Five-Axis CNC On-Machine Measurement With Synchronous FIFO Buffering
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Solution Overview
Problem
Existing on-machine measurement technologies for full-closed loop five-axis CNC machine tools face challenges in achieving synchronous real-time collection of machine axis positions and external sensor data due to finite reading frequency and latency within CNC systems, as well as data loss during high-speed transmission.
Innovation Solution
An on-machine real-time measurement system that utilizes grating scales, non-contact displacement sensors, and a synchronous communication module with a FIFO rotation buffering mechanism to ensure one-to-one correspondence between machine axis positions and external sensor data, using Ethernet/IP communication for real-time data transmission and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If data acquisition is based on CNC systems with finite reading frequency, then implementation is simple, but synchronous real-time data collection between machine axis positions and measurement sensors becomes challenging
Solution Approach 1:
The patent introduces an external counting device as an intermediary component that directly interfaces with the motor encoders of each machine axis. This mediator captures position data at the encoder level bypassing the CNC system's limited reading frequency, while still working within the existing CNC architecture. The external counting device acts as a bridge between the high-speed encoder outputs and the measurement sensor data collection, enabling synchronous real-time acquisition without requiring complete system redesign.
2Speed
If data acquisition is based on motor encoders with external counting devices, then real-time acquisition performance improves, but true synchronous correspondence between axis position data and measurement sensor data is not achieved and transmission errors are neglected
Solution Approach 1:
The patent implements a feedback mechanism where the external counting device continuously monitors motor encoder positions and compares them with measurement sensor data timestamps. When asynchronization or transmission errors are detected, the system generates correction signals and feedback messages to adjust the data collection timing and compensate for transmission delays. This closed-loop feedback ensures that even at high speeds, the position data and sensor measurements remain truly synchronous and accurate.
Solution Approach 2:
The system performs preliminary calibration and synchronization setup before actual measurement operations. The external counting device pre-synchronizes its counting clock with the machine axis motion cycles and pre-establishes timing relationships with measurement sensors. This preliminary action ensures that when high-speed data acquisition begins, all components are already synchronized, eliminating the need for complex real-time adjustments during measurement and maintaining precise synchronous correspondence throughout the measurement process.
3Measurement precision
If grating scales on full-closed loop CNC machine tool are used to detect real position, then measurement accuracy improves, but data loss occurs during high-speed transmission
Solution Approach 1:
The patent segments the high-speed position data transmission into smaller, manageable data packets that are processed and transmitted in discrete units. Instead of attempting to transmit complete high-resolution position data at full speed, the system divides the data stream into segments that can be reliably transmitted without overload. Each segment is independently validated and acknowledged, preventing data loss by ensuring that no single transmission bottleneck compromises the entire data stream. Lost segments can be individually retransmitted without affecting other data.
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 system enhances measurement accuracy and efficiency by eliminating clamping errors, ensuring synchronous real-time data collection, and improving data transmission stability, thereby meeting the precision demands of complex surface structural parts.
Implementation Method 1
detect the real position of each machine axis by grating scales on the full-closed loop CNC machine tool
Implementation Method 2
displacement measurement component comprises a non-contact displacement sensor
Data Source
AI summary
The present invention provides an on-machine real-time measurement method and system for a full-closed loop five-axis computer numerical control machine tool. In the system, a high-precision coaxial fixture in a displacement measurement component is used for connecting the component with the machine tool spindle; a multifunctional evaluation electronics box reads the signals of the grating scale of each machine axis in real time, and synchronously triggers the displacement sensor to collect the measured workpiece surface information; a synchronous communication module caches the grating scale signals of each machine axis and the measurement signals of the sensor to the FIFO rotation buffering module of the host computer in parallel to reduce the burden of high-speed transmission; and the host computer performs data processing and coordinate transformation of the grating scale data and the measurement information in the FIFO module, and finally obtains the three-dimensional geometric information of the measured workpiece surface.