A New Motion-Planning Scheme for Overhead Cranes With High-Speed Hoisting

2004 ◽  
Vol 126 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Ho-Hoon Lee
Keyword(s):  
Motion Planning ◽  
High Speed ◽  
High Performance ◽  
Control Law ◽  
Planning Problem ◽  
Lyapunov Stability Theorem ◽  
Overhead Cranes ◽  
Swing Angle ◽  
Planning Scheme ◽  
Load Swing

This paper proposes a motion-planning method for a high-performance anti-swing control of overhead cranes, where the motion-planning problem is solved as a kinematic problem. First, an anti-swing regulating control law is proposed based on the Lyapunov stability theorem, where the proposed anti-swing control drives trolley velocity regulating error asymptotically to zero while suppressing load swing rapidly to zero for given arbitrary high-speed hoisting motions. Then a motion-planning scheme is designed based on the concept of minimumtime control, the proposed anti-swing control law, and typical anti-swing crane-operation practices. The motion-planning scheme is free from the usual mathematical constraints in anti-swing control such as small swing angle, small hoisting speed, and small hoisting distance. The effectiveness of the proposed motion planning is shown by generating high-performance anti-swing trajectories with high hoisting speed and hoisting ratio.

A New Trajectory-Generation Scheme for Overhead Cranes With High-Speed Load Hoisting

2004 ◽  
Author(s):  
Ho-Hoon Lee ◽  
Del Segura ◽  
Yi Liang
Keyword(s):  
High Speed ◽  
High Performance ◽  
Trajectory Generation ◽  
Control Law ◽  
Mathematical Tool ◽  
Lyapunov Stability Theorem ◽  
Overhead Cranes ◽  
Time Control ◽  
Load Swing ◽  
Generation Problem

This paper proposes a new trajectory-generation scheme for a high-performance anti-swing control of overhead cranes, where the trajectory-generation problem is solved as a kinematic problem. First, a new anti-swing control law is designed based on the load-swing dynamics, for which the Lyapunov stability theorem is used as a mathematical tool. Then a new trajectory-generation scheme is proposed based on the anti-swing control law and typical crane operation in practice. For g iven hoisting motions, trolley-traveling trajectory references are computed based on the concept of minimum-time control, and then anti-swing trajectories are generated based on the trajectory references through the anti-swing control law. The new trajectory-generation scheme generates a typical anti-swing trajectory in industry with high-speed load hoisting. The effectiveness of the proposed trajectory-generation scheme is shown by generating high-performance anti-swing trajectories with high hoisting speed and hoisting ratio.

A Path-Planning Strategy for Overhead Cranes With High Hoisting Speed

2002 ◽  
Author(s):  
Ho-Hoon Lee
Keyword(s):  
Path Planning ◽  
High Performance ◽  
Stability Theorem ◽  
Lyapunov Stability Theorem ◽  
Control Laws ◽  
Planning Strategy ◽  
Overhead Cranes ◽  
Time Control ◽  
Small Load ◽  
Load Swing

This paper proposes a path planning strategy for high-performance anti-swing control of overhead cranes, where the anti-swing control problem is solved as a kinematic problem. First, two anti-swing control laws, one for hoisting up and the other for hoisting down, are proposed based on the Lyapunov stability theorem. Then a new path-planning strategy is proposed based on the concept of minimum-time control and the proposed anti-swing control laws. The proposed path planning is free from the usual constraints of small load swing, slow hoisting speed, and small hoisting distance. The effectiveness of the proposed path planning is shown by computer simulation with high hoisting speed and hoisting ratio.

A Sliding-Mode Antiswing Trajectory Control for Overhead Cranes With High-Speed Load Hoisting

2006 ◽  
Vol 128 (4) ◽  
pp. 842-845 ◽  
Author(s):  
Ho-Hoon Lee ◽  
Yi Liang ◽  
Del Segura
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Sliding Mode ◽  
Trajectory Control ◽  
Overhead Cranes ◽  
Damping Control ◽  
Control Scheme ◽  
Planning Scheme ◽  
Load Swing ◽  
High Frequency Sampling

In this paper we propose a sliding-mode antiswing control for overhead cranes. The objective of this study is to realize an antiswing trajectory control with high-speed load hoisting. A sliding-mode antiswing trajectory control scheme is designed based on the Lyapunov stability theorem, where a sliding surface, coupling the trolley motion with load swing, is adopted for a direct damping control of load swing. The proposed control guarantees asymptotic stability while keeping all internal signals bounded. In association with a new antiswing motion planning scheme, the proposed control realizes a typical antiswing trajectory control in practice, allowing high-speed load-hoisting motion and sufficient damping of load swing. The proposed control is simple for a real-time implementation with high-frequency sampling. The effectiveness of the proposed control has been confirmed by experiments.

A Robust Anti-Swing Trajectory Control of Overhead Cranes With High-Speed Load Hoisting: Simulation Study

2009 ◽  
Author(s):  
Ho-Hoon Lee
Keyword(s):  
High Speed ◽  
Trajectory Control ◽  
Design Tool ◽  
Sliding Surface ◽  
Tracking Errors ◽  
New Approach ◽  
Overhead Cranes ◽  
Control Scheme ◽  
The Stability ◽  
Load Swing

This paper proposes a new approach for the anti-swing trajectory control of overhead cranes that allows simultaneous high-speed load hoisting. The objective of this study is to design an anti-swing trajectory control scheme that is robust to unavoidable mechanical inaccuracies and installation errors such as locally sloped trolley rails. First, a coupled sliding surface is defined based on the load-swing dynamics, and then the stability of the coupled sliding surface is shown to be equivalent to that of trolley tracking errors. Next, a robust anti-swing trajectory control scheme, minimizing the coupled sliding surface asymptotically to zero, is designed based on the trolley and load-hoisting dynamics. Finally, the proposed control is extended to an adaptive scheme. In this study, the Lyapunov stability theorem is used as a mathematical design tool. The proposed control guarantees asymptotic stability of the anti-swing trajectory control while keeping all internal signals bounded. The proposed control provides a practical solution for the robustness problem caused by the usual mechanical inaccuracies and installation errors in application. The proposed control also provides clear gain-tuning criteria for easy application. The validity of the theoretical results is shown by computer simulation.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

Performance Analysis of Various Multipliers Using 8T-full Adder with 180nm Technology

2020 ◽  
Vol 13 (6) ◽  
pp. 864-870
Author(s):  
Sai Venkatramana Prasada G.S ◽  
G. Seshikala ◽  
S. Niranjana
Keyword(s):  
Low Power ◽  
Power Dissipation ◽  
High Speed ◽  
High Performance ◽  
Full Adder ◽  
Fundamental Operation ◽  
Wallace Tree ◽  
Power Delay Product ◽  
The Comparative Study ◽  
Wallace Tree Multiplier

Background: This paper presents the comparative study of power dissipation, delay and power delay product (PDP) of different full adders and multiplier designs. Methods: Full adder is the fundamental operation for any processors, DSP architectures and VLSI systems. Here ten different full adder structures were analyzed for their best performance using a Mentor Graphics tool with 180nm technology. Results: From the analysis result high performance full adder is extracted for further higher level designs. 8T full adder exhibits high speed, low power delay and low power delay product and hence it is considered to construct four different multiplier designs, such as Array multiplier, Baugh Wooley multiplier, Braun multiplier and Wallace Tree multiplier. These different structures of multipliers were designed using 8T full adder and simulated using Mentor Graphics tool in a constant W/L aspect ratio. Conclusion: From the analysis, it is concluded that Wallace Tree multiplier is the high speed multiplier but dissipates comparatively high power. Baugh Wooley multiplier dissipates less power but exhibits more time delay and low PDP.

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