Active Roll Control Torque Smoothing for NVH Reduction
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Solution Overview
Problem
Active suspension systems in vehicles experience rotational lash events due to rapid changes in torque, leading to harsh rattles and noise, which are more pronounced at low speeds and can damage mechanical components, affecting vehicle quality and longevity.
Innovation Solution
A control system that manages torque profiles by applying predetermined levels of torque and adjusting torque request signals to minimize zero crossings and ramp rate changes, using a control function that activates based on vehicle speed and road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the actuator rapidly changes torque direction to respond to road inputs, then the active roll control system can maintain vehicle stability, but rotational lash events occur causing harsh noise and vibration
Solution Approach 1:
The control system predicts future torque demand based on current torque and recent torque changes. By anticipating torque direction changes before they occur, the system can prepare the actuator in advance, reducing sudden torque reversals that cause rotational lash and NVH events while maintaining effective roll control.
Solution Approach 2:
The control function serves multiple purposes: it maintains vehicle stability through active roll control while simultaneously predicting torque demand to minimize rotational lash events. This multi-functional approach allows the same control mechanism to address both vehicle stability and NVH reduction without requiring separate systems.
2Adaptability or versatility
If multiple rotational lash events occur in quick succession, then the system can adapt to varying road conditions, but harsh rattles are perceived in the vehicle cabin
Solution Approach 1:
By predicting torque demand based on recent torque changes, the system anticipates upcoming torque direction changes and prepares the actuator accordingly. This preliminary action reduces the frequency and intensity of rotational lash events that cause harsh rattles, while still allowing the system to adapt to varying road conditions through controlled torque adjustments.
3Measurement precision
If the gearbox is quickly re-engaged after rotational lash, then the actuator can maintain precise control, but impulsive forces radiate through the suspension system
Solution Approach 1:
The control system predicts torque demand changes before they occur, allowing the actuator to prepare for torque direction changes in advance. This reduces sudden gearbox re-engagement events that generate impulsive forces, while maintaining precise control through smooth, anticipated torque transitions.
4Productivity
If torque demand frequently crosses zero, then the actuator can respond to changing suspension requirements, but the measured impulse increases with rate-of-change of torque
Solution Approach 1:
By predicting future torque demand based on current torque and recent changes, the system reduces unnecessary zero-crossing events. The actuator only changes torque direction when truly necessary for roll control, and does so in a controlled manner that minimizes the rate-of-change of torque, thereby reducing measured impulse while maintaining productivity.
Data Source
AI summary
Aspects relate to a control system and method for a vehicle suspension system in a vehicle (900). The control system (100, 200) is configured to: receive a torque request signal (165) indicative of a requested torque value to be applied to an actuator (272, 282) of a roll control system; determine whether the requested torque value is within a predetermined range of torque demand values, wherein the predetermined range covers a zero torque demand value; and if the requested torque is within the predetermined range of torque demand values, output a signal to control the roll control system in dependence on a control function; wherein the control function is configured to: apply and maintain a positive predetermined level of torque to the actuator when the requested torque value is positive; and apply and maintain a negative predetermined level of torque to the actuator when the requested torque value is negative.