Linear Motion Controller Leak Magnetic Field Correction
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Solution Overview
Problem
Existing controllers of linear motion devices face challenges in accurately controlling the position due to misalignment of magnetic sensors or magnetization variations, and interference from the magnetic field generated by the driving coil, leading to increased production costs and potential overcorrection issues.
Innovation Solution
A controller for linear motion devices that includes a magnetic field sensor, a calibration operation circuit, a device position instruction signal generation circuit, and a leak magnetic field correction circuit, which corrects detection errors caused by the driving coil's magnetic field interference by obtaining and adjusting position signals during calibration, ensuring accurate position control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a magnetic field sensor is used to detect the position of the linear motion device, then the position control becomes automated and efficient, but the detected magnetic field may be interfered with by the magnetic field generated by the driving coil, leading to detection errors
Solution Approach 1:
The patent applies preliminary action by performing calibration operations before normal position control. The calibration process pre-determines the relationship between drive coil currents and magnetic field sensor outputs, storing this calibration data for later use. This preliminary calibration allows the system to compensate for magnetic field interference during actual operation without affecting real-time control performance.
Solution Approach 2:
The patent introduces an intermediary element - the calibration data - that mediates between the driving coil and the magnetic field sensor. By using the calibration information obtained under known conditions, the system can correct the raw sensor readings to eliminate the interference effect, thus enabling accurate position detection despite the presence of the driving coil's magnetic field.
2Ease of manufacture
If the mounting position of the magnetic sensor or magnetization of the magnet varies, then production becomes more flexible and cost-effective, but the relationship between position and detected magnetic field deviates from design assumptions, causing control inaccuracies
Solution Approach 1:
The calibration operation performed during manufacturing serves as a preliminary action that captures the actual relationship between position and magnetic field for each individual device. This calibration data, stored in memory, compensates for variations in sensor mounting position or magnet magnetization, allowing the system to achieve accurate control despite manufacturing tolerances.
Solution Approach 2:
The patent changes the operational parameters by using empirically determined calibration factors instead of relying on theoretical design values. By adjusting the interpretation of sensor readings based on actual measured relationships during calibration, the system adapts to manufacturing variations and maintains control accuracy.
3Measurement precision
If correction operations are performed to compensate for magnetic field interference, then position control accuracy improves, but complex correction algorithms may cause overcorrection or require excessive computational resources
Solution Approach 1:
The patent creates a simplified model or copy of the magnetic field interference characteristics through calibration measurements. Instead of using complex real-time calculations to model and compensate for interference, the system uses pre-measured calibration data that replicates the interference pattern under various conditions, enabling accurate correction through simple lookup and interpolation operations.
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 position control of linear motion devices even with misalignment or magnetization variations, reducing production costs and preventing overcorrection by effectively managing the magnetic field interference from the driving coil.
Implementation Method 1
a magnetic field sensor (21) configured to detect a magnetic field generated by the magnet (32) and configured to output a detection position signal value (Vip) corresponding to a value of the detected magnetic field
Implementation Method 2
a leak magnetic field correction circuit (34) configured to correct a detection error of the magnetic field sensor (21) due to a leak magnetic field of the driving coil (29)
Data Source
AI summary
The present disclosure relates to controllers of linear motion devices and control methods of the same, in particular, to a controller of a linear motion device and a control method of the same capable of controlling the position of the linear motion device accurately, in a case where a misalignment of the mounting position of a magnetic sensor or a magnetizing variation of a magnet occurs, or in a case where a magnetic field detected by the magnetic sensor receives an interference of the magnetic field generated by a driving coil of the linear motion device.