Steering Actuator Integral Suppression for Driver Comfort
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Solution Overview
Problem
Electric power steering devices cause discomfort in drivers due to changes in steering feeling resulting from automatic steering control, especially when the steering torque is below a threshold value, leading to sudden changes in assistance components and potential loss of control.
Innovation Solution
An actuator control device with a turning control value calculation unit, target value setting unit, and integral suppression unit to manage the actuator based on driver input and environmental factors, suppressing integral value increases to maintain consistent steering feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integral control is applied to control the actuator so that the actual state amount approaches the target value, then the automatic steering accuracy is improved, but the steering reaction force increases over time causing discomfort to the driver
Solution Approach 1:
The patent applies dynamics by making the integral suppression threshold variable rather than fixed. The threshold is set differently based on the steering torque magnitude: a first threshold when steering torque is below a reference value, and a second threshold when steering torque is above the reference value. This dynamic adjustment allows the integral control to be suppressed appropriately under different operating conditions, preventing excessive steering reaction force while maintaining steering accuracy when needed.
Solution Approach 2:
The patent changes the parameter of the integral suppression threshold based on the steering torque condition. When the steering torque is below the reference value, a first threshold is applied; when above, a second threshold is applied. This parameter change strategy allows the system to adapt the integral control behavior to the current steering state, preventing discomfort caused by increasing steering reaction force while maintaining control accuracy.
2Stability of the object's composition
If the integral term is limited to prevent excessive increase, then the steering reaction force stability is improved, but the automatic steering response becomes slower
Solution Approach 1:
The patent uses dynamic threshold adjustment based on steering torque to balance stability and response speed. When steering torque is low (driver is not actively steering), a more restrictive first threshold suppresses integral accumulation to prevent reaction force instability. When steering torque is high (driver is actively steering), a more permissive second threshold allows faster integral response for better tracking accuracy, thus balancing stability and response speed adaptively.
Solution Approach 2:
The patent changes the integral suppression threshold parameter according to the steering torque condition. This parameter change enables the system to switch between conservative integral control (for stability) and aggressive integral control (for response speed) based on the driver's steering intent, achieving both stability and responsiveness in different operating conditions.
3Ease of operation
If the integral control is actively suppressed to maintain steering feeling consistency, then the driver comfort is improved, but the ability to correct steering deviations is reduced
Solution Approach 1:
The patent dynamically adjusts the integral suppression based on steering torque conditions. When steering torque is below the reference value (driver is not actively steering), the first threshold suppresses integral control to maintain consistent steering feeling and driver comfort. When steering torque exceeds the reference value (driver is actively steering), the second threshold relaxes the suppression, allowing integral control to function properly for reliable steering deviation correction, thus balancing comfort and reliability.
Solution Approach 2:
The patent changes the integral control suppression parameter based on the steering torque state. This parameter change strategy ensures that integral control is suppressed only when appropriate (low torque conditions) to maintain comfort, while remaining active when needed (high torque conditions) for reliable steering correction, achieving both driver comfort and control reliability.
Data Source
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AI summary
An actuator control device includes: a turning control value calculation unit (40) configured to calculate a turning control value that controls an actuator (20) configured to turn a steered wheel on a basis of an operation state amount by a driver with respect to a steering mechanism of the vehicle; a target value setting unit (37) configured to set a target value of a state amount indicating a traveling direction of the vehicle on a basis of a surrounding environment of the vehicle; a target value control unit (41, 45 - 47, 80, 82) configured to control the actuator by integral control so that actual the state amount approaches the target value; and an integral suppression unit (42 - 44, 73) configured to suppress an increase in a first integral value calculated in the integral control according to a second integral value calculated according to the operation state amount.