Automatic Parking Idle Speed Prediction and Braking Force Control
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Solution Overview
Problem
Existing automatic parking control systems face challenges in accurately predicting idle speed changes to cancel vehicle driving force changes, leading to discomfort and reduced parking position accuracy due to delays in brake and engine response times.
Innovation Solution
An automatic parking control device with an electronic control unit that executes a rotation prediction process to calculate predicted idle speed changes, a driving force prediction process, and a braking force control process, incorporating processes like predicted rotational speed delay, rate limiting, and first-order delay to adjust braking force accordingly, regardless of brake or engine response delay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the automatic parking control uses creep running with idle operation to move the vehicle to a target parking position, then the vehicle can be moved automatically, but the vehicle driving force changes when idle speed changes, causing shock and discomfort to occupants
Solution Approach 1:
The control device predicts the change in idle speed before it occurs and applies braking force in advance to counteract the resulting driving force change. This preliminary anti-action prevents the shock and discomfort that would otherwise occur when the idle speed changes during automatic parking control.
Solution Approach 2:
The system performs preliminary prediction of idle speed changes using a rotation prediction process that considers brake response delay time and engine response delay time. By predicting the idle speed change in advance, the control device can prepare the appropriate braking force adjustment before the actual speed change occurs, ensuring smooth compensation.
2Object-affected harmful factors
If the system actively adjusts braking force change timing to alleviate occupant discomfort, then comfort is improved, but parking position accuracy decreases due to deviation from driving force change timing
Solution Approach 1:
The rotation prediction process performs preliminary calculation of idle speed changes by advancing the actual idle speed change timing by the brake response delay time. This allows the control device to determine the precise timing and magnitude of braking force adjustments needed to maintain both comfort and parking position accuracy.
Solution Approach 2:
The system uses feedback from the predicted idle speed changes to continuously adjust the braking force. By comparing the predicted driving force changes with actual conditions and adjusting the braking force accordingly, the system maintains both occupant comfort and accurate parking position without timing deviations.
3Manufacturing precision
If the system predicts idle speed change portion to calculate target vehicle braking force, then parking position accuracy is maintained, but the complexity of the control system increases due to multiple prediction and control processes
Solution Approach 1:
The control device integrates multiple functions into a single system: it performs rotation prediction, driving force prediction, and braking force control all through one control device. This multi-functionality maintains parking position accuracy while avoiding the need for separate dedicated systems for each function, thereby limiting the increase in overall system complexity.
4Force
If the brake response delay time is longer than the engine response delay time, then the brake device can provide sufficient braking force, but the prediction of idle speed changes becomes more difficult and parking control accuracy decreases
Solution Approach 1:
When brake response delay time exceeds engine response delay time, the rotation prediction process advances the idle speed change timing by the brake response delay time to predict when the braking force will actually take effect. This preliminary prediction ensures accurate timing of braking force application despite the longer brake response delay, maintaining parking control accuracy.
Solution Approach 2:
The system replaces direct mechanical response timing with a computational prediction model that accounts for brake response delay time and engine response delay time differences. This substitution allows the control device to calculate the optimal braking force timing and magnitude, ensuring accurate parking control even when mechanical brake response is slower than engine response.
Data Source
AI summary
An automatic parking control device is configured to: execute a rotation prediction process to calculate a predicted idle speed change portion by advancing an actual idle speed change portion by a brake response delay time; execute a driving force prediction process to calculate a predicted driving force change portion according to the predicted idle speed change portion; execute a braking force control process to calculate a change portion of a target vehicle braking force that cancels the predicted driving force change portion and instruct it to a brake device; and, when the brake response delay time is longer than an engine response delay time, execute a rotational speed control delay process to delay a target idle speed change by a rotational speed control delay time being longer than or equal to a difference obtained by subtracting the engine response delay time from the brake response delay time.