Steering Controller Torque Switching for Sensor Anomalies
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Solution Overview
Problem
Existing steering controllers for electric motor-driven steerable wheels fail to properly address anomalies in sensor readings or feedback control processes, leading to reduced controllability and steering performance.
Innovation Solution
A steering controller that calculates torque and angle command values based on both steering-side and angle-side operation amounts, with a determination process to assess controllability and switch between these values when efficiency drops, ensuring continuous motor control and minimizing abrupt torque changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the torque command value is calculated only from the angle-side operation amount through angle feedback control, then the steering angle accuracy is improved, but the system reliability deteriorates when anomalies occur in sensor readings or feedback control processes
Solution Approach 1:
The patent calculates the torque command value in advance through two parallel pathways: angle feedback control (providing high precision) and torque control (providing reliability). By preparing both calculation results beforehand and storing them, the system ensures that when an anomaly occurs, a reliable backup value is already available for immediate switching, thus resolving the contradiction between precision and reliability.
Solution Approach 2:
The patent dynamically changes the parameter source for torque command calculation based on system state. It switches between angle-side operation amount (for high precision) and steering-side operation amount (for reliability) depending on whether anomalies are detected. This parameter switching mechanism allows the system to optimize between precision and reliability based on real-time conditions.
2Reliability
If the system switches torque command value sources when controllability drops, then the motor control reliability is improved, but the device complexity increases due to multiple calculation processes and switching logic
Solution Approach 1:
The patent segments the torque command calculation into distinct modular processes: angle feedback control process, torque control process, determination process, and switch process. Each module has a specific function and can be independently developed and tested. This segmentation reduces overall system complexity by making the control architecture more organized and manageable despite the multiple processes involved.
Solution Approach 2:
The patent introduces a determination process as an intermediary that assesses controllability and decides whether switching is necessary. This intermediary component simplifies the overall control logic by centralizing the decision-making function, rather than having complex switching logic distributed throughout the system. The intermediary manages the complexity by providing a clear interface between the calculation processes and the switching mechanism.
3Productivity
If both angle feedback control and torque control processes are implemented, then the steering performance is improved, but the response time increases due to multiple calculation steps
Solution Approach 1:
Both torque command values are calculated in advance through parallel processing before any switching decision is needed. By performing the calculations preliminarily and storing the results, the system eliminates the need for sequential calculation when switching is required, thus minimizing the time loss while maintaining high steering performance through dual-process optimization.
Data Source
AI summary
A steering controller includes processing circuitry configured to execute a torque control process that calculates a steering-side operation amount, an angle feedback control process that calculates an angle-side operation amount, and an operation process that operates a drive circuit of an electric motor to adjust torque of the electric motor to a torque command value. The processing circuitry is further configured to execute a switch process that switches, when determining that a controllability of the electric motor is less than or equal to a predetermined efficiency, the torque command value from a value based on the angle-side operation amount to a value based on the steering-side operation amount instead of the angle-side operation amount.