Longitudinal Acceleration Control for Curve Approach
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Solution Overview
Problem
Existing vehicle motion control systems fail to accurately adjust acceleration and deceleration to match the driver's sensory experience, especially when lateral motion is not involved, such as on straight roads before entering a curve, leading to inadequate deceleration control.
Innovation Solution
A vehicle motion control system that calculates a longitudinal acceleration command value based on curve shape, vehicle position, estimated maximum lateral acceleration, road grade, and driver input, adjusting the acceleration and deceleration to match the driver's intended motion by changing the longitudinal acceleration command value as the vehicle approaches a curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If deceleration control is carried out so that the deceleration before curves is constant, then the control is simple to implement, but the performed deceleration may not sufficiently correspond to a sensory deceleration of the driver depending on curves and vehicle speeds
Solution Approach 1:
The patent applies dynamics by transitioning from constant deceleration control to temporal change deceleration control. The system dynamically adjusts the deceleration profile over time based on the vehicle's approach to a curve, using a temporal change parameter that modifies deceleration magnitude as the vehicle nears the curve. This dynamic adjustment allows the deceleration to better match the driver's sensory expectations while maintaining reasonable control complexity through parameterized temporal functions.
2Measurement precision
If a temporal change of the deceleration is set for every curve, then the deceleration corresponds better to driver sensory experience, but a large number of adaptation steps and a vast quantity of data are required
Solution Approach 1:
The patent applies parameter changes by introducing a temporal change parameter that modifies the deceleration profile based on the vehicle's distance to and speed approaching a curve. Instead of storing extensive curve-specific deceleration data, the system uses a parametric approach where deceleration is determined by general parameters (temporal change factor, distance to curve, vehicle speed) that can be calculated in real-time. This reduces data storage requirements while maintaining accurate sensory deceleration correspondence.
3Reliability
If deceleration control is performed based on target vehicle speed from preset lateral acceleration set value, then departure from road is suppressed, but the total deceleration before entering into the curve can be defined but a temporal change of the deceleration cannot be defined
Solution Approach 1:
The patent applies segmentation by separating the deceleration control into two independent components: (1) a target vehicle speed component that ensures road departure suppression based on lateral acceleration limits, and (2) a temporal change component that defines how deceleration evolves over time as the vehicle approaches the curve. This segmentation allows each component to be optimized independently - the target speed for safety and the temporal profile for driver comfort - while working together to achieve both road departure suppression and natural sensory deceleration.
Data Source
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AI summary
There is provided a vehicle motion control system (1) which carries out acceleration and deceleration of a vehicle which satisfies driving feeling of a driver even in the state where a lateral motion of the vehicle is not involved. The vehicle motion control system (1) includes a curve shape acquisition section (2) for acquiring a curve shape ahead of an own vehicle, an own vehicle position acquisition section (3) for acquiring a position of the own vehicle, and a vehicle motion control calculation section (4) for calculating a command value of a longitudinal acceleration generated for the vehicle based on the curve shape and the position of the own vehicle. The vehicle motion control calculation section (4) calculates a plurality of negative longitudinal acceleration command values during travel of the own vehicle from before a curve to a point where a curve curvature becomes constant or maximum after the vehicle enters into the curve. The longitudinal acceleration command values are changed based on at least one of: an estimate of the maximum lateral acceleration which is presumably generated during traveling a curve ahead of the own vehicle; a grade of the road ahead of the own vehicle, pedal operation by the driver, and a turning direction.