Torsion Model Controller Structure for Shaft Elasticity Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing controller structures in machine tools face following errors due to the elasticity of the mechanism between the drive and the object, leading to deviations in position and speed, which result in inaccuracies in the programmed tool path.
Innovation Solution
A controller structure that includes a position controller, a speed controller, and a circuit for generating a pre-control current, which is applied to a torsional pre-control model to compensate for torsional effects, reducing tracking errors by incorporating a differentiator and multiplier for parameterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a very precise position measuring device is attached to the object and a rotary encoder is located on the drive, then position and speed can be detected, but following errors occur due to elasticity of the mechanism between drive and object
Solution Approach 1:
The patent applies preliminary action by calculating and applying a pre-control current before the actual positioning action. The pre-control current compensates for torsional effects in advance by using the second derivative of the position setpoint to predict and counteract elastic deformation, thereby preventing following errors before they occur.
Solution Approach 2:
The patent changes the parameter of drive current by adding a pre-control current component. This additional current parameter compensates for the elastic deformation of the mechanism, adjusting the drive behavior to account for torsional effects and improve positioning accuracy.
2Adaptability or versatility
If cascaded controller structures with position, speed and current controllers are used, then control functionality is comprehensive, but device complexity increases
Solution Approach 1:
The patent reduces complexity by implementing a pre-control current calculation that compensates for torsional effects in advance. This preliminary action allows the system to achieve better accuracy without requiring complex modifications to the cascaded controller structure, effectively simplifying the overall control architecture.
Data Source
Figure 1~2
AI summary
The device has a position controller (1) for generation of rotational speed reference value from a position reference value and a position actual value. A model, differentiator (12) and multiplier (11) are provided for generation of pre control current from the position reference value, where the pre-control current is added to a reference current value. The pre-control current is provided to a model for torsion pre-controlling of a shaft between a drive and an object, where output signal of the model is added to the rotational speed reference value.