Semi-Active Seat Damper Control for Endstop Jerk Reduction
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Solution Overview
Problem
Current seat dampers, even semi-active ones, fail to completely eliminate the jerking sensation and lead/lag bounce issues when approaching endstops, as they primarily respond to relative movement and do not effectively attenuate vibrations at these points, leading to undesirable transmission of impacts to the seat occupant.
Innovation Solution
A method for controlling the damping force of a semi-active seat damper system that involves measuring acceleration and displacement signals, calculating scaled values, and generating control signals to adjust damping forces dynamically, using a combination of endstop control and skyhook control mechanisms to prevent hard impacts at endstops, thereby smoothing the ride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If semi-active dampers use only relative movement-based control, then the device complexity is reduced, but the vibration attenuation performance deteriorates at endstop positions
Solution Approach 1:
The patent implements feedback control by measuring absolute acceleration of the seat and using it to generate skyhook control signals. The controller continuously monitors acceleration and adjusts damping forces in real-time based on the measured motion state, creating a closed-loop control system that improves vibration attenuation without excessive complexity
Solution Approach 2:
The control system is segmented into two independent but complementary control mechanisms: endstop control (based on relative displacement and velocity) and skyhook control (based on absolute acceleration). These segmented control strategies are combined through signal aggregation to achieve comprehensive vibration attenuation across different operating conditions
2Device complexity
If passive dampers oppose relative movement, then the damping force generation is simplified, but the transmission of vibrations is amplified under certain conditions
Solution Approach 1:
The patent transitions from static passive damping to dynamic semi-active damping by continuously adjusting the damping coefficient based on real-time motion measurements. The damping force is dynamically modified using skyhook control signals derived from absolute acceleration, allowing the system to adapt to varying vibration conditions and prevent harmful vibration amplification
Solution Approach 2:
The damping parameter (damping coefficient) is changed dynamically during operation based on the measured absolute acceleration and relative motion. The controller adjusts the damping force magnitude according to the vibration state, transforming the fixed parameter of passive dampers into a variable parameter that optimizes vibration attenuation performance
3Reliability
If semi-active dampers add control mechanisms, then the vibration attenuation improves, but the device complexity increases
Solution Approach 1:
The controller serves multiple functions: it processes acceleration signals, generates skyhook control signals, processes relative displacement signals, generates endstop control signals, and aggregates both control strategies. This multi-functional control unit achieves improved vibration attenuation without requiring separate dedicated systems for each control aspect
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces the transmission of harsh impacts to the seat occupant by applying a progressively firmer damping force as the seat approaches endstops, enhancing ride comfort by minimizing jerking and bounce effects.
Implementation Method 1
A semi-active damper resembles a passive one in that it does not include a pump or other source of pressurized fluid. A semi-active damper can only generate damping forces in response to and in opposition to relative movement between the members interconnected by it.
Implementation Method 2
Such control may be realized by using an adjustable valve device in association with the orifice or passageway interconnecting the variable volume chambers of the damper, together with a controller for dynamically adjusting the valve during damper operation.
Data Source
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AI summary
A method is disclosed to smooth the ride of a seat occupant by controlling the damping force of a fluid damper positioned between the seat and base. The method selects between different subprocesses to minimize the ride discomfort and to minimize peak seat accelerations and endstop jerks. The controller uses the input from the different subprocesses to create the best ride for the immediate operational conditions.