Vehicle Suspension Control System for Wading Depth
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Solution Overview
Problem
Existing motor vehicle suspension systems fail to accurately detect unrequested suspension height changes, which can lead to undesirable adjustments during wading or belly out events, affecting wading depth and traction.
Innovation Solution
A control system that uses a receiver for measured height signals and a suspension modeling module to detect discrepancies between modeled and measured heights, inhibiting self-levelling mode when unrequested changes are detected, and outputs signals to manage suspension height and engine control systems accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the self-levelling mode is active to maintain suspension height, then the suspension height is maintained at target height, but the system incorrectly responds to unrequested height changes during wading or belly out events by reducing suspension height, thereby reducing wading depth capability and traction
Solution Approach 1:
The system uses feedback from height sensors to detect unrequested suspension height changes by comparing measured heights with modelled expected heights. When a discrepancy exceeds a threshold, the system identifies this as an external force event (wading or belly out) and adjusts control behavior accordingly, preventing incorrect self-levelling responses that would reduce wading capability.
Solution Approach 2:
The control system dynamically switches between self-levelling mode and inhibited mode based on detected conditions. When unrequested height changes are detected, the system transitions from active height control to a mode where height changes are permitted, allowing the vehicle to maintain optimal suspension height for wading operations or belly out recovery.
2Reliability
If the self-levelling mode actively adjusts suspension height, then height deviations are corrected, but unnecessary height adjustments occur during wading or belly out events, reducing traction and wading depth capability
Solution Approach 1:
The system continuously monitors suspension height via height sensors and compares measured values against modelled expected values. When the difference exceeds a predetermined threshold, the system identifies an external force event and inhibits further self-levelling adjustments, preventing unnecessary corrections that would compromise wading depth capability and traction.
3Device complexity
If simple height sensing is used to detect suspension height changes, then the system is simple to implement, but it cannot distinguish between requested and unrequested height changes, leading to incorrect control responses
Solution Approach 1:
The system introduces a suspension model as an intermediary that calculates expected suspension heights based on vehicle dynamics, road conditions, and suspension unit characteristics. This model serves as a reference against which actual measured heights are compared, enabling the system to distinguish between requested height changes (consistent with model predictions) and unrequested changes (deviating from model predictions), thereby improving detection accuracy without significantly increasing hardware complexity.
Data Source
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AI summary
The present application relates to a control system (49) for controlling a motor vehicle suspension (3). The suspension (3) has a plurality of adjustable height suspension units (19, 21, 23, 25) and a suspension control means (53) is provided to control the suspension units (19, 21, 23, 25). The control system (49) has a receiver for receiving height data form height sensors (41, 43, 45, 47) to provide height measurements for each suspension unit (19, 21, 23, 25). A suspension modelling means is provided for modelling the height of each suspension unit (19, 21, 23, 25). The control system (49) is configured to detect an unrequested suspension height change when the difference between the modelled height and the measured height of one or more suspension units (19, 21, 23, 25) exceeds a threshold. The present application also relates to a motor vehicle; and a method of detecting an unrequested suspension height change.