Adaptive Brake Force Filtering for Smooth Automatic Parking
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Solution Overview
Problem
Existing brake control systems for automatic parking can cause vehicle shaking and discomfort for occupants due to inappropriate braking force control, leading to transmission of unwanted vibrations during parking maneuvers.
Innovation Solution
A brake controller that calculates target braking force through feedback control and applies a low-pass filter to smooth the output when the change in braking force is within a tolerable range, switching to direct output when the change is outside this range to prevent delays and vibrations, thereby maintaining occupant comfort during parking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low-pass filter is applied to smooth target braking force, then occupant comfort is improved by reducing vibrations, but response delay increases making braking less responsive
Solution Approach 1:
The patent applies a low-pass filter dynamically based on the vehicle's operational state. The filter is selectively activated during parking maneuvers when smooth braking is prioritized, while being deactivated during normal driving when responsive braking is critical. This dynamic application resolves the contradiction by adapting the filtering behavior to contextual requirements.
Solution Approach 2:
The patent changes the filtering parameter (filter application status) based on detected driving conditions. By monitoring whether the vehicle is performing parking maneuvers, the system adjusts the degree of smoothing applied to target braking force, thereby optimizing the balance between comfort and responsiveness for each operational context.
2Manufacturing precision
If feedback control is used to calculate target braking force, then braking precision is improved, but oscillations and vibrations occur making occupants uncomfortable
Solution Approach 1:
The patent introduces a low-pass filter as an intermediary between the feedback control system and the brake actuator. This filter mediates the high-frequency oscillations generated by precise feedback control, smoothing the target braking force before it reaches the brake system, thereby eliminating vibrations while preserving the precision benefits of feedback control.
Solution Approach 2:
The patent converts the harmful high-frequency oscillations generated by feedback control into a beneficial smoothing effect. By applying the low-pass filter, the system transforms the rapid fluctuations that cause vibrations into a smooth, stable braking force profile that enhances comfort while maintaining control precision.
3Object-affected harmful factors
If the low-pass filter time constant is increased to reduce vibrations, then occupant comfort is improved, but the filter becomes less effective at tracking rapid braking force changes
Solution Approach 1:
The patent dynamically adjusts the filter characteristics based on operational context. During parking maneuvers where smooth braking is acceptable, a larger time constant is effectively applied. During normal driving when rapid response is needed, the filter is bypassed entirely, maintaining full tracking capability. This dynamic adaptation resolves the trade-off between smoothing and tracking.
Data Source
AI summary
A brake controller includes a control circuit that calculates target braking force every predetermined period, in accordance with feedback control on at least acceleration or speed of a vehicle steered for parking; and a filter circuit that outputs, to a brake device, output braking force obtained by applying a low-pass filter having a predetermined time constant to the target braking force when the amount of change in the target braking force over time is within a predetermined tolerable range. When the amount of change is outside the tolerable range, the filter circuit outputs, to the brake device, the target braking force as output braking force or outputs thereto output braking force calculated by correcting smoothed target braking force, which is obtained by applying the low-pass filter to the target braking force, so that a difference between the smoothed target braking force and the target braking force is within the tolerable range.