Laser Processing Head Focus Control Under External Acceleration
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Solution Overview
Problem
Existing laser processing heads struggle to maintain precise focus position during highly dynamic machine movements due to external accelerations, which cause unwanted movement of the optics and delayed correction in the position control loop.
Innovation Solution
A method and device that utilize an acceleration sensor to detect external accelerations and directly increase the motor current of a servomotor to counteract the resulting forces, minimizing position deviation by integrating acceleration feedback into the current control loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If synchronous linear motor is used for direct translation of motor movement into optics movement without gear or spindle, then backlash-free implementation is achieved, but mechanical inhibition to keep optics in desired position during external acceleration is lost
Solution Approach 1:
An acceleration sensor detects external accelerations acting on the laser processing head, and this information is fed back to the control circuit. The control circuit generates a counteracting force specification based on the detected acceleration, which is applied to the servomotor to compensate for position deviations before they occur.
Solution Approach 2:
The acceleration sensor detects external accelerations in advance, and the control circuit calculates and applies the necessary counteracting force through the servomotor before the optics actually deviate from the target position. This preliminary action prevents position errors rather than correcting them after detection.
2Manufacturing precision
If position control loop is used to correct lens position deviation, then focus position is restored, but delayed reaction occurs after significant deviation has already happened
Solution Approach 1:
The acceleration sensor detects external accelerations before they cause significant position deviation. The control circuit calculates and applies the necessary counteracting force through the servomotor in advance, preventing the optics from deviating from the target position rather than correcting the position after deviation occurs.
Solution Approach 2:
The acceleration sensor continuously monitors external accelerations and provides real-time feedback to the control circuit. This feedback enables the system to generate and apply compensating forces dynamically, maintaining focus position accuracy without the delays inherent in traditional position-corrective feedback loops.
3Reliability
If motor current is increased to generate additional counteracting force, then position stability during acceleration is improved, but energy consumption increases
Solution Approach 1:
The servomotor current is dynamically adjusted based on the detected acceleration magnitude. The control circuit applies only the necessary counteracting force required to compensate for the external acceleration, rather than continuously applying maximum force. This partial action approach maintains position stability while minimizing unnecessary energy consumption.
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 approach allows for precise maintenance of the focus position without initial position deviation, as the additional force generated by increased motor current immediately counteracts external disturbances, reducing the delay in correcting for position changes.
Implementation Method 1
an acceleration sensor (48) is provided, which detects an acceleration acting in the direction of the optical axis of the optics (26)
Implementation Method 2
the servomotor (28) generates an additional force that counteracts the force generated by the detected acceleration
Data Source
Figure 1~2
AI summary
The invention relates to method and device for controlling a focus point of a working laser beam (14) for machining workpieces (20) and a laser machining head (10) equipped therewith in which the focus point of the working laser beam (14) is adjusted by displacing an optical system (24) along an optical axis (26) of the optical system (24) by means of an actuator motor (28). The method comprises the following steps: - generating and outputting a specification for a current control circuit (40) of the actuator motor (28) with a position controller (38) in order to move the optical system (24) into a target position and hold it there, - detecting an acceleration acting in the direction of the optical axis of the optical system with an acceleration sensor (48), and - varying the specification that is output for the current control circuit (40) of the actuator motor (28) on the basis of the detected acceleration using a pilot circuit (50), such that the actuator motor (28) generates an additional force which counteracts the force generated by the detected acceleration.