Numerical Control Device Vibration Suppression via Dynamic Model Parameters
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Solution Overview
Problem
Existing numerical control devices for machine tools fail to effectively suppress vibration in relative displacement between the tool and workpiece due to changes in the inertia of the machine tool, such as changes in the weight of the workpiece or positional relationships, as they do not account for these changes in their correction mechanisms.
Innovation Solution
A numerical control device that includes a tool-side displacement measurement unit, a workpiece-side displacement measurement unit, a drive signal measurement unit, a relative displacement calculation unit, a model parameter operation unit, a relative displacement prediction unit, and a command value correction unit, which calculates and corrects position commands to minimize relative displacement by adjusting prediction model parameters based on real-time measurements and optimization methods like particle swarm optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a prediction model is used to suppress vibration in relative displacement, then machining accuracy is improved, but the correction becomes inaccurate when inertia changes occur
Solution Approach 1:
The prediction model parameters are made dynamically adjustable rather than fixed. The system continuously updates parameters based on actual machining data, allowing the model to adapt to changing inertia conditions caused by workpiece weight variations or positional changes, thereby maintaining accuracy across different operating conditions
Solution Approach 2:
The system changes the parameters of the prediction model based on detected inertia variations. By monitoring actual relative displacement and comparing it with predicted values, the system adjusts model parameters to reflect current machine tool conditions, enabling accurate vibration suppression even when inertia changes occur
2Object-affected harmful factors
If feedforward correction is applied based on a fixed prediction model, then vibration is suppressed under constant conditions, but correction accuracy deteriorates when workpiece weight or position changes
Solution Approach 1:
The system introduces feedback mechanisms where actual relative displacement measurements are continuously fed back to update the prediction model. This closed-loop approach allows the system to detect inertia changes and adjust correction strategies accordingly, maintaining reliability when workpiece weight or position changes
Solution Approach 2:
The system performs preliminary measurements and model updates during machining operations to anticipate and prepare for inertia changes. By continuously refining the prediction model based on actual data, the system maintains accurate vibration suppression before significant inertia variations affect machining quality
Data Source
AI summary
A numerical control device includes: a tool-side displacement measurement unit; a workpiece-side displacement measurement unit; a drive signal measurement unit; a relative displacement calculation unit between the tool and the workpiece; a relative displacement prediction unit calculating a relative displacement predicted value from the drive signal, from a prediction model representing a relationship between the drive signal and the relative displacement; a model parameter operation unit generating prediction model parameters constituting the prediction model, from the drive signal, the relative displacement, and the predicted value; and a command value correction unit outputting a post-correction position command obtained by correcting a position command to the drive unit using the prediction model parameters. The model parameter operation unit changes the prediction model parameters to reduce a difference between the relative displacement and the predicted value.