Development and Analysis of a Parallel Structure Mechanism with Slotted Arcuate Guides and a Constant Entry Point

The development and study of new mechanisms of a parallel structure ensuring the constancy of the point of instrument entry into the working area is an urgent task of surgery and scientific medicine. A structural synthesis of a parallel structure mechanism designed for robotic laparoscopic surgery has been performed. The proposed mechanism is equipped with arcuate guides with slots installed on the base perpendicular to each other. At the intersection of the slots, there is a bushing through which a straight shaft connected to the output link moves linearly. This arrangement provides a constant entry point, which allows the developed mechanism to be used in laparoscopic surgery and studies of plasma properties. For this mechanism, the inverse problem of positions has been solved, the working area has been determined, and a 3D model has been developed.

Nonlinear repetitive control of the metal cutting machine feed module with saturated input

The article discusses the methodology for constructing an automatic control system for the feed module of the cutting tool for lathes in the presence of input saturation. The presence of the saturation function is due to restrict unwanted movements of the feed module actuator. The generator for periodic signals, the hyperstability criterion, L-dissipativity conditions and an implicit reference model are used as the solution methods for structural synthesis of the control system. At the stage of simulation, the functioning quality of the developed control system is illustrated.

STRUCTURAL AND PARAMETRIC OPTIMIZATION OF GAS-HYDRODYNAMIC MEASURING TRANSDUCERS OF PHYSICAL AND MECHANICAL PARAMETERS OF FLUIDS

The article is devoted to improving the methods for building throttle diagrams of gas-hydrodynamic measuring transducers of physical and mechanical parameters of fluids. The authors reviewed modern throttle transducers of various parameters, built on different diagrams, with different numbers and types of throttle elements, with different output signals. We established that the goodness of the measuring transducer is determined both by the structural diagram and the design characteristics of the throttle elements of a specific measuring diagram. The article proposes using structural synthesis with parametric optimization to achieve the specified characteristics of the gas-hydrodynamic transducers. The aim is to develop an effective method for building throttle diagrams of gas-hydrodynamic measuring transducers of physical and mechanical parameters of fluids using structural optimization of diagrams and to evaluate each dia-gram using parametric optimization methods with the appropriate criterion that quantifies the goodness of the measur-ing transducer. To achieve this goal, the authors analyzed the criteria and resources of structural and parametric optimization of gas-hydrodynamic transducers. In particular, the following resources of structural synthesis of measuring transducers’ dia-grams are analyzed: diagram order and throttle arrangement, type of throttles, output signals, supply mode of the transducer. Approaches to parametric optimization of throttle diagrams are offered: based on the mathematical model, one defines the objective function, forms restrictions on variable and fixed values, substantiates optimization parameters, chooses the optimization method. As a result of the research, the authors developed a technique for structural and parametric optimization of gas-hydrodynamic measuring transducers, making it possible to synthesize throttle diagrams and build mathematical models of transducers of specific parameters of the fluid with optimal characteristics.

Structural synthesis of plane kinematic chain inversions without detecting isomorphism

A plane kinematic chain inversion refers to a plane kinematic chain with one link fixed (assigned as the ground link). In the creative design of mechanisms, it is important to select proper ground links. The structural synthesis of plane kinematic chain inversions is helpful for improving the efficiency of mechanism design. However, the existing structural synthesis methods involve isomorphism detection, which is cumbersome. This paper proposes a simple and efficient structural synthesis method for plane kinematic chain inversions without detecting isomorphism. The fifth power of the adjacency matrix is applied to recognize similar vertices, and non-isomorphic kinematic chain inversions are directly derived according to non-similar vertices. This method is used to automatically synthesize 6-link 1-degree-of-freedom (DOF), 8-link 1-DOF, 8-link 3-DOF, 9-link 2-DOF, 9-link 4-DOF, 10-link 1-DOF, 10-link 3-DOF and 10-link 5-DOF plane kinematic chain inversions. All the synthesis results are consistent with those reported in literature. Our method is also suitable for other kinds of kinematic chains.

Structural Synthesis and Analysis of Mechanisms with an Output Link Performing Two Rotational and One Translational Movements

The article considers mechanisms based on a hinged flat parallelogram with an additional link, ensuring the ability to maintain the insertion point of the tool installed on the output link. A rotational kinematic pair coupled to the base allows the plane of rotation of the articulated parallelogram to change the angle of inclination. The proposed design should have a greater load capacity than the available analogues, since the rotational kinematic pair mating the articulated parallelogram with the base is made in the form of two semi-axes, and the output link is located between the intermediate links of this parallelogram. The equality of the rotation angles of the output link and the intermediate links of the articulated parallelogram is ensured by the presence of additional links or belt drives. Three-dimensional models of these mechanisms are presented, and their structural synthesis is carried out in various modifications. Depending on the modification, it becomes possible to apply such mechanisms not only in industry, including additive technologies, but also in the field of medicine during surgical operations and in the study of plasma properties.

Design and Analysis of Parallel Mechanism with Linear Drives Located on the Base at Specified Angles

The article considers a novel parallel mechanism with drives located on the base at different angles to its plane. This arrangement allows performing a relative movement between objects under water or in space (in aggressive environments). The new mechanism topology is compact for transportation and efficient for operation in aggressive environments. Structural synthesis has been performed; the number of degrees of freedom of the output link was calculated. A general approach to solving the inverse kinematics problem of positions is proposed and an example for a kinematic chain is shown. Denavit — Hartenberg matrices are used to solve the problem of positions. The position of the output link described by this matrix is used to represent the points of this link in the base coordinate system. The constraint equations are applied, which are the distances between the points of the base and the output link.

Synthesis of devices for efficient energy conversion

The synthesis of devices for efficient energy conversion is shown. It is shown that simple aggregation as the most obvious way to obtain three-phase converters based on single-phase circuit solutions can lead to disadvantages during their operation. The article demonstrates some techniques of the method of structural synthesis, which made it possible to improve the circuit design of a three-phase rectifier with zone-phase regulation and improve the shape of the rectified current curve.