Dual-Encoder Link Sensor for Tip Displacement Correction
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Solution Overview
Problem
Existing technologies fail to accurately detect displacement of a machine tip due to bending of links, which affects machining accuracy in industrial robots and machine tools.
Innovation Solution
A displacement detection sensor comprising two encoders attached to relative links with differently positioned scale members and detectors, allowing detection of tip displacement based on scale differences caused by external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encoder is attached to the output shaft of a joint to control the position, then the effects of twisting and backlash are eliminated, but displacement due to bending of links cannot be detected
Solution Approach 1:
The patent transitions from one-dimensional rotation angle detection to two-dimensional position detection by using two encoders with scale members at different radial distances. This dimensional expansion enables detection of both rotational position and radial displacement (link bending) simultaneously, resolving the contradiction between joint control reliability and tip displacement measurement precision
2Measurement precision
If a displacement detector is attached to the free end to detect deflection, then tip positioning can be corrected, but the system complexity increases
Solution Approach 1:
The patent makes the encoder system multi-functional by configuring two encoders to simultaneously perform joint position control and link bending detection. The same encoder components (detectors and scale members) serve dual purposes, eliminating the need for separate displacement detectors and reducing overall system complexity while maintaining high measurement precision
3Measurement precision
If two encoders with different scale member distances are used, then tip displacement can be detected through scale differences, but the device complexity increases
Solution Approach 1:
The patent segments the detection function into two distinct encoder channels with scale members at different radial distances. Each encoder independently measures position information, and the control device processes the segmented data to calculate tip displacement. This segmentation enables accurate displacement detection while maintaining modular system architecture that manages complexity
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
Accurately detects and corrects machine tip displacement, enhancing machining precision by accounting for link bending and twisting.
Implementation Method 1
the two encoders comprise two scale members having different distances from the axis, and two detectors for detecting respective scales of the two scale members
Data Source
AI summary
This displacement detecting sensor is provided with two encoders attached to a first link and a second link that are coupled in such a way as to be capable of moving relative to a certain axis, wherein: the two encoders are provided with two scale members at different distances from the axis, and two detectors for detecting scales on the respective two scale members; a positional relationship between the scale members and the detectors changes in accordance with an external force accepted at the distal end of the second link, generating a difference between the two scales detected by the two encoders; and the displacement of the distal end of the second link can be detected on the basis of the two scales.