Coordinating Multi-Axis Drive Gain to Reduce Path Distortion
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Solution Overview
Problem
Machine tools with multiple axis drives experience path distortions due to inconsistencies in following errors of individual axes, leading to dimensional errors in machined workpieces, despite optimal frequency matching of axes.
Innovation Solution
Specifying an effective amplification factor uniform across all axis directions, which is determined by the amplification factors of the first and second axle drives, ensuring that all drive arrangements follow a predetermined trajectory with the same effective gain, thereby reducing path distortions and limiting the effect of more dynamic axes to achieve good path behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple individual axle drives are used in one axis direction to increase dynamics and reduce traversing range, then the response speed and positioning accuracy improve, but path distortions occur due to inconsistencies in following errors between axes
Solution Approach 1:
The patent implements feedback control by continuously monitoring the following errors of individual axle drives and using a control factor to adjust the setpoint values. The control unit receives actual position feedback from encoders and compares it with the setpoint trajectory, then generates corrective control signals to minimize path distortions and ensure coordinated movement of multiple axle drives.
Solution Approach 2:
The patent dynamically adjusts the control factor parameter based on the dynamics characteristics of different axle drives. By modifying the control factor, the system optimizes the response of each axle drive to setpoint changes, ensuring that faster axes do not overshoot while slower axes maintain adequate tracking performance, thus resolving the contradiction between speed and precision.
2Manufacturing precision
If control factors are adjusted to limit the effect of more dynamic axes, then path behavior improves, but the complexity of control increases
Solution Approach 1:
The patent employs a universal control factor that serves multiple functions: it coordinates the movement of multiple axle drives, limits the effect of more dynamic axes, and ensures consistent following errors across all axes. This single control parameter handles multiple control objectives simultaneously, simplifying the overall control architecture while achieving precise path following.
3Productivity
If amplification factors are optimized for individual axle drives, then each drive achieves optimal performance, but inconsistencies in following errors cause path distortions
Solution Approach 1:
The patent intentionally introduces asymmetry in the control approach by applying different control factors to different axle drives based on their individual dynamics characteristics. Faster axes receive control factors that limit their response to prevent overshoot, while slower axes receive factors that enhance their tracking capability. This asymmetric control strategy compensates for the inherent differences in drive performance and eliminates path distortions.
Data Source
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AI summary
A method for coordinating drive arrangements (ATi, ATj) in a machine tool which act in different axial directions (i, j) comprises the following steps: a first nominal value (xi,anominal) is prescribed for a first controlled axial drive (Ai,a) in a first drive arrangement (ATj) acting in a first axial direction (i), a control factor is prescribed for supplying a variable which is proportional to a control error (?Xi, a) in the first controlled axial drive (Ai,a) to at least one second controlled axial drive (Ai