Infant Swing Encoder Coupling for Backlash-Free Motion Sensing
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Solution Overview
Problem
Conventional infant swing apparatuses face inaccuracies in determining swing motion direction and amplitude due to backlash in gear reduction systems, leading to incorrect motor control signals.
Innovation Solution
A motorized infant swing apparatus with a swing motion sensing unit featuring an encoder wheel directly coupled to the pivot shaft via static friction, eliminating the need for intermediate gear transmission and thus avoiding backlash-related measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gear reduction system is used to drive the swing arm, then the motor can operate at high speed with low torque, but backlash in the gear stages causes inaccurate detection of swing direction and amplitude
Solution Approach 1:
The system is segmented into two independent rotational systems: one for driving (motor to swing arm via gears) and one for sensing (encoder wheel to pivot shaft). The encoder wheel is mounted on a separate pivot shaft that is directly coupled to the swing arm, isolating the sensing path from the gear train and eliminating backlash interference in motion detection.
Solution Approach 2:
A second pivot shaft serves as an intermediary element that directly couples the swing arm's angular displacement to the encoder wheel, bypassing the gear reduction system. This intermediary shaft transfers motion purely for sensing purposes without the backlash inherent in gear stages.
2Force
If multiple gear stages are used for reduction, then the correct torque is achieved, but each stage introduces backlash that delays direction change detection
Solution Approach 1:
The drive and sense functions are segmented into separate mechanical paths. The drive path uses multiple gear stages to achieve proper torque multiplication, while the sense path uses a direct coupling through a second pivot shaft to immediately detect direction changes without the time delay caused by gear backlash.
3Device complexity
If the encoder wheel is mounted on the motor shaft, then the sensing unit is simple, but backlash in the gear system causes incorrect encoder readings
Solution Approach 1:
The encoder wheel is mounted on a separate pivot shaft rather than the motor shaft, creating two independent rotational systems. This segmentation ensures that the encoder wheel rotates in direct correspondence with the swing arm's angular displacement, providing accurate measurements independent of gear train backlash.
Solution Approach 2:
The second pivot shaft acts as an intermediary that directly couples the swing arm's motion to the encoder wheel, providing an accurate reference for motion detection that is not influenced by the gear reduction system's backlash.
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 design enables precise monitoring and control of swing motion, ensuring accurate and efficient operation by isolating the encoder wheel from drive unit backlashes, resulting in improved directional changes and amplitude detection.
Implementation Method 1
the second pivot shaft is directly coupled with the first pivot shaft in angular displacement via a friction interaction
Data Source
AI summary
An infant swing apparatus comprises a first pivot shaft coupled with a swing arm, a motorized drive unit configured to drive rotation of the first pivot shaft in alternate directions, and a swing motion sensing unit including an encoder wheel securely mounted with a second pivot shaft. The second pivot shaft is directly coupled with the first pivot shaft in angular displacement via frictional interaction. As a result, the rotation of the first pivot shaft and corresponding swing motion can monitored in a precise manner.