• Title/Summary/Keyword: Two-Degrees-of-Freedom

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A Method for Measuring Nonlinear Characteristics of a Robot Manipulator Having Two-degree-of-freedom

  • Harada, H.;Toyozawa, Y.;Kashiwagi, H.
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.221-224
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    • 2005
  • The authors have recently developed a method for identification of Volterra kernels of nonlinear systems by using M-sequence and correlation technique. In this paper, we apply the proposed method to identification of a robot manipulator which has two degrees of freedom. From the results of the experiment, the nonlinear characteristics of the robot manipulator can be identified by the proposed method.

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Improvement of Maneuvering Feeling of Human-Mechanical Cooperative System and Its Application to Electric Power Steering System

  • Mukai, Yasuhiko;Ukai, Hiroyuki;Iwasaki, Makoto;Matsui, Nobuyuki;Hayashi, Jiro;Makino, Nobuhiko;Ishikawa, Hiroshi
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.728-733
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    • 2003
  • In human-mechanical cooperative systems, a significant issue is to improve the control performance and the maneuvering feeling of human operation. However, since it is not easy to evaluate the feeling of operators numerically, control engineers design controllers only through experience. Thus, in this paper, a new evaluation method for control performance of human-mechanical cooperative system is proposed based on the reserge waveform. Various distortions of waveform represent deteriorations of control performance and maneuvering feeling. In some cases, since there is a tradeoff between the control performance and the maneuvering feeling, it is difficult to compensate for both of them by usual feedback controllers. To overcome this situation, the two degrees of freedom control system is applied to human-mechanical cooperative system. Some numerical simulation results for an electric power steering system are shown to confirm the effectiveness of proposed control design method.

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Decoupled Neural Network Reference Compensation Technique for a PD Controlled Two Degrees-of-Freedom Inverted Pendulum

  • Seul Jung;Cho, Hyun-Taek
    • International Journal of Control, Automation, and Systems
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    • v.2 no.1
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    • pp.92-99
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    • 2004
  • In this paper, the decoupled neural network reference compensation technique (DRCT) is applied to the control of a two degrees-of-freedom inverted pendulum mounted on an x-y table. Neural networks are used as auxiliary controllers for both the x axis and y axis of the PD controlled inverted pendulum. The DRCT method known to compensate for uncertainties at the trajectory level is used to control both the angle of a pendulum and the position of a cart simultaneously. Implementation of an on-line neural network learning algorithm has been implemented on the DSP board of the dSpace DSP system. Experimental studies have shown successful balancing of a pendulum on an x-y plane and good position control under external disturbances as well.

Linear Dynamic Simulation using SIMULINK (SIMULINK를 이용한 선형 동적 해석)

  • Kim Seong Keol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.3
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    • pp.110-116
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    • 2005
  • Linear dynamic simulations with one and two degrees of freedom were built from SIMULINK in MATLAB commercial program. Before starting the simulations, initial conditions and system parameters which are mass, spring constant and coefficient of damping are easily inputted by user through each pop-up window, and the conditions for the simulation including time step, analysis methodology and so on can be modified with ease. Also, as soon as the simulations are started, the windows for animations which shows deformed motions dynamically with real time are popped-up and the graphical results are shown in time and frequency domains, simultaneously, The results of the simulations were verified through some examples of textbooks of mechanical vibrations. It was found that the programs would help us to solve any kind of linear dynamic simulation for one and two degrees of freedom.

Study on the efficient dynamic system condensation (동적 해석의 효율적 축소 기법에 관한 연구)

  • Baek, Sung-Min;Cho, Meang-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.631-636
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    • 2007
  • Eigenvalue reduction schemes approximate the lower eigenmodes that represent the global behavior of the structures. In the, we proposed a two-level condensation scheme(TLCS) for the construction of a reduced system. In first step, the of candidate elements by energy estimation, Rayleigh quotient, through Ritz vector calculation, and next, the primary degrees of freedom is selected by sequential elimination from the degrees of freedom connected the candidate elements in the first step. In the present study, we propose TLCS combined with iterative improved reduced system(IIRS) to increase accuracy of higher modes intermediate range. Also, it possible to control the accuracy of the eigenvalues and eigenmodes of the reduced system. Numerical examples demonstrate performance of proposed method.

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Speed Control of AC Servo Motors using Adaptive Two-Degrees-of Freedom Controller Design (2자유도 적응 제어기에 의한 AC 서보모터의 속도제어)

  • Lee, Seok-Ho;Lee, Je-Hie;Huh, Uk-Youl
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.645-648
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    • 1995
  • We propose speed controller of AC servo motors using adaptive two-degrees-of freedom controller design. The overall control system consists of three elements: a forward speed controller, parameter identifier and disturbance observer. This servosystem can improve the characteristics of the closed loop systems with the disturbance observer by eliminating the disturbance torque without changing the command input response. Moreover, the system can be adaptable to the parameter variation by employing adaptive scheme. We will show the control performances through the simulation results.

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A modified index for damage detection of structures using improved reduction system method

  • Arefi, Shahin Lale;Gholizad, Amin;Seyedpoor, Seyed Mohammad
    • Smart Structures and Systems
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    • v.25 no.1
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    • pp.1-22
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    • 2020
  • The modal strain energy method is one of the efficient methods for detecting damage in the structures. Due to existing some limitations in real-world structures, sensors can only be located on a limited number of degrees of freedom (DOFs) of a structure. Therefore, the mode shape values in all DOFs of structures cannot be measured. In this paper, a modified modal strain energy based index (MMSEBI) is introduced to locate damaged elements of structures when a limited number of sensors are used. The proposed MMSEBI is based on the reconstruction of mode shapes using Improved Reduction System (IRS) method. Therefore, in the first step by employing IRS method, mode shapes in slave degrees of freedom are estimated by those of master degrees of freedom. In the second step, the proposed MMSEBI is used to located damage elements. In order to evaluate the efficiency of the proposed method, two numerical examples are considered under different damage patterns considering the measurement noise. Moreover, the universal threshold based on statistical hypothesis testing principles is applied to damage index values. The results show the effectiveness of the proposed MMSEBI for the structural damage localization when comparing with the available damage index named MESBI. The results demonstrate that the presented method can be used as a practical strategy for structural damage identification, especially when a limited number of sensors are installed on the structure. Finally, the combination of MMSEBI and IRS method can provide a reliable tool to identify the location of damage accurately.

A Study on Position of Six-Degrees-of-Freedom of vibration Model and Orientation Decision by Adaptive Control Method (6자유도 진동모댈의 위치 및 자세결정을 위한 적응제어기법의 적용에 관한 연구)

  • Kim, J.Y.;Song, S.K.;Han, J.H.;Oh, Y.H.;Cho, S.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.6
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    • pp.94-101
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    • 1994
  • About vibration model of Six-degrees-of-freedom(DOF), in mass load, examined results for knowing dynamic interference and response variation is as follows; In case of putting mass load upon the object, experimented results on two-degrees-of-freedom of the translation-1 direction and the rotation-1 direction at open-loop-control system, about 0.19 arcsed in input of the translation-$0.1{\mu}m$ and $0.022{\mu}m$ on input of the rotation-0.5 arcsec, the justicse of motion equation is acknowledged as confirming the appearance of the interference-$0.022{\mu}m$. In establishing calculation of transformation matrix by using analogue circuit, as simulating results that used incomplete differentiation, interference is $1.7{\times}10^{-3}$ arcsec on input of the translation-$0.1{\mu}m$ and $1.4{\times}10^{4}{\mu}m$ on input of the rotation-0.5 arcsec in open-loop-control system. Also it is $4.2{\times}10^{-4}$ arcsec on input of the translation-$0.1{\mu}m$ and $5.6{\times}10^{-5}{\mu}m$ on input of the rotation-0.5 arcesc in closed-loop-control system. As closed-loop-control system is better than open-loop-control system, equivalent accordance is confirmed on original response. Finally, fundamental validity of this theory is acknowledged.

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Tracking control for multi-axis system using two-degrees-of-freedom controller

  • Park, Ho-Joon;Lee, Je-Hee;Huh, Uk-Youl
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10a
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    • pp.380-384
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    • 1996
  • This paper represents an adaptive position controller with the disturbance observer for multi-axis servo system. The overall control system consists of three parts : the position controller, the disturbance observer with free parameters and cross-coupled controller which enhances contouring performance by reducing errors. Using two-degrees-of freedom conception, we design the command input response and the closed loop characteristics independently. The servo system can improve the closed loop characteristics without affecting the command input response. The characteristics of the closed loop system is improved by suppressing disturbance torque effectively with the disturbance observer. Moreover, the cross-coupled controller enhances tracking performance. Thus total position control performance is improved. Finally, the performance of the proposed controller shows that it improves the contouring performance along with the reference trajectory in the XY-table.

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On the structure of a discrete-time $H_{\infty}$ two-degrees-of-freedom controller (이산시간 $H_{\infty}$ 2-자유도 제어기의 구조에 관한 연구)

  • 최병욱
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.569-572
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    • 1996
  • Explicit state-space formulate for an H$_{.inf}$ based two-degrees-of-freedom robust controller are derived in discrete-time. The controller provides robust stability against coprime factor uncertainty, and a degree of robust performance in the sense of making the closed-loop system match a prespecified reference model. It is shown that the controller consists of a plant observer, the chosen reference model, and a generalized state feedback law associated with the plant and model states. The controller structure is shown to be relatively simple and thus may reduce the computational load on the digital control processor.

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