Parking Speed Drift Mitigation via Look-Ahead Setpoint Control
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Solution Overview
Problem
Current automated parking systems fail to accurately manage vehicle speed during parking maneuvers due to external disturbances and imprecision in engine response, leading to speed drifts and reduced maneuver comfort.
Innovation Solution
A system that calculates a speed error based on a setpoint and measured speed, detects a local minimum point in the speed curve, and adjusts the speed setpoint to mitigate speed drifts by activating a recovery speed setpoint when the error exceeds a threshold, ensuring stable vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the internal combustion engine is used for vehicle propulsion during parking maneuvers, then the vehicle can maintain motion, but the long response time (up to 4 seconds) and imprecision in torque application cause speed drifts and reduce control accuracy
Solution Approach 1:
The system calculates a look-ahead speed setpoint based on future timing rather than current speed errors, anticipating the engine's delayed response. This preliminary action compensates for the 4-second response lag by pre-calculating what the speed should be, rather than reacting to current deviations
Solution Approach 2:
The system continuously monitors actual vehicle speed and compares it with the calculated look-ahead speed setpoint, using this feedback loop to adjust torque commands and maintain accurate speed control despite the engine's inherent response delays
2Measurement precision
If the speed setpoint is continuously adjusted to correct speed drifts, then speed control accuracy improves, but the system complexity increases due to additional calculation modules and threshold comparisons
Solution Approach 1:
The system changes the parameter used for speed control from simple proportional control to a look-ahead speed setpoint based on timing calculations. This parameter transformation simplifies the control logic by using time-based predictions rather than complex continuous adjustments
Solution Approach 2:
The look-ahead speed setpoint acts as an intermediary between the desired speed and the actual engine response. Rather than directly controlling engine torque based on speed errors, the system uses this intermediate timing-based speed reference to mediate the control process
3Reliability
If external disturbances such as slope changes or obstacles are encountered, then the vehicle speed drops below setpoint, but rapid acceleration follows as the engine compensates, causing speed overshoots and reducing maneuver comfort
Solution Approach 1:
The look-ahead speed setpoint anticipates the need for compensation before speed drifts occur. By calculating the expected speed based on future timing rather than reacting to current errors, the system applies preliminary counter-action that prevents overshoots when disturbances occur
Solution Approach 2:
The system cushions against the harmful effects of external disturbances by using a smoothed, time-based speed reference. This beforehand cushioning prevents the aggressive corrections that would otherwise cause rapid acceleration and overshoot following speed drops
Data Source
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AI summary
Method (50) for detecting and mitigating speed drifts of a motor vehicle, in which: a speed error is calculated at a given instant as a function of a speed setpoint value at a previous instant and a measured value of the vehicle's speed, said speed error is compared with a threshold value, a local minimum point of the vehicle's speed curve is calculated when said speed error is greater than the threshold value, the local minimum point is detected, and a resumption speed setpoint is calculated when the local minimum point is detected.