Vehicle Braking Control Device Pressure Oscillation
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Solution Overview
Problem
Existing braking control systems for vehicles face challenges in achieving accurate and smooth adjustment of braking fluid pressure, often resulting in oscillatory fluid pressure control due to interference between feedback and feedforward control mechanisms.
Innovation Solution
A braking control device that calculates target fluid pressure based on wheel speed, deceleration state, and turning state, using separate feedback and feedforward control to avoid interference, with an electric motor driving a fluid pump and a controller managing electromagnetic valves to regulate fluid pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the opening degree of the pressure increasing valve is adjusted to control braking fluid pressure, then the braking fluid pressure can be regulated, but the supply current of the electric motor changes causing output torque and rotational speed to change, resulting in control interference and oscillatory fluid pressure
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the actual fluid pressure in the wheel cylinder and compares it with the target fluid pressure. Based on the pressure difference, the controller adjusts the supply current to the electric motor to maintain stable fluid pressure. This closed-loop feedback system eliminates the oscillatory behavior caused by the coupling between valve opening degree and motor current, as the feedback mechanism compensates for disturbances and maintains pressure stability.
2Speed
If feedforward control is used to determine supply current based on substantial accommodation capacity sum, then response speed improves, but control interference occurs due to coupling between valve opening degree and supply current
Solution Approach 1:
The patent segments the control system into independent feedback and feedforward control channels. The feedback control channel handles stability by continuously adjusting supply current based on actual fluid pressure measurements. The feedforward control channel handles response speed by pre-calculating required supply current based on target fluid pressure and substantial accommodation capacity. This segmentation decouples the control functions, allowing both speed and reliability to be optimized simultaneously without mutual interference.
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 approach enables accurate, stable, and robust braking fluid pressure control by separating feedback and feedforward control, preventing oscillations and improving the overall precision and reliability of the braking system.
Implementation Method 1
an electric motor (MT) which drives the fluid pump (HP)
Implementation Method 2
a controller (ECU) which controls the electric motor (MT)... pumps a brake fluid (BF) from a reservoir (RV) to a wheel cylinder (WC)
Data Source
AI summary
This braking control device pumps a brake fluid from a reservoir to each wheel cylinder by one fluid pump and includes an electric motor which drives the fluid pump; and a controller which controls the electric motor. The controller calculates a target fluid pressure on the basis of at least one among the vehicle wheel speed, the vehicle deceleration state, and the turning state of the vehicle, calculates a target discharge amount for the fluid pump on the basis of the target fluid pressure, and controls the electric motor on the basis of the target discharge amount. The controller has a front wheel calculation map of the relationship between the fluid pressure and the inflow volume of the brake fluid corresponding to a front wheel cylinder, and a rear wheel calculation map corresponding to a rear wheel cylinder, and calculates the target discharge amount on the basis of the maps.