Vehicle Curve Speed Control Using Composite Acceleration Limits
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Solution Overview
Problem
Existing vehicle control systems that adjust lateral acceleration based on curve information may set target accelerations that are either too large or too small, leading to deteriorated riding comfort, as they do not consider both lateral and longitudinal accelerations effectively.
Innovation Solution
A vehicle control apparatus that includes a road shape acquisition unit, lateral movement parameter setting unit, curve limitation speed calculation unit, acceleration parameter setting unit, travelling speed correction unit, and speed control unit, which collectively set and adjust travelling speeds to ensure composite accelerations remain within predetermined limits, balancing lateral and longitudinal accelerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target acceleration in the back direction at the curve start point is set to the magnitude equal to the maximum lateral acceleration, then the lateral acceleration can be controlled within limits, but the riding comfort deteriorates due to excessive or insufficient acceleration
Solution Approach 1:
The patent changes the parameter from a fixed acceleration limit to a dynamically calculated curve limitation speed based on composite acceleration. The ECU calculates the curve limitation speed by considering both lateral acceleration (from curve radius) and longitudinal acceleration (from vehicle dynamics), then adjusts the target speed to keep the composite acceleration within acceptable limits, resolving the contradiction between control reliability and riding comfort
Solution Approach 2:
The patent transitions from controlling only lateral acceleration (one dimension) to controlling composite acceleration that includes both lateral and longitudinal components (two dimensions). By calculating the curve limitation speed based on the combination of lateral acceleration from curve geometry and longitudinal acceleration from vehicle dynamics, the system achieves balanced control that maintains both safety and comfort
2Reliability
If the curve limitation travelling speed is calculated based only on lateral acceleration, then the lateral acceleration can be kept within limits, but the longitudinal acceleration may exceed acceptable ranges
Solution Approach 1:
The patent modifies the control parameter from lateral acceleration alone to composite acceleration that incorporates both lateral and longitudinal components. The ECU calculates the curve limitation speed by integrating lateral acceleration (from curve radius and target speed) and longitudinal acceleration (from vehicle dynamics and speed changes), ensuring that the combined acceleration remains within acceptable limits and preventing excessive longitudinal acceleration
Solution Approach 2:
The patent merges the control of lateral and longitudinal accelerations into a unified composite acceleration control system. By combining the lateral acceleration component (determined by curve geometry and target speed) with the longitudinal acceleration component (determined by vehicle dynamics and speed changes), the system calculates a comprehensive curve limitation speed that simultaneously controls both acceleration types, eliminating the harmful effect of excessive longitudinal acceleration
Data Source
AI summary
To provide a vehicle control apparatus which can control appropriately the travelling speed at traveling on the curve, considering not only the lateral acceleration at traveling on the curve but also the longitudinal acceleration. A vehicle control apparatus calculates a curve limitation travelling speed at which the lateral acceleration of the own vehicle becomes the maximum lateral acceleration or less, based on the road shape and the maximum lateral acceleration; corrects the curve limitation travelling speed so that a composite acceleration of the own vehicle at traveling on the curve road becomes within a limit range which is set according to the maximum lateral acceleration, the maximum longitudinal acceleration in the front direction, and the maximum longitudinal acceleration in the back direction; and controls the vehicle according to the curve limitation travelling speed after correction.