Adaptive Backlash Control in Vehicle Powertrains
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Solution Overview
Problem
Existing systems for controlling backlash in vehicle powertrains face challenges due to uncertainties in operational parameters, leading to unacceptably slow tip-in responses and rough transitions, as they struggle to accurately determine when the driveline is in the backlash region and traverse it smoothly.
Innovation Solution
A method and system that employ a control strategy with adaptive torque management, modifying the torque request based on backlash predictions and occurrences, reducing torque duration or level when backlash is imminent, and implementing a modified strategy after each backlash event to ensure smooth transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control strategy is used to control torque request after backlash predictor and before backlash occurrence, then the driveline can be controlled to traverse backlash region, but the tip-in response becomes unacceptably slow due to decreased backlash transition rate
Solution Approach 1:
The control strategy dynamically adjusts torque request based on real-time detection of backlash region entry and traversal progress. The system transitions from a static torque control approach to a dynamic one that modifies torque levels during different phases of backlash traversal, enabling both smooth transitions and fast response by adapting torque application to the current driveline state
Solution Approach 2:
The system implements feedback by continuously monitoring driveline parameters to detect when the driveline enters and traverses the backlash region. This feedback information is used to modify the torque request in real-time, allowing the control system to respond appropriately to actual driveline conditions rather than relying on fixed control parameters, thereby achieving both smooth transitions and acceptable response speed
2Ease of operation
If torque adjustments are made to control backlash by lowering pre-lash requested torque, then the rate that driveline passes through backlash decreases, but this leads to unacceptably slow tip-in response
Solution Approach 1:
The control system performs preliminary action by detecting the entry into the backlash region before actual backlash occurs (using backlash predictor). This early detection allows the system to prepare appropriate torque control actions in advance, modifying the torque request strategy proactively rather than reactively, thereby achieving smooth transitions without excessive delay in tip-in response
Solution Approach 2:
The system dynamically modifies the torque request based on the detected phase of backlash traversal. Instead of uniformly lowering torque throughout the process, the control strategy adapts torque levels to the specific moment in the backlash sequence, applying different torque adjustments during different phases to balance smoothness and response speed
Data Source
AI summary
A system and method for controlling backlash in a vehicle powertrain includes the step of controlling a torque request of the powertrain with a first control strategy after an occurrence of a backlash predictor and prior to an occurrence of backlash. The first control strategy is modified when backlash occurs during the first control strategy. The torque request is controlled with the modified first control strategy after another occurrence of a backlash predictor and before another occurrence of backlash.