Steer-By-Wire Handwheel Virtual End Stop From Roadwheel Travel
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Solution Overview
Problem
In Steer-by-Wire (SbW) systems, there is no physical end travel for the handwheel actuator, making it challenging to learn and protect the end-of-travel values, which is crucial for preventing over-travel and protecting the mechanical system.
Innovation Solution
A system and method that utilize sensor data from the roadwheel actuator to determine the mechanical end-of-travel value, which is then used to calculate the handwheel actuator's end-of-travel active value and damping value. These values are combined with a reference torque value to selectively control the handwheel, ensuring proper end-of-travel protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical end stop methods are used for handwheel actuator, then physical end travel can be defined, but SbW systems cannot implement this because there is no physical connection between handwheel and roadwheel
Solution Approach 1:
The patent replaces the traditional mechanical end stop system with a software-based virtual end stop. The controller determines a virtual end-of-travel position for the handwheel actuator based on the actual end-of-travel position of the roadwheel actuator, eliminating the need for physical mechanical connections while maintaining end-of-travel protection functionality.
Solution Approach 2:
The patent introduces a virtual end-of-travel position as an intermediary concept between the handwheel actuator and roadwheel actuator. This virtual position serves as the software equivalent of a mechanical end stop, allowing the system to define and protect against handwheel actuator end-of-travel conditions without direct mechanical coupling.
2Reliability
If software-based end stop control is implemented, then end-of-travel protection can be achieved in SbW systems, but complex calculations involving multiple parameters are required
Solution Approach 1:
The patent transforms the end-of-travel control problem from a mechanical position-based system to a software-based system that uses multiple parameters including handwheel actuator position, roadwheel actuator position, steering ratios, and damping coefficients. The controller dynamically adjusts these parameters to determine the virtual end-of-travel position and apply appropriate damping forces.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously monitors the positions of both handwheel and roadwheel actuators, compares the current state against the calculated virtual end-of-travel position, and dynamically adjusts the damping force applied to the handwheel actuator based on the deviation from the virtual end stop.
3Measurement precision
If virtual end-of-travel position is calculated based on roadwheel actuator position, then accurate protection can be provided, but the system must continuously monitor and process sensor data
Solution Approach 1:
The patent performs preliminary calculations of the virtual end-of-travel position based on the roadwheel actuator's actual end-of-travel position and steering ratios. By pre-calculating and storing these virtual end stop positions, the system reduces the computational burden during real-time operation, allowing for faster response while maintaining measurement precision.
Data Source
AI summary
A system for controlling an end-of-travel of a handwheel is disclosed. The system comprises: a processor; and a memory that includes instructions that, when executed by the processor, cause the processor to: receive sensor data from at least one sensor associated with a roadwheel actuator of a vehicle; determine, based on the sensor data, a mechanical end-of-travel value of the roadwheel actuator of a roadwheel actuator of the vehicle; determine, based on the mechanical end-of-travel value of the roadwheel actuator and a speed of the vehicle, a handwheel actuator end-of-travel active value and an end-of-travel damping value; determine an end-of-travel value of a handwheel actuator based on the handwheel actuator end-of-travel active value, the end-of-travel damping value, and a reference torque value; and selectively control the handwheel of the vehicle based on the end-of-travel value of the handwheel actuator.