Steering Wheel Judder Compensation During Vehicle Braking
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Solution Overview
Problem
Existing methods for reducing steering wheel vibration during vehicle braking, such as damping torque injection and disturbance suppression using band-pass filters, either alter steering system characteristics or require complex frequency and phase adjustments, leading to suboptimal results.
Innovation Solution
An apparatus and method that include a judder compensation logic unit to calculate and apply judder compensation torque based on motor current, vehicle speed, and wheel speed, using frequency calculators, judder compensators, and converters to extract and filter judder frequency components, and a diagnosis unit to determine operation states for effective vibration reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If damping torque injection method is used to suppress vibration, then steering wheel vibration is reduced, but steering system characteristics are altered causing sense of difference during steering
Solution Approach 1:
The patent extracts only the harmful judder frequency components from the motor current signal using band-pass filters, while leaving other steering control signals intact. This selective extraction allows vibration suppression without altering overall steering system characteristics, resolving the contradiction between vibration reduction and maintaining natural steering feel
Solution Approach 2:
The patent introduces a judder compensation logic unit as an intermediary that processes motor current signals, extracts judder components, generates compensation torques, and injects them back into the motor control. This intermediary structure enables targeted vibration cancellation while preserving the original steering system behavior and characteristics
2Object-affected harmful factors
If disturbance suppression method with band-pass filter is used, then vibration at specific frequency is suppressed, but complex frequency and phase adjustments are required
Solution Approach 1:
The patent implements a feedback mechanism where the judder compensation logic unit continuously monitors motor current, extracts judder frequency components, calculates compensation torques, and injects them back in real-time. This closed-loop feedback approach automatically adapts to varying judder conditions without requiring manual frequency and phase adjustments, reducing system complexity
Solution Approach 2:
The patent dynamically changes the compensation torque parameter based on extracted judder frequency components and their magnitudes. By automatically adjusting compensation parameters through signal processing rather than manual tuning, the system reduces operational complexity while maintaining effective vibration suppression
3Measurement precision
If judder compensation torque is calculated based on motor current filtering, then accurate judder extraction is achieved, but additional processing units are required
Solution Approach 1:
The patent designs the judder compensation logic unit to perform multiple functions: filtering motor current signals, extracting judder frequency components, calculating compensation torques, and controlling motor adjustment. This multi-functional approach consolidates processing requirements into a single unit, reducing overall system complexity while maintaining high measurement precision
Data Source
AI summary
An apparatus for reducing vibration of a steering wheel may include: a judder compensation logic unit configured to calculate judder compensation torque for removing a judder which occurs in a steering wheel of a vehicle, based on one or more of a motor current, vehicle speed and vehicle wheel speed; and a judder compensation diagnosis unit configured to determine an operation state of the judder compensation logic unit based on one or more of the vehicle wheel speed, steering torque and a brake state.