Adaptive Clutch Torque Estimation for Transmission Control
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Solution Overview
Problem
Automatic transmissions face challenges in accurately controlling clutch torque due to variations in transmission components and environmental factors, leading to uncertainties in torque estimation, which can result in inefficient shifting and potential engine flare or tie-up conditions.
Innovation Solution
Implementing a method that adjusts shift schedules based on the magnitude of uncertainty in estimated clutch torque, either by avoiding specific gears with high uncertainty or increasing shift time to reduce uncertainty, using a controller to manage clutch operations and adapt models for improved torque estimation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission operates using a fixed shift schedule, then the control logic is simple and predictable, but the clutch torque estimation accuracy deteriorates due to variations in transmission components and environmental factors
Solution Approach 1:
The patent applies dynamics by making the shift schedule adaptive rather than fixed. The controller dynamically adjusts shift timing and clutch torque based on real-time uncertainty estimates. When uncertainty is high, the system modifies shift behavior to reduce uncertainty; when uncertainty is low, it maintains normal operation. This dynamic adaptation resolves the contradiction by allowing simple fixed schedules when conditions permit while enabling complex adaptive behavior when accuracy is compromised.
Solution Approach 2:
The patent implements feedback by continuously monitoring clutch torque estimation uncertainty and using this information to adjust subsequent shift operations. The system estimates uncertainty based on component variations and environmental factors, then feeds this information back to modify the shift schedule. This closed-loop feedback mechanism improves torque estimation accuracy without requiring permanently complex control logic, as the complexity is only activated when needed.
2Reliability
If the transmission increases shift time to reduce clutch torque uncertainty, then the torque estimation accuracy improves, but the shifting speed and responsiveness deteriorate
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting shift time based on uncertainty levels. Rather than using a fixed or uniformly increased shift time, the system modifies the time parameter selectively - extending shift duration only when uncertainty thresholds are exceeded and maintaining normal shift speeds when uncertainty is acceptable. This selective parameter adjustment resolves the contradiction by improving accuracy only when necessary without permanently sacrificing shifting speed.
3Adaptability or versatility
If the transmission uses multiple clutches for gear operation, then the gear selection flexibility improves, but the uncertainty in clutch torque estimation increases due to component variations
Solution Approach 1:
The patent applies local quality by treating each clutch individually with its own uncertainty estimation and adaptive control strategy. Rather than applying a uniform approach to all clutches, the system evaluates component variations and environmental factors specific to each clutch, then adjusts control parameters locally. This allows the transmission to maintain gear selection flexibility while improving torque estimation accuracy for each specific clutch based on its actual condition rather than relying on generic estimates.
Data Source
AI summary
A transmission for a vehicle includes a plurality of clutches that are individually selectively engaged to establish particular power flow paths. The amount of torque flowing through any clutch can be estimated while the clutch is being engaged, being disengaged, or being held locked. The estimated magnitude of clutch torque aids in proper control of the transmission, including how and when to shift between gears. A method and system for determining the uncertainty of estimated clutch torque is provided. Based on the magnitude of uncertainty of estimated clutch torque, the shift schedule can alter to specifically avoid actions that would increase the uncertainty, or the time between shifting gears can increase to reduce the effects of the uncertainty.