Inductive Coil Layout for Steering Torque and Position Sensing
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Solution Overview
Problem
Existing steering systems, particularly steer-by-wire systems, lack accurate methods to determine the angular position of the steering wheel and the angular deflection between input and output shafts, which is crucial for determining torque and providing appropriate power steering assistance.
Innovation Solution
An inductive sensor system comprising upper and lower rotors with metallic patterns, circularly wound transmitter and receiver coils, and a stationary circuit board to sense relative angular displacement and position, using electromagnetic principles to generate and detect electromagnetic fields for precise torque and position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensor systems are used in steer-by-wire systems, then the system structure is simple, but the accuracy of determining angular position and torque is insufficient
Solution Approach 1:
The sensor system is divided into multiple independent coil sets (first transmitter coil set, second transmitter coil set, first receiver coil set, second receiver coil set) that can be independently configured and positioned. Each coil set targets specific measurement functions (angular position or torque), allowing the system to achieve high measurement precision through distributed sensing while maintaining modular complexity that is easier to manufacture and assemble.
Solution Approach 2:
The patent introduces a vertical stacking dimension by positioning coil sets on different layers of the circuit board (first coil set on first surface, second coil set on second surface). This three-dimensional arrangement allows multiple sensing functions to coexist in a compact space, improving measurement accuracy through spatial separation while avoiding planar complexity constraints.
2Measurement precision
If multiple coil sets are used to improve measurement accuracy, then measurement precision improves, but mutual coupling between coils increases
Solution Approach 1:
Coil sets are arranged in vertical layers on different surfaces of the circuit board, separating them in the vertical dimension. This spatial separation reduces mutual coupling between transmitter and receiver coils while maintaining their functional relationships, thereby improving signal quality and measurement precision without sacrificing the benefits of multiple coil sets.
Solution Approach 2:
The circuit board serves as an intermediary substrate that provides controlled impedance traces and shielding structures between coil sets. This intermediary structure manages electromagnetic field interactions, reducing mutual coupling effects while maintaining signal integrity for accurate torque and position sensing.
3Ease of manufacture
If coil sets are positioned radially inside the metallic pattern, then manufacturing is simplified, but electromagnetic interference increases
Solution Approach 1:
The patent positions coil sets on vertical surfaces of the circuit board rather than solely on horizontal planes, creating spatial separation between coils and metallic patterns. This vertical positioning reduces electromagnetic coupling with metallic patterns while maintaining manufacturing simplicity through standardized PCB fabrication processes.
Solution Approach 2:
Different coil sets are positioned in different radial zones relative to the metallic pattern (some inside, some outside), optimizing the local electromagnetic environment for each sensing function. This localized positioning strategy balances ease of manufacture with electromagnetic interference reduction for specific measurement requirements.
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 system provides accurate detection of torque applied to the steering wheel and its position, enhancing the precision of power steering assistance by improving rotational accuracy and reducing interference from common mode factors.
Implementation Method 1
one or more transmitter coil sets configured to generate electromagnetic field
Implementation Method 2
one or more receiver coil sets for sensing relative angular displacement movement between the upper rotor and the lower rotor
Data Source
AI summary
An inductive sensor system includes: a circuit board having coil sets. The coil sets include: a first transmitter coil set having a first main transmitter coil and a first transmitter bias coil; a first receiver coil set having a first main receiver coil and a first receiver bias coil; a second transmitter coil set having a second main transmitter coil and a second transmitter bias coil; and a second receiver coil set having a second main receiver coil and a second receiver bias coil. The circuit board further includes: a first electronic control unit (ECU) associated with the first transmitter coil set and the first receiver coil set; and a second ECU that is separate from the first ECU, the second ECU being associated with the second transmitter coil set and the second receiver coil set.