Vehicle Suspension Control Using Steering Angle Speed for Roll Rate Segmentation
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Solution Overview
Problem
Existing vehicle suspension control systems face challenges in distinguishing between roll rates caused by steering inputs and road surface inputs, leading to potential unnecessary pitch behavior and reduced travel stability.
Innovation Solution
A suspension control system that utilizes a roll rate output unit to determine the presence of a steering input based on steering angle speed, outputting the roll rate if the speed exceeds a certain value, and zero otherwise, allowing for the separation of roll rates from steering and road surface inputs, thereby preventing computation of target pitch moments based on road surface-induced roll rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target pitch moment is generated based on the roll rate detected by the roll rate sensor, then the phase difference between roll angle and pitch angle is reduced to improve steering stability, but unnecessary pitch behavior is generated when the roll rate is caused by road surface input
Solution Approach 1:
The roll rate signal is segmented into two distinct components: steering-input-induced roll rate and road-surface-input-induced roll rate. This segmentation is achieved by comparing the detected roll rate with the steering angle speed, allowing the system to process only the relevant component for pitch moment calculation, thereby eliminating unnecessary pitch behavior while maintaining steering stability
Solution Approach 2:
The steering angle speed serves as an intermediary parameter to distinguish between steering-induced and road-surface-induced roll rates. By using this intermediary, the system can accurately identify the source of roll motion and selectively process only the steering-related component for pitch control, preventing harmful pitch behavior from road disturbances
2Measurement precision
If the roll rate caused by steering input is relatively small, then it is difficult to distinguish from road surface input, but using the detected roll rate directly causes unnecessary pitch behavior
Solution Approach 1:
The steering angle speed acts as an intermediary reference to enhance the detectability of small steering-induced roll rates. By comparing the roll rate signal against this intermediary parameter, the system can reliably distinguish subtle steering inputs from road surface disturbances, maintaining measurement precision while preventing harmful pitch behavior
Solution Approach 2:
The system uses feedback from the steering angle sensor to continuously monitor steering input levels. This feedback mechanism allows the control unit to adjust the pitch moment calculation based on actual steering conditions, ensuring that small but legitimate steering-induced roll rates are properly recognized while filtering out road-surface-induced signals
Data Source
AI summary
A suspension control system includes: variable damping force dampers provided between a vehicle body and each wheel; a roll rate output unit configured to determine if a steering angle speed based on a steering angle is equal to or greater than a prescribed determination value, to output a roll rate detected by a roll rate sensor if the steering angle speed is equal to or greater than the determination value, and to output zero if the steering angle speed is less than the determination value; a pitch moment computation unit configured to compute a target pitch moment of the vehicle body based on an output of the roll rate output unit; and a damping force computation unit configured to compute a target damping force of each damper based on the target pitch moment.