Modular Linear Motor Sensor Compensation
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Solution Overview
Problem
The existing linear motors with scannable measurement tracks face issues due to varying spacings between stator modules, leading to positioning errors and manufacturing complexities, which can result in inaccurate placement of pipette tips in pipetting applications, potentially causing adhesion issues and hindering the insertion process.
Innovation Solution
The implementation of at least two sensor units on the rotor device, arranged to scan measurement tracks on adjacent stator modules, allows for the determination and correction of spacings between modules, enabling precise positioning by evaluating displacement and using a correction function to adjust the rotor's position relative to the stator's zero point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous single-piece measurement track is used to bridge spacings between stator modules, then the measurement track can cover the entire movement range, but the manufacturing and installation become elaborate and expensive
Solution Approach 1:
The measurement track is divided into multiple separate segments, each assigned to individual stator modules. These segments are detected by sensor units that can identify their respective module boundaries. The control system then compensates for the spacings between modules by calculating the cumulative distance based on detected module boundaries, effectively replacing a single continuous track with multiple manageable segments.
2Ease of manufacture
If stator modules are arranged with spacings to allow modular assembly, then the device becomes easier to assemble and maintain, but positioning errors occur due to varying spacing distances
Solution Approach 1:
Sensor units on the rotor device continuously detect the measurement tracks on stator modules, providing feedback about the actual position and identifying module boundaries. The control system uses this feedback to calculate the cumulative distance traveled, automatically compensating for variations in spacing between modules. This closed-loop approach maintains positioning accuracy despite modular assembly spacings.
3Reliability
If a long single-piece measurement track is used, then positioning can be continuous across the entire movement range, but the installation becomes more complex and costly
Solution Approach 1:
The measurement system is segmented into multiple independent measurement segments, each associated with a stator module. Instead of requiring a single continuous track spanning the entire movement range, the system uses multiple shorter track segments that are easier to manufacture and install. The control system seamlessly combines these segments by detecting module boundaries and calculating cumulative distances.
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 modular setup ensures accurate positioning of the rotor device, compensates for systematic length errors caused by module spacings, and allows for flexible assembly and maintenance of the linear motor, enhancing the precision and reliability of linear movements in applications like pipetting apparatuses.
Implementation Method 1
interaction of magnetic fields of the permanent magnets with the magnetic fields of the coils, through which current flows if required
Implementation Method 2
at least two sensor units scanning the measurement track are provided, which are arranged in the movement direction of the rotor device in a distance from each other such that in case of an arrangement of the rotor device at one of the connection points between the two stator modules the respective measurement tracks on the adjacent stator modules are each scannable by one of the two sensor units
Data Source
AI summary
A linear motor, comprises at least one stator device (14) with a plurality of permanent magnets (18, 18-1, 18-2) of different polarity and with at least one carrier rail (24), and at least one rotor device (12) with at least three electrical coils (44) and with at least one supporting means (26), which can be or which is supported on the carrier rail (24) of the stator device (14), wherein the rotor device (12) and the stator device (14) are moveable to and fro with respect to each other along a movement direction (FR) defined by the carrier rail (24) by interaction of magnetic fields of the permanent magnets (18, 18-1, 18-2) with the magnetic fields of the coils (44), through which current flows if required, wherein the stator device (14) is formed from at least one stator module (16-1, 16-2), wherein the stator module (16-1, 16-2) is configured such that a stator device (16) with two or more consecutively arranged stator modules (16-1, 16-2) can be formed, and wherein at the stator module (16-1, 16-2) at least one measurement track (40, 40-1, 40-2, 40-3) scannable by a sensor unit (52-1, 52-2) of the rotor device (12) is provided, which runs substantially parallel to the movement direction (FR). On the rotor device (12) at least two sensor units (52-1, 52-2) scanning the measurement track (40, 40-1, 40-2, 40-3) are provided, which are arranged along the movement direction (FR) of the rotor device (12) in a distance (SA) such that if the rotor device (12) is arranged on a connection point (64, L) between two stator modules (16-1, 16-2) the respective measurement tracks (40, 40-1, 40-2, 40-3) of the adjacent stator modules (16-1, 16-2) are scannable by one of the two sensor units (52-1, 52-2), respectively.