Numerical Controller Synchronization for Servo Motor Positional Discrepancies
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Solution Overview
Problem
In die casting and pressing machines, synchronous control of multiple servomotors leads to uneven force transmission and increased loads on connecting parts due to differences in position and speed between control axes when switching from a servo-off to a servo-on state, causing positional discrepancies and mechanical stress.
Innovation Solution
A numerical controller that detects actual speeds at the servo-on state and sets a common initial speed for all axes, along with acceleration and deceleration control, to synchronize the movement and reduce positional differences, thereby minimizing load on connecting parts and avoiding abrupt speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If actual speeds at servo-on are set as initial speeds and identical move commands are initiated, then the positional control can be started smoothly, but the difference in position between control axes gradually increases causing increased loads on connecting parts
Solution Approach 1:
The patent changes the parameter of initial speed from using actual speeds to using a common predetermined speed for all control axes. This parameter change ensures that all axes start from the same speed reference, preventing the gradual increase in positional differences that would otherwise occur when using actual speeds as initial values.
Solution Approach 2:
The patent applies preliminary action by setting a common initial speed before move commands are initiated. This preliminary speed setting ensures that all control axes are synchronized at the start, preventing subsequent positional discrepancies and reducing loads on connecting parts during the movement phase.
2Extent of automation
If a plurality of servomotors are connected and operated synchronously with identical move commands, then synchronous control is achieved, but uneven force transmission occurs due to displaced ejecting points
Solution Approach 1:
The patent changes the speed parameter from using actual varied speeds to using a common predetermined speed for all axes. This standardization compensates for the uneven force transmission caused by displaced ejecting points, ensuring that all servomotors operate from the same speed reference and maintain synchronous control stability.
3Device complexity
If acceleration rates are kept identical for all control axes, then simple control is maintained, but positional differences between axes increase causing mechanical stress
Solution Approach 1:
The patent applies preliminary action by establishing a common initial speed and a common predetermined acceleration rate before movement begins. This preliminary synchronization ensures that all control axes start from the same reference point and maintain consistent acceleration patterns, preventing positional discrepancies and reducing mechanical stress while keeping control simple.
Data Source
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AI summary
Initial speeds in the move commands for respective control axes at servo-on are determined according to parameter setting, or the comparative relationship or difference in speed among the actual speeds of the control axes so that difference in position between the control axes does not increase as the move commands are executed after the servo-on. The actual speeds of the control axes are set as initial speeds in the move commands, and a target axis is specified on the basis of the comparative relationship among their actual speeds and the other control axes are accelerated or decelerated at the acceleration or deceleration rate specified in the move commands to attain the position and speed of the target axis, so that differences in position and speed among the control axes are gradually decreased as the move commands are executed after the servo-on, thereby preventing abrupt speed changes and suppressing mechanical shocks.