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 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 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 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.

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.

HIGH-PERFORMANCE MULTI-BODY COLLISION DETECTION FOR THE REAL-TIME CONTROL OF A CTS SYSTEM

2005 ◽  
Vol 29 (2) ◽  
pp. 163-177
Author(s):  
M. Ahmadi ◽  
M. Jaber ◽  
F.C. Tang
Keyword(s):  
Real Time ◽  
Collision Detection ◽  
High Speed ◽  
High Performance ◽  
Robot Manipulator ◽  
Real Time Control ◽  
The Real ◽  
Time Control ◽  
Multi Body ◽  
Joint Velocity

This paper presents a high performance methodology for the real-time implementation of collision detection on a Captive Trajectory Simulation (CTS) system. The CTS system includes a slow-moving redundant robot manipulator operating inside a wind tunnel environment with transonic conditions. Collisions can occur between robot links or the links and other objects present in the environment. A multi-body dynamic pruning method is proposed based on joint velocity bounds, which can significantly reduce the number of required collision checks without compromising the system’s safety due to its conservative assumptions. A balance is achieved between the accuracy and the speed of computations via the convex subhull subdivision of the objects, which reduces the geometrical details to further decrease the load of computations. Combining the above two strategies results in smaller and more consistent sample times allowing the collision detection to run in real-time as an integral part of a robot with a high speed control loop.

A NURBS Interpolator Using Multiprocessor on Chip for High Performance Motion Control

2011 ◽  
Vol 130-134 ◽  
pp. 1929-1932
Author(s):  
Wei Tang ◽  
Xiao Dong Zhang ◽  
Yong Ding ◽  
Jing Jing
Keyword(s):  
Motion Control ◽  
High Speed ◽  
High Performance ◽  
Experimental Tests ◽  
High Accuracy ◽  
Motion Controller ◽  
Real Time Control ◽  
Time Control ◽  
Nurbs Interpolation ◽  
On Chip

Modern CNC system adopts the NURBS interpolation for the purpose of achieving high-speed and high accuracy performance. However, in conventional control architectures, the computation of the basis functions of a NURBS curve is very time consuming due to serial computing constraints. In this paper, a novel multiprocessor-based motion controller on chip utilizing its high-speed parallel computing power is proposed to realize the NURBS interpolation. The motion control algorithm and I/O control are also embedded in the chip to implement real-time control and NURBS interpolation simultaneously. The experimental tests using an X-Y table verify the outstanding computation performance of the multiprocessor-based motion controller on chip. The result indicates that shorter sampling time (0.1 ms) can be achieved for NURBS interpolation and high-accuracy motion control.

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.

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