Trajectory Control Device for Multi-Axis Processing Machines
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Solution Overview
Problem
Existing trajectory control methods for processing machines face challenges in accurately following commanded paths due to transitional changes in normal direction acceleration and changing moving directions, leading to trajectory errors and increased calculation complexity, especially when the number of axes is high.
Innovation Solution
A trajectory control device that includes an integrated-length calculation unit, a simulated servo-response filter unit, a reference-response calculation unit, a response compensation unit, and a servo control unit, which calculates an integrated command length, simulates servo responses, determines a reference response position, and adjusts command positions to compensate for servo delays, ensuring accurate path following.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional trajectory control is used with servo control on each movable axis, then the control system is simple to implement, but trajectory errors occur when the moving direction changes due to response delay
Solution Approach 1:
The invention calculates the integrated command length in advance and uses it to determine the corrected command position. By performing the length integration beforehand and using it as a reference for position correction, the system proactively compensates for trajectory errors before they occur, rather than reacting to errors after they happen. This preliminary calculation approach improves trajectory accuracy without requiring complex real-time correction mechanisms.
Solution Approach 2:
The integrated command length serves as an intermediary parameter that bridges the command position and the actual servo response. Instead of directly controlling each axis based on command positions, the system uses the integrated length as a mediator to coordinate the motion of multiple axes, ensuring they move harmoniously along the command path and reducing trajectory errors caused by response delays.
2Manufacturing precision
If command position correction is applied to suppress trajectory errors, then trajectory accuracy improves, but calculation complexity increases due to look-ahead requirements
Solution Approach 1:
The invention extracts the integrated command length calculation as a separate, standalone function that can be performed independently of the main trajectory control loop. By separating the length integration step from the position correction logic, the system eliminates the need for complex look-ahead operations while still achieving accurate trajectory following. This extraction simplifies the overall calculation structure.
Solution Approach 2:
The integrated command length is calculated in advance as a preliminary step before trajectory correction is applied. This preliminary calculation provides a ready-to-use reference value that simplifies subsequent position correction operations, eliminating the need for complex real-time look-ahead calculations and reducing overall computational complexity.
3Productivity
If high feed rate is used to improve productivity, then machining time decreases, but trajectory errors increase due to servo response delay
Solution Approach 1:
The system uses the integrated command length as a feedback reference to continuously monitor and correct the actual position of the movable portion. By comparing the integrated length with the commanded position and applying corrections based on this feedback, the system maintains high trajectory accuracy even at high feed rates where servo response delays would normally cause significant errors.
Data Source
AI summary
A trajectory control device that controls a trajectory of a movable portion of a processing machine so as to follow a command path accurately. The trajectory control device includes an integrated-length calculation unit that calculates an integrated command length being a length integrated from a start position along a command path, a simulated servo-response filter unit that calculates an integrated response length, a reference-response calculation unit that calculates a reference response position, a response compensation unit that calculates a corrected command position on each of the plurality of axes, and a servo control unit that controls each of the plurality of axes.