scholarly journals Simultaneous Optimization of Damping and Tracking Controller Parameters Via Selective Pole Placement for Enhanced Positioning Bandwidth of Nanopositioners

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Douglas Russell ◽  
Andrew J. Fleming ◽  
Sumeet S. Aphale
Keyword(s):  
High Speed ◽  
Design Method ◽  
Damping Ratio ◽  
Simultaneous Optimization ◽  
Pole Placement ◽  
Control Scheme ◽  
Optimal Damping ◽  
Tracking Controllers ◽  
Tracking Controller ◽  
Resonant Systems

Positive velocity and position feedback (PVPF) is a widely used control scheme in lightly damped resonant systems with collocated sensor actuator pairs. The popularity of PVPF is due to the ability to achieve a chosen damping ratio by repositioning the poles of the system. The addition of a tracking controller, to reduce the effects of inherent nonlinearities, causes the poles to deviate from the intended location and can be a detriment to the damping achieved. By designing the PVPF and tracking controllers simultaneously, the optimal damping and tracking can be achieved. Simulations show full damping of the first resonance mode and significantly higher bandwidth than that achieved using the traditional PVPF design method, allowing for high-speed scanning with accurate tracking. Experimental results are also provided to verify performance in implementation.

Improving the B-Spline Method of Dynamically-Compensated Cam Design by Minimizing or Restricting Vibrations in High-Speed Cam-Follower Systems

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
J. K. Jiang ◽  
Y. R. Iwai
Keyword(s):  
High Speed ◽  
Design Method ◽  
Damping Ratio ◽  
Radius Of Curvature ◽  
Spline Method ◽  
Application Process ◽  
B Spline ◽  
Cam Design ◽  
Cam Follower ◽  
Design Values

This paper presents an improved method for dynamically-compensated (tuned) cam design by minimizing or restricting vibrations in high-speed cam-follower systems. Using this approach, cams can be synthesized with a variety of design requirements and reduced residual vibrations. An example of the dynamically-compensated B-spline method illustrates the application process and demonstrates the improvement effect. While preserving the features of the B-spline method, the improved design method allows the cams to satisfy requirements, such as pressure angle, radius of curvature, and contact stress, and also reduces the residual vibrations caused by deviations in actual cam speed or system damping ratio from their design values.

Rotordynamic Performance of Flexure Pivot Hydrostatic Gas Bearings for Oil-Free Turbomachinery

2007 ◽  
Vol 129 (4) ◽  
pp. 1020-1027 ◽  
Author(s):  
Xuehua Zhu ◽  
Luis San Andrés
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Damping Ratio ◽  
Extreme Temperature ◽  
Gas Bearings ◽  
Speed Increase ◽  
Feed Pressure ◽  
Motor Test ◽  
Direct Stiffness ◽  
Commercial Applications

Micro-turbomachinery demands gas bearings to ensure compactness, light weight, and extreme temperature operation. Gas bearings with large stiffness and damping, and preferably of low cost, will enable successful commercial applications. Presently, tests conducted on a small rotor supported on flexure pivot hydrostatic pad gas bearings (FPTPBs) demonstrate stable rotordynamic responses up to 100,000rpm (limit of the drive motor). Test rotor responses show the feed pressure raises the system critical speed (increase in bearing direct stiffness) while the viscous damping ratio decreases. Predictions correlate favorably with experimentally identified (synchronous) direct stiffness bearing force coefficients. Identified experimental gas bearing synchronous damping coefficients are 50% or less of the predicted magnitudes, though remaining relatively constant as the rotor speed increases. Tests without feed pressure show the rotor becomes unstable at ∼81krpm with a whirl frequency ratio of 20%. FPTPBs are mechanically complex and more expensive than cylindrical plain bearings. However, their enhanced stability characteristics and predictable rotordynamic performance makes them desirable for the envisioned oil-free applications in high speed micro-turbomachinery.

Development of High-Speed Response Electromagnetic Linear Actuator Using for Pneumatic Control Valve

2014 ◽  
Vol 532 ◽  
pp. 41-45 ◽  
Author(s):  
Myung Jin Chung
Keyword(s):  
Optimal Design ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Design Method ◽  
Control Valve ◽  
Design Parameters ◽  
Linear Actuator ◽  
Analytic Model ◽  
Electromagnetic Linear Actuator ◽  
Quadratic Programming Method

Analytic model of electromagnetic linear actuator in the function of electric and geometric parameters is proposed and the effects of the design parameters on the dynamic characteristics are analyzed. To improve the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design method aims to minimize the response time and maximize force efficiency. By this procedure, electromagnetic linear actuator having high-speed characteristics is developed.

Theoretical Prediction of Motions of High-Speed Planing Boats in Waves

1978 ◽  
Vol 22 (03) ◽  
pp. 140-169
Author(s):  
Milton Martin
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Nonlinear Effects ◽  
Theoretical Method ◽  
Valuable Insight ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Response Amplitude Operators ◽  
Phase Angles ◽  
Good Agreement

A theoretical method is derived for predicting the linearized response characteristics of constant deadrise high-speed planing boats in head and following waves. Comparisons of the theoretical predictions of the pitch and heave response amplitude operators and phase angles with existing experimental data show reasonably good agreement for a wide variety of conditions of interest. It appears that nonlinear effects are more severe at a speed to length ratio of 6 than of, say, 4 or less, principally because of the reduction of the damping ratio of the boat with increasing speed, and the consequent increase in motions in the vicinity of the resonant encounter frequency. However, it is concluded that the linear theory can provide a simple and fast means of determining the effect of various parameters such as trim angle, deadrise, loading, and speed on the damping, natural frequency, and linearized response in waves, and that this can furnish valuable insight into the actual boat dynamics, even though the accurate predictions of large motions and peak accelerations would require a nonlinear analysis.

Dynamic Performance Analysis on High-Speed Railway Continuous Girder Bridge

2011 ◽  
Vol 280 ◽  
pp. 186-190
Author(s):  
Shou Tan Song ◽  
Ji Wen Zhang ◽  
Xin Yuan
Keyword(s):  
High Speed ◽  
Moving Load ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Wheel Load ◽  
Dynamic Coefficients ◽  
Bridge Structures ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Dynamic Performance Analysis

The dynamic performance of continuous girder under the train in a series of speed is studied through examples, and the main conclusions are given in the following. The resonance mechanism of continuous girder is similar to simply supported beam. The vehicle wheel load forms regular moving load series, which induces periodical action and resonance of the bridge. The damping ratio of bridge itself has less effect on the amplitude at the loading stage, but significant effects appear when the load departs from the bridge. The count of continuous spans also has less impact on the dynamic coefficients, so three continuous spans can be adopted for calculation and analysis. Span and fundamental frequency have significant influence on dynamic coefficients of bridge structures. To extend the span of the bridge structure can reduce the dynamic coefficient while keeping its frequency invariant. The fundamental frequencies of different bridges are corresponding to certain resonant speeds, which calls for the attention in the design.

Integrated optimal design of a high-speed planar parallel manipulator

2018 ◽  
Vol 233 (9) ◽  
pp. 2976-2990 ◽  
Author(s):  
Zhengsheng Chen ◽  
Minxiu Kong
Keyword(s):  
Optimal Design ◽  
Parallel Manipulator ◽  
High Speed ◽  
Design Method ◽  
Tracking Error ◽  
Dimensional Synthesis ◽  
Tracking Accuracy ◽  
Nsga Ii ◽  
Parameters Tuning ◽  
Planar Parallel Manipulator

To obtain excellent comprehensive performances of the planar parallel manipulator for the high-speed application, an integrated optimal design method, which integrated dimensional synthesis, motors/reducers selection, and control parameters tuning, is proposed, and the 3RRR parallel manipulator was taken as the example. The kinematic and dynamic performances of condition number, velocity index, acceleration capability, and low-order frequency are taken into accounts for the dimensional synthesis. Then, to match motors/reducers parameters and keep an economical cost, the constraint equations and the parameters library are built, and the cost is chosen as one of the optimization objectives. Also, to get high tracking accuracy, the dynamic forward plus proportional–derivative control scheme is introduced, and the tracking error is chosen as one of the optimization objectives. Hence, the optimization model including dimensional synthesis, motors/reducers selection and controller parameters tuning is established, which is solved by the genetic algorithm II (NSGA-II). The result shows that comprehensive performances can be effectively promoted through the proposed integrated optimal design, and the prototype was constructed according to the Pareto-optimal front.

scholarly journals A Model-Free Control Scheme for Attitude Stabilization of Quadrotor Systems

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1586
Author(s):  
Jaemin Baek ◽  
Jinmyung Jung
Keyword(s):  
Pole Placement ◽  
Tracking Errors ◽  
Attitude Stabilization ◽  
Delayed Information ◽  
Model Free ◽  
System A ◽  
Control Scheme ◽  
Fast Convergence Rate ◽  
Model Free Control ◽  
Quadrotor System

This paper presents an extended time-delayed control (ETDC) scheme and applies it to a quadrotor system. The proposed ETDC scheme uses a one-sample delayed information of the system for canceling out the uncertainties and disturbances in nonlinear quadrotor system, which involves a combination of pole-placement term to deal with the pole assignment. Thus, the proposed one requires no prior knowledge about the quadrotor dynamics, which is called model-free control scheme, and then assures fast convergence rate while providing simplicity structure. To suppress time-delayed estimation (TDE) errors generated by using one-sample delayed information of the system, a new auxiliary control scheme is designed in the proposed ETDC scheme. It results in a proper switching gain without undesirable side effect, including chattering and input fluctuation. Moreover, given that it does not require any number of additional parameters, the number of the parameters in the proposed ETDC scheme has no change compared to that in conventional time-delayed control. From these benefits, the proposed one can be recognized as a simple and effective alternative to the quadrotor system with nonlinearity and complexity. The tracking errors are proved to be uniformly ultimately bounded through Lyapunov function. The effectiveness of the proposed ETDC scheme is verified by the simulation with the quadrotor system, which is compared to that of the conventional time-delayed control scheme.

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