Motion Guide Load Measurement Using Position-Linked Displacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing load measuring methods for motion guide devices are inaccurate due to the interference caused by strain gauges, which shift the center of gravity and make it difficult to determine the direction of the load, and require a new strain graph for each size change of the device.
Innovation Solution
A load measuring system that includes a position detecting unit, sensors to measure displacement in radial and horizontal directions, and a calculating unit to determine the load based on detected position and displacement information, allowing for accurate load measurement without direct strain gauge attachment and eliminating the need for a new strain graph with size changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain gauge is interposed between the sliding member and the table of the movable portion to measure the load, then the load can be measured, but the center of gravity of the movable portion shifts to a higher position, causing a greater moment during acceleration and deceleration, which makes the load measurement inaccurate
Solution Approach 1:
The invention extracts the measurement function from the strain gauge and relocates it to the rolling bodies. Instead of measuring load through the sliding member structure, the system uses sensors attached to the rolling bodies to directly detect the load transmitted through them, eliminating the interference caused by strain gauge installation on the sliding member structure
Solution Approach 2:
The rolling bodies serve as intermediaries between the sliding member and the table, and also as the mounting location for the sensors. This intermediary position allows direct measurement of the load transmitted through the rolling contact, providing accurate load data without affecting the center of gravity or moment characteristics of the sliding member
2Measurement precision
If strain gauges are attached to a pair of sleeves of the sliding member to calculate the load, then the load can be calculated, but it is difficult to judge in which direction the load acts from the strain gauge output
Solution Approach 1:
The invention segments the load measurement into three independent directional components by placing sensors on different orientations of the rolling bodies. Each sensor measures load in a specific direction (radial, horizontal, or axial), allowing clear identification of load direction without ambiguity
Solution Approach 2:
The invention adds dimensional information to the load measurement by using sensors oriented in multiple directions. Instead of relying on a single strain gauge that provides ambiguous one-dimensional data, the system uses multiple sensors to capture load components in different spatial dimensions, enabling precise determination of load direction
3Measurement precision
If strain gauges are attached to the sliding member to measure load, then the load can be measured, but it is necessary to prepare a new graph representing the relationship between amount of strain and load every time the size of the motion guide device changes
Solution Approach 1:
The invention changes the measurement parameter from strain (which requires calibration graphs for different device sizes) to direct displacement measurement of the rolling bodies. The sensors measure the actual physical displacement caused by load, which can be directly converted to force using Hooke's law without requiring device-specific calibration curves
Solution Approach 2:
The invention replaces the strain-based measurement system (which relies on electrical resistance changes and requires calibration) with a direct mechanical displacement measurement system. By measuring the physical displacement of the rolling bodies and applying Hooke's law, the system eliminates the need for strain graphs and calibration procedures
Data Source
AI summary
Provided is a motion guide device load measuring system that can accurately measure loads acting on a motion guide device in use. The load measuring system includes a position detecting unit (4) for detecting the position of a sliding member (12) relative to a track member (11) in a direction of relative movement, and at least one sensor (2a-2d, 3a-3d) for detecting the relative displacement of the sliding member (12) relative to the track member (11) in a radial direction and/or a horizontal direction. A calculating unit (6) calculates loads acting on the motion guide device (1), in association with the position of the sliding member (12), on the basis of position information detected by the position detecting unit (4) and displacement information detected by one or more of the sensors (2a-2d, 3a-3d).