Steer-by-Wire Vibration Torque Control for Stable Steering Feel
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Solution Overview
Problem
Steer-by-wire steering systems experience unwanted oscillations and vibrations in the steering mechanism due to additional vibration torque applied to the steering wheel, which can lead to undesirable steering wheel vibrations and affect vehicle handling.
Innovation Solution
A method and control unit for a steer-by-wire steering system that introduces a counter-torque and vibration torque into the steering wheel, with amplitude control and monitoring to prevent transmission of unwanted vibrations to the steering device, using actuators and a control unit to synchronize steering wheel and wheel positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vibration torque is applied to the steering wheel for driver warning, then driver alertness is improved, but unwanted vibrations are transmitted to the steering mechanism
Solution Approach 1:
The control system segments the vibration torque control into multiple levels: a first vibration torque level that does not cause unwanted vibrations, and a second higher level for more urgent warnings. The system selectively applies appropriate vibration levels based on detected vibration movements, allowing driver alertness improvement while avoiding harmful vibrations in the steering mechanism.
Solution Approach 2:
The system dynamically adjusts the vibration torque amplitude based on real-time monitoring of steering mechanism vibrations. When vibration movements are detected, the system reduces or suspends vibration torque application, and resumes it when vibrations subside. This dynamic adaptation allows the system to maintain driver alertness while preventing harmful vibrations.
2Ease of operation
If vibration torque amplitude is increased for stronger warning effect, then driver warning effectiveness is improved, but steering mechanism vibrations increase
Solution Approach 1:
The vibration torque control is segmented into multiple amplitude levels. The first level provides sufficient warning effectiveness for normal conditions, while a second higher level is reserved for urgent warnings. The system monitors steering mechanism vibrations and selectively applies the appropriate level, ensuring warning effectiveness without compromising steering stability.
Solution Approach 2:
The system employs feedback control by continuously monitoring vibration movements in the steering mechanism and adjusting the vibration torque amplitude accordingly. When vibrations are detected, the system reduces or suspends torque application, and resumes it when vibrations decrease. This feedback mechanism ensures that warning effectiveness is maintained while preventing excessive steering mechanism vibrations.
3Object-affected harmful factors
If steering angle is excluded from control signal to prevent wheel movement, then unwanted steering movement is prevented, but system complexity increases
Solution Approach 1:
Instead of excluding the steering angle from the control signal, the system extracts and removes only the vibration torque component from the control signal transmitted to the steering actuator. This approach prevents unwanted steering movements caused by vibration torque while maintaining the normal steering angle information in the control signal, thereby avoiding increased system complexity.
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
The solution effectively prevents the transmission of steering wheel vibrations to the steering mechanism, ensuring stable vehicle handling by aligning steering wheel and wheel positions, allowing for safe and effective warning vibrations without affecting vehicle control.
Implementation Method 1
the first actuator introduces a vibration torque acting in alternating steering wheel rotation directions into the steering wheel to generate steering wheel vibrations
Implementation Method 2
the first actuator introduces a steering counter-torque into the steering wheel, which counteracts a driver steering torque to convey a real steering feel
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for operating a steer-by-wire steering system (10) for a motor vehicle, comprising a steering wheel (11) and at least one first actuator (12) that controls the rotational position of the steering wheel (11), and a steering device (13), in particular a rack (14), and at least one second actuator (15) that cooperates with the steering device (13) to control the steering position of at least one wheel (16), wherein the first actuator (12) is signal-connected to the second actuator (15) for transmitting a steering control signal, wherein in the method: - the first actuator (12) introduces a steering counter-torque into the steering wheel (11) that counteracts a driver steering torque to provide a real steering feel;and - the first actuator (12) introduces a vibration torque acting in alternating steering wheel rotation directions (DR) into the steering wheel (11) to generate steering wheel vibrations, wherein in the method: - the first actuator (12) is controlled such that the amplitude (A) of the vibration torque increases; - the movement behavior of the steering device (13) is monitored, wherein, upon detection of a vibration movement of the steering device (13), the increase in the amplitude (A) of the vibration torque is stopped; and - the first actuator (12) is controlled such that the amplitude (A) of the vibration torque is maintained at its stopped level (AStopp) or reduced by a predetermined value (ARed), wherein the amplitude (A) of the vibration torque is maintained at the stopped level (AStopp) or the reduced value (ARed) until the detected vibration movement of the steering device (13) at least decreases.;