scholarly journals A Knowledge-Driven Approach for 3D High Temporal-Spatial Measurement of an Arbitrary Contouring Error of CNC Machine Tools Using Monocular Vision

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 744 ◽  
Author(s):  
Xiao Li ◽  
Wei Liu ◽  
Yi Pan ◽  
Jianwei Ma ◽  
Fuji Wang
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Value Added ◽  
Calibration Method ◽  
Cnc Machine Tools ◽  
Depth Of Field ◽  
Cnc Machine ◽  
Vision Measurement ◽  
Contouring Error ◽  
High Efficient

Periodic health checks of contouring errors under unloaded conditions are critical for machine performance evaluation and value-added manufacturing. Aiming at breaking the dimension, range and speed measurement limitations of the existing devices, a cost-effective knowledge-driven approach for detecting error motions of arbitrary paths using a single camera is proposed. In combination with the PNP algorithm, the three-dimensional (3D) evaluation of large-scale contouring error in relatively high feed rate conditions can be deduced from a priori geometrical knowledge. The innovations of this paper focus on improving the accuracy, efficiency and ability of the vision measurement. Firstly, a camera calibration method considering distortion partition of the depth-of-field (DOF) is presented to give an accurate description of the distortion behavior in the entire photography domain. Then, to maximize the utilization of the decimal involved in the feature encoding, new high-efficient encoding markers are designed on a cooperative target to characterize motion information of the machine. Accordingly, in the image processing, markers are automatically identified and located by the proposed decoding method based on finding the optimal start bit. Finally, with the selected imaging parameters and the precalibrated position of each marker, the 3D measurement of large-scale contouring error under relatively high dynamic conditions can be realized by comparing the curve that is measured by PNP algorithm with the nominal one. Both detection and verification experiments are conducted for two types of paths (i.e., planar and spatial trajectory), and experimental results validate the measurement accuracy and advantages of the proposed method.

scholarly journals A Robotic Milling System Based on 3D Point Cloud

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 355
Author(s):  
Yongzhuo Gao ◽  
Haibo Gao ◽  
Kunpeng Bai ◽  
Mingyang Li ◽  
Wei Dong
Keyword(s):  
Large Scale ◽  
Calibration Method ◽  
Milling Process ◽  
Processing Method ◽  
Industrial Robots ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Automatic Production ◽  
Robotic Milling ◽  
Measurement Planning

Industrial robots have advantages in the processing of large-scale components in the aerospace industry. Compared to CNC machine tools, robot arms are cheaper and easier to deploy. However, due to the poor consistency of incoming materials, large-scale and lightweight components make it difficult to automate robotic machining. In addition, the stiffness of the tandem structure is quite low. Therefore, the stability of the milling process is always a concern. In this paper, the robotic milling research is carried out for the welding pre-processing technology of large-scale components. In order to realize the automatic production of low-conformity parts, the on-site measurement–planning–processing method is adopted with the laser profiler. On the one hand, the laser profiler hand–eye calibration method is optimized to improve the measurement accuracy. On the other hand, the stiffness of the robot’s processing posture is optimized, combined with the angle of the fixture turntable. Finally, the experiment shows the feasibility of the on-site measurement–planning–processing method and verifies the correctness of the stiffness model.

FPGA-Based Intelligent Software Hardening Chip for Computer Numerical Control System

2011 ◽  
Vol 105-107 ◽  
pp. 2217-2220
Author(s):  
Mu Lan Wang ◽  
Jian Min Zuo ◽  
Kun Liu ◽  
Xing Hua Zhu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Large Scale ◽  
Position Control ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Cnc System ◽  
Intelligent Software

In order to meet the development demands for high-speed and high-precision of Computer Numerical Control (CNC) machine tools, the equipped CNC systems begin to employ the technical route of software hardening. Making full use of the advanced performance of Large Scale Integrated Circuits (LSIC), this paper puts forward using Field Programmable Gates Array (FPGA) for the functional modules of CNC system, which is called Intelligent Software Hardening Chip (ISHC). The CNC system architecture with high performance is constructed based on the open system thought and ISHCs. The corresponding programs can be designed with Very high speed integrate circuit Hardware Description Language (VHDL) and downloaded into the FPGA. These hardening modules, including the arithmetic module, contour interpolation module, position control module and so on, demonstrate that the proposed schemes are reasonable and feasibility.

Optimization of Planar Honing Process for Surface Finish of Machine Tool Sliding Guideways

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Kory Chang ◽  
Masakazu Soshi
Keyword(s):  
Machine Tools ◽  
Cubic Boron Nitride ◽  
Three Dimensional ◽  
Numerical Control ◽  
Machining Process ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Manufacturing Method ◽  
Traditional Manufacturing ◽  
Sliding Guideways

Sliding guideways are often used as the foundation for linear motion in computer numerical control (CNC) machine tools due to their high damping capabilities especially for heavy duty machining applications. However, the traditional manufacturing process with grinding is time-consuming, and the product’s sliding performance has not been optimized nor clearly understood. In order to increase productivity, a machining center based manufacturing method with cubic boron nitride (CBN) milling tools was introduced and tested by researchers. While greatly reducing manufacturing time and cost, a rougher milled surface, in comparison to traditional grinding, is a possible concern for the performance as well as the life of sliding guideways. In this study, a novel planar honing process was proposed as a postprocess of CBN milling to create a finish surface on hardened cast iron sliding guideways used for CNC machine tools. A design of experiment (DOE) was conducted to statistically understand significant factors in the machining process and their relationship with surface topography. Effective planar honing conditions were discovered and analyzed with three-dimensional (3D) and two-dimensional surface parameters.

scholarly journals Vision-Based Three-Dimensional Reconstruction and Monitoring of Large-Scale Steel Tubular Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Yunchao Tang ◽  
Mingyou Chen ◽  
Yunfan Lin ◽  
Xueyu Huang ◽  
Kuangyu Huang ◽  
...  
Keyword(s):  
Point Cloud ◽  
Large Scale ◽  
Learning Algorithm ◽  
Vision System ◽  
Three Dimensional ◽  
Steel Tube ◽  
Dynamic Monitoring ◽  
Complex Environments ◽  
Cross Sectional ◽  
Vision Measurement

A four-ocular vision system is proposed for the three-dimensional (3D) reconstruction of large-scale concrete-filled steel tube (CFST) under complex testing conditions. These measurements are vitally important for evaluating the seismic performance and 3D deformation of large-scale specimens. A four-ocular vision system is constructed to sample the large-scale CFST; then point cloud acquisition, point cloud filtering, and point cloud stitching algorithms are applied to obtain a 3D point cloud of the specimen surface. A point cloud correction algorithm based on geometric features and a deep learning algorithm are utilized, respectively, to correct the coordinates of the stitched point cloud. This enhances the vision measurement accuracy in complex environments and therefore yields a higher-accuracy 3D model for the purposes of real-time complex surface monitoring. The performance indicators of the two algorithms are evaluated on actual tasks. The cross-sectional diameters at specific heights in the reconstructed models are calculated and compared against laser rangefinder data to test the performance of the proposed algorithms. A visual tracking test on a CFST under cyclic loading shows that the reconstructed output well reflects the complex 3D surface after correction and meets the requirements for dynamic monitoring. The proposed methodology is applicable to complex environments featuring dynamic movement, mechanical vibration, and continuously changing features.

Engraving and Milling Machine Design Based on Open CNC System

2011 ◽  
Vol 52-54 ◽  
pp. 881-886
Author(s):  
Shu Kun Cao ◽  
Zhi Ming Sui ◽  
Lu Ning Liu ◽  
Gui Cong Wang ◽  
Wei Wei Song
Keyword(s):  
High Efficiency ◽  
Design Method ◽  
Three Dimensional ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Milling Machine ◽  
Cnc Machine ◽  
Cnc System ◽  
Open Cnc ◽  
Open Cnc System

In view of application requirements, control axes, the development cycle and other factors of open CNC machine tools, we consider the modular as the guiding ideology and propose a design method of three-dimensional engraving and milling machine based on open CNC system. In this paper we make a detailed design for mechanism structure and control system. Experiments show that this machine has milling and engraving capabilities, can process metal and non-metallic parts, which is a high efficiency, multi-function numerical control equipment.

MULTI-AXIS LINKED SERVO SYSTEM CONTOURING ERROR CONTROL APPROACH BASED ON NURBS CURVE INTERPOLATION

2011 ◽  
Vol 10 (01) ◽  
pp. 21-27 ◽  
Author(s):  
GUOYONG ZHAO ◽  
YUGANG ZHAO
Keyword(s):  
Error Control ◽  
Servo System ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Nurbs Curve ◽  
Control Approach ◽  
Contouring Error ◽  
Curve Interpolation ◽  
Servo Controller

The contouring precision of computer numerical control (CNC) machine tools relates to whether the dynamic performances among all the axes match or not. In general, the cross-coupled controller (CCC) is a more efficient approach to enhance contouring precision than single-axis servo controller. Note that the contouring error CCC can not be separated from pathway programming in multi-axis linked servo system. In order to obtain satisfied contouring precision, the CCC approach connected with non-uniform rational basis spline (NURBS) curve interpolation is researched in detail in the paper. Above all, an "arc approximation algorithm" contouring error computing model is developed, according to the real cutter positions from each axis feedback and the interpolation dots stored in the interpolation buffer. Then the contouring error correction quantity PI control and distribution algorithm is put forward by introducing a zoom coefficient. The contrast experimental results on the CNC experiment table show that the developed CCC approach can reduce contouring error and improve tracking performance further.

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