Joint Coupling Research Articles

A Portable Dextrous Master with Force Feedback

Dextrous masters control robots and artificial environments through hand gestures. Commercial products have open-loop control, without force feedback to the operator. There is a need for portable systems that have force feedback, but are still sufficiently compact to be desktop. In this paper we discuss a prototype master providing force feedback for the Dataglove. The master structure and its actuator characteristics are presented first. Then a control model is given based on finger parameters and joint coupling. The glove calibration is subsequently discussed, taking into account the influence of the feedback structure. The experimental setup and initial results are presented last.

The role of the reciprocal apparatus in the hind limb of the horse investigated by a modified CODA-3 opto-electronic kinematic analysis system.

The function of the reciprocal apparatus in the hind limb of the horse was studied by kinematic gait analysis. For recording purposes a modified opto-electronic CODA-3 kinematic analysis system was used. The raw kinematic data were corrected for skin displacement artifacts by use of recently developed correction models. It was concluded that contradictory findings about the coupling of tarsal and stifle joints by the reciprocal apparatus, when comparing in vitro and in vivo studies, can be fully attributed to artifacts due to the movement of the skin markers over the underlying bony structures, occurring in the in vivo experiments.

Dynamic Analysis of Large Space Structures Using Transfer Matrices and Joint Coupling Matrices

Abstract Linear dynamic analysis of lattice structures using transfer matrices and joint coupling matrices is presented. A lattice structure is defined as a network of one-dimensional members that are connected by joints. Two examples are considered to illustrate how transfer matrices and joint coupling matrices may be used to compute natural frequencies of vibration. These two examples indicate that the transfer matrix and joint coupling matrix analysis is numerically accurate over a wide range of frequencies and becomes increasingly efficient, compared to the finite element method, as the frequency increases. Some suggestions for further improvements in computational efficiency and some comments about applicability to numerical analysis of wave propagation problems are given.

Strength, deformation and conductivity coupling of rock joints : Barton, N; Bandis, S; Bakhtar, K Norw Geotech Inst PublN162, 1986, 20P

Strength, deformation and conductivity coupling of rock joints : Barton, N; Bandis, S; Bakhtar, K Norw Geotech Inst PublN162, 1986, 20P

Strength, deformation and conductivity coupling of rock joints : Barton, N; Bandis, S; Bakhtar, K Int J Rock Mech Min SciV22, N3, June 1985, P121–140

La construction de barrages, tunnels et talus dans des roches porteuses d'eau et fissurees cause des interactions complexes entre la deformation des fissures et la contrainte effective. La deformation de la fissure peut prendre la forme de fermeture normale, d'ouverture, de cisaillement et de dilatation. Resultats de nombreuses annees de recherche sur les proprietes des diaclases synthetisees dans un modele de comportement de diaclases couplees. Description des methodes de caracterisation des diaclases pour obtenir les donnees d'entree necessaires

Strength, deformation and conductivity coupling of rock joints

Construction of dams, tunnels and slopes in jointed, water-bearing rock causes complex interactions between joint deformation and effective stress. Joint deformation can take the form of normal closure, opening, shear and dilation. The resulting changes of aperture can cause as much as three orders of magnitude change in conductivity at moderate compressive stress levels. Even the heavily stressed joints found in oil and gas reservoirs may also exhibit significant stress-dependent conductivity during depletion, and during waterflood treatments. The magnitudes of the above processes are often strongly dependent on both the character and frequency of jointing. In this paper the results of many years of research on joint properties are synthesized in a coupled joint behaviour model. Methods of joint characterization are described for obtaining the necessary input data. The model simulates stress- and size-dependent coupling of shear stress, diplacement, dilation and conductivity, and of normal stress, closure and conductivity. These processes are the fundamental building blocks of rock mass behaviour. Model simulations are compared with experimental behaviour and numerous examples are given.

Reduction of modal noise by using reduced spot excitation

The paper describes a computational model to estimate the reduction of nonlinear distortions due to a fiber-fiber joint by properly focusing the optical beam from a single transverse-mode semiconductor laser source to the input end of the first fiber. Mode mixing effects are included in the model. Material dispersion is found to make a negligible contribution in comparison with a typical source coherence time. In a typical situation, where the fiber joint coupling efficiency eta is better than 0.7, all harmonic distortion components produced in the joint could be reduced by ~10 dB by halving the input beam spot radius from the value equal to the fiber core radius.

Internal biliary drainage stent extension through slip joint coupling

Percutaneous placement of a permanent internal biliary drainage stent across a malignant obstruction of the bile ducts is a recently introduced palliative procedure [1 ]. Proximal extension of the malignant process or ascending cholangitis may necessitate proximal stent extension to reestablish free internal biliary drainage. Unless the original and extension stent are firmly linked together, separation is likely. An extension stent and a method to link it percutaneously to an existing stent is described.

Displacement Analysis of Spatial 7R Mechanisms Suitable for Constant-Velocity Transmission Between Parallel Shafts

Three types of spatial 7R mechanisms are identified as being suitable for transmitting motion with a constant velocity ratio between two parallel shafts. A displacement analysis of each type is made using a vector loop method in conjunction with the Unified Theory method. Numerical results are presented for an example of each type. It is also shown how the double Hooke joint coupling for parallel shafts is a special case of one of these three types.