Vehicle Cruise Control Uphill Speed Maintenance
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Solution Overview
Problem
Conventional automatic cruise control systems face difficulties in maintaining vehicle speed at a target speed when transitioning from downhill to uphill driving, as they struggle to immediately apply sufficient driving force, resulting in potential speed loss.
Innovation Solution
A system and method that control driving force and braking force to maintain vehicle speed by ensuring driving force is applied at or above a predetermined value when the vehicle speed exceeds the target, and applying braking force to prevent excessive speed increases, allowing smooth uphill travel without significant speed loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the automatic cruise control system executes driving force control to reduce speed when the vehicle travels downhill and exceeds the target speed, then the vehicle speed is controlled to match the target speed, but the vehicle cannot immediately obtain sufficient driving force when transitioning to uphill driving, resulting in speed loss and delayed response
Solution Approach 1:
The control system performs preliminary action by maintaining the driving force at a high level (equal to or greater than the force required to maintain position on an uphill incline) even when the vehicle speed exceeds the target speed during downhill travel. This ensures that when the vehicle transitions to uphill driving, the driving force is already sufficient to immediately ascend without speed loss, eliminating the delay in obtaining adequate driving force.
2Ease of operation
If the conventional system reduces driving force to control speed on downhill, then the vehicle speed is maintained at target speed, but the vehicle lacks sufficient driving force readiness for immediate uphill ascent
Solution Approach 1:
The system prepares the driving force in advance by maintaining it at a level sufficient for uphill driving (first driving force) even during downhill travel when speed exceeds the target. This preliminary maintenance of high driving force ensures both easy speed control during downhill (through coordinated braking) and reliable readiness for immediate uphill ascent.
Solution Approach 2:
The control system uses feedback from wheel speed sensors to detect when the vehicle speed exceeds the target speed during downhill travel, and automatically adjusts the driving force and braking force accordingly. The ECU continuously monitors wheel speeds and modulates the driving force maintenance and braking application to achieve both speed control and uphill readiness.
3Speed
If braking force is applied frequently and for extended duration to maintain constant speed, then the vehicle speed remains stable, but the load on the brakes increases
Solution Approach 1:
The system applies preliminary action by maintaining the driving force at a sufficient level before uphill transitions occur, which reduces the need for prolonged or frequent braking to maintain speed stability. By having the driving force already optimized, the vehicle can transition more smoothly between terrain types with less reliance on continuous brake application.
Data Source
AI summary
A system for controlling a vehicle that controls driving force and braking force such that a vehicle speed is maintained at a target vehicle speed. More specifically, when the vehicle speed exceeds the target vehicle speed, the system for controlling a vehicle maintains the driving force at or above a predetermined value, and applies braking force to the vehicle such that the vehicle speed is maintained at the target vehicle speed. This provides the vehicle with sufficient driving force for uphill driving following the downhill driving, and thus to travel uphill without significant speed loss. In other words, the vehicle ascends the uphill road smoothly at an approximately constant speed.