A persistent method for parameter identification of a seven-axes manipulator

SUMMARYThis paper presents a persistent method for the identification problem of open-chained robotic systems. Based on the Projection Equation, a new, direct method to collect the dynamic and friction parameters in linear form is worked out. However, in this form, linear dependencies in the parameters occur and they are canceled out with the help of the QR algorithm. The obtained linear independent parameters are the base parameters of the system. To ensure a good excitation, the identification is improved by using optimized trajectories defined by Fourier-series, taking also physical constraints into account. The evaluation of the dynamic robot parameters is realized with a least squares error optimization. Furthermore, the result strongly depends on a special choice of weighting matrices for the error. Experimental results for a seven-axes robotic system (standard six-axes industrial manipulator mounted on a linear axis) are presented in detail. Additionally, the influence of temperature effects to base parameter changes is discussed.

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Model-Free Control Approach of a Three-Tank System Using an Adaptive-Based Control

Volume 6: 13th International Conference on Multibody Systems, Nonlinear Dynamics, and Control ◽

10.1115/detc2017-67487 ◽

2017 ◽

Cited By ~ 1

Author(s):

Elmira Madadi ◽

Yao Dong ◽

Dirk Söffker

Keyword(s):

Tracking Error ◽

Identification Problem ◽

Dynamical Structure ◽

Modified Model ◽

Control Approach ◽

Model Free ◽

Tank System ◽

Model Free Control ◽

Complex Nonlinear Systems ◽

Error Optimization

For improving the dynamics of systems in the last decades model-based control design approaches are continuously developed. The task to design an accurate model is the most relevant and related task for control engineers, which is time consuming and difficult if in the case of complex nonlinear systems a complex modeling or identification problem arises. For this reason model-free control methods become attractive as alternative to avoid modeling. This contribution focuses on design methods of a model-free adaptive-based controller and modified model-free adaptive-based controller. Modified approach is based on the same adaptive model-free control algorithm performing tracking error optimization. Both approaches are designed for non-linear systems with uncertainties and in the presence of disturbances in order to assure suitable performance as well as robustness against unknown inputs. Using this approach, the controller requires neither the information about the systems dynamical structure nor the knowledge about systems physical behaviors. The task is solved using only the system outputs and inputs, which are measurable. The effectiveness of the proposed method is validated by experiments using a three-tank system.

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Identification Problem of Open-Channel Friction Parameters

Journal of Hydraulic Engineering ◽

10.1061/(asce)0733-9429(1997)123:12(1078) ◽

1997 ◽

Vol 123 (12) ◽

pp. 1078-1088 ◽

Cited By ~ 36

Author(s):

Rahman H. Khatibi ◽

John J. R. Williams ◽

Peter R. Wormleaton

Keyword(s):

Open Channel ◽

Identification Problem ◽

Friction Parameters

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Identification Problem of Open-Channel Friction Parameters

Journal of Hydraulic Engineering ◽

10.1061/(asce)0733-9429(1999)125:5(552) ◽

1999 ◽

Vol 125 (5) ◽

pp. 552-553 ◽

Cited By ~ 1

Author(s):

Ben Chie Yen ◽

Rahman H. Khatibi ◽

John J. R. Williams ◽

Peter R. Wormleaton

Keyword(s):

Open Channel ◽

Identification Problem ◽

Friction Parameters

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Simultaneous Output-Only Identification of Physical Parameters and Unknown Inputs for Linear Mechanical Systems

Volume 8: 27th Conference on Mechanical Vibration and Noise ◽

10.1115/detc2015-47659 ◽

2015 ◽

Cited By ~ 1

Author(s):

Mostafa Ghobadi ◽

Manoranjan Majji ◽

Ehsan T. Esfahani

Keyword(s):

Physical System ◽

Mechanical Systems ◽

Identification Problem ◽

Physical Parameters ◽

Physical Constraints ◽

Unknown Inputs ◽

Harmonic Signals ◽

Input Model ◽

Linear Mechanical System ◽

Output Only

This paper has studied the identification problem of linear mechanical systems where inputs are unknown and only displacement data are accessible for measurement. Eigensystem Realization Algorithm (ERA) has been used along with physical constraints considerations in time domain to simultaneously identify two separate models for the physical system and the unknown inputs. Inputs are assumed to be an arbitrary combination of harmonic signals with frequencies higher than natural frequencies of the physical system by which a linear mechanical system is meant in this paper. Adding physical constraints and utilizing canonical real Jordan form of the identified system leads to a unique analytical solution. To validate the theory part, a set of simulations has been run that demonstrates the physical parameters and input model can be estimated accurately.

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Regularization of the problems of planning and processing the test results of pipeline systems for hydraulic losses

MATEC Web of Conferences ◽

10.1051/matecconf/201821201006 ◽

2018 ◽

Vol 212 ◽

pp. 01006

Author(s):

Oksana Grebneva

Keyword(s):

Computer Modelling ◽

A Priori ◽

Identification Problem ◽

Test Results ◽

Initial Information ◽

Active Experiments ◽

Priori Information ◽

Parameter Values ◽

Modelling Methods ◽

Independent Parameters

The lack of reliable information on actual characteristics and parameters is the main deterrent to the effective application of mathematical and computer modelling methods for solving problems of optimal reconstruction, adjustment, and development of operational problems. The lack of such information is solved on the basis of applying the identification problems that require expert (approximate) specification of a priori parameter values. This leads to the sensitivity of the solution of identifying a problem to the errors in setting the initial information. One way to solve this problem is to apply regularization methods. In this paper, a numerical example proposes a rule for expert assignment of a priori information on the parameters of elements, which makes it possible to minimize its influence on the results of planning active experiments. In addition, the paper shows the independence of the solution of the identification problem from the composition of the vector of independent parameters.

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Characterization of frozen hydrated biological specimens by low-loss EELS

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132492 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1572-1573

Author(s):

Songquan Sun ◽

Richard D. Leapman

Keyword(s):

Water Content ◽

Direct Method ◽

Internal Standard ◽

Dry Weight ◽

Dark Field ◽

Protein Solutions ◽

Subcellular Compartment ◽

Differential Shrinkage ◽

Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

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A Simple Real-Space Channelling Theory for Electron Diffraction and HREM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100179075 ◽

1990 ◽

Vol 48 (1) ◽

pp. 64-65

Author(s):

D. Van Dyck

Keyword(s):

High Resolution ◽

Electron Diffraction ◽

Direct Method ◽

Real Space ◽

Zone Axis ◽

Phase Object ◽

High Resolution Images ◽

The Many ◽

Analytical Expressions ◽

Electron Wavefunction

The computation of the many beam dynamical electron diffraction amplitudes or high resolution images can only be done numerically by using rather sophisticated computer programs so that the physical insight in the diffraction progress is often lost. Furthermore, it is not likely that in this way the inverse problem can be solved exactly, i.e. to reconstruct the structure of the object from the knowledge of the wavefunction at its exit face, as is needed for a direct method [1]. For this purpose, analytical expressions for the electron wavefunction in real or reciprocal space are much more useful. However, the analytical expressions available at present are relatively poor approximations of the dynamical scattering which are only valid either for thin objects ((weak) phase object approximation, thick phase object approximation, kinematical theory) or when the number of beams is very limited (2 or 3). Both requirements are usually invalid for HREM of crystals. There is a need for an analytical expression of the dynamical electron wavefunction which applies for many beam diffraction in thicker crystals. It is well known that, when a crystal is viewed along a zone axis, i.e. parallel to the atom columns, the high resolution images often show a one-to-one correspondence with the configuration of columns provided the distance between the columns is large enough and the resolution of the instrument is sufficient. This is for instance the case in ordered alloys with a column structure [2,3]. From this, it can be suggested that, for a crystal viewed along a zone axis with sufficient separation between the columns, the wave function at the exit face does mainly depend on the projected structure, i.e. on the type of atom columns. Hence, the classical picture of electrons traversing the crystal as plane-like waves in the directions of the Bragg beams which historically stems from the X-ray diffraction picture, is in fact misleading.

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