Numerical Controller Acceleration Normalization for Machine Shock Reduction
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Solution Overview
Problem
Conventional acceleration/deceleration control in numerical controllers for machines with servo motors often results in high acceleration of tools or workpieces in orthogonal coordinate systems, leading to shock and increased cycle times due to mismatched movement amounts and directions between drive axis and machine coordinate systems.
Innovation Solution
A numerical controller that normalizes acceleration/deceleration information between machine and drive axis coordinate systems, using units like tangential direction acceleration calculation, speed limit calculation, and acceleration/deceleration processing to ensure control targets in both systems adhere to maximum allowable accelerations, reducing shock and optimizing cycle times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acceleration control is exerted in drive axis coordinate system based on maximum allowable acceleration set for each drive axis, then acceleration control is simplified and drive axis movement is controlled, but acceleration in machine coordinate system may exceed allowable limits causing shock
Solution Approach 1:
The patent introduces a coordinate transformation mechanism that acts as an intermediary between drive axis coordinate system and machine coordinate system. The transformation unit converts acceleration commands from drive axis coordinates to machine coordinates, and the determination unit uses this transformed information to prevent shock while maintaining control simplicity.
Solution Approach 2:
The patent dynamically adjusts acceleration parameters by transforming them between coordinate systems. The maximum allowable acceleration in machine coordinate system is determined based on transformed drive axis acceleration, allowing the control parameters to adapt to the actual machine coordinate requirements and prevent shock.
2Object-affected harmful factors
If maximum allowable acceleration is set considering maximum acceleration at coordinate value Y, then shock is prevented, but cycle time increases due to overly conservative settings
Solution Approach 1:
The patent implements dynamic acceleration control where the maximum allowable acceleration is not fixed but determined in real-time based on current machine coordinate position and velocity. The determination unit calculates appropriate acceleration limits dynamically, allowing higher acceleration when safe and reducing it only when necessary to prevent shock.
Solution Approach 2:
The system uses feedback from the transformed machine coordinate acceleration information to adjust drive axis acceleration commands. The determination unit continuously monitors the transformed acceleration and adjusts the maximum allowable acceleration to maintain shock prevention while optimizing cycle time.
3Device complexity
If acceleration control is exerted in drive axis coordinate system without coordinate transformation, then control processing is simpler, but accuracy of acceleration control in machine coordinate system deteriorates
Solution Approach 1:
The patent performs preliminary coordinate transformation of acceleration commands before executing the control. The transformation unit pre-calculates the relationship between drive axis and machine coordinate acceleration, allowing the determination unit to make accurate decisions without complex real-time calculations during execution.
Data Source
AI summary
To provide a controller capable of exerting acceleration/deceleration control more accurately than has been exerted conventionally and capable of reducing the occurrence of shock and shortening cycle time. A numerical controller outputs a movement command for a drive axis of a machine based on a command in a program for controlling the machine having the drive axis controlled by a servo motor. The numerical controller exerts acceleration/deceleration control over the drive axis so as to satisfy a condition for the acceleration/deceleration in each of a machine coordinate system as an orthogonal coordinate system in the machine and a drive axis coordinate system by normalizing each of acceleration/deceleration related information in the machine coordinate system and acceleration/deceleration related information in the drive axis coordinate system to a value in the drive axis coordinate system.