Steering Control Device Temperature Estimation Correction
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Solution Overview
Problem
The existing steering control devices face challenges in accurately estimating the temperature of the lubrication target part of the steering mechanism due to heat emission from the steering actuator, leading to inaccuracies in temperature detection by the temperature sensor.
Innovation Solution
A steering control device that includes a controller to estimate the temperature of the lubrication target part by calculating a value lower than the detected temperature sensor value, using heat emission parameters and drive correction values, and employing low-pass filtering to account for heat diffusion and delay, with options for residual heat correction and startup correction processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is disposed as close to the lubrication target portion as possible, then the temperature detection accuracy is improved, but the detected temperature is affected by heat emission from the steering actuator resulting in departure from the actual lubrication target temperature
Solution Approach 1:
The patent introduces an intermediary estimation process that mediates between the temperature sensor detection and the actual lubrication target temperature. Instead of directly using the sensor value, the system calculates an estimated temperature by subtracting a correction value (derived from heat emission parameters and drive correction values) from the detected temperature. This intermediary calculation resolves the contradiction by filtering out the heat emission interference while preserving the proximity advantage of the temperature sensor.
2Measurement precision
If a temperature sensor that directly detects the temperature of the lubrication target part is provided, then the temperature measurement accuracy is improved, but an increase in size of the lubrication target part is caused
Solution Approach 1:
The patent uses an intermediary estimation approach where the temperature sensor is placed on a nearby member rather than directly on the lubrication target part. The system calculates the actual lubrication target temperature by subtracting a correction value from the detected temperature. This intermediary calculation method achieves accurate temperature measurement without requiring the sensor to be integrated into the lubrication target part, thereby avoiding the increase in its size.
3Speed
If the detected value of the temperature sensor is used directly for steering control, then the control response is improved, but the steering control precision is reduced due to heat emission effects
Solution Approach 1:
The patent applies preliminary action by calculating the temperature correction value in advance based on heat emission parameters (such as motor current and torque) before using the temperature for steering control. The estimated temperature is computed by subtracting the pre-calculated correction value from the detected temperature, ensuring that the temperature compensation is already prepared when needed for control decisions. This preliminary calculation maintains fast response while improving precision.
Solution Approach 2:
The system implements feedback by continuously monitoring the heat emission parameters (motor current, torque) and dynamically adjusting the temperature correction value accordingly. The estimated temperature feeds back into the steering control system, creating a closed-loop that compensates for heat emission effects in real-time. This feedback mechanism ensures both rapid response and high precision in steering control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate temperature estimation of the lubrication target part, even when the detected value is affected by heat from the steering actuator, thereby improving the precision of steering control and reducing errors caused by heat emission.
Implementation Method 1
a detected value of a temperature sensor detecting a temperature of a predetermined member attached to the steering mechanism
Implementation Method 2
a member close to the temperature sensor receives heat due to emission of heat resulting from a current flow in the steering actuator
Implementation Method 3
employing low-pass filtering to account for heat diffusion and delay
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A steering control device has a steering actuator as an operation target, the steering actuator includes a motor and a steering mechanism mechanically connected to a rotary shaft of the motor. The steering control device includes a controller (62) configured to perform i) a low-temperature process of changing a torque of the motor when an estimated value (Tge) estimated from a temperature of a lubrication target part of the steering mechanism is equal to or lower than a predetermined value with respect to when the estimated value (Tge) is higher than the predetermined value and ii) an estimation process of calculating the estimated value (Tge) which is set be lower than a detected value (Tbc) of a temperature sensor (68) detecting a temperature of a predetermined member attached to the steering mechanism based on a heat emission parameter of the steering actuator associated with a current flow with the detected value (Tbc) as an input.