<p>Increasing demands for the precision of mechanical engineering products and the introduction of innovative technologies necessitate the improvement of CNC machines. This requires taking into account additional factors that influence processing errors. Smooth variations in the differential characteristics of motion are ensured by using spline interpolation, smooth feed control laws, and smooth 3D error compensation. However, the servo drive’s inability to respond to differential characteristics eliminates the benefits of smooth movements. Due to the non-stationary movement of the axes, the machined contour error is mainly determined by the servo error in the position control loop. The aim of this paper is to develop an acceleration and jerk FFW control method for an axis position servo with full compensation for the effect of differential characteristics on servo error. It investigates the existence of a stable correlation between the values of the servo error and interpolation acceleration and jerk. A model for predicting servo error as a function of interpolation acceleration and jerk has been proposed. This model is created for a specific machine tool based on the processing of experimental data. Experimental studies were carried out on a digital twin model, on machining centre’s MCVL 1000 and H630 and on a CNC-based investigation complex. For the digital twin model, the coefficient of determination <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="170_2025_15510_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">${R}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi>R</mi> </mrow> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation> of the predictive function for servo error was approximately 0.9992. However, noise and nonlinear distortions in experimental data from real equipment reduced this factor. The obtained values ranged from 0.5186 to 0.9124, depending on the degree of compensation for the influence of acceleration through acceleration feedforward control in the servo drive. The possibility of applying the proposed predictive function as an indicator of control quality by acceleration and jerk parameters in the process of CNC systems tuning is shown. The acceleration and jerk FFW control method to the position control loop is proposed. The effectiveness of this acceleration and jerk FFW control method has been confirmed experimentally. Research on the experimental setup CNC-based investigation complex confirmed that the proposed acceleration and jerk FFW control method provides full compensation of the influence of differential characteristics on the servo drive error.</p>

Prediction and compensation of motion differential characteristics influence on position error in CNC machine tools

期刊论文
发表日期：

2025年4月11日

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Volodymyr Kombarov,
Petr Fojtu,
Matej Sulitka,
Yevhen Aksonov,
Jiri Sveda,
Yevgen Tsegelnyk,
Volodymyr Sorokin,
Sergiy Plankovskyy

摘要

Increasing demands for the precision of mechanical engineering products and the introduction of innovative technologies necessitate the improvement of CNC machines. This requires taking into account additional factors that influence processing errors. Smooth variations in the differential characteristics of motion are ensured by using spline interpolation, smooth feed control laws, and smooth 3D error compensation. However, the servo drive’s inability to respond to differential characteristics eliminates the benefits of smooth movements. Due to the non-stationary movement of the axes, the machined contour error is mainly determined by the servo error in the position control loop. The aim of this paper is to develop an acceleration and jerk FFW control method for an axis position servo with full compensation for the effect of differential characteristics on servo error. It investigates the existence of a stable correlation between the values of the servo error and interpolation acceleration and jerk. A model for predicting servo error as a function of interpolation acceleration and jerk has been proposed. This model is created for a specific machine tool based on the processing of experimental data. Experimental studies were carried out on a digital twin model, on machining centre’s MCVL 1000 and H630 and on a CNC-based investigation complex. For the digital twin model, the coefficient of determination ${R}^{2}$ $R^{2}$ of the predictive function for servo error was approximately 0.9992. However, noise and nonlinear distortions in experimental data from real equipment reduced this factor. The obtained values ranged from 0.5186 to 0.9124, depending on the degree of compensation for the influence of acceleration through acceleration feedforward control in the servo drive. The possibility of applying the proposed predictive function as an indicator of control quality by acceleration and jerk parameters in the process of CNC systems tuning is shown. The acceleration and jerk FFW control method to the position control loop is proposed. The effectiveness of this acceleration and jerk FFW control method has been confirmed experimentally. Research on the experimental setup CNC-based investigation complex confirmed that the proposed acceleration and jerk FFW control method provides full compensation of the influence of differential characteristics on the servo drive error.