Vehicle Suspension Damping Control for Road-Adaptive Stability
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Solution Overview
Problem
The existing vehicle control devices face delays in damping force control intervention suitable for road surface conditions, leading to compromised riding comfort and steering stability due to inaccuracies in stroke speed estimation.
Innovation Solution
A vehicle control system that includes a control unit which acquires specifications related to vehicle travel, limits the variable range of damping force generated by a damping force generating device, and outputs a damping force control command to adjust damping force based on slip ratio, front/rear acceleration, and road surface friction, thereby improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If damping force control is based on stroke speed estimation from wheel speed signals, then the control system can operate without additional sensors, but the estimation accuracy decreases leading to delayed intervention and deteriorated riding comfort and steering stability
Solution Approach 1:
The patent introduces a damping force generation amount calculation unit that calculates the damping force generation amount based on wheel speed signals and vehicle specifications. This intermediary calculation process bridges the gap between indirect wheel speed measurements and the required damping force control, improving accuracy without adding direct stroke speed sensors.
Solution Approach 2:
The patent changes the control parameter from directly measuring stroke speed to calculating damping force generation amount based on wheel speed signals and vehicle specifications. By transforming the control approach to use available sensor data combined with vehicle specification parameters, the system achieves accurate damping force control without relying on imprecise stroke speed estimation.
2Device complexity
If damping force control intervention is delayed due to estimation accuracy issues, then the control system maintains simplicity, but riding comfort and steering stability are compromised
Solution Approach 1:
The patent performs preliminary calculation of the damping force generation amount based on wheel speed signals and vehicle specifications before actual damping force control is needed. This preliminary action ensures that accurate control data is ready in advance, preventing delayed intervention and maintaining both system simplicity and reliability.
3Speed
If the variable range of damping force is not limited based on travel specifications, then the control system responds quickly to road conditions, but the damping force may be inappropriate for specific road surfaces leading to reduced comfort and stability
Solution Approach 1:
The patent dynamically adjusts the variable range of damping force based on detected road surface conditions and vehicle travel specifications. The control system continuously adapts the damping force range to match current driving conditions, maintaining both rapid response capability and appropriate adaptability to different road surfaces through real-time parameter adjustment.
Data Source
AI summary
A vehicle control device includes a vertical VSE, a riding comfort control logic, a planar VSE, a steering stability control logic, a command limiting unit, a control command selection unit. The command limiting unit acquires specifications related to a traveling of a vehicle such as, for example, a slip rate and a four-wheel independent braking/driving force control flag through a CAN. The command limiting unit limits a variable range of a damping force generated by a suspension device provided between a vehicle body and wheels of the vehicle based on the specifications related to the traveling of the vehicle to obtain a first command value. The command limiting unit outputs the obtained first command value to the control command selection unit.