Electric Suspension Dead Zone Control
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Solution Overview
Problem
Existing electric suspension devices face challenges in accurately controlling damping force, particularly when a dead zone is set around the switch point for sprung speed, leading to inadequate suppression of vehicle behavior changes.
Innovation Solution
An electric suspension device that includes an information acquisition unit for acquiring sprung speed and acceleration, a bounce target value computation unit that adjusts the dead zone width based on these parameters, and a driving control unit to control the actuator using a control target load, ensuring accurate damping force control even when the dead zone includes the switch point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dead zone is set in the speed range including the switch point for sprung speed, then erroneous damping force control is avoided, but accurate damping force control is compromised
Solution Approach 1:
The patent applies dynamics by making the dead zone width variable rather than fixed. The control unit dynamically adjusts the width of the dead zone based on the absolute value of sprung speed, narrowing it as speed increases and widening it as speed decreases. This dynamic adjustment allows the system to maintain reliable error avoidance in the dead zone while improving measurement precision utilization at different operating conditions.
Solution Approach 2:
The patent changes the parameter of dead zone width from a constant value to a variable that depends on sprung speed magnitude. By setting the dead zone width to be inversely related to the absolute value of sprung speed, the system optimizes the balance between avoiding erroneous control (when sprung speed is near zero) and utilizing accurate speed measurements (when sprung speed is higher).
2Ease of operation
If the dead zone width is fixed, then control simplicity is maintained, but vibration suppression performance is insufficient
Solution Approach 1:
The patent transitions from a static fixed dead zone to a dynamic variable dead zone whose width automatically adjusts based on sprung speed conditions. This maintains ease of operation through automatic adaptation while significantly improving vibration suppression performance by optimizing the dead zone width for different operating conditions without requiring complex manual tuning.
3Measurement precision
If accurate sprung speed values in the dead zone are used, then control precision is improved, but erroneous damping force control occurs due to measurement errors
Solution Approach 1:
The patent changes the parameter of dead zone width based on the absolute value of sprung speed. By making the dead zone width proportional to 1/|sprung speed|, the system allows more precise utilization of speed measurements when |sprung speed| is high (where measurements are more reliable) while providing broader error protection when |sprung speed| is low (where measurement errors have greater impact).
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
This solution effectively suppresses vehicle behavior changes by finely tuning the dead zone width based on sprung speed and acceleration, enhancing vibration suppression and convergence performance.
Implementation Method 1
an actuator that is provided between a body and a wheel of a vehicle and generates damping force for damping vibration of the body
Data Source
AI summary
Provided is an electric suspension device including an electromagnetic actuator that is provided between a body and wheel of a vehicle and generates damping force for damping vibration of the body. It includes: an information acquisition unit that acquires information on a sprung speed and sprung acceleration of the vehicle; a bounce target value computation unit that computes a bounce target value for controlling the vehicle's bounce orientation based on the sprung speed; and a driving control unit that controls driving of the actuator with a control target load which is based on the bounce target value. The bounce target value computation unit has a bounce target load map in which the bounce target value is associated with the sprung speed. The bounce target value computation unit adjusts a width of a dead zone set in the map based on the information on the sprung speed and sprung acceleration.