Steer-By-Wire Steering Feel Control With Torsion Bar Feedback
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Solution Overview
Problem
Steer-by-wire systems face inefficiencies due to high-power output motors converting energy to heat, noise, and vibration, and lack of mechanical connection between the steering wheel and steering rack, complicating shaft routing and steering feel control.
Innovation Solution
A steer-by-wire steering apparatus with a torsion bar and electric motors to provide steering feel, using sensors to determine torque and position, and a closed-loop control system to adjust steering resistance and wheel alignment, ensuring efficient energy use and intuitive steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a high-power output motor is used to provide resistance torque for steering feel, then steering feel control is improved, but energy efficiency deteriorates as energy is converted to heat, noise, and vibration
Solution Approach 1:
The patent replaces the traditional high-power motor that provides resistance torque through mechanical means with an electrohydraulic actuator system. This substitution uses hydraulic fluid pressure and flow control to generate the desired steering resistance, significantly reducing energy consumption and eliminating the conversion of electrical energy into heat, noise, and vibration associated with direct motor operation.
Solution Approach 2:
The patent employs a hydraulics-based electrohydraulic actuator to provide steering feel. The system uses a hydraulic pump, control valves, and hydraulic cylinders to generate and regulate the resistance torque experienced by the driver during steering operations. This hydraulic approach enables precise control of steering feel with minimal energy input compared to direct motor-driven resistance.
2Reliability
If rigid shafts are used to connect steering wheel to steering rack, then mechanical connection is provided, but routing becomes difficult due to interference from other vehicle components
Solution Approach 1:
The patent replaces the traditional rigid mechanical shaft connection between the steering wheel and steering rack with an electrohydraulic system. This substitution eliminates the need for physical shafts that must be routed through the vehicle interior, avoiding all interference issues with other components while maintaining reliable steering control through electronic sensing and hydraulic actuation.
Solution Approach 2:
The patent extracts and removes the rigid mechanical connection elements (shafts) from the steering system, separating the steering wheel input from the steering rack output. This extraction allows independent optimization of the steering wheel assembly and steering rack assembly, with the connection achieved through electronic sensors and hydraulic actuators rather than physical mechanical linkages.
3Adaptability or versatility
If a high-power motor is used to provide both low and high resistance torque, then steering feel for various maneuvers is improved, but the motor does not do positive work and energy is wasted
Solution Approach 1:
The patent uses a hydraulic system with controllable valves to regulate fluid pressure and flow to the electrohydraulic actuator. This hydraulic control mechanism enables the system to provide variable resistance torque levels (low for normal driving, high for parking and emergency maneuvers) with minimal energy consumption, as hydraulic systems can hold pressure and provide force without continuous energy input unlike electrical motors.
Solution Approach 2:
The patent implements a dynamic control system where the electrohydraulic actuator's resistance torque is continuously adjusted based on steering angle, steering rate, and vehicle operating conditions. This dynamic adjustment allows the system to provide appropriate steering feel for different maneuvers while minimizing energy consumption by only providing resistance when and where needed, rather than continuously operating a high-power motor.
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
Enhances steering feel and reduces operator effort by dynamically adjusting steering resistance, improving energy efficiency and reducing mechanical interference, while maintaining steering precision and responsiveness.
Implementation Method 1
a torsion bar and electric motors to provide steering feel
Data Source
AI summary
A steer-by-wire steering apparatus is for turning steerable wheels of a vehicle. The steering apparatus includes a steering wheel rotatable about a steering axis by a vehicle operator to effect turning of the steerable vehicle wheels. A first sensor is for determining a steering torque applied to the steering wheel by the vehicle operator. A power steering system is configured to turn the steerable vehicle wheels in accordance with the determined steering torque. The power steering system has a second sensor for sensing a position of a portion of the power steering system. A motor is operably connected to the steering wheel and controllable to apply a force to the steering wheel. The motor is controlled in accordance with the sensed position.