Dynamic Torque Limiting for Automated Steering Handover
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Solution Overview
Problem
Current vehicle steering systems face challenges in smoothly transitioning and collaborating between human and automated control, particularly in scenarios where lane markings are unclear or road conditions change, leading to inconsistent and potentially unsafe driving experiences.
Innovation Solution
A vehicle steering system with a torque limiter module that dynamically adjusts the torque output based on vehicle parameters and driver input, ensuring a configurable torque limit that reduces as driver steering input increases, allowing for seamless handover of control between automated and human driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a fixed torque limit is applied to the steering motor, then the automated control authority is maintained, but the driver's ability to take over control smoothly is restricted
Solution Approach 1:
The torque limiter module dynamically adjusts the torque limit based on real-time detection of driver steering input rather than using a fixed limit. When driver input is detected, the system gradually reduces the torque limit, enabling smooth transition from automated to manual control. This dynamic adjustment resolves the contradiction by allowing the system to maintain automated authority when needed while facilitating smooth handover when the driver intervenes.
Solution Approach 2:
The system changes the torque parameter dynamically based on driver input conditions. The torque limit is not static but varies according to the detected driver steering torque, allowing the automated control authority to be maintained during normal operation while enabling smooth takeover when the driver applies steering input. This parameter change strategy resolves the contradiction between maintaining automation and enabling ease of operation.
2Manufacturing precision
If the torque output is increased to maintain lane positioning, then the lateral control precision is improved, but the driver's steering input is overridden more aggressively
Solution Approach 1:
The torque limiter module continuously monitors driver steering input and provides feedback to adjust the torque limit accordingly. When driver input is detected, the system reduces the torque limit to prevent aggressive override of driver intentions. This feedback mechanism resolves the contradiction by allowing high torque output for precise lane positioning only when the driver is not actively steering, while automatically reducing torque when driver input is present to avoid harmful overrides.
Solution Approach 2:
The system applies preliminary anti-action by preemptively reducing the torque limit when driver steering input is detected, before the automated torque can override the driver's intentions. This prevents the harmful effect of aggressive torque override while maintaining the ability to apply sufficient torque for precise lane positioning when the driver is not intervening.
3Ease of operation
If the torque limit is reduced to allow driver takeover, then the ease of operation is improved, but the automated control effectiveness is diminished
Solution Approach 1:
The torque limit adjusts dynamically based on the presence and magnitude of driver steering input. When no driver input is detected, the full torque limit is applied to maintain effective automated control. When driver input is detected, the torque limit is gradually reduced to facilitate smooth takeover. This dynamic approach resolves the contradiction by maintaining automated control effectiveness during automated operation while enabling easy driver takeover when needed.
Data Source
AI summary
A vehicle steering system includes an input configured to receive a signal representing a target steering angle, an output configured to provide a torque output command to a steering motor based on the target steering angle, and a torque limiter module configured to receive the torque output command and apply a torque limit thereto, prior to prior to the torque output command being provided to the steering motor. The torque limit is configurable dynamically based on at least one vehicle parameter. Aspects of the disclosure also relate to a method, a controller configured to implement the method, and a vehicle incorporating the controller or the system.