Input Link Research Articles

Adaptive Hydraulic Drive of Manipulator

At present in manipulators the hydraulic drives with one degree of freedom are used. Such drive provides single-valued function of constraint between input and output links motion. However for overcoming of variable force of resistance it is necessary to use the variable transfer ratio between input and output links. The adjustable drive should contain the controlled gear box. Such drive contradicts the demand of minimization of weight and sizes of modules of the manipulator. Use of electronic control systems for force regulating leads to extreme complication of drives, decrease in their reliability, raise of cost of manufacturing and maintenance.Recently the adaptive self-controlled mechanical systems were appeared. By analogy to the adaptive mechanism the hydraulic adaptive mechanism which provides force self-regulation without a control system has been developed and the patent for invention was received.In paper the description and research of the adaptive hydraulic mechanism and creation of the manipulator module with the simplest compact hydraulic drive are adduced.

Controlling the Movement of a TRR Spatial Chain With Coupled Six-Bar Function Generators for Biomimetic Motion

This paper describes a synthesis technique that constrains a spatial serial chain into a single degree-of-freedom mechanism using planar six-bar function generators. The synthesis process begins by specifying the target motion of a serial chain that is parameterized by time. The goal is to create a mechanism with a constant velocity rotary input that will achieve that motion. To do this, we solve the inverse kinematics equations to find functions of each serial joint angle with respect to time. Since a constant velocity input is desired, time is proportional to the angle of the input link, and each serial joint angle can be expressed as functions of the input angle. This poses a separate function generator problem to control each joint of the serial chain. Function generators are linkages that coordinate their input and output angles. Each function is synthesized using a technique that finds 11 position Stephenson II linkages, which are then packaged onto the serial chain. Using pulleys and the scaling capabilities of function generating linkages, the final device can be packaged compactly. We describe this synthesis procedure through the design of a biomimetic device for reproducing a flapping wing motion.

Singularity Traces of Single Degree-of-Freedom Planar Linkages That Include Prismatic and Revolute Joints

This paper extends the general method to construct a singularity trace for single degree-of-freedom (DOF), closed-loop linkages to include prismatic along with revolute joints. The singularity trace has been introduced in the literature as a plot that reveals the gross motion characteristics of a linkage relative to a designated input joint and a design parameter. The motion characteristics identified on the plot include a number of possible geometric inversions (GIs), circuits, and singularities at any given value for the input link and the design parameter. An inverted slider–crank and an Assur IV/3 linkage are utilized to illustrate the adaptation of the general method to include prismatic joints.

Strict-sense nonblocking networks with k degrees of freedom

In this paper we extended the well known conditions for strict-sense nonblocking operation of the three-stage Clos switching network to the case in which k multiplexing levels (called later in this paper as k degrees of freedom) are used on input, output, and interstage links. Up till now only the cases with one multiplexing level were considered in the literature—time-division or wavelength-division. Current research shows that transmission systems with many multiplexing levels will be used in the future to increase available transmission speed in telecommunication networks. There will be also a need for switching connecting paths going through such multiplexed links in large capacity optical cross-connect systems, routers, or data center networks. In this paper we proved the strict-sense nonblocking conditions for the three-stage Clos network with k degrees of freedom. We also analyzed the cost of switching fabrics of selected capacities and with three degrees of freedom in terms of the required number of elements.

A new ATLAS muon CSC readout system with system on chip technology on ATCA platform

The ATLAS muon Cathode Strip Chamber (CSC) backend readout system has been upgraded during the LHC 2013-2015 shutdown to be able to handle the higher Level-1 trigger rate of 100 kHz and the higher occupancy at Run-2 luminosity. The readout design is based on the Reconfigurable Cluster Element (RCE) concept for high bandwidth generic DAQ implemented on the Advanced Telecommunication Computing Architecture (ATCA) platform. The RCE design is based on the new System on Chip XILINX ZYNQ series with a processor-centric architecture with ARM processor embedded in FPGA fabric and high speed I/O resources. Together with auxiliary memories, all these components form a versatile DAQ building block that can host applications tapping into both software and firmware resources. The Cluster on Board (COB) ATCA carrier hosts RCE mezzanines and an embedded Fulcrum network switch to form an online DAQ processing cluster. More compact firmware solutions on the ZYNQ for high speed input and output fiberoptic links and TTC allowed the full system of 320 input links from the 32 chambers to be processed by 6 COBs in one ATCA shelf. The full system was installed in September 2014. We will present the RCE/COB design concept, the firmware and software processing architecture, and the experience from the intense commissioning for LHC Run 2.

Resistance distance method for determination of isomorphism, stiffness and best input link among planar Kinematic chains

The detection of isomorphism among kinematic chains and their derived mechanisms has been a hot area of research for the last several years. In this paper, a quantitative method (Resistance distance method) is proposed in order to compare all the distinct chains with specified number of links and degree of freedom, for rigidity of the chain and to select the best input link to introduce motion and to test isomorphism thoroughly and uniquely. In this method, the kinematic chains are represented in the form of resistance graph and from that graph a Laplacian matrix is generated which is further transformed into a resistance distance matrix.

Experimental demonstration of digital predistortion for orthogonal frequency‐division multiplexing‐radio over fibre links near laser resonance

Radio over fibre (RoF), an enabling technology for distribution of wireless broadband service signals through analogue optical links, suffers from non-linear distortion. Digital predistortion has been demonstrated as an effective approach to overcome the RoF non-linearity. However, questions remain as to how the approach performs close to laser resonance, a region of significant dynamic non-linearity, and how resilient the approach is to changes in input signal and link operating conditions. In this work, the performance of a digital predistortion approach is studied for directly modulated orthogonal frequency-division multiplexing RoF links operating from 2.47 to 3.7 GHz. It extends previous works to higher frequencies, and to higher quadrature amplitude modulation (QAM) levels. In addition, the resilience of the predistortion approach to changes in modulation level of QAM schemes, and average power levels are investigated, and a novel predistortion training approach is proposed and demonstrated. Both memoryless and memory polynomial predistorter models, and a simple off-line least-squares-based identification method, are used, with excellent performance improvements demonstrated up to 3.0 GHz.

Bi-Mobile Leg Mechanism Dynamic Model

The paper brings into attention the dynamic analysis of a bi-mobile mechanism selected from the literature and used for the leg of a mobile platform. Two solutions of bi-mobile mechanical systems applied in such purpose are found. In the classic theory of mechanisms the dynamic models for the mono-mobile mechanisms are known. Through the motion equation these put into evidence the variation of the reduced moment or reduced force applied to the input link for an entire cycle in the permanent regime functioning of the mechanism. In the case of the leg bi-mobile mechanism the approached dynamic model is based on the bi-mobile RTRTR active group firstly applied for a real technique solution in robotics. The mechanism may be also used for robot arms.

ON THE HYBRID-DRIVEN LINKAGE MECHANISM WITH ONE INPUT CYCLE CORRESPONDING TO TWO OUTPUT CYCLES

A hybrid-driven five-bar linkage mechanism with one input cycle corresponding to two output cycles is presented. The proposed linkage mechanism is driven by a constant-speed motor and a linear motor, respectively. The output link can generate two same required output cycles during a single input cycle, while the rotational input link rotates with a constant angular speed, and the linear input link follows a reciprocating motion along a specified linear guide fixed on the rotational input link. The configuration, displacement relationship between the input and output links, and conditions of mobility of this proposed mechanism were studied, and a kinematic analysis was performed. The selection of the instantaneous motion trajectory of the linear input link and an optimal dimensional synthesis are also described. An example is provided to verify the feasibility and effectiveness of this methodology.

A New Hybrid-Driven Five-Bar Linkage Mechanism

A new two-degree-of-freedom hybrid-driven five-bar linkage mechanism is presented. The proposed linkage mechanism has two input links: one rotational input link and one linear input link, driven by a constant-speed motor and a servomotor, respectively. The rotational input link rotates with a constant angular speed, and the linear input link follows a reciprocating motion along a specified linear guide fixed on the rotational input link. The configuration was studied, and a kinematic analysis was performed. An example is provided to verify the feasibility and effectiveness of this methodology.

Operation of Resonant DC/DC Converter in the BUCK Operation Regime

The series resonant DC/DC converter with isolation transformer is investigated. When switching frequency of input inverter bridge is above the resonant one a shortening of the naturally half-waves of current through a L-C resonant circuit takes place resulting in a circulating current through the DC supply source reducing a mean value of supply current and also reducing load voltage in respect to the one at normally resonant case. The main relations for the case with strong voltage supply source are obtained and operation regimes at raised switching frequency investigated using a computer modeling. Some conclusions are made for proper calculation of parameters. It is shown that the shape of the resonant circuit current at raised frequency grows to the triangular one and that asks for proper correction of the expressions obtained for sinusoidal case. Applying qZ input link processes quite differ from observed for the strong supply – arise charging of the capacitors of the link by influence of circulating current and this phenomena impedes to reducing of the load voltage. That qZ link does not allow to create proper regulation of load parameters.

KINEMATIC PERFORMANCE ANALYSIS OF 4-LINK PLANAR SERIAL MANIPULATOR

This investigation is all about determining condition number for four link planner serial manipulator. Condition number which measures the accuracy of end effector velocity is obtained from the Jacobian matrix of the four link planner serial manipulator. Inverse of a non-square matrix in the calculation of the condition number. Pseudo inverse procedure is used for the calculation of inverse of jacobian matrix using condition number. Isotropic condition for manipulator is found. “MAT Lab” 6.1.0 version is used to determine the condition number which is recently developed for complex matrix manipulations. A computer program in “MAT Lab” is written for finding Jocobian matrix, inverse of Jacobian matrix, norm of jacobian and norm of Jacobian matrix and the condition number for various input joint angles and link lengths.

Evolutionary Minimization of Network Coding Resources

A method to identify feasible minimal network coding configurations between a source and a set of receivers without altering or modifying the established network infrastructure is proposed. The approach minimizes the resources used for multicast coding while achieving the desired throughput in the multicast scenario. Because the problem of identifying minimal configurations of a graph is known to be NP-hard, our method first identifies candidate minimal configurations and then searches for the optimal ones using a genetic algorithm (GA). Because the optimization process considers the number of coding nodes, the mean number of coding node input links and the sharing of resources by sinks, the problem is thus a multiobjective problem. Two multiobjective algorithms, MOGA and VEGA, are chosen to solve the problem because they are simple enough not to place heavy demands on source nodes when the minimal configuration is sought. The optimization process is investigated by the simulation of a range of randomly generated networks of varying sizes. Performance differences between the multiple-objective GAs are observed, which seem to arise from the difference in their methods of searching. Nevertheless, both methods perform well in terms of identifying feasible minimal configurations with optimized coding resources. The performance is assessed by comparing the optimized solutions with randomly chosen starting configurations. There are always reductions in the number of coding nodes used, typically 50%, and resource sharing is multiplied by several times. Typical mean in-link savings are 10% but may range from zero to close to 30%. We thus show that relatively simple multiple-objective GAs can deliver optimized minimal coding configurations for the network coding multicast problem. Moreover, the approach here offers an improvement over solutions in the literature because our method remains feasible for relatively large networks and its implementation at the source simplifies the functions that must be employed at intermediate nodes.

A parallelogram-based compliant remote-center-of-motion stage for active parallel alignment.

Parallel alignment stage with remote-center-of-motion (RCM) is of key importance in precision out-of-plane aligning since it can eliminate the harmful lateral displacement generated at the output platform. This paper presents the development of a parallelogram-based compliant RCM stage for active parallel alignment. Different from conventional parallelogram-based RCM mechanism, the proposed stage is designed with compliant mechanisms, which endows the stage with many attractive merits when used in precision micro-/nanomanipulations. A symmetric double-parallelogram mechanism (SDPM) based on flexure hinges is developed as the rotary guiding component to realize desired RCM function. Due to the geometrical constraint of the SDPM, the operating space of the stage can be easily adjusted by bending the input links without loss of rotational precision. The stage is driven by a piezoelectric actuator and its output motion is measured by non-contact displacement sensors. Based on pseudo-rigid-body simplification method, the analytical models predicting kinematics, statics, and dynamics of the RCM stage have been established. Besides, the dimensional optimization is conducted in order to maximize the first resonance frequency of the stage. After that, finite element analysis is conducted to validate the established models and the prototype of the stage is fabricated for performance tests. The experimental results show that the developed RCM stage has a rotational range of 1.45 mrad while the maximum center shift of the RCM point is as low as 1 μm, which validate the effectiveness of the proposed scheme.

A method for optimal path synthesis of four-link planar mechanisms

The paper deals with the optimal synthesis of planar mechanisms as path generators. The formulation of the synthesis problem enables decreasing the number of design parameters. The angular position of the floating link (coupling link) connecting input and output links is described by function sine. The coupler link is treated as a free body which generates precisely desired motion. The objective is to determine the coupler dimensions for which the coupler joints approximate with a prescribed accuracy the trajectories which these joints trace in the assembled mechanism. The structural error for most typical kinematic pairs was derived in order to apply the method to a wide spectrum of four-link planar mechanisms. Compared with classical path synthesis approach, this technique measures the deviation of the paths of the coupler joints from their paths in the assembled mechanisms, not the deviation of the coupler path from the prescribed trajectory. Various modifications of the method were discussed to widen the range of possible applications. The problem was formulated as an optimization task. An objective function was constructed and minimized in searching for generators of desired motion using an evolutionary algorithm. Test paths were chosen to verify the effectiveness of the method. Numerical tests addressed also practical linkage applications. The technique was verified in the synthesis of four-bar linkage, crank-slider mechanism and mechanism with slotted link. The method was also applied to solve chosen motion synthesis tasks combining the positions and angular orientations of the link.

Characteristics of the double-cycled motion-ruled surface of the Schatz linkage based on differential geometry

This paper applies Euclidean invariants from differential geometry to kinematic properties of the ruled surfaces generated by the coupler link and the constraint-screw axes. Starting from investigating the assembly configuration, the work reveals two cycle phases of the coupler link when the input link finishes a full rotation. This leads to analysis of the motion ruled surface generated by the directrix along the coupler link, where Euclidean invariants are obtained and singularities are identified. This work further presents the constraint ruled surface that is generated by the constraint screw axes and unveils its intrinsic characteristics.

Operation of assistive apparatus through recognition of human behavior: Development and experimental evaluation of chair-typed assistive apparatus of nine-link mechanism with 1 degree of freedom

Because of deterioration of strength, range of joint motion, and balance ability, most care-dependent older adults require assistance to move from a seated position to a standing position. Although many sit-to-stand assisting apparatuses consisting of a seat, power transmission mechanism, and sensors have been developed, most of movements depend several actuators as the power transmission mechanism. This study aims to develop the chair-typed apparatus of nine-link mechanism with 1 degree of freedom at first, then to prove the possibility that the apparatus can be operated through the recognition of human behavior by one sensor. Here, the nine-link mechanism is divided into two mechanisms: the five link for raising the height; the four link for rotating. The mechanical part enables two input links for two mechanisms to be driven by one linear actuator simultaneously. The measurement with the infrared sensor enables the assistive apparatus to be operated automatically while patterns from measured data help the apparatus recognize what the user want to do: one is the sit-to-stand movement; the other is the stand-to-sit movement. It is discussed that the operating method through the human behavior is helpful for most older adults who are not familiar with the operation of machine.

SISO P-ILC Algorithm for Output Data Dropouts and Its Application in Wastewater Biological Treatment Plant

In order to improve the efficiency of sewage treatment, We construct P-ILC algorithm for output data dropouts.The P-ILC algorithm is used in the aeration tank of oxygen input link, and according to the actual situation, considering the data generating omissions, adjusting the algorithm can completely control the aeration tank of oxygen. After 15 iterations, we can completely control the oxygen in the aeration tank volume. We know more important is this algorithm may at any time according to need of aeration tank of oxygen supplement, when the lack of oxygen, can open the oxygen filling pump, when sufficient oxygen, close the oxygen filling pump, to achieve energy saving goals, ultimately makes the economic benefits to achieve the highest.

Optimal synthesis of four-bar steering mechanism using AIS and genetic algorithms

Synthesis of four-bar Ackermann steering mechanism was considered as an optimization problem for generating the best function between input and output links. The steering mechanism was designed through two heuristic optimization methods, namely, artificial immune system (AIS) algorithm and genetic algorithm (GA). The optimization was implemented using the two methods, length was selected as optimization parameter in the first method, whereas precision point distribution was considered in the second method. Two of the links in the first method had the same length to achieve a symmetric mechanism; one of these lengths was considered as optimization parameter. Five precision points were considered in the precision point distribution method, one of which was in the straight line condition, whereas the others were symmetric. The obtained results showed that the AIS algorithm can generate the closest function to the desired function in the first method. By contrast, GA can generate the closest function to the desired function with the least error in the second method.

Input link rotatability analysis of four-bar based Watt mechanisms with revolute and prismatic joints

This paper presents the input link rotatability analysis of four-bar based Watt six-link mechanisms, having at the most one prismatic joint. All assembly modes of such Watt mechanisms are considered in the analysis. For all the cases considered, explicit mathematical conditions are obtained, which can be used to check the input link rotatability of a given Watt mechanism. Apart from being of theoretical importance, the presented analysis is suitable for implementation within an optimization scheme, is computationally efficient and can be utilized to ensure that the synthesized mechanism does not shift from one branch to another, when put to use in practice. When incorporated within an evolutionary optimization algorithm, it can be effectively used to handle the rotatability constraint. The approach can be easily extended to Watt mechanisms containing more than one prismatic joint.