Suspension Damping Current Control for Low-Speed Ride Comfort
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Solution Overview
Problem
Existing control devices for two-wheeled vehicles struggle to maintain optimal ride quality across a wide velocity range, particularly in extremely low velocity ranges where control delays can lead to uncomfortable steering and deteriorated ride quality.
Innovation Solution
A control device with a reference unit, correction unit, and target setting unit that sets a target current for a damping force control valve. The correction unit adjusts a reference correction current based on the change velocity of the suspension, setting it to 0 in extremely low velocity ranges and to steady-state values in medium and high velocity ranges, ensuring smooth transitions in damping force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If skyhook control sets reference correction current to predetermined positive or negative values based on velocity sign, then control simplicity is maintained, but ride quality deteriorates due to timing deviation between sensor detection and control execution
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reference correction current based on the magnitude of velocity rather than simply its sign. The control device divides velocity into multiple ranges (first velocity range with |v| ≥ threshold, second velocity range with |v| < threshold) and sets different reference correction current values for each range. This transforms the control approach from a binary decision (positive/negative current based on velocity sign) to a multi-level parameter adjustment, resolving the timing deviation issue while maintaining control simplicity.
2Reliability
If reference correction current is set to non-zero values in low velocity ranges, then skyhook control effect is enhanced, but steering comfort deteriorates due to unnecessary damping force changes
Solution Approach 1:
The patent introduces a velocity threshold parameter to distinguish between significant and insignificant velocity changes. When velocity magnitude falls below this threshold (second velocity range), the reference correction current is set to zero, preventing unnecessary damping force adjustments that would compromise steering comfort. When velocity exceeds the threshold (first velocity range), the reference correction current takes non-zero values to maintain effective skyhook control. This parameter-based segmentation resolves the contradiction between control effectiveness and steering comfort.
Data Source
AI summary
A control device includes a reference unit, a correction unit, and a target setting unit. The correction unit sets a reference correction current serving as a reference in determining the correction current to 0 in an extremely low velocity range of a change velocity of a stroke amount, sets the reference correction current to a predetermined steady-state value in a medium and high velocity range of the change velocity, and sets the reference correction current to a value equal to or larger than 0 and equal to or smaller than the steady-state value in a low velocity range of the change velocity.