Smooth Path Blending for 5-Axis Machine Tools

2020 ◽  
Author(s):  
Shingo Tajima ◽  
Burak Sencer ◽  
Hayato Yoshioka ◽  
Hidenori Shinno
Keyword(s):  
Coordinate System ◽  
Finite Impulse Response ◽  
Analytical Techniques ◽  
Computationally Efficient ◽  
Spherical Coordinate ◽  
Tool Positioning ◽  
Positioning Errors ◽  
Smooth Path ◽  
Cad Cam ◽  
Position And Orientation

Abstract 5-axis machining is widely used to manufacture complex sculptured parts, such as impellers used in jet engines. In order to machine complex part surfaces, the surface is discretized by a series of short-segmented point to point linear segments by CAD/CAM systems. Smooth non-stop motion of the tool must be interpolated along those discrete tool-paths. This paper proposes novel discrete linear path smoothing algorithms to interpolate tool position and orientation commands synchronously for 5-axis machining. Finite Impulse Response (FIR) filtering based feed profiling technique is developed to generate a smooth tool-pose trajectory with both local and global smoothing functionality. Analytical techniques are proposed to confine the blending errors within user specified tolerances. The proposed technique is computationally efficient and suitable for real-time implementation on modern NC systems. Path blending errors are defined in both the Cartesian workpiece coordinate system for tool positioning errors and the spherical coordinate system for tool orientation errors. Both position and orientation contouring errors are controlled in each coordinate system with respect to the user-defined tolerances. Simulation results validate that the proposed FIR based corner smoothing algorithm can generate smooth and non-stop trajectories for 5-axis machining. It can lead to significant cycle time gain without jeopardizing part tolerances.

Five-axis trajectory generation considering synchronisation and nonlinear interpolation errors

2022 ◽  
pp. 1-26
Author(s):  
Robert Ward ◽  
Burak Sencer ◽  
Bryn Jones ◽  
Erdem Ozturk
Keyword(s):  
Coordinate System ◽  
Real Time ◽  
Finite Impulse Response ◽  
Interpolation Scheme ◽  
Computationally Efficient ◽  
Synchronization Errors ◽  
Novel Approach ◽  
Tool Centre Point ◽  
Tool Motion ◽  
Five Axis

Abstract This paper presents a novel real-time interpolation technique for 5-axis machine tools to attain higher speedand accuracy. To realize computationally efficient real-time interpolation of 6DOF tool motion, a joint workpiece-machine coordinate system interpolation scheme is proposed. Cartesian motion of the tool centre point (TCP) isinterpolated in the workpiece coordinate system (WCS), whereas tool orientation is interpolated in the machinecoordinate system (MCS) based on the finite impulse response (FIR) filtering. Such approach provides several ad-vantages: i) it eliminates the need for complex real-time spherical interpolation techniques, ii) facilitates efficientuse of slower rotary drive kinematics to compensate for the dynamic mismatch between Cartesian and rotary axesand achieve higher tool acceleration, iii) mitigates feed fluctuations while interpolating near kinematic singulari-ties. To take advantage of such benefits and realize accurate joint WCS-MCS interpolation scheme, tool orientationinterpolation errors are analysed. A novel approach is developed to adaptively discretize long linear tool movesand confine interpolation errors within user set tolerances. Synchronization errors between TCP and tool orienta-tion are also characterized, and peak synchronization error level is determined to guide the interpolation parameterselection. Finally, blending errors during non-stop continuous interpolation of linear toolpaths are modelled andconfined. Advantages of the proposed interpolation scheme are demonstrated through simulation studies and vali-dated experimentally. Overall, proposed technique can improve cycle times up to 10% while providing smooth and accurate non-stop real-time interpolation of tool motion in 5-axis machining.

scholarly journals Design of Cut off-Frequency Fixing Filters by Error Compensation of MAXFLAT FIR Filters

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 553
Author(s):  
Daewon Chung ◽  
Woon Cho ◽  
Inyeob Jeong ◽  
Joonhyeon Jeon
Keyword(s):  
Closed Form ◽  
Error Compensation ◽  
Finite Impulse Response ◽  
Cutoff Frequency ◽  
Closed Form Solution ◽  
Form Solution ◽  
Fir Filters ◽  
Frequency Error ◽  
Computationally Efficient ◽  
Filter Type

Maximally-flat (MAXFLAT) finite impulse response (FIR) filters often face a problem of the cutoff-frequency error due to approximation of the desired frequency response by some closed-form solution. So far, there have been plenty of efforts to design such a filter with an arbitrarily specified cut off-frequency, but this filter type requires extensive computation and is not MAXFLAT anymore. Thus, a computationally efficient and effective design is needed for highly accurate filters with desired frequency characteristics. This paper describes a new method for designing cutoff-frequency-fixing FIR filters through the cutoff-frequency error compensation of MAXFLAT FIR filters. The proposed method provides a closed-form Chebyshev polynomial containing a cutoff-error compensation function, which can characterize the “cutoff-error-free” filters in terms of the degree of flatness for a given order of filter and cut off-frequency. This method also allows a computationally efficient and accurate formula to directly determine the degree of flatness, so that this filter type has a flat magnitude characteristic both in the passband and the stopband. The remarkable effectiveness of the proposed method in design efficiency and accuracy is clearly demonstrated through various examples, indicating that the cutoff-fixing filters exhibit amplitude distortion error of less than 10−14 and no cut off-frequency error. This new approach is shown to provide significant advantages over the previous works in design flexibility and accuracy.

Comparison Considerations Toward Investigating the Factors of Load and Age Group on the Maximum Reach Envelope

2020 ◽  
pp. 001872082096501
Author(s):  
Heather Johnston ◽  
Colleen Dewis ◽  
John Kozey
Keyword(s):  
Coordinate System ◽  
Three Dimensional ◽  
Spherical Coordinate System ◽  
Upper Body ◽  
Group Differences ◽  
Anthropometric Measures ◽  
Younger Adults ◽  
Present Measurement ◽  
Spherical Coordinate ◽  
Cylindrical Coordinate

Objective The objectives were to compare cylindrical and spherical coordinate representations of the maximum reach envelope (MRE) and apply these to a comparison of age and load on the MRE. Background The MRE is a useful measurement in the design of workstations and quantifying functional capability of the upper body. As a dynamic measure, there are human factors that impact the size, shape, and boundaries of the MRE. Method Three-dimensional reach measures were recorded using a computerized potentiometric system for anthropometric measures (CPSAM) on two adult groups (aged 18–25 years and 35–70 years). Reach trials were performed holding .0, .5, and 1 kg. Results Three-dimensional Cartesian coordinates were transformed into cylindrical ( r, θ , Z) and spherical ( r, θ, ϕ) coordinates. Median reach distance vectors were calculated for 54 panels within the MRE as created by incremented banding of the respective coordinate systems. Reach distance and reach area were compared between the two groups and the loaded conditions using a spherical coordinate system. Both younger adults and unloaded condition produced greater reach distances and reach areas. Conclusions Where a cylindrical coordinate system may reflect absolute reference for design, a normalized spherical coordinate system may better reflect functional range of motion and better compare individual and group differences. Age and load are both factors that impact the MRE. Application These findings present measurement considerations for use in human reach investigation and design.

Optimal Design and Structural Precision Analysis for a Spherical Coordinate System 3D Scanner Guiding Device

2014 ◽  
Vol 705 ◽  
pp. 164-168
Author(s):  
Sang Wook Park ◽  
Hee Young Maeng ◽  
Ju Wook Park
Keyword(s):  
Optimal Design ◽  
Data Collection ◽  
Reverse Engineering ◽  
Coordinate System ◽  
Fem Analysis ◽  
Spherical Coordinate System ◽  
3D Scanner ◽  
Spherical Coordinate ◽  
Overall Performance ◽  
Improved Design

Recently, automatic 3D scanning devices are commonly researched and developed for better productivity of the reverse engineering fields. In this paper, a 3D scanner utilizing a spherical coordinate system was designed and analyzed using FEM analysis. The system was designed for optimal performance, high precision, minimal deflection, and speed of data collection. FEM analysis allowed us to properly design the system to achieve these goals, with focus on the deflection of the cantilever arm. Results of the FEM analysis and figures showing the apparatus design are provided. Successive prototypes are shown to increase in overall performance and reliability through improved design and analysis.

Extrinsic Calibration of Portable Manipulators

1992 ◽  
Author(s):  
Steven B. Shooter ◽  
Charles F. Reinholtz
Keyword(s):  
Closed Form ◽  
Nuclear Reactors ◽  
Video Feedback ◽  
Sufficient Information ◽  
Steam Generators ◽  
Extrinsic Calibration ◽  
Tool Positioning ◽  
Orthogonal Plane ◽  
Position And Orientation ◽  
Operator Control

Abstract Portable manipulators are installed for operation and then removed upon completion of their task. Typical applications of portable manipulators include the inspection of nuclear reactors, inspection and repair of nuclear steam generators and asbestos removal in buildings. In such operations, it is difficult to precisely position the manipulator at a fixed location within its workplace, yet this is critical for accurate tool positioning. It can be possible, however, to position the tool tip at several points in the environment using video feedback and manual operator control of the manipulator. This provides sufficient information to determine the position and orientation of the manipulator base frame with respect to the environment, hereafter referred to as extrinsic calibration. Following extrinsic calibration, subsequent moves of the manipulator can be automated. This paper describes a closed-form method for performing extrinsic calibration by contacting the tool to a total of six places on three orthogonal plane surfaces of reference.

scholarly journals A Lattice Boltzmann Scheme for Diffusion Equation in Spherical Coordinate

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Debabrata Datta ◽  
T K Pal
Keyword(s):  
Diffusion Equation ◽  
Coordinate System ◽  
Lattice Boltzmann ◽  
Spherical Coordinate System ◽  
Cartesian Coordinate System ◽  
Spherical Coordinate ◽  
Cartesian Coordinate ◽  
Lattice Boltzmann Models ◽  
Boltzmann Method ◽  
Good Agreement

Lattice Boltzmann models for diffusion equation are generally in Cartesian coordinate system. Very few researchers have attempted to solve diffusion equation in spherical coordinate system. In the lattice Boltzmann based diffusion model in spherical coordinate system extra term, which is due to variation of surface area along radial direction, is modeled as source term. In this study diffusion equation in spherical coordinate system is first converted to diffusion equation which is similar to that in Cartesian coordinate system by using proper variable. The diffusion equation is then solved using standard lattice Boltzmann method. The results obtained for the new variable are again converted to the actual variable. The numerical scheme is verified by comparing the results of the simulation study with analytical solution. A good agreement between the two results is established.

scholarly journals Source mechanisms and near-source wave propagation from broadband seismograms

1994 ◽  
Vol 37 (6) ◽  
Author(s):  
J. Virieux ◽  
A. Deschamps ◽  
J. Perrot ◽  
J. Campos
Keyword(s):  
Wave Propagation ◽  
Coordinate System ◽  
Ray Tracing ◽  
Dynamic Range ◽  
Time Derivative ◽  
Quality Data ◽  
Heterogeneous Structure ◽  
Spherical Coordinate ◽  
Seismic Rupture ◽  
Converted Phases

Recording seismic events at teleseismic distances with broadband and high dynamic range instruments provides new high-quality data that allow us to interpret in more detail the complexity of seismic rupture as well as the heterogeneous structure of the medium surrounding the source where waves are initially propagating. Wave propagation analysis is performed by ray tracing in a local cartesian coordinate system near the source and in a global spherical coordinate system when waves enter the mantle. Seismograms are constructed at each station for a propagation in a 2.5-D medium. Many phases can be included and separately analyzed; this is one of the major advantages of ray tracing compared to other wave propagation techniques. We have studied four earthquakes, the 1988 Spitak Armenia Earthquake (Ms = 6.9), the 1990 Iran earthquake (Ms = 7.7), the 1990 romanian earthquake (Ms = 5.8) and the 1992 Erzincan, Turkey earthquake (Ms = 6.8). These earthquakes exhibit in different ways the complexity of the rupture and the signature of the medium surrounding the source. The use of velocity seismograms, the time derivative of displacement, increases the difficulty of the fit between synthetic seismograms and real seismograms but provides clear evidence for a need of careful time delay estimations of the different converted phases. We find that understanding of the seismic rupture as well as the influence of the medium surrounding the source for teleseismically recorded earthquakes requires a multi-stop procedure: starting with ground displacement seismograms, one is able to give a first description of the rupture as well as of the first-order influence of the medium. Then, considering the ground velocity seismograms makes the fit more difficult to obtain but increases our sensitivity to the rupture process and early converted phases. With increasing number of worldwide broadband stations, a complex rupture description is possible independently of field observations, which can be used to check the adequacy of such complicated models.

A Service Robot with Lightweight Arms and a Trinocular Vision Sensor

2010 ◽  
Vol 439-440 ◽  
pp. 396-400
Author(s):  
Xian Hua Li ◽  
Shi Li Tan ◽  
Wu Xin Huang
Keyword(s):  
Control System ◽  
Coordinate System ◽  
Inverse Kinematics ◽  
Robot Control ◽  
Service Robot ◽  
Algebraic Solution ◽  
Vision Sensor ◽  
Solution Methods ◽  
Space Coordinate ◽  
Position And Orientation

This paper describes a household service robot with two lightweight arms and a trinocular vision sensor. According to DH convention, the coordinate system of two arms is established, and position and orientation of the hand is computed. The inverse kinematics of the arm is solved with geometric and algebraic solution methods. By the trinocular vision sensor, robot can recognize the bottle and get its 3-D space coordinate. Through experiments, both correctness of the algorithm and stability of the robot control system are validated.

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