Electronic Parking Brake DAR Control for Smooth Drive-Away Release
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Solution Overview
Problem
The electronic parking brake (EPB) system's drive away release (DAR) function causes rapid acceleration when the parking brake is released in response to the accelerator pedal, leading to a lurching sensation, which can startle drivers and reduce usability.
Innovation Solution
A method of controlling the EPB system that monitors gear changes and accelerator pedal inputs, comparing them to predetermined values, and adjusts the gear position and driving force to minimize rapid acceleration by cooperative control among brake, transmission, and drive control units, including determining road gradients and ensuring seatbelt conditions are met before releasing the parking brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the parking brake is released automatically in response to accelerator pedal operation, then the DAR function convenience is improved, but rapid acceleration and lurching sensation occur
Solution Approach 1:
The control unit maintains the transmission in P position for a predetermined time after detecting accelerator pedal operation while the parking brake is released. This preliminary action delays the transmission gear change, allowing the parking brake to be fully released before the vehicle begins to move, thereby preventing the lurching sensation caused by simultaneous brake release and acceleration.
Solution Approach 2:
The system dynamically adjusts the timing of gear position changes based on the operational state of the parking brake and accelerator pedal. By making the transmission control adaptive rather than fixed, the system optimizes the sequence of events to eliminate the harmful lurching effect while preserving the convenience of automatic brake release.
2Speed
If the gear position is changed immediately when DAR function is activated, then the vehicle response speed is improved, but rapid acceleration and driver anxiety are caused
Solution Approach 1:
The control unit delays the gear position change from D position to N position until after the parking brake has been fully released and for a predetermined time period. This preliminary delay ensures that the vehicle is ready to move smoothly without sudden acceleration, reducing driver anxiety while maintaining appropriate response speed.
Solution Approach 2:
The system implements a timed sequence of operations where the gear position changes occur at specific intervals after accelerator pedal detection and brake release. This periodic control approach ensures smooth transitions and prevents abrupt acceleration by spacing out the gear change events appropriately.
Data Source
AI summary
In a method of controlling an electronic parking brake system to overcome an existing problem occurring in drive away release (DAR) mode, a control unit monitors whether or not a gear change signal is input in a vehicle stopped state, a P position state, or a parking brake applied state. When the gear change signal is input, an accelerator pedal input value of a driver is compared with a predetermined pedal input set value while a gear position of a transmission is maintained in the P position. When the accelerator pedal input value does not exceed the predetermined pedal input set value, a control operation is performed for automatic releasing of a parking brake. When a set time has passed after start of the control operation for the automatic releasing, a control operation of changing the gear position to the D position or the R position is performed.