Input Link Research Articles

Kinematic analysis of the method increasing the accuracy of treatment of conic surfaces

A method for processing high-precision conical surfaces under conditions of free grinding on a lever machine is proposed, which allows adjusting the process parameters taking into account the technological heredity of the workpiece from the point of view of the distribution pattern of the allowance to be removed from its surface. The scheme of implementation of the method in which the main links are a tool in the form of a faceplate and a separator for maintaining the required accuracy of its flatness. In order to develop a method of targeted control of the actuation of the working surface of the tool to maintain the required accuracy of its flatness, mathematical modeling of the motion patterns of the links of the actuator of the base machine, on which the proposed device for processing conical parts is installed, was performed. In the process of mathematical simulation structural analysis of the executive mechanism of the lever machine is carried out, connection between the generalized coordinate and provisions of links of the executive mechanism of the lever machine is established, position of the lever and the upper link in the vertical plane is probed, geometrical parameters of reflexive rotational motion of the upper link are considered, the ratio for calculation of length of a crank of the executive mechanism of the machine depending on amplitude of figurative movement of its output link is obtained. An analytical relationship has been established between the input and output links of the machine actuator, which makes it possible to calculate the length of the first of the marked links depending on the required amplitude of the oscillatory motion of the second of them and creates the prerequisites for the development of engineering methods for controlling the process of forming high-precision conical surfaces under conditions of free grinding.

A robomech class parallel manipulator with three degrees of freedom

This paper presents the methods of structural-parametric synthesis and kinematic analysis of a parallel manipulator with three degrees of freedom working in a cylindrical coordinate system. This parallel manipulator belongs to a RoboMech class because it works under the set laws of motions of the end-effector and actuators, which simplifies the control system and improves its dynamics. Parallel manipulators of a RoboMech class work with certain structural schemes and geometrical parameters of their links. The considered parallel manipulator is formed by connecting the output point to a base using one passive and two active closing kinematic chains (CKC). Passive CKC have zero degree of freedom and it does not impose a geometrical constraint on the movement of the output point, so the geometrical parameters of the links of the passive CKC are freely varied. Active CKCs have active kinematic pairs and they impose geometrical constraints on the movement of the output point. The geometrical parameters of the links of the active CKCs are determined on the basis of the approximation problems of the Chebyshev and least-square approximations. For this, the equations of geometrical constraints are derived in the forms of functions of weighted differences, which are presented in the forms of generalized (Chebyshev) polynomials. This leads to linear iterative problems. The direct and inverse problems of the kinematics of the investigated parallel manipulator are solved. In the direct kinematics problem, the coordinates of the output point are determined by the given position of the input links. In the inverse kinematics problem, the positions of the input links are determined by the coordinates of the output point. The direct and inverse problems of the kinematics of the investigated parallel manipulator are reduced to solving problems on the positions of Sylvester dyads. Numerical results of structural-parametric synthesis and kinematic analysis of the considered parallel manipulator are presented. The numerical results of the kinematic analysis show that the maximum deviation of the movement of the output point from the orthogonal trajectories is 1.65 %

The kinematic design of mold clamping mechanism with minimal maximum acceleration

Typically, the motion of the output link of the mode clamping mechanism has reciprocating linear motion, but the motion of the input link can be reciprocating rocking motion or reciprocating linear motion. In addition, the mold clamping mechanism must have a dead-position configuration for the mold at the closed position. This article focuses on the kinematic design of a mold clamping mechanism having an input link with reciprocating linear motion and having dead-position configuration at closed positions. First, four design concepts of mold clamping mechanisms are proposed based on the mechanism creative design methodology. Then, one of the design concepts is chosen as the design example to illustrate the kinematic design of the mode clamping mechanism with minimal maximum acceleration. According to the design requirements, the best design of the mode clamping mechanism of this article is better than the existing patent by reducing 43.5% acceleration and 18.6% driving force.

Power Flow and Efficiency Analysis of a Ravigneaux Hybrid Transmission

In urban mobility, special attention must be paid to the energy requirements in vehicles, air quality and noise pollution. This can be achieved in two ways: the first is the use of low-emission hybrid vehicles, the second is the use of gear transmission system with improved efficiency. Both will reduce fuel consumption and provide more environmental protection. In the current work, a low-emission Ravigneaux hybrid transmission with thirteen operation modes is shown to be feasible. A fuel-efficient strategy is developed to control the fuel consumption of hybrid modes and reduce emissions. An efficiency analysis for all driving modes of the Ravigneaux hybrid transmission is conducted. The concept of potential power is used to determine the power ratios of any three links in the fixed reference frame (FRF) when the input link in the moving reference frame (MRF) is predictable. A single equation is developed that can be manipulated to determine all the powers flowing through the train. A numerical example is provided to give a complete view of the expected efficiency values. The proposed Ravigneaux hybrid transmission is found to be suitable for urban rather than external routes. The results can provide a theoretical bases for design works of hybrid transmissions with complex planetary gears.

KINETOSTATIC ANALYSIS OF DOUBLE-SATELLITE PLANETARY MECHANISM WITH ELLIPTICAL GEARWHEELS

Non-circular gears can be used in modern machines and mechanisms for the implementation of various types of output link movement and have high strength and compactness compared to linkage mechanisms. The article considers the problem of kinetostatic analysis of the planetary mechanism, which provides the rotationally reciprocating motion of the stirred tank impeller. Proposed mechanism is a two-satellite single-row planetary gear with two external gears, in which one pair of gears is elliptical gearwheels. There are constructed calculation schemes, kinetostatic balance equations are compiled and solved for each link of the mechanism. There are found reactions in kinematic pairs and a balancing moment on the input shaft of the mechanism, which are presented as functions of forces on the angle of rotation of the input link. The results can be used in the synthesis, analysis and design of various machines and mechanisms with the proposed kinematic scheme of planetary gear.

Applying an adaptive method of the orthogonal Laguerre filtration of noise interference to increase the signal/noise ratio

A relevant task for control systems is to reduce the impact of noise interference in order to increase the signal/noise ratio (SNR). This issue is relevant to other technical systems as well. This work addresses the orthogonal Laguerre filtration of noise processes, which are described by the linear random processes. The proposed method of filtration makes it possible to reduce the influence of noise interference, which is described by the stationary linear random processes, in the operation of correlation systems. The essence of this method implies the use of orthogonal Laguerre filters as the input links of the correlation system. The sequence of the noise processes, which are uncorrelated over a significant time interval of their mutual shift, has been derived on the basis of orthogonal Laguerre filtration of the stationary white noise. Such processes are described by the stationary linear random processes and are the models of a wide range of noise interference, which are explored in the operation of various technical systems, including control, detection, recognition, measurement systems, etc. The application of this method decreases the effect of noise interference with different correlation-spectral characteristics and increases the SNR at the output from the correlation system. Practical tasks on reducing the action of stationary noise interference have been solved within the framework of the proposed adaptive method of orthogonal Laguerre filtration; to this end, the article shows a structural-logical scheme of the correlation system. Using the software, the algorithm of the adaptive filtration based on the complex Laguerre filters has been implemented. The implementation has been carried out for an actual noise interference that belongs to the RLC class of noise, employing the pre-training of the filter. The effectiveness of reducing the impact of the predefined stationary noise interference has been confirmed by the derived efficiency coefficients the size of –6 dB and –16 dB for the set of the interference zeroing points

Application of System Analysis for Technological Processes Investigation

System analysis is used as the effective way for design and modification of different kinds of technical systems. Application of system analysis to any technological process allows to present the links between input and output parameters which makes it possible to analyze its effectiveness and effect on the process for manufacturing of the object with necessary level of quality. The paper presents results of system analysis application for multioperational technological processes. The main aim of hot rolling process is manufacturing the hot rolled metal sheet with definite geometrical parameters which are necessary for further cold rolling process. The scheme of hot rolling operation with its input and output links is presented. The obtained results can be used for mathematical modeling of hot rolling operation. It is shown the application of system analysis for technological process of coating on the example of vacuum ion-plasma coating process. Because of existence of operated, noncontrolled, and indignant parameters of the coating process application of system analysis is the effective way for structural analysis of this technical system. It is proposed to supplement system analysis with function-oriented analysis. This approach can state the links between properties of the object which are sufficient for its application and technological parameters of the manufacturing technological process.

A novel design of compliant forceps with serpentine flexures

ABSTRACT Recent advancement in medical engineering demands a prefect solution for various problems. In this work, we proposed compliant forceps with the novel serpentine flexure. Compliant mechanisms are flexible mechanisms which are jointless in nature, which transfer force and displacement from input link to output link through an elastic body deformation. The compliant mechanism provides an optimum solution for many micro applications, which is suitable for solving many problems in medical engineering. Forceps require a limited level of parallel movement to hold the required amount of tissues. In traditional forceps, ‘U’ shaped flexure restricts the parallel motion. Hence, this work the proposed Forceps uses serpentine flexure to overcome the parallel motion problems. Here, a parallel Serpentine flexure-based forceps is developed. The mathematical modelling for serpentine flexures is developed. A generic equation is been developed to estimate the stiffness of the serpentine flexure model, stiffness is estimated for two different types of flexure model. The finite element model (FEM) of serpentine flexures is developed using ANSYS and stiffness is validated. Mathematical and FEM results are promising with minimum variations. Finally, forceps are developed using leverage mechanism concepts with the serpentine flexure hinges and FEM is performed. FEM results of forceps are promising.

Split-Capacitor Dual-Active-Bridge Converter

In this article, a split-capacitor (SC) dual-active-bridge (DAB) converter is proposed. In the proposed converter, dc-link capacitors in both the input and output are split, and primary and secondary windings of the transformer are connected to midpoints of the input and output dc links, respectively. Although the switch current stress of the proposed converter is twice that of conventional DAB converter, its switch voltage stress is reduced to half. Therefore, the proposed converter has higher conduction loss than the conventional DAB converter, however, the switching loss can be reduced, which implies that the proposed converter is beneficial and can achieve higher efficiency than the conventional DAB converter as switching frequency increases. In addition, owing to the SC structure, no dc-blocking capacitors are required and the proposed converter can be readily connected to neutral-point-clamped or half-bridge-type converters without increasing the number of dc-link capacitors. To verify the performances of the proposed converter, 3-kW prototypes are built, tested, and compared.

Diffusion Average-Estimate Bias-Compensated LMS Algorithms Over Adaptive Networks Using Noisy Measurements

In this paper, we consider the problem of distributed estimation over adaptive networks in the presence of noisy input, output and communication links. First, a diffusion average-estimate bias-compensated LMS (D-ABC-LMS) algorithm is devised for processing these noisy measurements. Different from the existing diffusion schemes, it consists of three steps: (i) bias-compensated weight update, (ii) average estimation and (iii) weight combination, where the second step utilizes a moving average technique to process imprecise exchange weights caused by communication link noise. Then, we analyze the stability and convergence of the D-ABC-LMS algorithm, and derive closed-form expressions to predict its steady-state mean-square deviation (MSD) and network MSD (NMSD). In addition, by introducing one more step via the adaptive mixture of the noisy exchange weight vectors and their denoised estimates, we propose a diffusion mixed average-estimate bias-compensated LMS (D-MABC-LMS) method for increasing the convergence rate of the D-ABC-LMS scheme. Finally, computer simulation results show the superiority of the proposed algorithms over previously reported techniques using noisy measurements over adaptive networks.

Kinematic and Force Analysis of Irregular Motion Stirrer with Elliptical Gear

Agitated reactors are one of the most popular types of equipment in the chemical, food and oil refining industries. Currently, various authors have proved that a constant speed of the impeller leads to low efficiency of the mixing process, the formation of stagnant zones and a decrease in the quality of the product. The paper proposes to transmit irregular motion to the impeller by transmission with elliptical gears. To conduct further dynamic analysis of the transmission, evaluate the efficiency and design of the actuator of the stirred tank, a kinematic and force analysis is carried out in this paper. Analogues of the velocity and acceleration of the output link, as well as reactions in the kinematic pairs of the mechanism for all positions of input link are found.

Synthesis of a Spatial RRSS Mechanism for Path Generation Using the Numerical Atlas Method

Abstract An open path synthesis method for a spatial revolute-revolute-spherical-spherical (RRSS) mechanism is presented in this paper. The mathematical model for the trajectory curve is established. The characteristics of an RRSS mechanism in a standard installation position are revealed: the projection points of the coupler curve on the Oxy plane rotate by the corresponding input angles around the z-axis, and the generated points lie on an ellipse. Based on this finding, a 17-dimensional path generation problem can be translated into two lower-dimensional matching recognition problems and one actual size and installation position calculation problem. The path generation can be achieved by three steps. First, a database of four dimensional rotation angle parameters is established. By comparing the similarities between the mechanism feature curve of the prescribed open curve and its corresponding mechanism feature ellipse (MFE), the angles of installation, the initial angle of the input link, and the elliptic feature parameters of the desired RRSS mechanism can be approximately determined. Then, a 13-dimensional dynamic self-adapting numerical atlas database is established, which contains six basic dimensional types (BDTs) and seven wavelet feature parameters, and the BDTs of the desired RRSS mechanism are obtained. Finally, based on the relationship between the MFE of the prescribed curve and the BDTs of the desired RRSS mechanism, the calculation models for the actual link lengths and installation positions of the desired RRSS mechanism were established. Three examples are presented in this paper.

Structural Analysis of Linkage Mechanisms of Hydraulic Manipulators

The structural schemes of hydraulic manipulators used in the roundwood handling operations are presented. The seventeen schemes of manipulators are considered. The characteristic technological processes are identified, the nominal motions of the attachment mounted on the manipulator are described and the structure of the manipulator used in each process is considered. The variety of structures of linkage mechanisms in manipulators is associated both with the accumulation of Assur groups and with the increase in the Assur group class. Mechanisms with the number of Assur groups up to 4 are used. Assur groups of 2nd and 3rd classes are mainly found in the mechanisms. Adding the degree of freedom to the manipulator is accompanied by emerging of an additional kinematic chain in the structure. The structures studied are divided into two groups: the first covers the structures in which the input links are attached to the column; the second consists of structures with internal inputs. Variants of additional classification features are proposed for structures with internal inputs. The known provisions of structural analysis as a whole allow the analysis to be performed if the internal input is separated out as an individual input link. Otherwise, it is necessary to correct the approaches to the structural analysis of mechanisms having internal input links.

Design and development of a 5R 2DOF parallel robot arm for handling paper pot seedlings in a vegetable transplanter

This paper presents a complete mechatronic approach in designing and developing a robotic arm for handling paper pot seedlings in a transplanter for the purpose of inclusion of automation and possible reduction of heavy mechanical components in pot seedling transplanters by utilizing microcontrollers and embedded systems. The robot arm developed was of two degrees of freedom (DOF), five revolute joints (5R) with parallel arm structure using 3D printed parts, commercially available embedded microcontrollers and sensors. The gripper which was connected to the parallel robot arm performed pick and place operations at a desired path. For achieving the preferred maximum and minimum reach of the gripper, a suitable method for synthesizing the link length has been discussed. A complete logical technique to program microcontrollers was developed which enabled smooth actuation of both the independent input links simultaneously. Parabolic blends were utilized at the beginning and at the end of the robot input joint trajectory for minimizing dynamic vibrations during continuous operation. The developed robot arm was flexible to change the number of pickup points in a row, pickup and drop co-ordinates within the workspace envelope. Finally, the robot arm was tested and evaluated for picking and placing 15 numbers (4 replications, 60 runs) of actual paper pots filled with vermicompost, soil and sand. Each pot weighed approximately 80 g with a moisture content of approximately 5%. The robot arm took 2.1 to 2.4 s to pick and drop a pot seedling from a distance of 116.6 mm with a maximum power consumption of 20.47 W. Experimental results showed that no pots were missed in picking and dropping, no visual cracks and damage appeared on the pots. The repeatability of the robot arm was 2.1 mm in X-axis and 3.4 mm in Y-axis.

Minimal structural perturbations for controllability of a networked system: Complexities and approximations

SummaryLink additions/deletions and actuator/sensor failures are common structural perturbations for real networked systems. In this paper, we consider three related problems on determining the minimal cost structural perturbations, including link additions, link deletions, and input deletions to make a networked system structurally controllable/uncontrollable, mainly focusing on their computational complexities and approximations. Formally, given a structured system, it is proven that (i) it is NP‐hard to add the minimal cost of links, including links among state variables (ie, state links) and links from the existing inputs to state variables (ie, input links), from a given set of links to make the system structurally controllable; (ii) it is NP‐hard to determine the minimal cost of links whose deletions deteriorate structural controllability of the system, even when the removable links are restricted in either the input links or the state links. It is also proven that determining the minimal cost of inputs whose deletions cause structural uncontrollability is strongly NP‐hard even with dedicated input structure. Furthermore, some fundamental approximation results for these problems are established. These results may serve an answer to the general hardness and approximability of optimally designing (modifying) a structurally controllable network topology and of measuring controllability robustness against link/input failures. Additionally, several polynomial‐time tractable cases of the aforementioned problems are also identified.

Slider position control for slider-crank mechanisms with Jacobian compensator

In this work, a position control for slider-crank mechanisms without Jacobian and joint measurements is presented. A Jacobian compensator that depends on the sign of the direction of rotation of the input link and the output link is proposed. A linear sensor is mounted at the slider to measure its position. Simulations and experiments are presented using two different Whitworth mechanisms to validate and compared the proposed approach with Jacobian-based controllers.

Network Capacity Maximization Using Route Choice and Signal Control With Multiple OD Pairs

In this paper, we investigate a hybrid dynamical system which incorporates flow swap process, green-time proportion swap process, and flow divergence for a general network with multiple Origin-Destination (OD) pairs and multiple routes, where flow swap process is specified in which traffic swaps from more costly to less costly input links, green-time proportion swap process is specified in which green time at each intersection swaps from less pressurized stages to more pressurized stages, flow may diverge at each intersection from one OD pair to other OD pairs. Unlike the dynamical system model, where bottleneck delays need to be intentionally constructed to yield the equilibrium flow vector and green-time proportion vector, we propose a novel control policy to fill the gap by only adjusting the green-time proportion vector. We derive a sufficient condition for the existence of equilibrium of the dynamical system under the mild constraints that 1) the travel cost function and stage pressure function should be continuous functions and 2) the flow and green-time proportion swap processes project all flow and green-time proportion vectors on the boundary of the feasible region onto itself. We derive the condition of unique equilibrium for fixed green-time proportion vector and show that with varying green-time proportion vector, the set of equilibria is a compact, non-convex set, and with the same partial derivative of travel cost function with respect to the flow and green-time proportion vectors. Finally, we prove the stability of the proposed dynamical system by using Lyapunov stability analysis.

Oscillations and control of spherical parallel manipulator

In recent years, there has been a growing number of studies in spherical parallel mechanisms, particularly synthesis, kinematics, and work area singularities. The interaction of degrees of freedom and geometry leads to the nonlinear phenomena, in the dynamics of mechanism. There are few studies into the dynamic properties of such mechanisms. This article deals with the dynamic property of the parallel spherical manipulators, with three degrees of freedom, and presents determination of acceleration input links, oscillations, and the problem of control. Algorithm of control is based on the concept of minimized coordinates, velocities, and acceleration using inverse dynamic problems. This allows synthesis of this algorithm, which can realize a motion in accordance with prescribed trajectories. Finally, the results of calculations are defined.

Improving the Accuracy Rate of Link Quality Estimation Using Fuzzy Logic in Mobile Wireless Sensor Network

Link quality estimation is essential for improving the performance of a routing protocol in a wireless sensor network. Many methods have been proposed to increase the performance of the link quality estimation; however, most of them are not able to evaluate link quality accurately. In this study, a method that uses fuzzy logic to combine both hardware-based and software-based metrics is proposed to improve the accuracy rate for evaluating a link quality. This proposed method consists of three types of modules, the Fuzzifier module, the Inference module, and the Defuzzifier module. The Fuzzifier module is used to determine the degree to which input link quality metrics belong to each fuzzy set through proposed membership functions. The Inference module obtains the rule outputs based on the proposed fuzzy rules and the given inputs acquired from the Fuzzifier module. The Defuzzifier module is used to aggregate the rule outputs inferred from the Inference module. The result from the Defuzzifier module is then used to evaluate the link quality. A simulation conducted to compare the accuracy rates of the proposed method and those found in related works showed that the proposed method had higher accuracy rates for evaluating a link quality.

KULEX-Hand: An Underactuated Wearable Hand for Grasping Power Assistance

In this paper, we present KULEX-hand, a novel underactuated hand exoskeleton for grasping power assistance for patients having a partially paralyzed hand or the elderly with weakened muscle strength. This mechanism consists of an underactuated finger for grasp motion generation, a spherical four-bar linkage for power transmission, and a passive thumb link with a flexure hinge structure. Based on the natural closing motion of the human index finger, the motion generation linkage was synthesized as a planar five-bar in which two input links were coupled with a four-bar linkage. Therefore, after contact occurs on the proximal link, the synthesized linkage can mimic the grasping motion of the human middle and distal phalanges. The kinetoelastic relation of the underactuated finger was derived using the theory of screws. Based on this relation, guidelines were proposed for selecting the springs for achieving a stable pinch grasp. A prototype was designed, and the naturalness of motion was evaluated from an experiment with five subjects.