Vehicle Control Device for Steering Responsivity
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Solution Overview
Problem
Conventional vehicle control systems face challenges in improving responsivity and steering stability when using tires with reduced longitudinal spring constants, which affect the vehicle's ability to maintain initial responsivity and linear feeling during steering maneuvers.
Innovation Solution
A vehicle control system that includes a steering angle sensor and a controller, which sets additional deceleration based on the tire longitudinal spring constant, increasing vertical load on front road wheels to enhance ground contact area and cornering force, thereby improving responsivity and linear feeling, and compensates for reduced damping performance at higher speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tire longitudinal spring constant is reduced to improve fuel economy and increase ground contact area, then tire rolling resistance is reduced and ground contact area increases, but initial responsivity and steering stability deteriorate
Solution Approach 1:
The control device applies preliminary action by proactively increasing vertical load on the front road wheels before or during steering maneuvers. This preliminary loading compensates for the reduced damping performance of tires with lower longitudinal spring constants, ensuring that initial responsivity and steering stability are maintained despite the energy-efficient tire design.
Solution Approach 2:
The control device dynamically changes the vertical load parameter on the front road wheels based on steering conditions. By adjusting this parameter in real-time, the system compensates for the reduced tire longitudinal spring constant, maintaining optimal steering performance while allowing the tire to operate in a lower spring constant state for improved fuel economy.
2Force
If the tire longitudinal spring constant is reduced to increase ground contact area during driving/braking and turning, then driving/braking and turning performances improve, but initial responsivity and linear feeling with respect to steering manipulation deteriorate
Solution Approach 1:
The control device applies a counteracting force by increasing vertical load on the front road wheels. This counterweight effect compensates for the loss of linear feeling and initial responsivity caused by reduced tire longitudinal spring constant, balancing the benefits of increased ground contact area with maintained steering characteristics.
Solution Approach 2:
The system performs preliminary action by pre-loading the front road wheels vertically before steering maneuvers occur. This preliminary action ensures that when steering manipulation is applied, the tires maintain adequate contact pressure and damping characteristics, preserving linear steering feel despite the reduced spring constant.
3Speed
If additional deceleration is increased to compensate for reduced tire longitudinal spring constant, then vehicle responsivity improves, but damping performance may be affected at higher speeds
Solution Approach 1:
The control device employs dynamic adjustment of additional deceleration based on vehicle speed and steering conditions. By making the deceleration parameter variable rather than fixed, the system optimizes responsivity at lower speeds while preventing excessive deceleration that would compromise damping performance and stability at higher speeds.
Solution Approach 2:
The control device uses feedback mechanisms to monitor vehicle behavior and adjust additional deceleration accordingly. This feedback control ensures that deceleration is increased sufficiently to compensate for reduced tire spring constant when needed, while automatically reducing deceleration when vehicle speed indicates that damping performance requires preservation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively enhances vehicle responsivity and steering stability by rapidly increasing vertical load on front road wheels during steering maneuvers, especially at higher speeds, and maintains improved damping performance, addressing the limitations of reduced tire longitudinal spring constants.
Implementation Method 1
sets additional deceleration to be added to the vehicle based on a detection value of the steering angle sensor, and controls the vehicle to generate the set additional deceleration in the vehicle
Implementation Method 2
compensates for reduced damping performance at higher speeds
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Provided is a vehicle control system capable of controlling the behavior of a vehicle, in conformity to a tire longitudinal spring constant, to improve responsivity and linear feeling of the vehicle behavior with respect to a steering manipulation. The vehicle control system comprises a steering angle sensor (8) and a PCM (14). The PCM is configured to set, based on a detection value of the steering angle sensor, an additional deceleration to be added to a vehicle (1), and control the vehicle to generate the set additional deceleration in the vehicle, wherein the additional deceleration is set to be larger when a tire longitudinal spring constant (Kt) of each road wheel of the vehicle is relatively small than when it is not relatively small.