A simulational model of 6 dof Stewart platform type parallel manipulator is presented. The manipulator is driven by electrohydraulic actuators. A novel invariant error dynamics controller is used. The developed control scheme employs the dynamic and hydraulic model of the system. The manipulator model consists of the rigid body equations of motion and the hydraulic dynamics of the main elements...

In the table contact phase of gymnastics vaulting both dynamic and static friction act. The purpose of this study was to develop a method of simulating Coulomb friction that incorporated both dynamic and static phases and to compare the results with those obtained using a pseudo-Coulomb implementation of friction when applied to the table contact phase of gymnastics vaulting. Kinematic data wer...

Friction is an undesired phenomenon in many drive systems. Feedforward of a suitable estimate of friction is an effective method to compensate the friction-dependent position errors in the steady state. The speed of reconstruction of the real friction is crucial for the grade of improvements which can be achieved for the transient behaviour. A nonlinear model-based approach is presented in this...

The stick-slip friction system is known to exhibit very different macro and microscopic behaviors. For large movements, the system exhibits the familiar stick-slip friction characteristics; and for very fine movements, the elastic deformation seems to prevail. While there have been tremendous efforts to understand the stick-slip friction mechanism, most people would agree that the complexity of...

A friction display system is proposed for virtual environments. Since a user’s fingertip is often placed inside a ring or thimble of a haptic interface , the finger pad cannot move relative to the finger structure as freely as it would move in the real world. Thus, it is necessary to imitate the real world movement of the human finger pad in the virtual environment. This paper quantifies the fr...

We review the state of the art in friction estimation and rendering for haptic interfaces and present a method based on a modified Karnopp friction model. We illustrate some of the advantages of this approach and show how it can be used to create accurate and convincing displays of sliding friction, including pre-sliding displacement and stick-slip behavior. We also present the results of human...

We present a new compensation technique for a friction model, which captures problematic friction effects such as Stribeck effects, hysteresis, stick-slip limit cycling, pre-sliding displacement and rising static friction. The proposed control utilizes a PD control structure and an adaptive estimate of the friction force. Specifically, a radial basis function (RBF) is used to compensate the eff...

Wearless friction is investigated in a simple mechanical model called Frenkel-Kontorova-Tomlinson model. We have introduced this model in [Phys. Rev. B, 53, 7539 (1996)] where the static friction has already been considered. Here the model is treated for constant sliding speed. The motion of the internal degrees of freedom is regular for small sliding velocities or weak interaction between the ...

We present a simple model for the friction of two solid bodies moving against each other. In a self consistent way we can obtain the dependence of the macro-scopic friction force as a function of the driving velocity, the normal force and the ruggedness of the surfaces in contact. Our results are discussed in the context of friction laws used in earthquake models.

micro scale gas flows has attracted significant research interest in the last two decades. in this research, the fluid flow of gases in the stepped micro-channel at a wide range of knudsen number has been analyzed with using the lattice boltzmann (mrt) method. in the model, a modified second-order slip boundary condition and a bosanquet-type effective viscosity are used to consider the velocity...