Torque Allocation for Decoupled Vehicle Drives
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Solution Overview
Problem
Existing methods for operating decoupled electrical drives on a vehicle require complex pre-installation calibration to account for differences in drive properties, which is disadvantageous and does not adapt to subsequent changes in drive characteristics.
Innovation Solution
A method where a control device evaluates measured values during vehicle operation to determine allocation factors for torque distribution between the drives, using variables like steering angle, transverse acceleration, and yaw rate to adjust for imbalances and changes in drive characteristics, allowing for continuous re-adjustment of torque allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex pre-installation calibration is performed to determine allocation factors for torque distribution, then drive imbalances are compensated, but the process becomes time-consuming and costly
Solution Approach 1:
The system performs preliminary calibration actions during normal vehicle operation rather than requiring separate pre-installation calibration. The control device continuously collects measurement data from sensors during regular driving, automatically determining allocation factors without requiring dedicated calibration time or removing the vehicle from service.
Solution Approach 2:
The calibration process serves itself by using the vehicle's normal operation data to automatically determine allocation factors. The control device utilizes existing sensor measurements from steering angle, transverse acceleration, and yaw rate during regular driving to self-calibrate the torque distribution without external intervention or specialized equipment.
2Ease of operation
If fixed allocation factors are used for torque distribution, then the system is simple to operate, but it cannot adapt to subsequent changes in drive characteristics
Solution Approach 1:
The allocation factors transition from fixed to dynamic values that automatically adjust based on measured drive characteristics. The control device continuously updates allocation factors using real-time measurement data from vehicle operation, allowing the system to adapt to changing drive properties while maintaining simple operation through automated adjustments.
Solution Approach 2:
The system implements feedback by continuously monitoring measurement variables (steering angle, transverse acceleration, yaw rate) during vehicle operation and using this information to automatically adjust allocation factors. The control device compares measured values with expected values and modifies torque distribution accordingly, creating a closed-loop system that adapts to drive characteristic changes.
3Measurement precision
If manual calibration before installation is performed, then initial drive differences are compensated, but subsequent changes in drive properties are not accounted for
Solution Approach 1:
The calibration process becomes continuous rather than a one-time event. The control device continuously collects measurement data during vehicle operation and repeatedly determines allocation factors, ensuring that drive property measurements remain current and valid throughout the vehicle's operational life rather than becoming outdated over time.
Data Source
AI summary
When two (in particular electric) drives operate on wheels decoupled from each other in a motor vehicle, the drives should have an identical construction and the same properties. However, if one drive is stronger than the other, distribution factors other than 0.5 must define the target torque for the two drives, i.e. the fraction of a total torque, in order to provide a correction. The distribution factors are determined while the motor vehicle is in operation. For this purpose, a steering angle and an additional quantity such as the lateral acceleration or the yaw rate are determined and a check is performed to determine if the additional quantity has the correct functional dependency on the steering angle.