HAV Safe Speed Control Under Position Uncertainty
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Solution Overview
Problem
Existing methods for controlling highly automated vehicles (HAVs) fail to accurately consider uncertainty in vehicle position, leading to decreased accuracy in obstacle detection and safe movement along trajectories, particularly due to neglecting dynamic environmental constraints and requiring powerful computers for complex calculations.
Innovation Solution
An adaptive control method that determines the safe speed as the maximum permissible speed by assessing the vehicle's position and environmental uncertainty using wheel encoders, cameras, and sensors, forming hypotheses about the vehicle's position, planning trajectories, and comparing them with a digital obstacle map to estimate collision probabilities and adjust the traction motor and braking system accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex calculations are performed to determine safe speed considering position uncertainty, then collision probability decreases, but computational power requirements increase
Solution Approach 1:
The patent segments the continuous space of possible vehicle positions into discrete grid cells. By representing position uncertainty as a probability distribution across these discrete cells rather than continuous coordinates, the system reduces computational complexity while maintaining accuracy in collision probability assessment.
Solution Approach 2:
The patent pre-calculates and stores safe speed values in a lookup table based on position uncertainty parameters before actual vehicle operation. This preliminary computation eliminates the need for complex real-time calculations during vehicle movement, significantly reducing computational power requirements while maintaining reliability.
2Reliability
If position uncertainty is considered in trajectory planning, then safety increases, but control system complexity increases
Solution Approach 1:
The patent dynamically adjusts the safe speed based on the current position uncertainty parameters that vary during vehicle operation. Instead of using a fixed complex model, the system adapts the control parameters in real-time based on measured uncertainty, simplifying the control system while maintaining safety.
Solution Approach 2:
The patent transforms the complex position uncertainty representation into simplified parameters (standard deviation in x and y directions) that can be directly used for safe speed determination. This parameter transformation reduces control system complexity by converting complex spatial uncertainty into manageable scalar values.
3Reliability
If accurate position assessment is performed to determine safe speed, then collision probability decreases, but measurement precision requirements increase
Solution Approach 1:
The patent assesses position uncertainty with partial precision by focusing only on the essential parameters (standard deviation in x and y directions) rather than requiring complete and ultra-precise position information. This partial assessment is sufficient for determining safe speed and reducing collision probability without demanding excessive measurement precision.
Data Source
AI summary
The invention relates to methods of controlling the driving of highly automated vehicles (HAVs), which consists in that, while an HAV is driving, an on-board computer receives data from wheel encoders and from a steering wheel position sensor and the following are generated: a current state of the HAV and hypotheses about the position of the HAV, as well as a planned path, in the form of a desired trajectory on a map, and a digital map of obstacles. A future trajectory is predicted, the obtained trajectory is applied to each hypothesis about the position of the HAV, and each of the predicted trajectories is checked for the presence of collisions, wherein the probability of a collision with obstacles is estimated. On the basis of the data obtained, a safe driving speed is determined as the maximum permissible speed at which the probability of the HAV entering into a collision does not exceed a given threshold. The safe speed value obtained is sent to a speed control unit which sets control signals for the traction motor and the braking system.