New Command Shaping Methods for Reduced Vibration of a Suspended Payload With Constrained Trolley Motion

2007 ◽  
Author(s):  
Aaron R. Enes ◽  
Timothy Y. Hsu ◽  
Angela A. Sodemann
Keyword(s):  
System Modeling ◽  
Small Scale ◽  
Residual Vibration ◽  
Conveyor System ◽  
Command Shaping ◽  
Common Task ◽  
Modeling Errors ◽  
Point To Point ◽  
Manufacturing Environments ◽  
Command Signal

In manufacturing environments, a common task is to quickly move a suspended payload point-to-point along a fixed overhead conveyor track without inducing significant payload vibration. Recent research in command shaping has shown remarkably effective ways to reduce the swing of a suspended payload providing the motion of the trolley is not constrained. However, the development of a command shaper where the trajectory of the trolley is constrained to follow a fixed curvilinear path has not been explored. This paper will present the development of a simple feedforward command shaper for fast, low vibration, point-to-point movement of a payload suspended from a trolley constrained to follow a fixed generalized path. The command shaping method involves modifying the command signal by convolving it with a series of impulses. Prior work has suggested command shaping to be very effective for fast, low-vibration movement of flexible systems. In this paper, command shaping methods are applied to an overhead conveyor system constrained to move along a fixed curvilinear path. Two new command shapers are presented for canceling payload vibration induced by motion of the trolley along the path. The designed Tangential Vibration (TV) shaper reduces payload vibrations induced by tangential accelerations of the trolley along the path, while the Centripetal-Tangential Vibration (CTV) shaper reduces vibrations induced by both tangential and centripetal accelerations. A key result of this study is that a command shaper having at least three impulses is required to yield zero residual vibration for motion along a curvilinear path. A simple pendulum payload attached to an actual small-scale overhead trolley following a constrained path is used to evaluate the performance of the designed command shapers. It is shown that the designed shapers significantly reduce payload swing compared to unshaped performance. An experimental sensitivity analysis shows the designed shapers are robust to system modeling errors and variations in path parameters.

Reducing Trajectory Tracking Error of Flexible Mobile Robots Using Command Shaping With Error-Limiting Constraints

2017 ◽  
Author(s):  
Gerald Eaglin ◽  
Joshua Vaughan
Keyword(s):  
Mobile Robots ◽  
Trajectory Tracking ◽  
Tracking Error ◽  
Input Shaping ◽  
Flexible Systems ◽  
Command Shaping ◽  
Modeling Errors ◽  
Temporal Tracking ◽  
Point Motion ◽  
Point To Point

The ability to track a trajectory without significant error is a vital requirement for mobile robots. Numerous methods have been proposed to mitigate tracking error. While these trajectory-tracking methods are efficient for rigid systems, many excite unwanted vibration when applied to flexible systems, leading to tracking error. This paper analyzes a modification of input shaping, which has been primarily used to limit residual vibration for point-to-point motion of flexible systems. Standard input shaping is modified using error-limiting constraints to reduce transient tracking error for the duration of the system’s motion. This method is simulated with trajectory inputs constructed using line segments and Catmull-Rom splines. Error-limiting commands are shown to improve both spatial and temporal tracking performance and can be made robust to modeling errors in natural frequency.

Friction-Compensating Command Shaping for Vibration Reduction

2004 ◽  
Vol 127 (4) ◽  
pp. 307-314 ◽  
Author(s):  
Jason Lawrence ◽  
William Singhose ◽  
Keith Hekman
Keyword(s):  
Steady State ◽  
Coulomb Friction ◽  
Vibration Reduction ◽  
Input Shaping ◽  
Residual Vibration ◽  
Command Shaping ◽  
Point Motion ◽  
Common Operation ◽  
Point To Point ◽  
Theoretical Developments

Fast and accurate point-to-point motion is a common operation for industrial machines, but vibration will frequently corrupt such motion. This paper develops commands that can move machines without vibration, even in the presence of Coulomb friction. Previous studies have shown that input shaping can be used on linear systems to produce point-to-point motion with no residual vibration. This paper extends command-shaping theory to nonlinear systems, specifically systems with Coulomb friction. This idea is applied to a PD-controlled mass with Coulomb friction to ground. The theoretical developments are experimentally verified on a solder cell machine. The results show that the new commands allow the proportional gain to be increased, resulting in reduced rise time, settling time, and steady-state error.

Command Shaping Slewing Motions for Tower Cranes

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Jason Lawrence ◽  
William Singhose
Keyword(s):  
Nonlinear Dynamics ◽  
Rotational Motion ◽  
Effective Control ◽  
Input Shaping ◽  
Residual Vibration ◽  
Command Shaping ◽  
Tower Crane ◽  
Control Scheme ◽  
Point To Point ◽  
Gantry Cranes

Input shaping has been shown to be a practical and effective control scheme for reducing payload swing on industrial bridge and gantry cranes. However, when applied to tower cranes, standard input shapers will have degraded performance due to the nonlinear dynamics of rotational motion. To alleviate this problem, two new command generators for tower cranes are developed for a point-to-point slewing motion. It is shown that standard shaping techniques greatly reduce oscillation and the new tower crane command generators cause even less residual vibration. Simulations and experiments verify the results.

Effective Feedforward/Feedback Controller Design With Command Shaping to Reduce Residual Vibration

Manufacturing ◽  
2003 ◽  
Author(s):  
Peter H. Meckl ◽  
Young Joo Shin
Keyword(s):  
Control Strategy ◽  
High Speed ◽  
Controller Design ◽  
High Volume ◽  
Feedback Controller ◽  
Residual Vibration ◽  
Command Shaping ◽  
Minimum Residual ◽  
High Volume Production ◽  
Point To Point

Many manufacturing devices must execute motions as quickly as possible to achieve profitable high-volume production. This paper develops a control strategy that combines feedforward and feedback control with command shaping. First, the feedback controller is designed to increase damping and eliminate steady-state error. Next, the feedforward controller is designed to speed up the transient response. Finally, an appropriate reference profile is generated using command-shaping techniques to ensure fast point-to-point motions with minimum residual vibration. The particular focus of the paper is to understand the interactions between these individual control components. The resulting control strategy is demonstrated on a model of a high-speed semiconductor manufacturing machine.

On-Off Control With Specified Fuel Usage

1999 ◽  
Vol 121 (2) ◽  
pp. 206-212 ◽  
Author(s):  
William Singhose ◽  
Tarunraj Singh ◽  
Warren Seering
Keyword(s):  
Flexible Systems ◽  
Residual Vibration ◽  
Command Generation ◽  
Modeling Errors ◽  
Command Signals

A method for generating on-off command profiles for flexible systems is presented. The command profiles move a system without residual vibration while using a specified amount of actuator fuel. Robustness to modeling errors can be incorporated into the design of the command signals. Techniques are presented that facilitate implementation and indicate prudent choices for the amount of fuel to be used. The method is compared to other command generation techniques that balance fuel usage and slew time.

SMED for quick changeover in manufacturing industry – a case study

2018 ◽  
Vol 25 (7) ◽  
pp. 2065-2088 ◽  
Author(s):  
Jagdeep Singh ◽  
Harwinder Singh ◽  
Inderdeep Singh
Keyword(s):  
Manufacturing Industry ◽  
Setup Time ◽  
Industrial Engineering ◽  
Small Scale ◽  
Small Enterprises ◽  
Production Environment ◽  
Content Type ◽  
Northern India ◽  
Manufacturing Environments

Purpose The purpose of this paper is to uncover the significance of SMED in manufacturing environments. Design/methodology/approach The paper gives setup instructions and guidelines to prepare the standardized setup procedure without ignoring actual constraints in production environment. It uses a case study in a small-scale manufacturing unit of northern India to generate an integrated setup reduction approach, utilizing Single Minute Exchange of Die (SMED)-based industrial engineering tools to achieve faster setups. It describes the feasibility of quick changeovers in small enterprises based on an “SMED” approach. Finally, the paper carries out empirical analysis of the financial/non-financial benefits incurred from setup reductions. Findings Setup activities are a vital part of the production lead time of any product and so affect overall product cost. Industrial engineering techniques have been used to analyze the existing procedure of setups. A SMED approach can help eliminate unwanted activities, externalize the internal activities, if possible, and reduce them by simplification or standardization. Originality/value The paper demonstrates the practical application of SMED showing how it can bring real breakthroughs in reducing setup time in small-scale manufacturing.

Application of Digital Twin Concept for Supercritical CO2 Off-Design Performance and Operation Analyses

2020 ◽  
Author(s):  
Leonid Moroz ◽  
Maksym Burlaka ◽  
Tishun Zhang ◽  
Olga Altukhova
Keyword(s):  
Supercritical Co2 ◽  
Control Strategies ◽  
System Modeling ◽  
Performance Estimation ◽  
Cycle Performance ◽  
Small Scale ◽  
Part Load ◽  
Digital Twin ◽  
Design Performance ◽  
Cycle Simulation

Abstract To date variety of supercritical CO2 cycles were proposed by numerous authors. Multiple small-scale tests performed, and a lot of supercritical CO cycle aspects studied. Currently, 3-10 MW-scale test facilities are being built. However, there are still several pieces of SCO2 technology with the Technology Readiness Level (TRL) 3-5 and system modeling is one of them. The system modeling approach shall be sufficiently accurate and flexible, to be able to precisely predict the off-design and part-load operation of the cycle at both supercritical and condensing modes with diverse control strategies. System modeling itself implies the utilization of component models which are often idealized and may not provide a sufficient level of fidelity. Especially for prediction of off-design and part load supercritical CO2 cycle performance with near-critical compressor and transition to condensing modes with lower ambient temperatures, and other aspects of cycle operation under alternating grid demands and ambient conditions. In this study, the concept of a digital twin to predict off-design supercritical CO2 cycle performance is utilized. In particular, with the intent to have sufficient cycle simulation accuracy and flexibility the cycle simulation system with physics-based methods/modules were created for the bottoming 15.5 MW Power Generation Unit (PGU). The heat source for PGU is GE LM6000-PH DLE gas turbine. The PGU is a composite (merged) supercritical CO2 cycle with a high heat recovery rate, its design and the overall scheme are described in detail. The calculation methods utilized at cycle level and components’ level, including loss models with an indication of prediction accuracy, are described. The flowchart of the process of off-design performance estimation and data transfer between the modules as well. The comparison of the results obtained utilizing PGU digital twin with other simplified approaches is performed. The results of the developed digital twin utilization to optimize cycle control strategies and parameters to improve off-design cycle performance are discussed in detail.

Open Systems Formulation and Gaining Insight Using Lagrangian Bond Graphs

2000 ◽  
Author(s):  
Robin C. Redfield
Keyword(s):  
System Dynamics ◽  
Open Systems ◽  
Classical Method ◽  
System Modeling ◽  
Bond Graph ◽  
Small Scale ◽  
Bond Graphs ◽  
Model Modification ◽  
System Equations ◽  
Insight Into

Abstract Models of a small-scale water rocket are developed as an example of open system modeling by both the bond graph approach and a more classical method. One goal of the development is to determine the benefits of the bond graph approach into affording insight into the system dynamics. Both modeling approaches yield equivalent differential equations as they should, while the bond graph approach yields significantly more insight into the system dynamics. If a modeling goal is to simply find the system equations and predict behavior, the classical approach may be more expeditious. If insight and ease of model modification are desired, the bond graph technique is probably the better choice. But then you have to learn it!

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