Autonomous Vehicle Actuation Timing for Delay-Compensated Trajectory Control
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Solution Overview
Problem
Autonomous vehicles face delays in actuator command execution due to transmission and physical response times, leading to accumulation of errors in acceleration, deceleration, and steering, which affect the vehicle's control accuracy and safety.
Innovation Solution
Adjusting the timing of actuation commands based on fixed and variable delays, including environmental factors, by using processor-controlled systems to account for delays in actuator response times and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If autonomous vehicles generate future trajectory plans and convert them to actuator commands, then the vehicle can navigate autonomously to destination locations, but delays in command transmission and actuator response cause accumulation of errors in acceleration, deceleration, and steering control
Solution Approach 1:
The system performs preliminary actions by predicting future trajectory points and pre-calculating actuator commands in advance. The controller generates a sequence of future trajectory points and computes the corresponding actuator commands before they are needed, allowing the system to compensate for known delays in command transmission and actuator response. This proactive approach ensures that the vehicle follows the desired trajectory accurately despite inherent system delays.
Solution Approach 2:
The system dynamically adjusts control commands based on real-time vehicle state and environmental conditions. The controller continuously updates the trajectory prediction and re-calculates actuator commands to account for changing conditions, ensuring optimal control accuracy. This dynamic adaptation allows the system to maintain precise control despite varying delays in different operating conditions.
2Speed
If the vehicle control system generates commands based on future trajectory predictions, then autonomous navigation is achieved, but transmission delays and actuator response times cause the vehicle to deviate from the planned trajectory
Solution Approach 1:
The controller pre-calculates actuator commands for multiple future trajectory points ahead of time. By generating commands in advance and storing them in a command queue, the system eliminates the need to compute commands in real-time during critical moments. This preliminary action ensures that commands are ready immediately when needed, maintaining both high response speed and accurate trajectory following.
Solution Approach 2:
The system continuously monitors actual vehicle position and compares it with the predicted trajectory. Based on this feedback, the controller adjusts future trajectory predictions and re-calculates actuator commands to compensate for deviations caused by transmission delays and actuator response times. This closed-loop feedback mechanism ensures reliable trajectory following while maintaining fast response.
3Productivity
If actuator commands are sent without timing adjustment, then the control system is simple and fast, but errors accumulate due to fixed transmission delays and variable actuator response times
Solution Approach 1:
The system pre-compensates for delays by calculating the actuator response time for each command in advance and adjusting the command timing accordingly. The controller determines when each command should be sent to the actuator based on predicted future states and known or estimated actuator response characteristics. This preliminary timing adjustment prevents error accumulation while maintaining high control efficiency through batch processing of future commands.
Solution Approach 2:
The system dynamically adjusts command timing parameters based on the specific actuator and command type. Different actuators (acceleration, braking, steering) have different response characteristics, and the controller adapts the timing compensation for each. This parameter adjustment allows precise control without sacrificing efficiency, as the timing offsets are calculated once and applied systematically.
Data Source
AI summary
Aspects of the disclosure relate to controlling a vehicle in an autonomous driving mode. For instance, a trajectory is identified. The trajectory defines a future desired path for the vehicle and includes a control requirement having a corresponding point in time. A command for achieving the control requirement is generated. A fixed delay value corresponding to a delay caused by transmission of the command to an actuator of the vehicle is generated. A variable delay value corresponding to a delay caused by an amount of time to change a physical state of the actuator to a desired state according to the command is generated. The command is then sent to the actuator based on the fixed delay value, the variable delay value, and so that the actuator causes the vehicle to move according to the command.