Steering Motor Control Unit for Consistent Lane Keeping Assist
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Solution Overview
Problem
Existing steering systems that apply assist forces to the steering mechanism for driving assist control, such as lane keeping assist, experience variations in response due to frictional and inertia forces, leading to uncomfortable driver experiences and inconsistent assist force applications across different vehicles.
Innovation Solution
A steering system that includes a motor and a motor control unit with an angle command value calculating unit, angle feedback control unit, assist command value calculating unit, state quantity command value setting unit, and correction value calculating unit, which adjusts the assist force based on steering torque, vehicle state, and deviation from target values to maintain consistent assist force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If assist force is applied to steering mechanism for driving assist control, then vehicle can be assisted to travel in lane, but variation in frictional and inertia forces causes variation in assist force application across different vehicles
Solution Approach 1:
The system employs feedback control by detecting the actual turning angle of the steering mechanism and comparing it with the target turning angle. The control apparatus adjusts the assist force based on the deviation between actual and target values, creating a closed-loop control system that compensates for variations in frictional and inertia forces across different vehicles.
Solution Approach 2:
The control apparatus dynamically adjusts control parameters including assist force magnitude, target turning angle, and feedback gain based on detected vehicle state (speed, steering angle) and deviation from target trajectory. This parameter adaptation allows the system to maintain consistent assist force application despite variations in steering mechanism characteristics between vehicles.
2Productivity
If assist force varies between vehicles due to different frictional and inertia forces, then lane keeping assist control response varies, but this makes driver feel uncomfortable
Solution Approach 1:
The control apparatus adapts control parameters based on detected vehicle state and steering characteristics. By adjusting assist force magnitude and feedback gain according to actual vehicle behavior, the system maintains consistent control response across different vehicles while ensuring comfortable operation for the driver.
Solution Approach 2:
The system uses feedback from actual turning angle detection to continuously adjust assist force application. This closed-loop control ensures that despite variations in frictional and inertia forces between vehicles, the driver experiences consistent and comfortable assist control response.
3Device complexity
If simple assist force control is used, then system is simple, but frictional and inertia forces cause inconsistent assist force application
Solution Approach 1:
The control apparatus implements feedback control by detecting actual turning angle and comparing it with target turning angle. This relatively simple feedback mechanism enables the system to compensate for frictional and inertia force variations, achieving consistent assist force application without requiring complex system architecture.
Solution Approach 2:
The system uses the vehicle's own operational data (steering angle, vehicle speed, actual trajectory) to automatically adjust assist force application. This self-service approach allows the control system to adapt to different vehicle characteristics without requiring external calibration or complex pre-programming.
Data Source
AI summary
A steering system includes a motor control apparatus that controls driving of a motor based on an assist command value. The motor control apparatus includes an angle command value calculating unit that calculates an angle command value based on an input value including a steering torque, and calculates an assist component through execution of angle feedback control allowing a turning angle of a vehicle to follow the angle command value. The motor control apparatus calculates the assist command value based on the assist component. The motor control apparatus also calculates a correction value based on a deviation between a yaw rate of the vehicle and a yaw rate command value. An input value for the angle command value calculating unit is corrected based on the correction value.