Duplex Steering Control System with Cross-Validation
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Solution Overview
Problem
Existing steering control systems for vehicles may apply erroneous force to steering components due to abnormalities in the control device, leading to uncomfortable steering experiences for drivers and instability in vehicle travel, as it takes time to switch to a backup control system.
Innovation Solution
A steering control system with a duplex configuration, featuring a main and subsidiary actuator and control device pair, which computes and compares controlled variables to detect discrepancies or communication abnormalities, allowing for a swift switch to an independent mode where the subsidiary system compensates for erroneous outputs, thereby stabilizing steering and reducing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backup control device is provided to take over when the main control device malfunctions, then reliability is improved, but response time is worsened due to the delay in detecting the abnormality and switching
Solution Approach 1:
The patent applies preliminary action by having the backup control device pre-compute the controlled variable in advance while the main control device is still operating normally. This allows the backup device to be ready to take over immediately when a malfunction is detected, eliminating the delay that would otherwise occur during the switching process. The controlled variable is calculated ahead of time so that no computational delay occurs during the transition.
Solution Approach 2:
The patent implements feedback by having the main control device monitor the controlled variable computed by the backup control device. This feedback mechanism allows the main control device to detect when the backup device has completed its pre-computation and is ready to take over, enabling immediate switching without delay. The feedback loop ensures that the transition occurs at the optimal moment, maximizing response time.
2Duration of action of stationary object
If the main control device continues operating after an abnormality occurs, then continuity of control is maintained, but harmful effects increase due to erroneous force being applied to steering components
Solution Approach 1:
The patent uses feedback by having the main control device continuously monitor the controlled variable computed by the backup control device. This monitoring allows the main control device to detect abnormalities in the backup device's computations and switch to using the backup device's pre-computed controlled variable, thereby preventing erroneous force from being applied while maintaining continuity of control.
Solution Approach 2:
The patent applies preliminary action by having the backup control device pre-compute the controlled variable before it is actually needed. This pre-computation allows the system to switch control sources immediately when an abnormality is detected, preventing erroneous force application while maintaining uninterrupted steering control through the use of pre-calculated values.
3Reliability
If a duplex configuration with communication between control devices is implemented, then reliability is improved through cross-validation, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the control system into two independent control devices (main and backup), each capable of computing the controlled variable independently. This segmentation allows for cross-validation of computations while keeping each individual control device relatively simple in structure, as each device performs the same basic computational function without requiring complex integrated logic.
Solution Approach 2:
The patent uses copying by having the backup control device create a copy of the controlled variable computation that the main control device performs. This copying approach simplifies the architecture because both devices use identical computation logic, making the system easier to design and maintain while still providing the reliability benefits of cross-validation through comparison of the copied computational results.
Data Source
AI summary
An actuator that applies force to a member associated with steering, and a control device that controls the actuator, have duplex configuration. First and second control devices compute the same controlled variable as first and second controlled variables, respectively. In a normal mode, the control device controls the actuator according to the first controlled variable. The first and second control devices send and receive respectively computed controlled variables to and from each other via communications. When a discrepancy arises between the first and second controlled variables, or an abnormality occurs in communications between the first and second control devices, the operating mode is switched from the normal mode to an independent mode. In the independent mode, the first and second control devices control the first and second actuators, according to the first and second controlled variables, respectively.