Adaptive Cruise Control Braking Performance Index Deactivation
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Solution Overview
Problem
The existing Adaptive Cruise Control (ACC) systems face issues where a sudden change in braking performance can cause discomfort to drivers when the system is deactivated, due to a constant limit level for prohibiting ACC activation, leading to unpredictable braking sensations.
Innovation Solution
A traveling control apparatus that deactivates the ACC when a braking performance index derived from braking state information decreases by more than a predetermined variation width, ensuring a smooth transition back to driver control and minimizing discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant limit level is set for prohibiting ACC activation to prevent brake fading, then braking safety is improved, but driver comfort deteriorates due to sudden braking sensation changes when ACC is deactivated
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static constant limit level to a dynamic reference value that adapts based on initial braking performance. The reference value is dynamically adjusted according to the braking performance index at the time of ACC activation, allowing the system to maintain appropriate prohibition criteria while adapting to varying braking conditions, thereby preventing both brake fading and sudden sensation changes
Solution Approach 2:
The patent implements parameter changes by modifying the prohibition criterion from a fixed constant value to a variable reference value derived from the braking performance index. This parameter transformation allows the system to evaluate ACC activation prohibition based on relative changes in braking performance rather than absolute thresholds, resolving the contradiction between safety and comfort
2Reliability
If ACC activation is prohibited at a constant limit level, then the risk of brake fading during ACC operation is reduced, but the braking performance variation between activation and deactivation increases
Solution Approach 1:
The patent changes the parameter basis for prohibition from a constant absolute value to a relative variable value (reference value based on initial braking performance). This ensures that the prohibition criterion maintains a consistent relationship with the actual braking performance state, preventing both brake fading and unnecessary deactivation due to performance variations
Data Source
AI summary
A traveling control apparatus includes: an information obtainer configured to obtain braking state information of a braking device in the host vehicle; and an ACC-ECU configured to execute traveling control including constant speed traveling control to cause the host vehicle to travel at a constant speed based on a preset vehicle speed, and follow-up traveling control to cause the host vehicle to travel so as to follow another vehicle traveling ahead of the host vehicle at a predetermined inter-vehicle distance. The ACC-ECU deactivates the ACC at a time when a braking performance index EV1z, derived from braking state information obtained by the information obtainer while the ACC being in operation, is deemed to be decreased by more than a predetermined first variation width IN_dif1, as compared with a braking performance index EV1a at a time of the ACC having been activated.