Linear Motor Position Sensing With Two-Sided Hall Sensor Sections
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Solution Overview
Problem
Current position measurement systems for linear motion systems, such as DSPM-LSM, face challenges in achieving high precision and bidirectional movement while maintaining system modularization, accuracy, and long-term repeatability, often compromising on sensor quantity, accuracy, or modularization.
Innovation Solution
A position measuring mechanism that employs two sensors on either side of the stator, with a moving portion having a magnet array, and a processing unit that combines signals from these sensors to calculate the movement path and adjust the movement pattern, allowing bidirectional movement without increasing sensor quantity, and ensuring accurate position feedback by dividing the measuring range into sections based on signal amplitudes and subcycle positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If Hall sensors are arranged along the moving direction with overlapping measuring ranges to cover the entire moving range, then the measuring range is extended, but the system complexity and cost increase due to multiple sensors and their coordination
Solution Approach 1:
The measuring range is divided into multiple sections, with each Hall sensor responsible for a specific section. The processing unit determines which section the moving object is in and selects the corresponding sensor data, avoiding the need for complex coordination between overlapping sensor ranges while maintaining full coverage
Solution Approach 2:
Instead of arranging sensors along the moving direction (one-dimensional arrangement), the patent uses a single sensor with a lateral arrangement where the moving object passes through the sensor's sensitive area. This transforms the problem from needing multiple sensors in sequence to using one sensor that detects position across its lateral field
2Measurement precision
If sine signals and cosine signals from multiple magnets are combined to improve measurement precision, then the accuracy is improved, but the system complexity increases due to multiple sensors and processing units
Solution Approach 1:
A single Hall sensor serves multiple functions by detecting the position of the moving object across its entire lateral field. The sensor can identify which magnet is currently under it and determine position relative to that magnet, eliminating the need for multiple sensors while maintaining measurement capability across the full range
Solution Approach 2:
The moving object itself (with its magnet array) serves as the measuring scale. The Hall sensor detects the magnetic field of the passing magnets, and the processing unit uses this information to determine position, eliminating the need for separate complex measurement systems
3Adaptability or versatility
If a single sensor is used in a modular linear motor system, then the system modularization is maintained, but the bidirectional movement capability is compromised as the sensor cannot detect position when the carrier moves in the opposite direction
Solution Approach 1:
The Hall sensor is arranged laterally (perpendicular to the moving direction) with its sensitive area spanning across the path of the moving object. This allows the sensor to detect magnets regardless of the direction of motion, enabling bidirectional movement detection while maintaining system modularization
Solution Approach 2:
The patent uses asymmetric magnetic pole arrangements (N-S-N-S pattern) in the magnet array, which creates distinctive magnetic field patterns that allow the single Hall sensor to determine both position and direction of motion by detecting the polarity and strength of the magnetic field
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 solution enhances the accuracy and sensitivity of position feedback, simplifies stator current commutation, and maintains system modularization, enabling precise bidirectional movement while reducing the complexity and cost of the measurement system.
Implementation Method 1
the measurement module has a first sensing portion, a second sensing portion and a third sensing portion... the first sensing portion and the second sensing portion are respectively disposed at two ends of the stator... corresponding to a long axial direction of the base
Implementation Method 2
Doubly Salient Permanent Magnet-Linear Synchronous Motor (DSPM-LSM) of discontinuous stator mainly consists of a plurality of fixed stators respectively having a plurality of coils of different phases, and one carrier or a plurality of carriers with magnet arrays
Data Source
AI summary
The invention discloses a position measuring mechanism and a measuring method of a linear motion system in which two sensors are respectively disposed on two sides of a stator, in addition to allowing a moving portion to perform bidirectional movement, under a premise of not increasing a quantity of the sensors, a measuring range of the sensors can be calculated based on information measured by the sensors themselves. Furthermore, the invention further combines measurement sections respectively measured by the two sensors to ensure an accuracy of position feedback, instead of the conventional technique using an operational method of combining sinusoidal and cosine signals.