scholarly journals A Novel Position Domain Controller For Contour Tracking Performance Improvement

2021 ◽  
Author(s):  
Truong Dam
Keyword(s):  
Time Domain ◽  
Phase Error ◽  
Common Factor ◽  
Tracking Error ◽  
Numerical Control ◽  
Tracking Performance ◽  
Contour Error ◽  
Contour Tracking ◽  
Cnc Machine ◽  
Equivalent Time

A common problem with modern manufacturing processes that utilize high feed-rate machining is how to accurately track a given contour for the tool center point (TCP) of a system. Various methods have been developed to increase axial tracking performance and contouring performance of computerized numerical control (CNC) machines. These include: high gain feedback controllers, feedforward controllers, zero phase error tracking controllers (ZPETC), cross-coupled control (CCC), and iterative learning control to mention a few. The common factor amongst these methods is that they are all based in time domain. This thesis will propose a new control law based in position domain applied to contour tracking control of a CNC machine. The goal of this developed controller is to improve the overall tracking and contouring performance of a CNC system. The idea behind a position domain control involves transforming the dynamics of a system from time domain into position domain through a one-to-one mapping. In the position domain system control, the motion of one of the axis is used as an independent reference by sampling equidistantly to control the remaining axes according to the contouring requirements. The overall contour error in a position domain controller should be lower relative to an equivalent time domain controller since there will be a zero tracking error from the reference motion. The stability of the proposed position domain control is proven through the Lyapunov method. Simulations with linear and nonlinear TCP contours using the proposed position domain controller and an equivalent time domain controller indicate that the proposed position domain control can improve tracking and contouring performance. In addition, a position domain controller with cross-coupled control was also proposed to further improve contour performance.

scholarly journals A Novel Position Domain Controller For Contour Tracking Performance Improvement

2021 ◽  
Author(s):  
Truong Dam
Keyword(s):  
Time Domain ◽  
Phase Error ◽  
Common Factor ◽  
Tracking Error ◽  
Numerical Control ◽  
Tracking Performance ◽  
Contour Error ◽  
Contour Tracking ◽  
Cnc Machine ◽  
Equivalent Time

A common problem with modern manufacturing processes that utilize high feed-rate machining is how to accurately track a given contour for the tool center point (TCP) of a system. Various methods have been developed to increase axial tracking performance and contouring performance of computerized numerical control (CNC) machines. These include: high gain feedback controllers, feedforward controllers, zero phase error tracking controllers (ZPETC), cross-coupled control (CCC), and iterative learning control to mention a few. The common factor amongst these methods is that they are all based in time domain. This thesis will propose a new control law based in position domain applied to contour tracking control of a CNC machine. The goal of this developed controller is to improve the overall tracking and contouring performance of a CNC system. The idea behind a position domain control involves transforming the dynamics of a system from time domain into position domain through a one-to-one mapping. In the position domain system control, the motion of one of the axis is used as an independent reference by sampling equidistantly to control the remaining axes according to the contouring requirements. The overall contour error in a position domain controller should be lower relative to an equivalent time domain controller since there will be a zero tracking error from the reference motion. The stability of the proposed position domain control is proven through the Lyapunov method. Simulations with linear and nonlinear TCP contours using the proposed position domain controller and an equivalent time domain controller indicate that the proposed position domain control can improve tracking and contouring performance. In addition, a position domain controller with cross-coupled control was also proposed to further improve contour performance.

Cross-coupled PID control in position domain for contour tracking

Robotica ◽  
2014 ◽  
Vol 33 (6) ◽  
pp. 1351-1374 ◽  
Author(s):  
P. R. Ouyang ◽  
T. Dam ◽  
V. Pano
Keyword(s):  
Time Domain ◽  
Pid Control ◽  
Numerical Control ◽  
Tracking Performance ◽  
Contour Tracking ◽  
Cnc Machine ◽  
Reference Axis ◽  
Equivalent Time ◽  
Random Disturbances ◽  
Selection Of

SUMMARYAccurate contour tracking is one of the main tasks in modern manufacturing processes. By considering coupling effects among multiple axes, this paper proposes a cross-coupled proportional-integral-derivative (PID) control developed in position domain, and the controller is applied to a multi-axis computer numerical control (CNC) machine for contour tracking performance improvement. Stability analysis is conducted for the developed position domain cross-coupled PID control using the Lyapunov method, and guidelines for the selection of control gains are provided. The contour tracking performance are improved compared to an equivalent time domain controller, since the reference axis in position domain control does not contribute any error to the overall contouring error of the system. Simulation results demonstrate the effectiveness of cross-coupled PID position domain control for both linear and circular contour tracking, and prove the robustness of the controller to deal with random disturbances. It also shows that position domain cross-coupled PID control provides better contour tracking performance over position domain PID control and the equivalent time domain PID control.

Non-linear contour tracking using feedback PID and feedforward position domain cross-coupled iterative learning control

2017 ◽  
Vol 40 (6) ◽  
pp. 1970-1982 ◽  
Author(s):  
Jie Ling ◽  
Zhao Feng ◽  
Daojin Yao ◽  
Xiaohui Xiao
Keyword(s):  
Time Domain ◽  
Iterative Learning Control ◽  
Learning Control ◽  
Iterative Learning ◽  
Contour Error ◽  
Contour Tracking ◽  
Vector Method ◽  
Non Linear ◽  
And Performance ◽  
The Time Domain

In this paper, a position domain cross-coupled iterative learning controller combining proportional–integral–derivative (PID)-type iterative learning control (ILC) and proportional–derivative (PD)-type cross-coupling control (CCC) is presented aiming at non-linear contour tracking in multi-axis motion systems. Traditional individual control methods in the time domain suffer from poor synchronization of relevant motion axes. The complicated computation of coupling gains in CCC and cross-coupled ILC (CCILC) restricts their applications for non-linear contour. The proposed position domain CCILC (PDCCILC) approach introduces a position domain design concept into CCILC to improve synchronization and performance for non-linear contour tracking and it relies less on the accuracy of coupling gains than conventional CCILC. The stability and performance analysis are conducted using a lifted system representation. The contour error vector method is applied to estimate the coupling gains in simulations and experiments. Simulation and experimental results of three typical non-linear contour tracking cases (i.e. semi-circle, parabola and spiral) based on a two-axis micro-motion stage demonstrate superiority and efficacy of the proposed feedback PID and feedforward PDCCILC compared with existing ILC and CCILC in the time domain.

Optimal Feed-Forward Digital Tracking Controller Design

1994 ◽  
Vol 116 (4) ◽  
pp. 583-592 ◽  
Author(s):  
Tsu-Chin Tsao
Keyword(s):  
Controller Design ◽  
Reference Model ◽  
Phase Error ◽  
Tracking Error ◽  
Reference Signal ◽  
Tracking Performance ◽  
Design Parameters ◽  
Matching Problem ◽  
Feed Forward ◽  
Tracking Controller

This paper presents an approach for optimal digital feed-forward tracking controller design. The tracking problem is formulated as a model matching problem, in which the distance between a specified tracking reference model and the achievable tracking performance by feedforward compensation is minimized. Desired input/output characteristics, finite length preview action, tracking of specific classes of constrained signals, time domain reference signal velocity or acceleration bound, and frequency domain weighting are conveniently incorporated in the proposed controller design and their roles in tracking performance are discussed. The tracking error bound is also explicitly expressed in terms of the controller design parameters. An l1 norm optimal tracking controller is proposed as a solution to the mechanical tolerance control problem. A motion control example illustrates the design approach and several aspects of the resulting optimal feedforward controller, including the optimality of the zero phase error tracking controller.

Influence of Nonlinear Friction and Disturbance in the Control of a Mechatronic System: CNC Machine Tool Application

2011 ◽  
Author(s):  
Liz K. Rincon ◽  
Joa˜o M. Rosario
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Viscous Friction ◽  
Numerical Control ◽  
Machining Process ◽  
Contour Error ◽  
Nonlinear Friction ◽  
Cnc Machine ◽  
Mechatronic Systems ◽  
High Speeds

The CNC (Computer Numerical Control) machine tools are complex mechatronic systems applied to the manufacture with high precision and high speeds. To achieve high accuracy and operational efficiency, the disturbance and friction, which occur during machining process, should be reduced as low as possible. This paper develops an analysis of influence by cutting force and friction effect in the control of machine tool based on the CNC dynamic model and parameters identification. For this purpose, the study focuses on Coulomb and Viscous nonlinear friction and the external disturbances. The analysis uses control position error, contour error, and stability to determine the influence of friction and disturbance. The results show that Viscous friction has more critical influence on system than the Cutting force and Coulomb. The work contributes in recognizing which parameters have greater influence on the machine behavior through dynamic analysis with the identification strategy, in order to design and improve the control structure for a real CNC system.

scholarly journals Effects of side subsurface defects induced by CNC machine on the gain spatial distribution in neodymium phosphate glass

2016 ◽  
Vol 4 ◽  
Author(s):  
Bingyan Wang ◽  
Junyong Zhang ◽  
Shuang Shi ◽  
Kewei You ◽  
Jianqiang Zhu
Keyword(s):  
Phosphate Glass ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Side Surface ◽  
Processing Method ◽  
Numerical Control ◽  
Cnc Machine ◽  
Key Factor ◽  
Difference Time ◽  
Subsurface Defects

The processing method applied to the side surface is different from the method applied to the light pass surface in neodymium phosphate glass (Nd:glass), and thus subsurface defects remain after processing. The subsurface defects in the side surface influence the gain uniformity of Nd:glass, which is a key factor to evaluate the performance of amplifiers. The scattering characteristics of side subsurface defects were simulated by finite difference time domain (FDTD) Solutions software. The scattering powers of the glass fabricated by a computer numerical control (CNC) machine without cladding were tested at different incident angles. The trend of the curve was similar to the simulated result, while the smallest point was different with the complex true morphology. The simulation showed that the equivalent residual reflectivity of the cladding glass can be more than 0.1% when the number of defects in a single gridding is greater than 50.

scholarly journals Contour Error Modeling and Compensation of CNC Machining Based on Deep Learning and Reinforcement Learning

2021 ◽  
Author(s):  
Yakun Jiang ◽  
Jihong Chen ◽  
Huicheng Zhou ◽  
Jianzhong Yang ◽  
Pengcheng Hu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Reinforcement Learning ◽  
Tracking Error ◽  
Cnc Machining ◽  
Numerical Control ◽  
Contour Error ◽  
Error Prediction ◽  
Machining Accuracy ◽  
Good Precision ◽  
Compensation Strategy

Abstract Contour error compensation of the Computer Numerical Control (CNC) machine tool is a vital technology that can improve machining accuracy and quality. To achieve this goal, the tracking error of a feeding axis, which is a dominant issue incurring the contour error, should be firstly modeled and then a proper compensation strategy should be determined. However, building the precise tracking error prediction model is a challenging task because of the nonlinear issues like backlash and friction involved in the feeding axis; besides, the optimal compensation parameter is also difficult to determine because it is sensitive to the machining tool path. In this paper, a set of novel approaches for contour error prediction and compensation is presented based on the technologies of deep learning and reinforcement learning. By utilizing the internal data of the CNC system, the tracking error of the feeding axis is modeled as a Nonlinear Auto-Regressive Long-Short Term Memory (NAR-LSTM) network, considering all the nonlinear issues of the feeding axis. Given the contour error as calculated based on the predicted tracking error of each feeding axis, a compensation strategy is presented with its parameters identified efficiently by a Time-Series Deep Q-Network (TS-DQN) as designed in our work. To validate the feasibility and advantage of the proposed approaches, extensive experiments are conducted, testifying that, our approaches can predict the tracking error and contour error with very good precision (better than about 99% and 90% respectively), and the contour error compensated based on the predicted results and our compensation strategy is significantly reduced (about 70%~85% reduction) with the machining quality improved drastically (machining error reduced about 50%).

Modeling and adaptive compensation of tooth surface contour error for internal gearing power honing

2018 ◽  
Vol 233 (5) ◽  
pp. 1500-1514 ◽  
Author(s):  
Jiang Han ◽  
Yonggang Zhu ◽  
Lian Xia ◽  
Xiaoqing Tian ◽  
Bin Yuan
Keyword(s):  
Machine Tools ◽  
Tracking Error ◽  
Cross Coupling ◽  
Error Modeling ◽  
Numerical Control ◽  
Tooth Surface ◽  
Contour Error ◽  
Adaptive Compensation ◽  
Surface Contour ◽  
Gear Machine

The machining of high precision gears requires a strict and accurate co-movement relationship controlled by the electronic gearbox between the moving axes of the gear machine tools. This article proposes a tooth surface contour error modeling method and an adaptive electronic gearbox cross-coupling controller for internal gearing power honing. First, the electronic gearbox model is structured according to the generative machining principle of internal gearing power honing and the tooth surface contour error is established by means of homogeneous coordinate transformation and meshing principle. Then, the adaptive electronic gearbox cross-coupling controller is designed, which comprises the electronic gearbox cross-coupling controller and the fuzzy proportional–integral–derivative controllers whose universes of membership functions in fuzzy rules are optimized by particle swarm optimization to improve the adaptability and robustness to disturbance fluctuation and model uncertainty of the system. Finally, experiments are carried out on a self-developed gear numerical control system. The results have demonstrated that the estimated tooth surface contour error using the proposed method is very close to the actual one, and the proposed adaptive electronic gearbox cross-coupling controller can effectively reduce the tracking error and the tooth surface contour error when compared to the electronic gearbox cross-coupling controller and non–electronic gearbox cross-coupling controller (electronic gearbox controller without cross-coupling and adaptive compensation).

Key Technologies of Embedded Gear Machining CNC System

2013 ◽  
Author(s):  
Jiang Han ◽  
Xiao-qing Tian ◽  
Lian Xia ◽  
Fu-gen Li ◽  
Jie Cheng ◽  
...  
Keyword(s):  
Tracking Error ◽  
Mathematic Model ◽  
Numerical Control ◽  
Machining Process ◽  
Programming Algorithm ◽  
Contour Error ◽  
Programming System ◽  
Automatic Programming ◽  
Database Technology ◽  
Process Database

A reconfigurable gear machining numerical control system (NC/CNC) architecture is proposed in this paper. The CNC platform can be quickly applied to gear hobbing, shaping, milling and grinding machine, through simple reconfiguring or parameter setting. Parametric automatic programming technology, high speed and high precision electronic gearbox, process database technology are studied. Based on the analysis of the gear machining process, the mathematic model on automatic programming of gear machining is established. Based on the Windows CE operating system, the CNC gear machining automatic programming system is developed on the ARM+DSP hardware platform, including the design of human-machine interface, automatic programming algorithm and other modules. With the support of the automatic programming and process database modules, NC codes can be generated automatically just by inputting gear parameters, tool parameters and process parameters, then, the interpolation data structure can be generated by interpreter module. A new kind of software electronic gearbox (EGB) and its implementation methods are also researched in the embedded CNC. Data flow among the modules is analyzed. Finally, experiments are conducted, and the tracking error and contour error are analyzed. The results show that the proposed gear machining CNC architecture is effective.

scholarly journals Evaluation of the Feasibility of NaCaPO4-Blended Zirconia as a New CAD/CAM Material for Dental Restoration

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3819
Author(s):  
Ting-Hsun Lan ◽  
Yu-Feng Chen ◽  
Yen-Yun Wang ◽  
Mitch M. C. Chou
Keyword(s):  
Computer Aided Design ◽  
Optical Microscope ◽  
Dental Restoration ◽  
Numerical Control ◽  
Test Results ◽  
Cnc Machine ◽  
Computer Aided ◽  
Cad Cam ◽  
Aided Design ◽  
Better Than

The computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication technique has become one of the hottest topics in the dental field. This technology can be applied to fixed partial dentures, removable dentures, and implant prostheses. This study aimed to evaluate the feasibility of NaCaPO4-blended zirconia as a new CAD/CAM material. Eleven different proportional samples of zirconia and NaCaPO4 (xZyN) were prepared and characterized by X-ray diffractometry (XRD) and Vickers microhardness, and the milling property of these new samples was tested via a digital optical microscope. After calcination at 950 °C for 4 h, XRD results showed that the intensity of tetragonal ZrO2 gradually decreased with an increase in the content of NaCaPO4. Furthermore, with the increase in NaCaPO4 content, the sintering became more obvious, which improved the densification of the sintered body and reduced its porosity. Specimens went through milling by a computer numerical control (CNC) machine, and the marginal integrity revealed that being sintered at 1350 °C was better than being sintered at 950 °C. Moreover, 7Z3N showed better marginal fit than that of 6Z4N among thirty-six samples when sintered at 1350 °C (p < 0.05). The milling test results revealed that 7Z3N could be a new CAD/CAM material for dental restoration use in the future.

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