Wheel Actuator Position Sensing for Absolute Steering Rod Detection
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Solution Overview
Problem
Future steer-by-wire steering systems lack a reliable method for determining the absolute steering column position, especially from a stationary vehicle, and existing sensor technologies are complex, require large installation space, and are sensitive to tolerances.
Innovation Solution
A sensor device for a wheel actuator with a housing and integrated sensor unit that includes a transmission element and signal transmitter, allowing for absolute steering column position determination through a mechanical operative connection and minimal computational effort, with a simple design and assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used on the motor shaft and auxiliary shaft to calculate rotor position using the vernier principle, then the rotor position information can be determined, but the sensor system becomes complex to manufacture and operate
Solution Approach 1:
The patent extracts the position sensing function from the motor shaft and implements it directly on the steering rod through a simple encoder. This eliminates the need for multiple sensors on the motor shaft and auxiliary shaft, reducing sensor system complexity while maintaining the ability to determine position information.
Solution Approach 2:
The patent replaces the complex mechanical vernier principle with an optical encoder system. The encoder uses a coded disk with radial and circumferential markings that can be read optically, substituting mechanical sensor arrays with a simpler optical measurement system that provides the same position determination function.
2Loss of information
If rotor position information is used to determine steering rod position, then position data can be obtained, but unambiguous determination is not possible when the vehicle is stationary
Solution Approach 1:
The patent implements preliminary action by providing absolute position encoding directly on the steering rod. The coded disk contains both radial and circumferential markings that encode the absolute position information, allowing the system to determine the steering rod position unambiguously even when stationary, without relying on incremental changes from a reference position.
3Measurement precision
If a linear sensor is used for direct measurement of the handlebar position, then absolute position can be determined, but the sensor requires large installation space and complex assembly
Solution Approach 1:
The patent transitions from linear measurement to rotational measurement by placing an encoder disk on the rotating steering rod. Instead of measuring linear displacement directly, the system measures rotational position of the rod and converts this to linear position information through the known relationship between rod rotation and handlebar position, eliminating the need for large linear sensors.
Solution Approach 2:
The encoder disk serves multiple functions: it provides absolute position encoding, includes reference marks for orientation, and can be integrated into the existing steering rod structure. This multi-functional design eliminates the need for separate linear sensors and reduces installation complexity.
4Ease of operation
If a linear sensor with manual cable connection is used, then sensor data transmission is achieved, but the assembly process becomes relatively complex
Solution Approach 1:
The patent merges the sensor housing, encoder disk, and electrical connections into a single integrated assembly that mounts directly to the steering rod. This consolidation eliminates the need for separate cable connections and reduces the number of assembly steps, making the system easier to manufacture and install.
Data Source
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AI summary
The invention relates to a sensor device (100) for a component, in particular a longitudinally displaceable component, preferably a steering rod (101) of a vehicle (F), wherein the steering rod (101) can be driven by a wheel actuator (200) of a steer-by-wire system (S) of a vehicle (F), and wherein the wheel actuator (200) is configured to control the steering rod (101) of the vehicle (F) according to a steering request of the steer-by-wire system (S), the sensor unit (100) comprising: - a housing (10) for arranging the sensor device (100) on a transmission unit (201) for driving the component, in particular a transmission unit (201) of the wheel actuator (200), - a sensor unit (20) for determining a position of the component, in particular the steering rod (101) of the vehicle (F),wherein the sensor unit (20) comprises the following elements: - a transmission element (21) for providing a mechanical operative connection to a transmission element (202) of the transmission unit (201), - a signal transmitter (22) which is rotationally fixed to the transmission element (21) for indicating an angle of the transmission element (21), wherein the transmission element (21) is designed such that a maximum of one revolution of the transmission element (21) represents a full stroke of the component, in particular the steering rod (101) of the vehicle (F).