Adjustable Damping Force Damper Control System for Vehicle Stability
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Solution Overview
Problem
Existing adjustable damping force dampers struggle to maintain proper roll stiffness during vehicle turning while avoiding a deterioration in control responsibility, often causing unexpected feelings of loss of damping power due to misalignment of damping force control with the phase of tire turning.
Innovation Solution
A control system for an adjustable damping force damper that includes lateral acceleration and yaw rate sensors to calculate and compare target damping forces, ensuring precise control by considering both lateral acceleration at the vehicle's gravity point and axle position, and using the time derivative value of lateral acceleration for phase compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the damping force is increased to enhance road-holding performance and tire controllability, then the road-holding performance improves, but the shock attenuation capability deteriorates
Solution Approach 1:
The damper employs variable damping force capability, allowing the damping coefficient to be dynamically adjusted based on operating conditions. This enables the system to provide high damping force for road-holding when needed while providing low damping force for shock attenuation when needed, resolving the contradiction between these two opposing requirements.
2Productivity
If the damping force control phase is led by adding derivative value of yaw rate to improve control responsibility, then the control responsibility improves, but the damping force control becomes inaccurate during turning operations
Solution Approach 1:
The control system dynamically adjusts the damping force target value by changing control parameters based on vehicle state. It calculates the damping force target value using lateral acceleration and its time derivative, and selectively adds derivative value of yaw rate only when appropriate (when the calculated value is positive), thereby adapting the control strategy to actual driving conditions and resolving the contradiction between control responsiveness and accuracy.
3Stability of the object's composition
If the damping force is controlled to follow lateral acceleration phase during turning, then the roll stiffness improves, but the control accuracy deteriorates due to phase misalignment with tire motion
Solution Approach 1:
The control system performs preliminary calculation of the damping force target value based on lateral acceleration and its time derivative before actual damping force application. By calculating ahead and preparing the appropriate damping force target value, the system can respond more accurately to actual tire motion requirements, resolving the phase misalignment issue between damper control and tire motion during turning operations.
Data Source
AI summary
A control system for an adjustable damping force damper of a suspension apparatus of a vehicle, includes a lateral acceleration detecting unit detecting a lateral acceleration of the vehicle at a gravity point thereof, a yaw rate detecting unit detecting a yaw rate of the vehicle and a control unit controlling a damping force of the damper. The control unit calculates a first target damping force based on an output of the lateral acceleration detecting unit, calculates a second target damping force based on a lateral acceleration at an axel position which is estimated by an output of the yaw rate detecting unit, compares an absolute value of the first target damping force with that of the second target damping force and sets a target controlling value of the damping force in accordance with the first or second target damping force which has a larger absolute value.