Robust Negative Input Shapers for Vibration Suppression

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Joshua Vaughan ◽  
Aika Yano ◽  
William Singhose
Keyword(s):  
Rise Time ◽  
Vibration Suppression ◽  
Control Method ◽  
High Mode ◽  
Input Shaping ◽  
Bridge Crane ◽  
Modeling Errors ◽  
Parameter Variations ◽  
Mode Excitation ◽  
Theoretical Predictions

Input shaping is a control method that limits motion-induced oscillation in vibratory systems by intelligently shaping the reference command. As with any control method, the robustness of input shaping to parameter variations and modeling errors is an important consideration. For input shaping, there exists a fundamental compromise between robustness to such errors and system rise time. For all types of shapers, greater robustness requires a longer duration shaper, which degrades rise time. However, if a shaper is allowed to contain negative impulses, then the shaper duration may be shortened with only a small cost of robustness and possible high-mode excitation. This paper presents a thorough analysis of the compromise between shaper duration, robustness, and possible high-mode excitation for several negative input-shaping methods. In addition, a formulation for specified negative amplitude, specified insensitivity shapers is presented. These shapers provide a continuous spectrum of solutions for the duration/robustness/high-mode excitation trade-off. Experimental results from a portable bridge crane verify the theoretical predictions.

Time-Optimal Negative Input Shapers

1997 ◽  
Vol 119 (2) ◽  
pp. 198-205 ◽  
Author(s):  
W. E. Singhose ◽  
W. P. Seering ◽  
Neil C. Singer
Keyword(s):  
Rise Time ◽  
The Other ◽  
High Mode ◽  
Piezo Actuator ◽  
Input Shaping ◽  
Residual Vibration ◽  
Dc Motors ◽  
Mode Excitation ◽  
Time Optimal ◽  
Computer Controlled

Input shaping reduces residual vibration in computer controlled machines by convolving a sequence of impulses with a desired system command. The resulting shaped input is then used to drive the system. The impulse sequence has traditionally contained only positively valued impulses. However, when the impulses are allowed to have negative amplitudes, the rise time can be improved. Unfortunately, excitation of unmodeled high modes and overcurrenting of the actuators may accompany the improved rise time. Solutions to the problem of high-mode excitation and overcurrenting are presented. Furthermore, a simple look-up method is presented that facilitates the design of negative input shapers. The performance of negative shapers is evaluated experimentally on two systems; one driven by a piezo actuator and the other equipped with DC motors.

Comparison of Robust Input Shapers for Elimination of Residual Vibrations

2014 ◽  
Vol 490-491 ◽  
pp. 997-1002
Author(s):  
Çağlar Conker ◽  
Hakan Yavuz ◽  
Sadettin Kapucu ◽  
Mustafa Kaan Baltacioğlu ◽  
Hüseyi̇n Turan Arat ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Rise Time ◽  
Feedforward Control ◽  
Damping Ratio ◽  
Settling Time ◽  
Control Technique ◽  
System Response ◽  
Input Shaping ◽  
Positioning Accuracy ◽  
Modeling Errors

Input shaping is a feedforward control technique for improving the settling time and positioning accuracy, while minimizing residual vibrations. Shaped command profiles are generated by convolving a sequence of impulses. To design an input shaping controller, estimates of the system natural frequency and damping ratio are required. However, real systems cannot be modeled exactly, making the robustness to modeling errors an important consideration. Many robust input shapers have been developed, but robust shapers typically have longer durations that slow the system response. This creates a compromise between shaper robustness and rise time. This paper analyses the compromise between shaper duration and robustness for several robust input shapers

Assist Control Method Based on Operating Property for Task from Automated Transfer to Manual Positioning of Flexible Parts

2009 ◽  
Vol 3 (6) ◽  
pp. 700-708 ◽  
Author(s):  
Atsushi Ohzawa ◽  
◽  
Yoshifumi Morita ◽  
Yosuke Suzuki ◽  
Susumu Hara ◽  
...  
Keyword(s):  
Vibration Suppression ◽  
Control Method ◽  
Notch Filter ◽  
Frequency Component ◽  
Industrial Robots ◽  
Mode Switching ◽  
Input Shaping ◽  
Control Input ◽  
Flexible Parts ◽  
Force Signal

Industrial production lines combine both autonomous machinery such as industrial robots and operator-machine cooperative power-assist systems. There are a lot of flexible and large parts among assembly parts, because of the weight saving. In efficient switching among machine- and operator-oriented operation, vibration suppression is an important issue. This paper presents operator-based assist control for task from automated transfer to manual positioning of flexible parts. This involves a mode-switching compensator whose control input is continuous and an input-shaping compensator that suppresses flexible-parts vibration. The input-shaping compensator using a notch filter eliminates the vibration frequency component from the operating force signal. Filter gain is adjusted online based on operating properties. The effectiveness of our proposal is verified from (i) maneuverability based on time-response evaluation and task-achievement time, and (ii) operational feel subjectively evaluated based on questionnaires.

Human Operator Learning on Double-Pendulum Bridge Cranes

2007 ◽  
Author(s):  
Dooroo Kim ◽  
William Singhose
Keyword(s):  
Control Method ◽  
Performance Testing ◽  
Human Operator ◽  
Input Shaping ◽  
Double Pendulum ◽  
Bridge Crane ◽  
Theoretical Limit ◽  
Control Scheme ◽  
Human Operators ◽  
Input Shaping Control

Oscillation of crane payloads makes it challenging to manipulate payloads quickly, accurately, and safely. The problem is compounded when the payload creates a double-pendulum effect. This paper evaluates an input-shaping control method for reducing double-pendulum oscillations. Human operator performance testing on a 10-ton industrial bridge crane is used to verify the effectiveness and robustness of the method. The tests required the operators to drive the crane numerous times over a period of eight days. Data from these experiments show that human operators perform manipulation tasks much faster and safer with the proposed control scheme. Furthermore, considerably less operator effort is required when input shaping is used to limit the oscillation. These experiments also show that significant learning occurred when operators did not have the aid of input shaping. However, the performance never approached that achieved with input shaping without any training. With input shaping enabled, only moderate learning occurred because operators were able to drive the crane near its theoretical limit during their first tests.

Negative Input Shaping: Eliminating Overcurrenting and Maximizing the Command Space

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Khalid L. Sorensen ◽  
Aayush Daftari ◽  
William E. Singhose ◽  
Keith Hekman
Keyword(s):  
Rise Time ◽  
System Performance ◽  
Three Dimensional ◽  
Mitigation Strategies ◽  
Input Shaping ◽  
Bridge Crane ◽  
Flexible Systems ◽  
Filtering Method ◽  
Dimensional Simulation ◽  
Insight Into

Input shaping is a filtering method used for reducing oscillation in flexible systems. A class of these filters, called negative input shapers, has been developed to improve system rise-time beyond what is achievable using conventional input-shaping filters. However, negative input shapers can cause overcurrenting and subsequent system oscillation, when used with certain reference commands. This class of reference commands is examined in the context of the command space. The command space represents the space of all possible signals that may be issued to a system. It provides insight into how overcurrenting occurs, how overcurrenting can be mitigated, and the influence that mitigation strategies have on system performance. Two overcurrenting mitigation strategies are presented. The operational effects of overcurrenting and overcurrenting mitigation are evaluated using a three-dimensional simulation of a bridge crane, and experimental results from a 10ton industrial bridge crane.

Reference Command Shaping Using Specified-Negative-Amplitude Input Shapers for Vibration Reduction

2004 ◽  
Vol 126 (1) ◽  
pp. 210-214 ◽  
Author(s):  
William Singhose ◽  
Erika Ooten Biediger ◽  
Ye-Hwa Chen ◽  
Bart Mills
Keyword(s):  
Rise Time ◽  
Vibration Reduction ◽  
Input Shaping ◽  
Case Scenario ◽  
Worst Case ◽  
Performance Gap ◽  
Command Shaping ◽  
Mode Excitation ◽  
New Type ◽  
Command Signals

Residual vibrations can be greatly reduced by using specially-shaped reference command signals. Input shaping is one such technique that reduces vibration by convolving a sequence of impulses with any desired reference command. Several types of useful impulse sequences have been developed. Most of these have contained only positively valued impulses. However, rise time can be improved by using some negative impulses in the sequence. Unfortunately, the use of negative impulses can excite unmodeled high modes. A new type of impulse sequence containing negative impulses is proposed. These sequences are designed to fill the performance gap between all-positive impulse sequences and the negative sequences previously developed. A proof governing the worst case scenario provides an upper bound on high-mode excitation. The resulting class of impulse sequences allows the designer to make a precise trade off between rise time and vibration reduction.

Reducing Overshoot in Human-Operated Flexible Systems

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Joshua Vaughan ◽  
Paul Jurek ◽  
William Singhose
Keyword(s):  
Additional Constraint ◽  
Task Completion ◽  
Input Shaping ◽  
Bridge Crane ◽  
New Class ◽  
Input Shaper ◽  
Theoretical Predictions ◽  
Acceleration And Deceleration ◽  
Improved Performance ◽  
Performance Results

Input shaping accomplishes vibration reduction by slightly increasing the acceleration and deceleration periods of the command. The increase in the deceleration period can lead to system overshoot. This paper presents a new class of reduced-overtravel input shapers that are designed to reduce shaper-induced overtravel from human-operator commands. During the development of these new shapers, an expression for shaper-induced overtravel is introduced. This expression is used as an additional constraint in the input-shaper design process to generate the reduced-overtravel shapers. Experiments from a portable bridge crane verify the theoretical predictions of improved performance. Results from a study of eight industrial bridge crane operators indicate that utilizing the new reduced-overtravel input shapers dramatically reduces task completion time, while also improving positioning accuracy.

Robust Input Shaper Control Design for Parameter Variations in Flexible Structures

1999 ◽  
Vol 122 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Lucy Y. Pao ◽  
Mark A. Lau
Keyword(s):  
Design Method ◽  
Structural Parameters ◽  
Flexible Structures ◽  
Control Design ◽  
Input Shaping ◽  
Input Shaper ◽  
Modeling Errors ◽  
Parameter Variations ◽  
Damped Systems ◽  
Parameter Values

Input shaping has been shown to yield good performance in the control of flexible structures while being insensitive to modeling errors. However, previous studies do not take into account the distributions of the parameter variations. We develop a new input shaping method that allows the ranges of system parameter values to be weighted according to the expected modeling errors. Comparisons with previously proposed input shaper designs are presented to illustrate the qualities of the new input shaper design method. These new shapers will be shown to have better robustness under uncertainty in structural parameters and shorter shaper lengths for lightly damped systems. [S0022-0434(00)02201-2]

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