Autonomous Vehicle Actuator Timing for Delay-Compensated Trajectory Control
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Solution Overview
Problem
Autonomous vehicles face delays in executing commands due to transmission and physical state changes, leading to accumulation of errors in acceleration, deceleration, and steering systems, which affect the accuracy and safety of navigation.
Innovation Solution
The vehicle's computing devices adjust command timing and magnitude by determining fixed and variable delay values, accounting for transmission delays and physical system characteristics, and environmental factors to ensure accurate and timely execution of control requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commands are sent to actuators without delay compensation, then the control system is simple and responsive, but the vehicle trajectory deviates from the desired path due to accumulated errors
Solution Approach 1:
The system performs preliminary calculations to determine fixed and variable delay values for each actuator, then uses these pre-computed values to compensate command timing. By calculating delay values in advance and storing them for reuse, the system achieves accurate trajectory tracking without adding complex real-time computation overhead during command execution.
Solution Approach 2:
The system incorporates feedback mechanisms where the actual actuator responses and vehicle state are monitored, and delay values are continuously refined based on the difference between desired and actual trajectories. This feedback loop enables the control system to adapt and improve accuracy while maintaining manageable complexity through iterative optimization.
2Measurement precision
If delay values are calculated and applied for each command, then the control precision is improved, but the computational load and processing time increase
Solution Approach 1:
Delay values (both fixed and variable components) are pre-calculated based on actuator characteristics and stored in lookup tables or memory. When a command needs to be sent, the system simply retrieves the pre-computed delay value rather than performing complex calculations in real-time, thus maintaining high precision while minimizing processing time.
Solution Approach 2:
The system dynamically adjusts delay compensation based on current operating conditions by selecting from pre-computed delay values that correspond to different actuator states and environmental conditions. This dynamic selection from pre-prepared options allows the system to adapt to changing conditions without the computational overhead of real-time delay calculation.
3Adaptability or versatility
If environmental factors are considered in delay compensation, then the control accuracy under varying conditions is improved, but the system complexity and data processing requirements increase
Solution Approach 1:
The system pre-calculates delay values for various environmental conditions (temperature, humidity, altitude, road grade) and stores them in lookup tables. During operation, the system simply queries the appropriate pre-computed values based on current environmental sensors, achieving environmental adaptability without the complexity of real-time environmental modeling and calculation.
Solution Approach 2:
The system adjusts delay compensation by changing parameters (delay values) based on environmental conditions. By pre-establishing the relationship between environmental parameters and delay values, the system can adapt to different environments through simple parameter selection rather than complex environmental analysis, thus improving versatility while controlling complexity.
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.