Feed Shaft Control via Acceleration Feedback Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In machine tool control systems, the feedback of acceleration from a driven element away from the motor output axis leads to position and speed deflections in control commands, reducing the effectiveness of vibration restraint during machining.
Innovation Solution
A cascade connection is formed between a speed feedback loop and a position feedback loop, with state sensors like acceleration and position detectors placed on the machine structure and axis feed mechanism, allowing for acceleration and speed feedback signals to be adjusted and added to control commands to correct for deflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acceleration detection means is disposed at the driven element away from the motor output axis, then vibration restraint is achieved through acceleration feedback, but position and speed deflections occur in control commands reducing control accuracy
Solution Approach 1:
The patent introduces speed estimation value as an intermediary parameter that mediates between acceleration feedback and speed control. The speed estimation value is calculated by integrating acceleration feedback signal, then this estimation is used to correct the speed command without directly feeding back acceleration to the speed controller, thus avoiding deflection issues while maintaining vibration restraint
Solution Approach 2:
The patent replaces direct acceleration feedback to speed control with a substituted approach: acceleration is integrated to obtain speed estimation, and this estimation is used to generate correction signals. This substitution transforms the direct acceleration-feedback mechanism into an indirect speed-estimation-based mechanism, resolving the contradiction between vibration restraint and control accuracy
2Manufacturing precision
If acceleration feedback is applied to torque command for vibration restraint, then machining accuracy is improved, but position and speed deflections are generated in the control system
Solution Approach 1:
The patent segments the control system into distinct functional blocks: acceleration detection, integration to obtain speed estimation, correction value calculation, and torque command generation. By segmenting the control process, the patent can apply acceleration feedback for vibration restraint in the torque command while using separate correction paths to compensate for position and speed deflections, thus maintaining both machining accuracy and control stability
Solution Approach 2:
The patent performs preliminary integration of acceleration feedback to obtain speed estimation value before applying it to torque command correction. This preliminary action allows the system to prepare correction signals in advance, ensuring that vibration restraint is achieved while position and speed deflections are compensated, maintaining control signal stability
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a feed shaft control method, wherein a speed feedback loop having a speed controller (72) is disposed within a position feedback loop having a position controller (71), forming a cascade coupling, and an acceleration feedback signal which is outputted from a compensator (91) on the basis of an output signal of an acceleration detector (60) is subtracted from a torque instruction (τr). Furthermore, the method implements control wherein a speed is acquired on the basis of the output signal of the acceleration detector (60), and a signal obtained by multiplying the acquired speed by a gain (Ka3) is added to a speed instruction (ωr) which is outputted from the position controller (71).