Steering Control Unit Return Damping Compensation
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Solution Overview
Problem
Existing electric power steering systems face a trade-off between improving steering feel and adjusting the speed of the steering wheel returning to its neutral position, as the damping compensation value interferes with self-aligning torque, leading to decreased speed.
Innovation Solution
A steering control unit that calculates a basic assist component and damping compensation component based on steering operations, and a return damping compensation component to suppress the influence of damping compensation, allowing independent compensation of the steering wheel's return to neutral position without driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a damping compensation value is applied to reduce sudden change in steering angle, then steering feel is improved, but the speed of the steering wheel coming back to the neutral position decreases due to interference with self-aligning torque
Solution Approach 1:
The control circuit changes the parameter of damping compensation by calculating different compensation values based on the operating state quantity. When the steering wheel is returning to neutral without driver input, the damping compensation value is adjusted or cancelled to allow faster return speed, while maintaining steering feel improvement during normal steering operations.
Solution Approach 2:
The damping compensation is made dynamic by continuously monitoring the operating state quantity and adjusting the compensation value in real-time. The system transitions between different compensation states depending on whether the driver is actively steering or the wheel is returning to neutral, optimizing both steering feel and return speed under different conditions.
2Stability of the object's composition
If damping compensation is applied during steering wheel return, then sudden change in steering angle is suppressed, but the natural self-aligning torque action is interfered with
Solution Approach 1:
The harmful effect of damping compensation during natural return is eliminated by extracting or removing the damping compensation component when the operating state indicates the steering wheel is returning to neutral without driver input. This allows the self-aligning torque to act naturally without interference.
Solution Approach 2:
The control circuit uses feedback from the operating state quantity to determine when to apply or cancel damping compensation. By monitoring the state of the steering wheel and comparing it with the damping compensation effect, the system automatically adjusts the compensation to eliminate interference with self-aligning torque during natural return.
Data Source
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AI summary
Provided is a steering control unit that provides an improved steering feel and allows adjustment of the speed of a steering wheel coming back to its neutral position. The steering control unit includes a microcomputer (51) that controls the driving of a motor on the basis of a steering torque (Trq) to cause the motor to produce an assist force. The microcomputer (51) calculates a basic assist component (Tb*) that is a component of the assist force, on the basis of the steering torque (Trq). The microcomputer (51) calculates a damping compensation component (Td*) that suppresses a sudden change in a rotation angle (0m), on the basis of a rotational angular velocity (ω) that is a time rate of change of the rotation angle (0m). The microcomputer (51) calculates, independently of the damping compensation component (Td*), a return compensation component (Tr*) that suppresses influence of the damping compensation component (Td*), on the basis of the rotational angular velocity (ω). The microcomputer (51) compensates the basic assist component (Tb*) by using both the damping compensation component (Td*) and the return compensation component (Tr*), in a situation where the steering wheel comes back to the neutral position without a steering operation that a driver performs to return the steering wheel.