Vehicle Propulsive Force Control Device for Constant Speed Termination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle control devices that maintain constant speed on steep grades cause driver discomfort due to independent reduction rates of driving and braking forces, leading to unintended acceleration or deceleration after constant speed traveling control is terminated.
Innovation Solution
A vehicle control device with a configuration that includes first and second driving force request value generation devices, first and second braking force control amount generation devices, and a vehicle propulsive force control device, which adjusts driving and braking forces to maintain target speed by associating their reduction rates, ensuring the vehicle propulsive force does not exceed the propulsive force at the specific control termination time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the vehicle driving force and vehicle braking force are reduced independently toward zero after constant speed traveling control is terminated, then the control device can simplify the termination process, but the vehicle may accelerate or decelerate unintentionally causing driver discomfort
Solution Approach 1:
The control device calculates and sets the braking force reduction rate before actually reducing the forces, based on the current driving force reduction rate and vehicle state. This preliminary calculation ensures that the braking force is reduced at an appropriate rate relative to the driving force, preventing unintended acceleration or deceleration and maintaining driver comfort during the transition.
2Speed
If the vehicle braking force decreases more quickly than the vehicle driving force, then the driving force reduction is prioritized, but the vehicle accelerates on uphill grades causing driver discomfort
Solution Approach 1:
The control device continuously monitors the vehicle state including acceleration, gradient, and current force levels. Based on this feedback, it dynamically adjusts the braking force reduction rate to ensure it remains appropriate relative to the driving force reduction rate, preventing unintended acceleration on uphill grades while maintaining smooth control termination.
3Speed
If the vehicle driving force decreases more quickly than the vehicle braking force, then the braking force reduction is prioritized, but the vehicle decelerates on downhill grades causing driver discomfort
Solution Approach 1:
The control device uses real-time vehicle state feedback including acceleration and gradient information to monitor the relationship between driving force and braking force reduction rates. When detecting downhill conditions, it adjusts the braking force reduction rate to prevent excessive deceleration, ensuring smooth and comfortable control termination that adapts to the current driving conditions.
Data Source
AI summary
An electronic control device reduces, after a time at which constant speed traveling control is terminated (specific control termination time) not by an accelerating operation or braking operation but by, for example, an operation of a control switch, the vehicle driving force to a force corresponding to the amount of accelerating operation at the specific control termination time. Also, the electronic control device changes the vehicle braking force to a force corresponding to the amount of braking operation at the specific control termination time by controlling the braking hydraulic pressures with a hydraulic pressure circuit so that the value of a vehicle propulsive force, which takes a positive value when acting in the same direction as the driving force (and takes a negative value when acting in the opposite direction of the driving force) and which has a magnitude equal to a value resulting from subtracting the magnitude of the braking force from the magnitude of the driving force, is equal to or smaller than the value of the vehicle propulsive force at the specific control termination time.