Shock Absorber Damping Control via Deviation Calculation
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Solution Overview
Problem
Existing shock absorber control systems face challenges in regulating damping force effectively, especially with non-linear damping characteristics, leading to inaccuracies and reduced traveling comfort due to hunting phenomena and deviations between actual and calculated damping forces.
Innovation Solution
A damping force control device and method that includes a damping force varying mechanism and a control portion to calculate deviations between target and minimum damping forces, allowing open-loop control to achieve precise damping force regulation, even with non-linear characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the damping coefficient C is adjusted to control damping force in shock absorbers with non-linear damping characteristics, then the damping force regulation becomes simpler, but the control precision deteriorates because the gradient of the damping characteristic line varies along its course
Solution Approach 1:
The damping characteristic curve is divided into multiple linear approximation segments. Each segment corresponds to a specific stroke speed range and has its own damping coefficient. The control device selects the appropriate damping coefficient based on the current stroke speed, thereby achieving precise control across the entire operating range while maintaining simple regulation through coefficient selection.
2Ease of manufacture
If the damping coefficient C is calculated by dividing Sky Hook control force by stroke speed Vs, then the damping force calculation becomes straightforward, but the calculation error increases significantly when stroke speed Vs is around zero
Solution Approach 1:
The control device预先 determines multiple damping coefficients corresponding to different stroke speed ranges before operation. By selecting the appropriate pre-determined damping coefficient based on the current stroke speed range, the system avoids the problematic division operation when stroke speed is near zero, thereby preventing large calculation errors while maintaining straightforward control.
3Device complexity
If a single damping coefficient is used for the entire stroke speed range, then the control system becomes simpler, but the damping force control accuracy deteriorates due to the non-linear varying gradient of the damping characteristic
Solution Approach 1:
The control device dynamically selects the damping coefficient based on the current stroke speed. Instead of using a fixed damping coefficient, the system switches between multiple damping coefficients corresponding to different stroke speed ranges. This dynamic adaptation maintains simple control logic while achieving accurate damping force control across the entire operating range.
Data Source
AI summary
A damping force control device (1) for a shock absorber (Dn) interposed between a sprung member (Bn) and an unsprung member (Wn) of a vehicle (A) comprises a damping force varying mechanism (3) which supplements a minimum damping force (Fdn) that can be generated by the shock absorber (Dn) with a variable damping force (Fcn). The device (1) comprises a control portion (2) which calculates a deviation (εn) between a damping force target value (Fsn) and the minimum damping force (Fdn) (S207), and open-loop controls the damping force varying mechanism (3) using a variable damping force (Fcn) calculated on the basis of the deviation (εn) such that the damping force generated by the shock absorber (Dn) coincide with the damping force target value (Fsn) (S208-S212), thereby optimizing damping force control of the shock absorber (Dn), which has a non-linear damping characteristic.