MDPS Fail-Safe Vehicle Speed Error Detection
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Solution Overview
Problem
Current motor-driven power steering (MDPS) systems lack effective error detection and fail-safe mechanisms for vehicle speed data, leading to inconsistent steering feel and stability when errors occur, particularly at high speeds or when GPS data is unavailable.
Innovation Solution
A fail-safe apparatus and method that utilizes a vehicle speed sensor, gear stage input unit, and GPS vehicle speed calculation unit to determine vehicle speed errors by comparing sensor data with preset ranges and critical times, switching to GPS data or default speeds when errors are detected, ensuring reliable vehicle speed data and improved steering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vehicle speed sensor data is used for MDPS control, then steering response is fast and accurate, but system reliability deteriorates when sensor errors occur or GPS data is unavailable
Solution Approach 1:
The system pre-establishes multiple vehicle speed data sources (sensor, GPS, default values) and error detection criteria before operation. When the sensor is functioning normally, it uses primary data; when errors are detected or GPS is unavailable, it switches to alternative data sources. This preliminary preparation ensures reliable steering control without requiring complex real-time decision mechanisms.
Solution Approach 2:
The control unit acts as an intermediary that receives vehicle speed data from multiple sources (sensor, GPS, default values) and selectively determines the most reliable data for MDPS control. This intermediary function simplifies the system architecture by centralizing the data selection logic in the control unit rather than requiring complex switching mechanisms between components.
2Stability of the object's composition
If multiple data sources and error detection mechanisms are implemented, then steering stability is improved, but device complexity increases
Solution Approach 1:
The system changes the parameter of vehicle speed data by selecting from multiple sources (sensor data, GPS data, or default values) based on error detection results. This parameter change approach maintains steering stability by ensuring valid data is always used, while avoiding complex mechanical or structural modifications to the MDPS system.
Solution Approach 2:
The control unit continuously monitors vehicle speed data from the sensor and compares it against expected ranges and GPS data to detect errors. This feedback mechanism ensures steering stability by identifying and correcting data issues in real-time, while keeping the system architecture simple through centralized control logic in the existing ECU.
Data Source
AI summary
A fail safe apparatus for an MDPS system may include: a vehicle speed sensor configured to measure a vehicle speed; a gear stage input unit configured to receive a gear stage from a transmission of the vehicle; a GPS vehicle speed calculation unit configured to calculate a GPS vehicle speed based on location information of the vehicle; and a control unit configured to determine whether the vehicle speed is an error, based on one or more of the vehicle speed, the gear stage, and the GPS vehicle speed, and determine vehicle speed data of the MDPS system based on one or more of the gear stage and the GPS vehicle speed.