Results 1  10
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89
Single State ElastoPlastic Friction Models
 IEEE TRANSACTIONS ON AUTOMATIC CONTROL
, 2002
"... For control applications involving small displacements and velocities, friction modeling and compensation can be very important. In particular, the modeling of presliding displacement (motion prior to fully developed slip) can play a pivotal role. In this paper, it is shown that existing singlestat ..."
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Cited by 57 (4 self)
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For control applications involving small displacements and velocities, friction modeling and compensation can be very important. In particular, the modeling of presliding displacement (motion prior to fully developed slip) can play a pivotal role. In this paper, it is shown that existing singlestate friction models exhibit a nonphysical drift phenomenon which results from modeling presliding as a combination of elastic and plastic displacement. A new class of single state models is defined in which presliding is elastoplastic: under loading, frictional displacement is first purely elastic and then transitions to plastic. The new model class is demonstrated to substantially reduce drift while preserving the favorable properties of existing models (e.g., dissipativity) and to provide a comparable match to experimental data.
Optimal Robot Excitation and Identification
 IEEE Trans. Robot. Automat
, 1997
"... AbstractThis paper discusses experimental robot identification based on a statistical framework. It presents a new approach toward the design of optimal robot excitation trajectories, and formulates the maximumlikelihood estimation of dynamic robot model parameters. The differences between the ne ..."
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Cited by 49 (14 self)
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AbstractThis paper discusses experimental robot identification based on a statistical framework. It presents a new approach toward the design of optimal robot excitation trajectories, and formulates the maximumlikelihood estimation of dynamic robot model parameters. The differences between the new design approach and the existing approaches lie in the parameterization of the excitation trajectory and in the optimization criterion. The excitation trajectory for each joint is a finite Fourier series. This approach guarantees periodic excitation which is advantageous because it allows: 1) timedomain data averaging; 2) estimation of the characteristics of the measurement noise, which is valuable in case of maximumlikelihood parameter estimation. In addition, the use of finite Fourier series allows calculation of the joint velocities and accelerations in an analytic way from the measured position response, and allows specification of the bandwidth of the excitation trajectories. The optimization criterion is the uncertainty on the estimated parameters or a lower bound for it, instead of the often used condition of the parameter estimation problem. Simulations show that this criterion yields parameter estimates with smaller uncertainty bounds than trajectories optimized according to the classical criterion. Experiments on an industrial robot show that the presented trajectory design and maximumlikelihood parameter estimation approaches complement each other to make a practicable robot identification technique which yields accurate robot models.
A Search for Consensus Among Model Parameters Reported for the Puma 560 Robot
"... The PUMA 560 robot is the white rat of robotics research i t has been studied and used in countless experiments over many years and in many laboratories. However, it remains a challenge t o assemble the complete data needed f o r modelbased control of the robot. This paper presents a numerical c ..."
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Cited by 40 (2 self)
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The PUMA 560 robot is the white rat of robotics research i t has been studied and used in countless experiments over many years and in many laboratories. However, it remains a challenge t o assemble the complete data needed f o r modelbased control of the robot. This paper presents a numerical comparison of kinematic, dynamic and electrical parameters f o r the PUMA 560 robot which have been reported in the literature. For the first t ime, data f r o m several experiments are presented in a single system of coordinates, which facil i tates comparison. Diflerences in the data and ihe various methods of measurement are discussed. N e w data have been gathered and are presented where the record was incomplete. 1
A SemiImplicit TimeStepping Model For Frictional Compliant Contact Problems
, 2004
"... In this paper, we formulate a semiimplicit timestepping model for multibody mechanical systems with frictional, distributed compliant contacts. Employing a polyhedral pyramid model for the friction law and a distributed, linear, viscoelastic model for the contact, we obtain mixed linear complement ..."
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Cited by 31 (9 self)
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In this paper, we formulate a semiimplicit timestepping model for multibody mechanical systems with frictional, distributed compliant contacts. Employing a polyhedral pyramid model for the friction law and a distributed, linear, viscoelastic model for the contact, we obtain mixed linear complementarity formulations for the discretetime, compliant contact problem. We establish the existence and finite multiplicity of solutions, demonstrating that such solutions can be computed by Lemke’s algorithm. In addition, we obtain limiting results of the model as the contact stiffness tends to infinity. The limit analysis elucidates the convergence of the dynamic models with compliance to the corresponding dynamic models with rigid contacts within the computational timestepping framework. Finally, we report numerical simulation results with an example of a planar mechanical system with a frictional contact that is modeled using a distributed, linear viscoelastic model and Coulomb’s frictional law, verifying empirically that the solution trajectories converge to those obtained by the more traditional rigidbody dynamic model.
Modification of the Leuven integrated friction model structure
 IEEE Transactions on Automatic Control
, 2002
"... Abstract—This note presents a modification of the integrated friction model structure proposed by Swevers et al., called the Leuven model. The Leuven model structure allows accurate modeling both in the presliding and the sliding regimes without the use of a switching function. The model incorporate ..."
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Cited by 28 (4 self)
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Abstract—This note presents a modification of the integrated friction model structure proposed by Swevers et al., called the Leuven model. The Leuven model structure allows accurate modeling both in the presliding and the sliding regimes without the use of a switching function. The model incorporates a hysteresis function with nonlocal memory and arbitrary transition curves. This note presents two modifications of the Leuven model. A first modification overcomes a recently detected shortcoming of the original Leuven model: a discontinuity in the friction force which occurs during certain transitions in presliding. A second modification, using the general Maxwell slip model to implement the hysteresis force, eliminates the problem of stack overflow, which can occur with the implementation of the hysteresis force described in [10]. Index Terms—Friction, mechatronics, motion control, nonlinear systems. I.
Elastoplastic friction model: contact compliance and stiction
 Proceedings of the American Control Conference, Chicago: AACC
, 2000
"... The presliding displacement and stiction properties of friction models are investigated. It is found that existing singlestatevariable friction models possess either stiction or presliding displacement. Next, those models with continuous states are interpreted as examples of Prandlt’s elastoplast ..."
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Cited by 26 (3 self)
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The presliding displacement and stiction properties of friction models are investigated. It is found that existing singlestatevariable friction models possess either stiction or presliding displacement. Next, those models with continuous states are interpreted as examples of Prandlt’s elastoplastic material model. A class of general onestate models is derived that is stable, dissipative and exhibits both stiction and presliding displacement. 1
An experimental study of nonlinear stiffness, hysteresis, and friction effects in robot joints with harmonic drives and torque sensors,” Int
 J. of Robotics Research
, 1997
"... Despite widespread industrial applicatzon of harmonic drives, the source of some elastokinetic phenomena and their impact on overall system behavior has not been fully addressed thus far. Some of these phenomena severely influence the behavior of robot arms, both in free and constrained motions, whe ..."
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Cited by 23 (0 self)
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Despite widespread industrial applicatzon of harmonic drives, the source of some elastokinetic phenomena and their impact on overall system behavior has not been fully addressed thus far. Some of these phenomena severely influence the behavior of robot arms, both in free and constrained motions, when the end effector is in contact with an environment. The primary goal of this study is to derive an effective, controloriented model of a harmonicdrivebased robot joint. Systematic observations of an experimental robot with harmonic drives has revealed that the harmonic drive could not entirely transmit the input torque to the output shaft, due to a nonlinear meshing process between the flexible and circular spline teeth. The torque transmitted to the output shaft might saturate at a much lower value than expected (e.g., motor torque multiplied by the gear ratio). This phenomenon may severely influence the system behavior, particularly in force/impedance control tasks when full jointtorque capacity and wide bandwidth are needed. To understand the harmonicdrive behavior, as well as to derive a convenient form of its model, we have shown restrained motion experiments to be much more useful than freemotion experiments. In this article, we also introduce mathematical models and describe experiments related to other physical phenomena, such as nonlinear stiffness, hysteresis, and soft windup. The goal of our modeling strategy was not to develop a precise and possibly complicated model, but to generate an appropriate model that could be easily used by control engineers to improve joint behavior To visualize the developed model, equivalent mechanical and electrical schemes of the joint are introduced. Finally, a simple and reliable estimation procedure has been established for obtaining joint parameters, to ascertain the integrity of the proposed model. 1.
Control of Nonlinear Systems With Friction
 IEEE Transactions on Control Systems Technology
, 1998
"... In this paper we introduce a new continuous dynamic controller for a class of nonlinear systems which includes mechanical system models with a bristle model for nonlinear friction effects. We obtain sufficient conditions for global stabilization using an estimate for bristle defection and present ex ..."
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Cited by 14 (0 self)
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In this paper we introduce a new continuous dynamic controller for a class of nonlinear systems which includes mechanical system models with a bristle model for nonlinear friction effects. We obtain sufficient conditions for global stabilization using an estimate for bristle defection and present experimental results illustrating the benefits of our dynamic controller in the regulation of a high speed linear positioning table. Keywords: nonlinear systems, friction observers, Lyapunov stability. 1 Introduction Using modelbased friction compensation in low velocity high precision tracking control can effectively reduce steady state error [3] without the need for excessive integral gains. Coulomb friction, viscous and static friction, and the Stribeck effect have been modelled successfully (c.f. [3, 4, 10]). In [1] friction in a lubricated journal bearing is both measured and estimated using a friction observer. System performance substantially improved when the friction estimate was u...