Servo Controller Oscillation Offset for High-Frequency Cutting
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Solution Overview
Problem
Existing machine tools face challenges in achieving high-precision oscillating motion at high oscillation frequencies, as conventional control mechanisms struggle to respond effectively to changes in machining conditions and precision is compromised when increasing oscillation frequency.
Innovation Solution
A servo controller system that includes a position command acquiring unit, positional deviation calculating unit, spindle axis angle acquiring unit, oscillation command calculating unit, and oscillation offset calculating unit, which calculates and compensates for delays in responsiveness to generate precise oscillation commands, allowing for high-precision oscillating motion even at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high oscillation frequency is used to improve chip shredding performance, then machining effectiveness is improved, but control precision deteriorates due to inability to respond to rapid changes
Solution Approach 1:
The system pre-calculates oscillation commands at a higher frequency than the command distribution cycle, storing multiple oscillation cycles in advance. This allows the servo motor to receive pre-prepared high-frequency oscillation commands without waiting for real-time calculation, thereby maintaining control precision at high oscillation frequencies.
Solution Approach 2:
The system uses feedback from the servo motor's actual position and speed to dynamically adjust oscillation commands. By continuously monitoring the servo motor's responsiveness and adjusting commands based on actual performance, the system maintains precise oscillation control even at high frequencies where traditional open-loop control would fail.
2Speed
If oscillation frequency is increased to approach command distribution frequency, then response speed is improved, but command precision deteriorates due to insufficient sampling points
Solution Approach 1:
The system generates and stores multiple oscillation commands in advance at a frequency higher than the command distribution cycle. By preparing oscillation commands beforehand rather than calculating them in real-time, the system can distribute commands at the standard cycle frequency while the oscillation frequency remains high, ensuring sufficient sampling points for precise control.
Solution Approach 2:
The system dynamically adjusts the oscillation command generation based on the relationship between oscillation frequency and command distribution frequency. When oscillation frequency approaches command distribution frequency, the system modifies its command generation strategy to maintain adequate sampling resolution, ensuring command precision is preserved despite high-speed oscillation.
Data Source
AI summary
A controller including: a positional deviation calculating unit that calculates positional deviation using a position command directed to a servo motor for driving a cutting tool, etc., and a position feedback value corresponding to the position of the cutting tool, etc.; an oscillation command calculating unit that calculates an oscillation command using the position command and a spindle axis angle of the rotated work, etc., or using the position feedback value and the spindle axis angle; an oscillation offset calculating unit that calculates an offset for the oscillation command using the positional deviation, the oscillation command, and the spindle axis angle; and a driving unit that determines a drive signal for the servo motor based on the positional deviation, the oscillation command, and the oscillation offset, and outputs the drive signal.