eLSD Torque Arbitration for Yaw and Wheel Slip Control
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Solution Overview
Problem
Existing electronic limited slip differential (eLSD) systems face challenges in effectively managing torque distribution across wheels to maintain vehicle stability, especially during high-performance driving conditions.
Innovation Solution
The eLSD control system integrates a preemptive planar coordinator module, direct yaw feedback control module, wheel stability control module, and core arbitration clutch response module to determine and adjust clutch torque requests based on various targets, including longitudinal, yaw moment, and tractive limits, to optimize torque distribution and minimize wheel slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If eLSD systems adjust torque distribution to maintain vehicle stability, then vehicle stability is improved, but the system complexity increases due to multiple control modules and arbitration mechanisms
Solution Approach 1:
The control system is divided into multiple specialized modules: preemptive planar coordinator module for baseline torque distribution, direct yaw feedback control module for yaw rate correction, wheel stability control module for slip prevention, and powerhop module for vibration suppression. Each module handles a specific control aspect independently, improving overall vehicle stability while managing complexity through functional segmentation
Solution Approach 2:
A core arbitration clutch response module serves as an intermediary that receives torque requests from multiple control modules, prioritizes them based on criticality, and generates the final clutch torque command. This mediator coordinates conflicting control objectives and manages the interaction between different control strategies, resolving the complexity of integrating multiple stability control functions
2Manufacturing precision
If the system integrates multiple control modules for precise torque distribution, then torque distribution precision is improved, but the control algorithm complexity increases
Solution Approach 1:
Each control module focuses on a specific local control objective: the preemptive planar coordinator optimizes baseline torque distribution based on driving conditions, the direct yaw feedback module corrects yaw rate deviations, the wheel stability module prevents wheel slip, and the powerhop module suppresses suspension vibrations. This localized specialization enables precise torque distribution for each control aspect while keeping individual module algorithms manageable
Solution Approach 2:
The system implements multiple feedback loops: yaw rate feedback in the direct yaw feedback module compares actual yaw rate with target yaw rate and adjusts torque accordingly, wheel slip feedback in the wheel stability module monitors wheel slip conditions and modifies torque distribution to prevent slip, and vibration feedback in the powerhop module detects and suppresses powerhop events. These feedback mechanisms enable precise torque distribution through continuous error correction
3Loss of time
If the system prioritizes critical events like powerhop events, then response time to critical events is improved, but the overall control system complexity increases
Solution Approach 1:
The preemptive planar coordinator module proactively determines baseline clutch torque requests based on predicted driving conditions and tractive limits before critical events occur. This preliminary action establishes a stable baseline torque distribution that prevents many instability issues before they arise, reducing the need for reactive corrections and improving overall system responsiveness
Solution Approach 2:
The core arbitration clutch response module pre-establishes a prioritization scheme for different control modules, assigning priority levels to various control objectives. When multiple torque requests are generated simultaneously, the arbitration module applies pre-defined priority rules to resolve conflicts quickly without complex real-time decision-making, enabling fast response to critical events like powerhop while maintaining manageable system complexity
Data Source
AI summary
An eLSD control system includes: an eLSD configured to adjust torque to shafts of an axle of a vehicle; a preemptive planar coordinator module configured to determine targets for an eLSD clutch torque and generate a first clutch torque request based on the targets; a direct yaw feedback control module configured to track a target yaw rate for the vehicle, determine a yaw rate error, and generates a second clutch torque request to reduce the yaw rate error; a wheel stability control module configured to generate a third clutch torque request to minimize at least one of i) slip between wheels of the axle, and ii) slip on one of the wheels experiencing higher traction; and a core arbitration clutch response module configured to control the eLSD clutch torque of the eLSD based on the first clutch torque request, the second clutch torque request, and the third clutch torque request.