Ali Kireçci

A study on a hybrid actuator

Abstract Classically, constant speed motors drive some mechanical transmissions such as gears, cams and linkages in order to produce non-uniform motion in machines. Such machines may allow a limited flexibility, by changing dimensions of the components. To answer the need for flexibility constant speed motors are replaced by servomotors. Besides other disadvantages, the cost of this solution is often very high especially for large capacity machines. Hybrid machines, which are a combination of two types of motors and mechanisms, have flexibility at a reduced cost. A new hybrid actuator is proposed in the study presented here.

Modeling and simulation of a hybrid actuator

Modeling and kinematic analysis of a hybrid actuator is presented in this study. The dynamic behavior of hybrid actuator is studied by applying numerical simulation on the whole system. Lagrangian mechanics is applied to derive equations of motion. Simulation results are presented to demonstrate the ability of model developed with PID controller action. Similar following characteristics are obtained from numerical simulation, and the performance of the control system with PID controller is quite effective. In hybrid actuator configuration, a seven link mechanism having an adjustable crank is used. One input of the mechanism is given by a gearbox coupled to brushless DC servo motor, and the second input having an adjustable crank is provided by a permanent magnet DC servo motor coupled to a lead screw mechanism.

Experimental evaluation of a model reference adaptive control for a hydraulic robot: a case study

This paper presents the implementation of an explicit model reference adaptive control (MRAC) for position tracking of a dynamically unknown robot. An auto regressive exogenous (ARX) model is chosen to define the plant model and the control input is optimised in a H2 norm to reduce computational time and to simplify the algorithm. The theory of MRAC falls into a description of the various forms of controllers and parameter estimation techniques, therefore, applications may require very complicated solution methods depending on the selected laws. However, in this study, the proposed MRAC shows that applications may be as easy as classical control methods, such as PID, by guaranteeing the stability and achieving the convergency of the plant parameters. Despite the selected simple control model, simple optimisation method and drawbacks of the robot the experimental results show that MRAC provides an excellent position tracking compared with conventional control (PID). Many experimental implementations have been done on the robot and one of them is included in the paper.

Improved Trajectory Planning using Arbitrary Power Polynomials

Increasing demands for higher operational speeds, the need for flexible machinery and recent developments in microchip technology have made programmable machine systems an attractive alternative to conventional systems. However, some difficulties still remain for proper control of programmable systems, especially at higher speeds. These can be categorized into two groups: trajectory planning and trajectory tracking. Conventional trajectory planning methods are ineffective for general application, especially when velocity and acceleration conditions are included. There are many mathematical functions but polynomials are shown to be the most versatile for trajectory planning; however, these can give curves with unexpected oscillations, commonly called meandering. Tracking of a motion in this situation could engender severe practical problems. In this study, a new interpolation method using polynomials with arbitrary powers is proposed to overcome this disadvantage.

Motion control and implementation for an AC servomotor system

This paper presents a study on trajectory tracking problem for an AC synchronous servomotor. A mathematical model for the system including AC synchronous servomotor, gearbox, and a load is developed to examine the systems dynamic behavior. The system is controlled by a traditional PID (proportional + integral + derivative) controller. The required values for the controller settings are found experimentally. Different motion profiles are designed, and trapezoidal ones are implemented. Thus, the experimental validation of the model is achieved using the experimental setup. The simulation and experimental results are presented. The tracking performance of an AC servomotor system is illustrated with proposed PID controller.

Design of a pile-yarn-manipulating mechanism

Abstract A pile-yarn-manipulating mechanism for carpet weaving was designed and implemented. The pile-yarn-manipulating mechanism served to prepare the coloured pile yarn for a knotting mechanism according to a carpet pattern used as input. Such a mechanism required two auxiliary mechanisms (a holding mechanism and a cutting mechanism) to perform its function. A model for the pile yarn manipulating mechanism is presented herein. Important developments of weaving technology have been recorded. There are many carpet looms working at high speeds, but production methods of handmade carpets have not changed for several hundred years. The main difference between handmade and machine carpets is their texture type. The pile surface of machine carpets is produced by Jacquards mechanism, but it is produced independently in handmade carpets by the weaver. There are basically two kinds of knot, namely the Turkish knot and the Persian knot.

Investigation of the fastness properties and color values of cotton fabrics knitted from ring spun and Sirospun® yarns

Sirospun yarn production is a new approach to produce two‐folded and twisted yarns. This method integrates the spinning and folding action in a single step. Therefore, it may have some important advantages such as simplicity of the process, lower production costs, lower investment, space saving, etc. The purpose of the study is to compare the color fastness and colorimetric properties of sirospun yarn, single and two‐folded ring spun yarns produced by same cotton fiber blend. Therefore, three reactive dyes were applied at 1% omf (on mass of fabric) depth of shade to the single jersey fabrics which are produced by sirospun yarn, single and two‐folded ring spun yarns at three different counts. The examination of color coordinates of undyed and dyed samples on CIELAB color space shows that undyed sirospun fabrics show slightly higher whiteness than both undyed single and two‐folded ring fabrics for all three yarn counts. Also, the color strength values of the samples are determined as slightly different for all three dyes. The experimental studies show that sirospun yarns have no disadvantages with respect to conventional folded and twisted yarns when their fastness properties were compared.

A Study of Weaving ‘Turkish Knots’ in Handmade Carpets with an Electromechanical System

Abstract To form a Turkish knot in a handmade carpet, a study for a computer-controlled prototype loom and its drive system has been presented. The mechanisms involved in the prototype are described separately and the design considerations for each mechanism are given with the function requirements needed. The control of the knotting system is achieved with the actuators applied. The research on the subject is still continuing at the Department of Textile Engineering, University of Gaziantep.

Assessment of antioxidant activity and phycocyanin release of Spirulina loaded poly(ε-caprolactone) electrospun nanofibers

Abstract PCL with biodegradable property and Spirulina with various biological activities offer good alternative ingredients for the fabrication of functional nanofibers in tissue engineering. The aim of the study is to obtain PCL/Spirulina nanofibers with low diameters and to determine their wettability, antioxidant activity, and phycocyanin release to evaluate their potential as bioactive scaffolds in different applications. PCL/acetic acid/pyridine solutions with three different Spirulina concentrations were electrospun and the obtained nanofibers were investigated. The thinnest PCL/Spirulina nanofibers (117.20 nm) were obtained at 1.5% Spirulina concentration. Although PCL nanofibers with 6% Spirulina concentration showed the highest antioxidant activity and amount of phycocyanin released, PCL nanofibers with 3% Spirulina concentration having similar in vitro results showed superiority when considering the diameter and uniformity of the nanofibers and the cost of the material. The PCL/Spirulina nanofibers with small diameters and antioxidant activity could be regarded as potential extracellular matrix material for tissue engineering.