One-Pedal Drive Grade Compensation Torque Control
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Solution Overview
Problem
One-pedal drive systems in hybrid/electric vehicles face challenges in smoothly stopping the vehicle when a fault is detected, such as rolling back in an unintended direction, due to excessive feedforward and feedback torques, which can lead to unstable braking and failure to maintain zero speed without brake pedal application.
Innovation Solution
A controller in the vehicle adjusts the maximum magnitude of feedforward road grade compensation torque to a predefined value when a fault is detected, such as rolling back in an opposite direction with torques exceeding specific thresholds, to ensure stable braking and zero-speed maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feedforward road grade compensation torque is increased to compensate for road grade, then the vehicle can maintain better stopping performance on grades, but the system becomes unstable when faults occur and excessive torque causes rolling back in unintended directions
Solution Approach 1:
The system dynamically adjusts the feedforward torque magnitude based on detected fault conditions. When a fault is detected (vehicle rolling back more than a predefined time period with feedback data noise compensation torque exceeding threshold), the controller reduces the maximum magnitude of feedforward road grade compensation torque to a predefined value, allowing the system to adapt its torque application strategy to current operating conditions and prevent harmful effects
Solution Approach 2:
The system uses feedback from vehicle motion sensors to detect when the vehicle is rolling back in an unintended direction. This feedback mechanism monitors the actual vehicle behavior and compares it against expected behavior, triggering fault detection when discrepancies occur (vehicle moving opposite to travel direction with feedback torque exceeding threshold), which then prompts adjustment of the feedforward torque to prevent further unintended movement
2Reliability
If the feedback torque is increased to compensate for data noise, then the system can better maintain zero speed, but the overall system stability deteriorates when combined with high feedforward torque during faults
Solution Approach 1:
The controller dynamically adjusts the feedforward torque magnitude based on the interaction between feedback torque and detected fault conditions. When faults are detected (feedback data noise compensation torque exceeding threshold combined with vehicle rolling back), the system reduces the maximum feedforward torque to a predefined value, creating a dynamic balance that maintains zero-speed capability while preventing system instability
Data Source
AI summary
A vehicle includes a gear selector that selects between a drive and reverse gear. The gear selected defines an intended travel direction. The vehicle also includes a controller that, responsive to user input, activates a one-pedal drive system, and responsive to detecting the vehicle is rolling back for more than a predefined time period, a feedforward road grade compensation torque being opposite to the intended travel direction and having a magnitude greater than a feedforward threshold, and a feedback data noise compensation torque in the intended travel direction having a magnitude greater than a feedback threshold, reduces the maximum magnitude of the feedforward road grade compensation torque to a predefined value throughout a current key cycle for the vehicle.