Driveline Torque Control for Predictive Lash Crossing Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for addressing lash crossing in drivelines, such as virtual modeling and preloading motors, are inefficient and energy-consuming, particularly in complex electric vehicle drivetrains, leading to noticeable noise, vibration, and harshness (NVH) issues.
Innovation Solution
Implementing a feedback control scheme with a proportional-derivative loop to predict and modify torque commands in response to impending lash crossing events, using a motor controller to generate corrections and attenuate disturbances in the driveline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If model-based prediction is used to address lash crossing, then NVH characteristics are improved, but processing power requirements and system complexity increase
Solution Approach 1:
The system performs preliminary detection of lash crossing conditions by monitoring motor torque sign changes, and applies preliminary correction by adjusting the torque command before the actual lash crossing occurs. This proactive approach reduces the complexity of real-time complex modeling while maintaining effective NVH control.
Solution Approach 2:
The system implements a feedback control scheme where the motor controller continuously monitors driveline conditions, detects upcoming lash crossings through torque sign change detection, and applies corrective torque adjustments. This closed-loop feedback mechanism simplifies the control architecture compared to open-loop model-based prediction while achieving comparable NVH performance.
2Object-affected harmful factors
If preloading a motor on one axle is used to address lash crossing, then NVH characteristics are improved, but energy consumption increases and vehicle range decreases
Solution Approach 1:
Instead of continuous preloading, the system applies torque corrections periodically and selectively - only when lash crossing conditions are detected through torque sign change monitoring. This on-demand correction approach eliminates continuous energy consumption while maintaining effective NVH control during critical moments.
Solution Approach 2:
The motor controller itself performs the detection and correction functions using existing torque command signals, eliminating the need for separate preload mechanisms or additional actuators. The system uses its own operational data (torque sign changes) to trigger corrections, making the solution energy-efficient and self-contained.
3Measurement precision
If virtual modeling of driveline is used to predict lash crossing, then prediction accuracy is improved, but processing power requirements increase
Solution Approach 1:
The system extracts only the essential feature for lash crossing detection - the sign change of motor torque - from the complex driveline dynamics. By focusing on this single critical indicator rather than modeling the entire driveline virtual model, the system achieves sufficient prediction accuracy with minimal processing power requirements.
Solution Approach 2:
Instead of maintaining complex, computationally expensive virtual models, the system uses simple, lightweight torque sign change detection that requires minimal processing resources. This simplified 'disposable' detection method is refreshed continuously with each torque command update, providing accurate enough prediction without the burden of heavy computational models.
Data Source
AI summary
A method comprises: generating a torque command for a motor of a vehicle, the torque command generated by a motor controller based at least in part on driver input; generating, by a feedback control scheme of the motor controller, a correction for the torque command; determining, by the motor controller, whether a lash crossing event is expected to occur within a time period; in response to a determination that the lash crossing event is expected to occur within the time period, modifying the torque command with the correction to generate a resulting torque command; and controlling the motor using the resulting torque command.