A novel feedrate scheduling method based on Sigmoid function with chord error and kinematic constraints

Cloud Computing is Internet based computing where one can store and access their personal resources from any computer through Internet. Cloud Computing is a simple pay-per-utilize consumer-provider service model. Cloud is nothing but large pool of easily accessible and usable virtual resources. Task (Job) scheduling is always a noteworthy issue in any computing paradigm. Due to the availability of finite resources and time variant nature of incoming tasks it is very challenging to schedule a new task accurately and assign requested resources to cloud user. Traditional task scheduling techniques are improper for cloud computing as cloud computing is based on virtualization technology with disseminated nature. Cloud computing brings in new challenges for task scheduling due to heterogeneity in hardware capabilities, on-demand service model, pay-per-utilize model and guarantee to meet Quality of Service (QoS). This has motivated us to generate multi-objective methods for task scheduling. In this research paper we have presented multi-objective prediction based task scheduling method in cloud computing to improve load balancing in order to satisfy cloud consumers dynamically changing needs and also to benefit cloud providers for effective resource management. Basically our method gives low probability value for not capable and overloaded nodes. To achieve the same we have used sigmoid function and Euclidean distance. Our major goal is to predict optimal node for task scheduling which satisfies objectives like resource utilization and load balancing with accuracy.

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Sliding look-ahead window-based real-time feedrate planning for non-uniform rational B-splines curves

Advances in Mechanical Engineering ◽

10.1177/1687814018816926 ◽

2018 ◽

Vol 10 (12) ◽

pp. 168781401881692 ◽

Cited By ~ 1

Author(s):

Jiankang Liu ◽

Hongya Fu ◽

Jihao Qin ◽

Hongyu Jin

Keyword(s):

Critical Points ◽

Experimental Tests ◽

B Splines ◽

Feedrate Planning ◽

Online Simulation ◽

Feedrate Scheduling ◽

Look Ahead ◽

Modification Method ◽

Scheduling Method ◽

The Given

This article presents an online three-axis non-uniform rational B-splines preprocessing and feedrate scheduling method with chord error, axial velocity, acceleration, and jerk limitations. A preprocessing method is proposed to accurately locate the critical points by reducing pre-interpolation feedrate in feedrate limit violation regions. In the preprocessing stage, the non-uniform rational B-splines curve is subdivided into segments by the critical points and the corresponding feedrate constraints are obtained. A sliding look-ahead window-based feedrate scheduling method is proposed to generate smooth feedrate profile for the buffered non-uniform rational B-splines segments. The feedrate profile corresponding to each non-uniform rational B-splines block is constructed according to the block length and the given limits of acceleration and jerk. The feedrate modification method for non-schedulable short blocks is also described which aimed at avoiding feedrate discontinuity at the junction of two non-uniform rational B-splines blocks. With the proposed method, a successful feedrate profile could be generated with sufficient look-ahead trajectory length in the buffer, which enables that the preprocessing and feedrate planning to be performed progressively online. Simulation and experimental tests with different non-uniform rational B-splines curves are carried out to validate the feasibility and advantages of the proposed method. The results show that the proposed method is capable of making a balance between the machining efficiency, machining precision, and computational complexity.

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S-Shape Feedrate Scheduling Method with Smoothly-Limited Jerk in Cyber-Physical Systems

International Conference on Reliable Systems Engineering (ICoRSE) - 2021 - Lecture Notes in Networks and Systems ◽

10.1007/978-3-030-83368-8_6 ◽

2021 ◽

pp. 54-68

Author(s):

Volodymyr Kombarov ◽

Volodymyr Sorokin ◽

Yevgen Tsegelnyk ◽

Sergiy Plankovskyy ◽

Yevhen Aksonov ◽

...

Keyword(s):

Cyber Physical Systems ◽

Physical Systems ◽

Feedrate Scheduling ◽

Scheduling Method

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Double B-Spline Curve-Fitting and Synchronization-Integrated Feedrate Scheduling Method for Five-Axis Linear-Segment Toolpath

Applied Sciences ◽

10.3390/app10093158 ◽

2020 ◽

Vol 10 (9) ◽

pp. 3158 ◽

Cited By ~ 2

Author(s):

Xiangyu Gao ◽

Shuyou Zhang ◽

Lemiao Qiu ◽

Xiaojian Liu ◽

Zili Wang ◽

...

Keyword(s):

Curve Fitting ◽

Rotary Motion ◽

Linear Segment ◽

B Spline ◽

Feedrate Scheduling ◽

Fitting Method ◽

Scheduling Method ◽

Tip Position ◽

Curve Fitting Method ◽

Fitting Error

The discontinuities of a five-axis linear-segment toolpath result in fluctuation in the feedrate, acceleration and jerk commands that lead to machine tool vibration and poor surface finish. For path smoothing, with the global curve-fitting method it is difficult to control fitting error and the local corner-smoothing method has large curvature extreme. For path synchronization, the parameter synchronization method cannot ensure smooth rotary motion. Aiming at these problems, this paper proposes a double B-spline curve-fitting and synchronization-integrated feedrate scheduling method. Two C2-continuous and error-bounded B-spline curves are produced to fit tool-tip position and tool orientation, respectively. The fitting error is controlled by locally refining the curve segments that exceed the fitting tolerance. The tool-tip position trajectory is firstly planned to address axial kinematic constraints in the feedrate scheduling process. Then the feedrate is deformed for the tool orientation to guarantee smooth rotary motion as well as to share the same motion time with the tool-tip position segment by segment. The feasibility and effectiveness of the proposed method have been validated by simulations and experiments on the S-shape test piece. Simulations show that the proposed curve-fitting method can generate smooth toolpath and constrain fitting error. The proposed feedrate scheduling method can guarantee smooth rotary motion and keep axial motions under kinematic limits, compared with the method that does not consider axial kinematic constraints and the parameter synchronization method. Experimental results verify that the proposed curve-fitting method can generate smooth tool path under fitting tolerance, and the proposed feedrate scheduling method can produce smooth and restricted axial motions.

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A Bidirectional Adaptive Feedrate Scheduling Method of NURBS Interpolation Based on S-Shaped ACC/DEC Algorithm

IEEE Access ◽

10.1109/access.2018.2875403 ◽

2018 ◽

Vol 6 ◽

pp. 63794-63812 ◽

Cited By ~ 5

Author(s):

Hepeng Ni ◽

Chengrui Zhang ◽

Shuai Ji ◽

Tianliang Hu ◽

Qizhi Chen ◽

...

Keyword(s):

Feedrate Scheduling ◽

Nurbs Interpolation ◽

Scheduling Method

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Look-ahead-window-based interval adaptive feedrate scheduling for long five-axis spline toolpaths under axial drive constraints

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405420937538 ◽

2020 ◽

Vol 234 (13) ◽

pp. 1656-1670

Author(s):

De-Ning Song ◽

Yu-Guang Zhong ◽

Jian-Wei Ma

Keyword(s):

High Efficiency ◽

Cutting Tool ◽

Joint Space ◽

Cartesian Space ◽

Feedrate Scheduling ◽

Look Ahead ◽

Scheduling Method ◽

The Look ◽

Current Interval ◽

Five Axis

Scheduling of the five-axis spline toolpath feedrate is of great significance for high-quality and high-efficiency machining using five-axis machine tools. Due to the fact that there exists nonlinear relationship between the Cartesian space of the cutting tool and the joint space of the five feed axes, it is a challenging task to schedule the five-axis feedrate under axial drive constraints. Most existing methods are researched for routine short spline toolpaths, however, the five-axis feedrate scheduling method expressed for long spline toolpaths is limited. This article proposes an interval adaptive feedrate scheduling method based on a dynamic moving look-ahead window, so as to generate smooth feedrate for long five-axis toolpath in a piecewise manner without using the integral toolpath geometry. First, the length of the look-ahead window which equals to that of the toolpath interval is determined in case of abrupt braking at the end of the toolpath. Then, the interval permissible tangential feed parameters in terms of the velocity, acceleration, and jerk are determined according to the axial drive constraints at each toolpath interval. At the same time, the end velocity of the current interval is obtained through looking ahead the next interval. Using the start and end velocities and the permissible feed parameters of each interval, the five-axis motion feedrate is scheduled via an interval adaptive manner. Thus, the feedrate scheduling task for long five-axis toolpath is partitioned into a series of extremely short toolpaths, which realizes the efficient scheduling of long spline toolpath feedrate. Experimental results on two representative five-axis spline toolpaths demonstrate the feasibility of the proposed approach, especially for long toolpaths.

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