Sound insulation design of the thin partitions on the base of concentrated parameters model

Introduction. The theoretical and practical approach on the base of the discrete parameter's method to the acoustic insulation of the thin partitions by Candidate of Science, Prof. Zakharov A.V. is given in this issue. The method allowed to develop a logically conclusive and consistent physical airborne sound insulation model for one-layered massive and light partitions either. This issue concentrates on providing of the engineer calculation technique of the sound insula-tion for the thin partitions and, also, on comparison of the technique's results with the computations by the current normative documents. Materials and methods. The application of the same “Mass Action Law's” formula both for the normal and the oblique noise wave's incidence on the sound isolating plate, regardless the sound waves angles, is mathematically and physically approved. The essence of the concentrated parameters, such as concentrated and reduced material's mass, is revealed. The equations of momentum conservation law and kinetic energy conservation are used to obtain the coefficient of the oscillation velocity transmission. The formulas for airborne sound insulation at the diapasons before and after the sound wave's coincidence frequency are written. Results. The damping air property's influence on the thin partition's sound insulation is considered, and it's formulas are represented. The formulas for taking into account the reduction of sound insulation at the resonances in sound protective slab or in a partition are also given. The general equation for the thin partition's sound insulation by the method of localized (discrete) parameters are derived. The example of detailed calculation of the sound isolation of the thin asbestos-cement partition is demonstrated. The comparison between the medial three octave deviations of the sound isolation values and the experimental results in case of the SP (Russian normative document) method and in case of the introduced author's method for the different construction materials is represented. Conclusions. The proposedsound insulation calculation method for the thin light partitions, which is based on the concentrated parameters model, gives very close to experiments results. So, it enables to find the insulation figures across the entire standard frequency range, according to the initial physical and technical materials' and constructions' features.

Orientation Singularity Analysis of Parallel Manipulators

<p>In this paper, an approach for orientation singularity analysis of parallel manipulators (PMs) is proposed by introducing several performance indices referred to the<br />unique form of screw based Jacobian in the velocity transmission as well as force transmission. Here, to prove the effectiveness of the approach, an example of 3 degrees of freedom (DOF) prismatic-revolute-spherical (PRS) parallel manipulator (PM) is first presented to illustrate the fact that the distributions of singularity boundary of the proposed approach is consistence with the result referred to nonredunant PMs by Liu et al. [22]. Further, the proposed approach is an appropriate one not only for nonredunant PMs, but also for a class of redunant PMs by providing another example of the redunant variable geometry truss (VGT) PM, since the performance index of orientation singularity for the manipulator can be<br />created only by determining the unique form of screw based Jacobian.</p>

Performance Analysis of 3-URU Spherical Parallel Mechanism Designed Based on Velocity Transmission and Force Constraint Indices

In this paper was observed performances of developed three degrees of freedom (dof) parallel mechanism named 3-URU spherical parallel mechanism. The mechanism is composed of three identical limbs mounted symmetrically to base (fixed link) and platform (output link). The limb is constructed by universal-revolute and universal joints. The kinematic constants of mechanism consisting of link lengths, radius of platform, radius of base, mounting angle of limb and platform to base and platform were determined with consideration of velocity transmission and force constraint indices. To evaluate performance of mechanism, it was manufactured a prototype of mechanism designed base on these two mentioned indices. There are three steps proposed to realize the mechanism, (i) kinematic synthesis to determine of kinematic constants, (ii) design of mechanical components to define shape and dimension of links and joints by considering collision in wokingspace and static analysis, (iii) evaluation of mechanism performances consisting of workingspace, controllability of platform motion and static payload. Based on obtained results, it can be clarified that, the mechanism can produce spherical motion of platform which rotates on steady point recognized as center of platform rotation. The platform can achieve maximum inclination angle, 80 degree and at this posture occurs translational error, 0.0102 mm. On the other hand, the mechanism can support payload ten times of weight of moving parts.

Design of Constant-Velocity Transmission Devices Using Parallel Kinematics Principle

This paper presents a new type of constant-velocity transmission devices based on parallel mechanisms with properties of equal-diameter spherical pure rolling. The method we used is essentially an extension of the planar ellipse gear to the spherical one. Both the fixed and moving axodes of a specified parallel mechanism are obtained, as traced by the spatial instant screw axis (ISA) with respect to the fixed and moving coordinate systems. Based on Poinsot’s theorem and achievements, a series of these parallel mechanisms which satisfy constant-velocity condition have been disclosed correspondingly. Their motion range and transmission performances are also explored by taking the 3-4R mechanism as an instance. As the main part of this paper, two important applications for this type of constant-velocity transmission devices are also explored. One is used as a gearless spherical gear, and the other is used as a constant-velocity universal joint (CVJ). Simulations were fulfilled on ADAMS to verify the transmission performance in terms of different applications.

Workspace Analysis and Performance Evaluation of a 6/6 Cable-Suspended Parallel Robot

This paper mainly addressed the workspace analysis and performance evaluation of a special class of the 6/6 cable-suspended parallel robot. Based on the screw theory and the static equilibrium, the Jacobian matrix of the cable -suspended parallel robot is constructed. The workspace volume is characterized as the set of points where the centroid of the moving platform can reach with tensions in all suspension cables for a constant orientation. This paper attempts to tackle some aspects of optimal design of this special class of the 6/6 cable-suspended parallel robot by addressing the variations of the workspace volume and the accuracy of the robot using different geometric configurations, different ratios and orientations of the moving platform. The global condition index is used as a performance index of a robot with respect to the force and velocity transmission over the whole workspace.

Development of Particle Velocity Transfer Path Analysis

The transfer path analysis (TPA) in terms of sound pressure has been implemented for decades in many application areas, such as car, train and construction machine. In this article, we propose a transfer path analysis where particle velocity is employed as the measure of TPA. Sound pressure is a scalar quantity, while particle velocity, which is the other fundamental quantity of sound, is a vector quantity. The phase differences among particle velocity vector components have to be generally considered. For TPA, not only the six degrees-of-freedom of each path motion, but also the three degrees-of-freedom of the particle velocity at the receiver location have to be considered together for an effective path rank ordering. We first propose the formulation of the particle velocity transfer path analysis where the same formulation of the standard sound pressure transfer path analysis is assumed to hold true for each direction of particle velocity. In order to verify the proposed particle velocity transfer path analysis, we carry out an experiment using a simple test box structure. As a result we have found that the error in the particle velocity vector synthesis is acceptably small, and is as small as the error in the standard sound pressure synthesis, which indicates that the same synthesis method can be employed. We then perform rank ordering of the particle velocity transmission paths. Here, a simple method of path rank ordering is applied. Lastly, we briefly discuss sound energy as a measure of TPA.

Singularity, isotropy, and velocity transmission evaluation of a three translational degrees-of-freedom parallel robot

SUMMARYPerformance evaluation of a parallel robot is a multicriteria problem. By taking Delta robot as an object of study, this paper presents the kinematic performance evaluation of a three translational degrees-of-freedom parallel robot from the viewpoint of singularity, isotropy, and velocity transmission. It is shown that the determinant of a Jacobian matrix cannot measure the distance from the singular configuration due to the existing inverse kinematic singularity of a Delta robot. The determinants of inverse and direct kinematic Jacobian matrices are adopted for the measurement of distance from the singular configuration based on the theory of numerical linear dependence. The denominator of the Jacobian matrix will be lost in the computation of the condition number when the end-effector is on the centerline of the workspace, so the Delta robot may also be nearly at a singular configuration when the condition number of the Jacobian matrix is equal to 1. The velocity transmission index whose physical meaning is the maximum input angular velocity when the end-effector translates in the unit velocity is presented. The evaluation of singularity, isotropy, and velocity transmission of a Delta robot is investigated by simulation. The velocity transmission index can also be used for the velocity transmission evaluation of a parallel robot with pure rotational degrees-of-freedom based on the principle of similarity. The physical meaning is modified to be the maximum input velocity when the end-effector rotates in the unit angular velocity.

Design of a Simple and Modular 2-DOF Ankle Physiotherapy Device Relying on a Hybrid Serial-Parallel Robotic Architecture

The aim of this work is to propose a new 2-DOF robotic platform with hybrid parallel-serial structure and to undertake its parametric design so that it can follow the whole range of ankle related foot movements. This robot can serve as a human ankle rehabilitation device. The existing ankle rehabilitation devices present typically one or more of the following shortcomings: redundancy, large size, or high cost, hence the need for a device that could offer simplicity, modularity, and low cost of construction and maintenance. In addition, our targeted device must be safe during operation, disallow undesirable movements of the foot, while adaptable to any human foot. Our detailed study of foot kinematics has led us to a new hybrid architecture, which strikes a balance among all aforementioned goals. It consists of a passive serial kinematics chain with two adjustable screws so that the axes of the chain match the two main ankle-axes of typical feet. An active parallel chain, which consists of two prismatic actuators, provides the movement of the platform. Thus, the platform can follow the foot movements, thanks to the passive chain, and also possesses the advantages of parallel robots, including rigidity, high stiffness and force capabilities. The lack of redundancy yields a simpler device with lower size and cost. The paper describes the kinematics modelling of the platform and analyses the force and velocity transmission. The parametric design of the platform is carried out; our simulations confirm the platform's suitability for ankle rehabilitation.