Rear Wheel Toe Angle Actuation Abnormality Judgment
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Solution Overview
Problem
Conventional vehicle control systems fail to effectively judge abnormal actuations in the cooperative movement of rear wheel toe angles, leading to inadequate control of vehicle turning, as they do not consider the actuation range of both left-and-right rear wheels simultaneously, resulting in potential instability and misjudgment of normal or abnormal conditions.
Innovation Solution
A vehicle control system that includes first and second actuators for independently changing the toe angles of left-and-right wheels, with a judging means that sets reference values based on vehicle speed and front wheel steering angle to determine abnormal actuations by comparing actual toe angles to predefined ranges, ensuring cooperative actuation within normal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional vehicle control systems monitor each actuator independently (e.g., only checking if rear wheel toe angle follows target toe angle), then the monitoring system is simple to implement, but the system cannot accurately judge abnormal actuation in cooperative movement range, leading to potential misjudgment of normal or abnormal conditions
Solution Approach 1:
The patent combines the monitoring of left and right rear wheel actuators into a unified evaluation system. Instead of independently checking each actuator's toe angle against target values, the system evaluates the cooperative movement relationship between both actuators by calculating the difference between their actual toe angles and determining whether this difference falls within a predetermined normal range, thereby achieving accurate abnormal actuation judgment through integrated monitoring.
2Reliability
If the system evaluates abnormal actuation based on cooperative movement range of left-and-right rear wheels, then the abnormal actuation judgment accuracy is improved, but the control system complexity increases due to additional reference value settings and range comparisons
Solution Approach 1:
The patent changes the evaluation parameter from individual actuator performance (toe angle tracking) to relational parameter (difference between left and right rear wheel toe angles). By setting a predetermined normal range for this difference parameter and comparing actual values against it, the system reliably judges abnormal actuation while maintaining relatively simple control logic based on parameter comparison.
3Measurement precision
If the system only monitors individual actuator performance without considering cooperative actuation range, then the monitoring process is simple, but the system fails to detect abnormal conditions that occur during vehicle turning when actuators operate in cooperative mode
Solution Approach 1:
The patent extracts the essential characteristic of cooperative actuation by focusing on the difference between left and right rear wheel toe angles. Instead of measuring and analyzing the complex cooperative movement of both actuators simultaneously, the system extracts the key parameter (toe angle difference) that represents the cooperative relationship, making it simple to detect and measure abnormal conditions during vehicle turning.
Data Source
AI summary
The main calculation section (37a) of a toe angle alteration control ECU (37) in a vehicle control system receives target toe angles αTL and αTR. from a steering control ECU (130) and controls a motor (31L) for changing the toe angles of a left rear wheel and a motor (31R) for changing the toe angle of a right rear wheel independently. Stroke sensors (38L, 38R) detect actual toe angles αL and αR and inputs to the judging portion (85) of actuations of the sub calculation section (37c). In accordance with a pre-stored judgment table (85a), the judging portion (85) of actuations calculates an allowable actuation range, which is a combination of the toe angles αL and αR of the left-and-right rear wheels depending on vehicle speed VS, and judges whether the actuation of the motor (31L, 31R) is suitable for the turning of a vehicle or not depending on whether the actual toe angles αL and αR. is within the allowable actuation range or not.