Longitudinal Speed Control Activation for Smooth Speed-Limit Deceleration
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Solution Overview
Problem
Existing adaptive cruise control systems empirically determine the activation time for longitudinal speed regulation, leading to uncomfortable decelerations and jerks when approaching speed limit zones, which can be perceived by drivers and passengers.
Innovation Solution
A method to calculate the optimal time for activating longitudinal speed regulation by constructing deceleration profiles based on kinematic equations, considering comfort constraints such as deceleration and jerk values, and automatically triggering the control when road conditions permit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driver is prompted to acknowledge new speed information early (using empirical 5-second timing), then the vehicle can reach the speed limit sign, but the deceleration becomes abrupt and causes discomfort to driver and passengers
Solution Approach 1:
The system calculates and prepares multiple deceleration profiles in advance, each corresponding to different acknowledgment times. By pre-computing these profiles with varying deceleration rates, the system can select the most appropriate one that balances reaching the speed limit sign with maintaining comfort, rather than using a fixed empirical timing.
Solution Approach 2:
The system dynamically adjusts the deceleration profile based on real-time vehicle parameters (current speed, position, acceleration, jerk) and the selected comfort criterion. Instead of using a static 5-second acknowledgment time, the system continuously evaluates multiple profiles and selects the optimal one, making the deceleration process adaptive and dynamic rather than fixed.
2Device complexity
If the system uses a fixed empirical acknowledgment time, then the control logic is simple, but the deceleration profiles do not optimize for comfort constraints
Solution Approach 1:
The system changes the deceleration parameters (acceleration, jerk) based on the selected comfort criterion. By varying these parameters across multiple pre-calculated profiles, the system optimizes for smooth deceleration while still reaching the speed limit sign. This approach maintains relatively simple control logic by pre-computing profiles rather than performing complex real-time optimization.
3Ease of operation
If the system constructs multiple deceleration profiles with comfort constraints, then the deceleration becomes smooth and comfortable, but the calculation complexity increases
Solution Approach 1:
The system performs the computationally intensive work of constructing multiple deceleration profiles with different comfort characteristics in advance, before real-time operation. By pre-calculating these profiles offline or during system initialization, the runtime complexity is reduced to merely selecting from pre-computed options rather than generating them in real-time.
Solution Approach 2:
The system constructs more deceleration profiles than strictly necessary (excessive action) to ensure that an optimal comfortable profile is available for any given situation. By over-provisioning the set of available profiles with varying comfort characteristics, the system guarantees that a suitable profile exists without needing to perform complex real-time optimization calculations.
Data Source
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AI summary
The invention relates to a method for determining when to activate the regulation of the longitudinal speed of a motor vehicle, the method consisting in determining (200) the position of the start of a detected speed-limitation zone (100) relative to the vehicle and the limited-speed information pertaining to said zone; in constructing (400) a plurality of deceleration profiles that will bring the speed of the vehicle down to that limited speed taking account of the longitudinal position, the longitudinal speed, the longitudinal acceleration and the longitudinal jerk of the vehicle; in adopting (500), from among these profiles, a determined deceleration profile that meets determined comfort constraints, with the shortest deceleration time; and, from the profile adopted, in determining (600) the position of the vehicle at the end of said time, converted into distance; and in commanding (700) the deceleration of the vehicle when the vehicle reaches said distance relative to the start of said zone.