Virtual Brake Control for Downhill Speed Holding in EVs
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Solution Overview
Problem
Current downhill driving technologies for electrified vehicles, such as smart cruise control (SCC) and downhill brake control (DBC), are inadequate in maintaining desired speed and can generate noise, impairing drivability and not fully satisfying driver-set speed requirements during downhill driving.
Innovation Solution
An electrified vehicle system that uses a brake position sensor and controller to generate a virtual brake signal based on inclination and brake pedal input, allowing for improved control by determining a preset virtual brake-based control condition and outputting a braking command, thereby reducing driver intervention and maintaining desired speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If smart cruise control (SCC) function is used for downhill driving, then speed maintenance within predetermined range is achieved, but the function cannot activate control when brake pedal is pressed and terminates control upon brake pedal manipulation
Solution Approach 1:
The control system automatically determines virtual brake signal generation conditions based on brake pedal input values and inclination, eliminating the need for manual activation/deactivation by the driver. The system serves itself by monitoring brake pedal position and autonomously deciding when to generate virtual brake signals for downhill speed control.
Solution Approach 2:
The controller pre-establishes threshold values for brake pedal input based on road inclination before downhill driving occurs. These preliminary设定的 thresholds enable the system to automatically recognize when virtual brake signal generation is needed, ensuring reliable control activation without waiting for driver input.
2Reliability
If downhill brake control (DBC) function is used for downhill driving, then speed maintenance within predetermined range is achieved, but speed control is limited and desired speed set by driver may not be fully satisfied
Solution Approach 1:
The control system dynamically adjusts the virtual brake signal generation strategy based on real-time brake pedal input values and road inclination. By continuously adapting the control parameters according to driver input intensity and road conditions, the system can satisfy various driver desired speeds while maintaining reliable downhill control.
Solution Approach 2:
The controller changes control parameters including virtual brake signal magnitude and generation timing based on the relationship between brake pedal input value and inclination-specific thresholds. This parameter adjustment enables flexible adaptation to different driver speed requirements while maintaining control reliability.
3Reliability
If DBC function is used for downhill driving, then speed control within predetermined range is achieved, but noise is generated during control process which impairs drivability
Solution Approach 1:
The controller generates virtual brake signals selectively based on whether brake pedal input exceeds inclination-specific thresholds, rather than continuously. This partial action approach maintains control reliability only when needed, reducing unnecessary brake actuations that generate noise and improve drivability.
Solution Approach 2:
The control system continuously monitors brake pedal input values and compares them against thresholds determined by road inclination. This feedback mechanism enables the system to recognize when driver input indicates a need for virtual brake signal generation, allowing selective control activation that reduces noise while maintaining reliability.
4Ease of operation
If virtual brake signal-based control is implemented, then driving convenience is improved by minimizing driver intervention, but system complexity increases due to additional control logic
Solution Approach 1:
The control system integrates virtual brake signal generation functionality into the existing brake control architecture, allowing the same controller to handle both normal brake operations and downhill virtual brake control. This multi-functionality approach minimizes additional hardware complexity while achieving reduced driver intervention.
Solution Approach 2:
The patent combines the virtual brake signal generation logic with the existing brake control system, merging multiple functions (brake monitoring, inclination-based threshold determination, virtual signal generation) into a unified control process. This integration reduces overall system complexity compared to separate dedicated systems.
Data Source
AI summary
An electrified vehicle with a brake position sensor and a controller and a downhill driving control method for the electrified vehicle include the controller which is configured to determine whether a virtual brake-based control condition is satisfied and outputs a braking command based on a virtual brake signal generated based on a first threshold value when the virtual brake-based control condition is satisfied.