Noise effect on adaptive command shaping methods for flexible manipulator control

©2001 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other worksDOI: 10.1109/87.896749Since its introduction, the command shaping method to design command shapers as robust as possible based on the has been applied to the control of many types of flexible manipu- available infonnation on a given system (e.g., expected varialators and sthe effectiveness in the vibration suppression has been tion range of the natural frequency) [11]. Unfortunately, the roverified. However, designing an effective command shaper requires a priori knowledge about the system parameters. Recently, some bustness of the shaper comes at the expense of the command efforts have been made to make the command shaper adapt to the shaper length, which means more delay in the response. Morechanges in the system parameters. In this paper, the indirect and _. over, this approach still requires a fair amount of a priori knowlthe direct adaptive command shaping methods in the time domain edge about the system parameters for proper design. The second are compared, especially in terms of the noise effect on the per- approach is to make the command shaper adapt to uncertain formance. Analysis shows that the direct approach is less sensitive . to the noise and this analytic result is verified by the proper simu- or varying system parameters. The indirect adaptive command lation. Finally, experimental results using the direct approach are shaping method has focused on the system identification either included. in the frequency domain [3], [14] or in the time domain [2], [8]

Numerical model of journal bearing lubrication considering a bending stiffness effect

An analysis for operating characteristics of journal bearing lubrication system is performed based on the numerical model. Dynamic bearing lubrication characteristics such as oil film pressure and thickness distribution can be analyzed through a numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD). In particular, the oil film thickness variation by elastic deformation is considered in the elastohydrodynamic analysis by applying the bending stiffness effect of journal. And the oil film thickness variation by the bending stiffness effect is applied to the fluid governing equations to calculate the oil film pressure in the elastohydrodynamic lubrication region. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. Also, a numerical example for the journal bearing lubrication system is demonstrated and compared with the experimental results. The numerical results considering the bending stiffness effect show a good agreement with the experimental results

Limitations and improvements of time-delay command shaping filters for flexible machine control

Ph.D.Wayne J. Boo

Adaptive Command Shaping Using Adaptive Filter Approach in Time Domain

©1999 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Presented at the 1999 American Control Conference, June 2-4, 1999, San Diego, California.DOI: 10.1109/ACC.1999.782744  Since its introduction, the command shaping method has been applied to the control of many different types of flexible manipulators. A properly designed command shaper cancels the resonance poles of the system regardless of the given reference input to the system. However, designing an effective command shaper requires a priori knowledge about the system parameters. Recently, some efforts have been made to make the command shaper less sensitive to the uncertainty of the system parameters and to make the command shaper adapt to the unknown system parameters. This research is an effort to develop an effective adaptive command-shaping algorithm in the time domain. In the paper, the authors propose an adaptive command-shaping algorithm using an adaptive filtering technique in the time domain and verify the effectiveness of the proposed algorithm with proper experiments

Vibration cancellation in complex support structures for precision robots

© 1997 ASMEPresented at the at the ASME International Mechanical Engineering Congress and Exposition (IMECE), Dallas, TX, Nov. 16-21, 1997.This paper examined the effectiveness of the Optimal Arbitrary Time-delay filter applied to cancel the undesired elastic modes of vibration in complex supporting structures for precision robot which is under development. To achieve the desired positioning precision, suppressing the structure vibration is essential. For this to be done OAT filter method was chosen. Modeling of the system has been performed and using this model, simulations were done without and with OAT filter. The ability of OAT filter in canceling the vibration of the structure was demonstrated in the simulation results. And to verify this results, experiment involving OAT filter within the robot control system has been done on the current version of the precision robot. Even though the dynamics response of supporting structure in the precision robot system has an inherent characteristics of small magnitude and high value of natural frequencies, response due to the filtered command showed that the filter successfully reduced vibration in magnitude and got rid of the residual vibrations faster than the response with unfiltered command

Time-Delay Command Shaping Filters: Robust and/or Adaptive

Time-delay command shaping filters for reducing the vibrational response of flexible systems are introduced and discussed. Special attention is given to the role played by robustness and adaptation in producing effective filters even when system parameters change. Results from several authors are used to compare and contrast these approaches

Calibration of Visco-Hyperelastic Model for Tensile Behavior of Porcine Skin

Uniaxial tensile tests were performed on porcine skin to investigate the tensile stress-strain constitutive characteristic at qua-sistatic deformations using uniaxial tensile tests. Experimental results were then used to determine the parameters of the various constitutive model types for rubber, including the Mooney-Rivlin, Yeoh, Ogden, and others. The Prony series viscoelastic model was also calibrated based on the stress relaxation test. To investigate the calibrated constitutive equations (visco-hyperelastic), the falling impact test was conducted. From the viewpoint of the maximum impact load, the error was approximately 15.87%. Overall, the Ogden model predicted the experimental measurements most reasonably. The calibrated constitutive model is expected to be of practical use in describing the mechanical properties of porcine skin

Determination of Uniaxial Tensile Behavior of Hypodermis in Porcine Skin Based on Rule of Mixtures

In this study, we investigate the mechanical behavior of each skin layer, in terms of the nominal stress-strain curve by uniaxial tensile tests using specimens of porcine skin in two forms: dermis containing epidermis, and all three layers. All tests were performed under cyclic loading at the constant strain rate of 10-3 s-1 at ambient temperature. To measure the precise initial crosssectional areas of each layer, the thickness of each skin layer was quantified by counting the number of pixels on the photo-image using image-processing software. In the tensile test, force-strain curves of the total skin and dermis with epidermis were obtained. Subsequently, a rule of mixtures was applied to determine the nonlinear mechanical properties of the hypodermis layer. In conclusion, we could define the uniaxial tensile behavior of the hypodermis, and additionally predict the weight effect of the dermis and hypodermis layers in the tensile test

An efficient Generalized Geometry Contact algorithm including modal reduction flexible bodies

In the MFBD (Multi-Flexible-Body Dynamics) (RecurDyn, 2017), the contact analysis is very important. To develop the general purpose contact algorithm for rigid and flexible bodies, the Generalized Geometry Contact algorithm, which is called ‘Geo Contact', has been developed by Choi's (Choi et al., 2013), (Choi and Choi, 2012), (Choi, 2009) for the contact problems between the rigid and flexible bodies with the general shaped geometries. In the previous researches, the nodal approach for flexible body was considered. But, the flexible body is classified as two types. The one is a nodal flexible body based on the Finite Element Method and the other is a modal reduction flexible body. The modal reduction flexible body is widely used in the MFBD system for the efficient analysis for small deformation problems. In order to get a flexible body of modal reduction, the CMS (Component Mode Synthesis) analysis of Craig-Bampton's (Craig and Bampton, 1965) is widely used. Therefore, in this study, we will expand the existing contact algorithm to the modal reduction flexible body. The node of the modal reduction flexible body can be deformed like as the nodal flexible body. Therefore, the contact algorithm is similar to the nodal flexible body. We made two interface functions in pre and post processing in the previous Generalized Geometry Contact (Geo Contact) algorithm in order to support the contact for the modal reduction flexible body. Consequentially, this method can be applied for various contact cases with three types of bodies. There are total six cases using three types of bodies such as (1) rigid-rigid body, (2) rigid-nodal flexible body, (3) rigid-modal reduction flexible body, (4) nodal flexible-modal reduction flexible body, (5) nodal flexible-nodal flexible body, and (6) modal reduction flexible-modal reduction flexible body. We will show that whole contact cases work well with Generalized Geometry Contact algorithm with some examples