Vehicle Bend Speed Control Using Local Curve Maxima
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Solution Overview
Problem
Existing methods for determining optimal driving speeds around bends often fail to accurately account for complex bend courses, leading to inappropriate speed adjustments by automated and predictive driving speed control systems.
Innovation Solution
A method that determines the curve course of a route portion ahead using digital maps and sensors, identifies local curve maxima, and sets permissible bend speeds based on curve characteristics and physical load limits, allowing for precise and reliable speed control by dividing the bend into sections and applying speed limits through interpolation and look-up tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single speed limit is applied to the entire bend, then the control system is simple to implement, but the speed control accuracy deteriorates because it cannot account for varying curve characteristics within the bend
Solution Approach 1:
The bend is divided into multiple bend sections based on local curve maxima, with each section having its own speed limit. This segmentation allows the system to account for varying curve characteristics within the bend while maintaining manageable complexity through automated identification and processing of curve sections.
Solution Approach 2:
The speed limit is made dynamic by determining specific permissible bend speeds for each local curve maximum and interpolating between them. This creates a variable speed profile that adapts to the actual curve geometry, improving accuracy over a static single-speed-limit approach.
2Measurement precision
If multiple speed limits are determined for different positions within the bend, then the speed control accuracy is improved, but the device complexity increases due to multiple speed limits and interpolation requirements
Solution Approach 1:
The bend is divided into multiple bend sections based on local curve maxima, with each section having its own speed limit. This segmentation allows the system to account for varying curve characteristics within the bend while maintaining manageable complexity through automated identification and processing of curve sections.
Solution Approach 2:
The speed limit is made dynamic by determining specific permissible bend speeds for each local curve maximum and interpolating between them. This creates a variable speed profile that adapts to the actual curve geometry, improving accuracy over a static single-speed-limit approach.
3Measurement precision
If the bend is divided into multiple bend sections with local curve maxima as borders, then the speed control precision is improved, but the calculation complexity increases
Solution Approach 1:
The bend is divided into multiple bend sections based on local curve maxima, with each section having its own speed limit. This segmentation allows the system to account for varying curve characteristics within the bend while maintaining manageable complexity through automated identification and processing of curve sections.
Solution Approach 2:
The curve course is evaluated in advance to identify local curve maxima and determine bend sections before the vehicle reaches them. This preliminary analysis allows the control system to prepare appropriate speed limits for each section, reducing real-time computational complexity.
4Measurement precision
If additional permissible bend speeds are determined by interpolation when deviation exceeds a threshold, then the speed control accuracy is improved, but the calculation time increases
Solution Approach 1:
Additional permissible bend speeds are determined by interpolation only when the deviation between speeds at the beginning and end of a bend section exceeds a pre-determined threshold. This partial action approach ensures high accuracy when needed while avoiding unnecessary calculations when the speed profile is already sufficiently smooth, thus balancing precision with computational efficiency.
Data Source
AI summary
A driving speed of a vehicle is limited when driving around a bend. A course of a curve of a route portion lying ahead of the vehicle is determined using a digital map. Depending on the course of the curve and on physical load limits of the vehicle, a course of a permissible bend speed is determined. The vehicle is controlled such that the determined permissible bend speeds are not exceeded when driving around the bend. By evaluating the course of the curve, a route portion, in which the curve is greater than a pre-determined curve limit value, is identified as a bend portion. Local curve maxima are identified in the identified bend portion. A permissible bend speed is determined for each local curve maximum depending on the curve and on a permissible lateral acceleration.