Rotary Axis Position Estimation Using Tool Load Feedback
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Solution Overview
Problem
Current methods for estimating the position of a rotary axis in a lathe turning process rely heavily on operator skill and are prone to inaccuracies, leading to inefficiencies in removing remaining portions of machined objects.
Innovation Solution
An estimating device and system that utilize a combination of motors and sensors to accurately determine the position of a rotary axis by controlling tool movement along perpendicular directions, acquiring load data, and compensating for positional deviations, with a learning unit to optimize model functions for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position of the rotary axis is estimated by operator trial and error fitting operation, then the process is simple to implement, but the estimation accuracy depends significantly on operator skill and is insufficient
Solution Approach 1:
The patent replaces the manual mechanical trial-and-error fitting operation with an automated estimation system that uses motor load detection and calculation processing. The load acquisition unit measures motor load values during tool movement, and the estimation unit calculates the rotary axis position based on these load values, eliminating the need for operator skill while achieving high precision.
Solution Approach 2:
The system enables the machine tool to automatically determine its own rotary axis position through self-measurement of motor load characteristics during tool approach movements. The estimation unit processes the measured load data to identify the position where the tool contacts the rotary axis, allowing the system to self-calibrate without external intervention or operator skill.
2Manufacturing precision
If the tool is deviated even slightly from the position of the rotating shaft, then the remaining portion cannot be removed, but achieving exact positioning requires highly accurate estimation
Solution Approach 1:
The system uses feedback from the load acquisition unit that continuously monitors motor load during tool movement. When the tool approaches the rotary axis position, the load value changes characteristically, providing feedback signal that the estimation unit uses to precisely determine the contact position. This feedback mechanism enables accurate positioning by detecting the exact moment when the tool contacts the rotary axis.
Solution Approach 2:
The system performs preliminary measurement movements of the tool toward the rotary axis position before final positioning. The load acquisition unit measures motor load during these preliminary approach movements, and the estimation unit calculates the precise rotary axis position based on these preliminary measurements, enabling accurate final positioning without trial-and-error adjustments.
3Extent of automation
If automated estimation using motor load is implemented, then operator skill dependency is reduced, but the system requires additional sensors and control mechanisms
Solution Approach 1:
The patent makes the existing motor serve multiple functions: it not only drives the tool movement but also acts as a sensor through its load acquisition capability. The same motor that performs the cutting operation also provides the load measurement data needed for position estimation, eliminating the need for separate sensing devices and reducing overall system complexity.
Solution Approach 2:
The estimation unit acts as an intermediary that processes the raw load data from the load acquisition unit and translates it into precise position information. This intermediary processing layer integrates the measurement and control functions, coordinating the data flow between the motor, load sensor, and control system without requiring complex additional hardware.
Data Source
AI summary
An estimating device estimating a rotary axis position of a workpiece includes first and second position acquisition units acquiring tool positions in first and second directions, a load acquisition unit acquiring first and second directional loads of the tool in the first and second directions, a determination unit determining whether or not the first and second directional loads each are a threshold or less, a turning control unit performing a lathe turning on the workpiece until the first directional load becomes the threshold or less and thereafter performing a lathe turning thereon until the second directional load becomes the threshold or less, and an estimating unit estimating the rotary axis position based on a first directional position of the tool when the first directional load has become the threshold or less, and a second directional position thereof when the second directional load has become the threshold or less.