Electric Power Steering Control Device Monitoring Without LAN Circuit
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Solution Overview
Problem
Conventional electric power steering control systems require a LAN communication circuit in the sub-control device, increasing costs and complexity, and there is a need for a more reliable and cost-effective monitoring solution without this circuit.
Innovation Solution
The system includes a torque-detecting unit, motor-current-detecting unit, and processing units in both the main and sub-control devices to monitor abnormalities, such as discrepancies in car-speed signals and motor currents, allowing for safe operation without a LAN communication circuit in the sub-control device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a LAN communication circuit is provided in the sub-control device to monitor the main control device, then the reliability of the monitoring system is improved, but the cost and device complexity increase
Solution Approach 1:
The patent extracts the LAN communication circuit from the sub-control device, eliminating the need for complex communication infrastructure in the monitoring unit. The sub-control device directly accesses control signals and sensor data from the main control device through shared hardware resources, achieving monitoring functionality without requiring a separate communication network.
Solution Approach 2:
The patent makes the sub-control device utilize existing hardware resources (control signal lines, sensor data buses) that are already present in the system for primary control functions. By using these existing pathways for dual purposes (both control and monitoring), the system achieves reliable monitoring without adding dedicated communication circuits.
2Reliability
If a LAN communication circuit is provided in the sub-control device, then the monitoring capability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the monitoring function with the existing control signal pathways. The sub-control device monitors abnormalities by analyzing control signals and sensor data that already flow through the system for primary control operations. This consolidation eliminates the need for separate communication infrastructure, reducing component count and manufacturing cost while maintaining detection capability.
Solution Approach 2:
The existing control system infrastructure serves dual purposes: it performs primary control functions and simultaneously provides the data pathway for monitoring. The control signals and sensor data that are necessary for operation also enable the sub-control device to detect abnormalities without requiring additional dedicated monitoring channels.
Data Source
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AI summary
A main control device generates a first signal and a second signal, which is substantially equivalent to the first signal, in accordance with the input signal, a sub-control device includes a comparison-judgment-processing unit that compares the first signal with the second signal, and judges that an abnormality occurs when a state, in which a deviation between the both signals is greater than equal to a predetermined value, is continued in a time being equal to a first predetermined time, and a limitation unit is configured in such a way that the limitation unit adds a predetermined limitation to the output of the main control device in accordance with a result for which the comparison-judgment-processing unit judges that the abnormality occurs.