path based on perception information that perceives a driving environment surrounding the vehicle at the point in time. In addition, a backward turning path is generated from an end point of the forward turning path based on a maximum backward turning angle associated with the ADV. The three-point turn path is then generated based on the forward turning path and the backward turning path to drive the vehicle to make the three-point turn.