Inductive Torque Sensor Difference Angle Calculation
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Solution Overview
Problem
Existing methods for determining the difference angle between two rotors with unequal periodicities in inductive torque sensors suffer from undesirable inductive coupling and output signal irregularities due to the discontinuity of the arc tangent function.
Innovation Solution
A method that calculates the difference angle using integer arithmetic, scaling measurement signals to fit within an integer data type range, and multiplying and subtracting them to avoid arithmetical integer overflow, allowing for cost-effective implementation in an integrated circuit, while also considering the uniqueness range based on periodicities to avoid inductive coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the arc tangent function is used to calculate the difference angle from sine and cosine signals, then the angular position can be determined, but output signal irregularities occur due to the discontinuity of the arc tangent function
Solution Approach 1:
The patent extracts only the necessary trigonometric relationships (sin(α-β) and cos(α-β)) from the full arc tangent calculation, avoiding the discontinuity problem by working directly with sine and cosine components rather than converting to an angular value that suffers from periodic discontinuities
Solution Approach 2:
Instead of calculating the angle and then finding the difference, the patent inverts the approach by directly calculating the sine and cosine of the angle difference from the product of the individual sine and cosine signals, bypassing the arc tangent function entirely
2Object-affected harmful factors
If unequal periodicities are used for the two measurement signals, then inductive coupling effects are avoided, but the calculation of the difference angle becomes more complex
Solution Approach 1:
The patent changes the parameters of the measurement signals by assigning different periodicities (different numbers of sine/cosine periods) to the two channels, which fundamentally alters the signal characteristics to eliminate inductive coupling while the mathematical approach handles the unequal periodicities through cross-multiplication
3Measurement precision
If floating point arithmetic is used for the calculation algorithm, then accurate results are obtained, but cost-effective implementation in integrated circuits becomes difficult
Solution Approach 1:
The patent substitutes the mechanical/floating-point arithmetic system with an integer-based computational system, replacing complex floating-point operations with simpler integer multiplication and addition operations that are naturally suited for digital integrated circuit implementation
Solution Approach 2:
The patent changes the numerical parameter representation from floating-point to integer format, scaling the input signals appropriately so that all calculations can be performed using integer arithmetic while maintaining the necessary precision for the application
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
Enables accurate calculation of the difference angle and torque between two movements with unequal periodicities, reducing measurement errors and inductive coupling, and allowing for scalable and efficient implementation in various mechanical systems.
Implementation Method 1
at least one exciter coil (1a, 1b), at least one oscillator circuit (2a, 2b), which are coupled to the exciter coils (1a, 1b) and couple an alternating voltage periodic signal into the exciter coils (1a, 1b) during operation
Implementation Method 2
at least two rotors (3a, 3b) which are rotatable relative to each other and relative to the stator circuit board (5) and influence the strength of the inductive coupling between the exciter coil (1a, 1b) and the receiver structures
Data Source
AI summary
A method for determining a difference value includes multiplying one measurement signal, representing a current mechanical movement acquired at a first periodicity, with a second periodicity of another measurement signal, which represents another current mechanical movement, based on an integer algorithm, and using a potentially occurring arithmetical integer overflow, to provide a resulting multiplication result, and multiplying the other measurement signal by the first periodicity based on an integer algorithm, and using a potentially occurring arithmetical integer overflow to provide a resulting other multiplication result, wherein the measurement ranges for the measurement signal and the other measurement signal are each scaled such that they each apply a full range of a provided integer data type. The method includes determining a difference value between the multiplication result and the other multiplication result using an integer algorithm, and using a potentially occurring arithmetical integer overflow.