Active Steering Nibble Control Algorithm for Electric Power Steering
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Solution Overview
Problem
Steering nibble and brake judder in electric steering systems cause customer concerns and increase warranty costs, with existing chassis modifications often having negative effects on vehicle characteristics and being expensive to implement.
Innovation Solution
An active control algorithm using a controller and electric motor to convert wheel speed into frequency, select nibble enable frequencies, calculate filter coefficients, apply a gain scheduler and tuned resonator filter to the steering column torque signal, and generate an active nibble cancelling torque signal to cancel steering wheel vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chassis modifications are implemented to reduce steering nibble and brake judder, then vibration reduction is improved, but vehicle characteristics are negatively affected and manufacturing cost increases
Solution Approach 1:
The patent replaces mechanical chassis modifications with an electronic control system. A controller receives steering wheel angle and vehicle speed signals, processes them through a tuned resonator filter to generate a compensation torque signal, and applies this torque via an electric motor to actively cancel vibrations. This substitutes physical structural changes with electronic signal processing and active feedback control.
Solution Approach 2:
The system implements feedback control by continuously monitoring steering wheel angle and vehicle speed, processing these signals through the tuned resonator filter to generate compensation torque, and applying this torque to counteract vibrations in real-time. The closed-loop feedback mechanism allows the system to adapt to varying vibration conditions dynamically.
2Object-affected harmful factors
If active steering nibble control is implemented using electronic control and electric motor, then steering nibble reduction is improved, but device complexity increases
Solution Approach 1:
The electric motor and controller serve multiple functions: they provide normal power steering assistance to the driver while simultaneously generating compensation torque to cancel steering nibble and brake judder vibrations. The tuned resonator filter processes multiple input signals (steering wheel angle, vehicle speed) to generate appropriate compensation signals, making the system multi-functional rather than adding separate dedicated vibration cancellation hardware.
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
Effectively reduces steering nibble and brake judder without affecting steering feel, providing a cost-effective solution that minimizes warranty costs by precisely targeting specific frequencies and rejecting vibrations before they reach the steering wheel.
Implementation Method 1
calculating an active nibble cancelling torque signal from the nibble signal and applying the active nibble cancelling torque signal to the electric motor to cancel steering wheel nibble vibration
Data Source
AI summary
A system and method for actively cancelling steering nibble and/or brake judder in an electric power steering system using a controller and an electric motor by converting a selected wheel speed to a frequency, selecting a nibble order, determine nibble enable frequencies for cancellation, selecting a damping factor based on changes in vehicle velocity, calculating filter coefficients based on the selected damping factor, the selected nibble order and the wheel frequency, applying a gain scheduler to a steering column torque signal for the nibble enable frequencies, applying a tuned resonator filter to an output of the gain scheduler and using the filter coefficients to produce a nibble signal, calculating an active nibble cancelling torque signal from the nibble signal and applying the active nibble cancelling torque signal to the electric motor to cancel steering wheel nibble vibration.