Parallel mechanisms analysis and design are the main trends of advance robotic engineering. This article is devoted to the novel parallel mechanisms with six degrees of freedom. The presented mechanisms can be applied in additive technologies, robotic–assisted surgery. The proposed mechanisms contain six drives and six kinematic chains. They have the properties of a partial kinematic decoupling, which allows realized separately translational and rotational movements. The presented mechanisms is a simple kinematic scheme. The drives can provide a ratio 1:1 of with the movement of the output link. The paper considers the solution of kinematics problems, velocity analysis, singularities. The velocity problem is solved by differentiating the coupling equations. Singularities were detected by studying the properties of Jacobi matrices. The singularities depend only on the orientation of the output link. These mechanisms have a large working area free of singularities. The working area is determined by solving the coupling equations. The solved problems allow to solve the control such mechanisms in the future.
Chain transmissions are widely used in drives of hoisting-and-transport and ag-ricultural machines, as well as in a number of machine tools and technological equipment in various branches of industry. However, a significant disadvantage of these transmissions is the high vibration activity under high dynamic loading. In this regard, the study of dynamic loads that occur during chain vibrations and affect the operability of the machine drive is one of the essential tasks of its dynamics. The article presents experimental studies performed in order to determine the maximum dynamic loads in a chain transmission of a machine drive with transverse vibrations of the chain. The most common case of transverse vibrations of a chain loop is studied as a string with fixed ends. This type of vibration is typical of chain transmissions with large masses of sprockets and parts attached to them. The article presents a description of an original test bench with an automated system for collecting and processing experimental data and a test procedure. The obtained experimental data are presented in the form of tables and graphical dependences of the maximum dynamic loads on the tension force of the chain average per cycle of vibrations and the amplitude of its transverse vibrations in the center of the span, related to its length. As a result of approximation of the experimental data array, an empirical formula is proposed that can be used in dynamic calculations of the drive. It is established that the maximum dynamic load and its amplitude increases with the increase of the ratio of the amplitude of transverse vibrations of the chain in the middle of its span to its length and the initial tension force of the chain. The ratio of the dynamic load amplitude to the tension force of the chain decreases with the increase of the latter.
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