Steering Feedback Actuator Torque Amplification
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Solution Overview
Problem
Steer-by-wire steering systems lack haptic feedback, making it difficult for drivers to accurately assess driving situations and impairing vehicle steerability and safety, while existing feedback actuators require complex control systems and large electric motors for realistic torque simulation.
Innovation Solution
A compact feedback actuator design where the electric motor and transmission are integrated within a casing tube, using a gear with a predetermined transmission ratio to amplify motor torque into the steering shaft, allowing a smaller, higher-speed motor to produce a realistic restoring torque with reduced control complexity and space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct coupling of motor shaft to steering shaft is used, then control complexity is reduced, but motor size must be large to generate sufficient restoring torque
Solution Approach 1:
A transmission mechanism is introduced as an intermediary between the motor shaft and steering shaft. This transmission includes a pinion gear mounted on the motor shaft and a rack gear integrated with the steering shaft, enabling torque multiplication and speed reduction while allowing the use of a compact motor with sufficient torque output.
2Force
If high restoring torque is generated directly by motor, then realistic driving experience is achieved, but control currents must be relatively high
Solution Approach 1:
The transmission mechanism acts as a mechanical multiplier, converting high-speed, low-torque motor output into low-speed, high-torque output at the steering shaft. This allows the motor to operate in its efficient high-speed range while still delivering the high restoring torque needed for realistic feedback, thereby reducing control current requirements.
Solution Approach 2:
The transmission ratio is optimized to transform the motor's operational parameters, allowing the motor to operate at higher speeds with lower currents while the transmission delivers the required high torque to the steering shaft, thus changing the effective parameters of the feedback actuator system.
3Volume of moving object
If transmission is integrated within casing tube, then installation space is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The transmission components (pinion gear, rack gear, bearings) are integrated within the casing tube as a compact assembly. The rack gear is directly integrated with the steering shaft, eliminating the need for separate mounting structures and reducing overall installation space while maintaining functional precision through careful design of the integrated components.
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
This design enables precise and intuitive steering feedback with a compact, lightweight actuator that simplifies control efforts and reduces motor size, improving steerability and safety while maintaining a realistic driving experience.
Implementation Method 1
an electric motor which has a stator connected to the casing unit and a rotatably drivable rotor shaft
Implementation Method 2
a gear with a predetermined transmission ratio to amplify motor torque into the steering shaft
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a feedback actuator (5) for a steering device (1), comprising a steering shaft (51), which is supported in a jacket unit in such a way that the steering shaft can be rotated about the longitudinal axis (21) of the steering shaft, which jacket unit can be attached to a vehicle, which feedback actuator comprises an actuator unit having an electric motor (9), which electric motor has a stator (81) connected to the jacket unit and a rotationally drivable rotor shaft (84), which can be connected to the steering shaft (51) in a torque-transmitting manner, wherein the electric motor (8) is arranged inside the jacket unit. In order to enable more accurate application of the restoring torque to the steering shaft with little control complexity and while achieving a compact design, the rotor shaft (84), according to the invention, is connected to an input shaft of a transmission (9), which has an output shaft connected to the steering shaft (51) and which his arranged inside the jacket unit.