Linear Motor Load Measurement via Current Calculation
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Solution Overview
Problem
Existing measurement devices that use load cells to measure loads applied to measurement targets face challenges such as increased device size and the need for additional instrumentation.
Innovation Solution
A measurement device comprising a rod-type linear motor with magnets and coils, where the motor applies a load to a measurement target, and a magnetic sensor detects changes in the magnetic field to calculate the load without the need for a load cell, allowing for precise load measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load cell is provided between the actuator and the measurement target to measure the load, then the load measurement can be performed, but the size of the entire device is increased
Solution Approach 1:
The patent extracts the measurement function from a separate load cell instrument and integrates it into the actuator's control unit. The control unit calculates load by processing current signals from the linear motor, eliminating the need for a physical load cell and reducing device size while maintaining measurement capability
Solution Approach 2:
The control unit is given multiple functions: it both controls the linear motor's operation and performs load measurement calculations. By processing the same current signals used for motor control, the system achieves measurement functionality without adding separate measurement hardware
2Measurement precision
If a load cell is mounted on the mover of the actuator to measure the applied load, then accurate load measurement is achieved, but the device complexity and size are increased
Solution Approach 1:
The actuator system performs its own measurement function by utilizing its existing components. The control unit processes current signals from the linear motor to calculate load, allowing the system to self-measure without external measurement instruments
Solution Approach 2:
The patent replaces the mechanical load cell measurement system with an electrical/electronic measurement approach. By calculating load from current signals through mathematical relationships, the system substitutes physical measurement instrumentation with computational methods
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 load measurement with reduced device size and cost, while preventing measurement errors and undesired impacts during load application, improving measurement accuracy and efficiency.
Implementation Method 1
a rod-type linear motor 10 that has a plurality of magnets 103 arranged such that the same poles face each other; and a coil housing case 102 that has a plurality of coils 104 surrounding the rod 101
Implementation Method 2
wherein the motor applies a load to a measurement target, and a magnetic sensor detects changes in the magnetic field to calculate the load
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A measurement device (1) is provided with: a linear motor (10); a driving unit (22) that applies a load to a measurement target by moving a mover provided in the linear motor (10); and a load measurement unit (21) that calculates the load which is applied by the mover to the measurement target, by multiplying a thrust constant of the linear motor (10) by a value of current which flows in the linear motor (10) when the mover is moved.