Steering Reaction Force Control After Reset Without Wheel Re-Correction
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Solution Overview
Problem
In steer-by-wire systems, the instantaneous stop of the control calculation unit due to power source failure or microcomputer reset can lead to unintended steering wheel behavior, causing driver discomfort due to repeated correction processes for aligning the steering and turning wheel positions.
Innovation Solution
The steering control device incorporates two reaction force control circuits that store completion status of a preparation process, allowing the system to skip this process upon reset if it was previously completed normally, and transition to a redundant control state to prevent unintended wheel movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control calculation unit executes the preparation process whenever it returns to normal operation after a reset, then the position relation between steering wheel and turning wheels is corrected, but unintended steering wheel behavior occurs causing driver discomfort
Solution Approach 1:
The system performs the preparation process (middle point learning and steer angle synchronization) in advance when the control calculation unit normally operates. The completion status is stored in advance, so when a reset occurs, the system can skip the preparation process by checking the stored completion status, thereby preventing unintended steering wheel behavior while ensuring position relation correction has already been accomplished.
2Reliability
If the control calculation unit stops operation due to power source failure or reset, then system reliability is compromised, but repeated execution of preparation process causes unintended behavior
Solution Approach 1:
The system uses feedback from the stored preparation process completion status to determine whether to execute the preparation process after a reset. By checking the stored status information, the control calculation unit can make an informed decision to skip or execute the preparation process, thereby maintaining normal steering wheel behavior while recovering from power source failures or resets.
3Measurement precision
If the preparation process is executed every time the control calculation unit restarts, then position synchronization is ensured, but driver discomfort increases due to automatic steering wheel rotation
Solution Approach 1:
The preparation process including middle point learning and steer angle synchronization is executed in advance during normal operation. The completion status is stored beforehand, allowing the system to skip this process after resets without compromising position synchronization, thereby preventing driver discomfort from automatic steering wheel rotation while maintaining precise position synchronization.
Data Source
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AI summary
A steering control device includes a first reaction force control circuit and a second reaction force control circuit. Each of the first reaction force control circuit and the second reaction force control circuit are configured to control a reaction force motor (21), to execute, at a starting time, a preparation process including a process that requires the steering wheel (11) to automatically rotate through the reaction force motor (21), and to store, at a time of execution completion of the preparation process, information indicating whether the preparation process has been normally completed. In a case where the first reaction force control circuit has been reset, when the information indicates that the preparation process has been normally completed, the first reaction force control circuit that has been reset is configured to not execute the preparation process at a time of restarting after completion of the reset.