Scaled bilateral teleoperation using discrete-time sliding mode controller

In this paper, the design of a discrete-time slidingmode controller based on Lyapunov theory is presented along with a robust disturbance observer and is applied to a piezostage for high-precision motion. A linear model of a piezostage was used with nominal parameters to compensate the disturbance acting on the system in order to achieve nanometer accuracy. The effectiveness of the controller and disturbance observer is validated in terms of closed-loop position performance for nanometer references. The control structure has been applied to a scaled bilateral structure for the custom-built telemicromanipulation setup. A piezoresistive atomic force microscope cantilever with a built-in Wheatstone bridge is utilized to achieve the nanonewtonlevel interaction forces between the piezoresistive probe tip and the environment. Experimental results are provided for the nanonewton-range force sensing, and good agreement between the experimental data and the theoretical estimates has been demonstrated. Force/position tracking and transparency between the master and the slave has been clearly demonstrated after necessary scalin

Function based control for bilateral systems in tele-micromanipulation

Design of a motion control system should take into account (a) unconstrained motion performed without interaction with environment or any other system, and (b) constrained motion with system in contact with environment or other systems. Control in both cases can be formulated in terms of maintaining desired system configuration what makes essentially the same structure for common tasks: trajectory tracking, interaction force control, compliance control etc. The same design approach can be used to formulate control in bilateral systems aimed to maintain desired functional relations between human and environment through master and slave motion systems. Implementation of the methodology is currently being pursued with a custom built Tele-micromanipulation setup and preliminary results concerning force/position tracking and transparency between master and slave are clearly demonstrated

Development of a micromanipulation system with force sensing

This article provides in-depth knowledge about our undergoing effort to develop an open architecture micromanipulation system with force sensing capabilities. The major requirement to perform any micromanipulation task effectively is to ensure the controlled motion of actuators within nanometer accuracy with low overshoot even under the influence of disturbances. Moreover, to achieve high dexterity in manipulation, control of the interaction forces is required. In micromanipulation, control of interaction forces necessitates force sensing in milli-Newton range with nano-Newton resolution. In this paper, we present a position controller based on a discrete time sliding mode control architecture along with a disturbance observer. Experimental verifications for this controller are demonstrated for 100, 50 and 10 nanometer step inputs applied to PZT stages. Our results indicate that position tracking accuracies up to 10 nanometers, without any overshoot and low steady state error are achievable. Furthermore, the paper includes experimental verification of force sensing within nano-Newton resolution using a piezoresistive cantilever endeffector. Experimental results are compared to the theoretical estimates of the change in attractive forces as a function of decreasing distance and of the pull off force between a silicon tip and a glass surface, respectively. Good agreement among the experimental data and the theoretical estimates has been demonstrated

Bilaterally controlled micromanipulation by pushing in 1-D with nano-Newton scale force feedback

In this thesis the focus is on mechanical micromanipulation which means manipulation of micro objects using mechanical tools. Pushing is a type of motion of the micro parts and pushing ability on micro scale is inevitable for many applications such as micro assembly of systems or characterization of tribological properties of micro scale things. The aim of the work in this thesis was to obtain an improved performance in 1-D pushing of micrometer scaled objects in the sense of giving more control to human operator where it allows human intervention via bilateral control with force feedback in nano-Newton scale. For this purpose a system which can practice 1-D pushing of micrometer scaled objects by human operator is built. A bilateral architecture which is composed of master and slave sides has been used in the system. The micrometer scaled object is pushed by the piezoactuator which constitutes the slave side and the master side is a DC motor where the shaft is turned by the human operator via a rectangular prism rod. This system can be considered as an improved system comparing with the ones in literature, since it has a number of different advantages together. One of them is the ability to calibrate the relation between the movement of the slave system and the cycle that is made by the DC motor shaft which is controlled by the operator. This gives the availability to decide how sensitive will the slave side motion be to the master side motion. Moreover, thanks to the nano-Newton scale force sensing ability of the system user has the chance to use this as a force feedback within the bilateral structure, where by the way the operator will understand when the piezoresistive cantilever beam touched the object that is going to be pushed by it. The operator also understands when there is an obstacle or opposite force that keeps the object from continuing on its track

Model following control with discrete time SMC for time-delayed bilateral control systems

This paper proposes a new algorithm based on model following control to recover the uncompensated slave disturbance on time delayed motion control systems having contact with environment. In the previous works, a modified Communication Disturbance Observer (CDOB) was shown to be successful in ensuring position tracking in free motion under varying time delay. However, experiments show that due to the imperfections in slave plant Disturbance Observer (DOB) when there is rapid change of external force on the slave side, as in the case of environment contact, position tracking is degraded. This paper first analyzes the effect of environment contact for motion control systems with disturbance observers. Following this analysis, a model following controller scheme is proposed to restore the ideal motion on the slave system. A virtual plant is introduced which accepts the current from the master side and determines what the position output would be if there was no environment. Based on the error bet ween actual system and model system, a discrete time sliding mode controller is designed which enforces the real slave system to track the virtual slave output. In other words, convergence of slave position to the master position is achieved even though there is contact with environment. Experimental verification of the proposed control scheme also shows the improvement in slave position tracking under contact forces

Design and control of laser micromachining workstation

The production process of miniature devices and microsystems requires the utilization of non-conventional micromachining techniques. In the past few decades laser micromachining has became micro-manufacturing technique of choice for many industrial and research applications. This paper discusses the design of motion control system for a laser micromachining workstation with particulars about automatic focusing and control of work platform used in the workstation. The automatic focusing is solved in a sliding mode optimization framework and preview controller is used to control the motion platform. Experimental results of both motion control and actual laser micromachining are presented

Açık döngülü piezo-elektrik doğrusal sürücüler için histerez telafisi

Bu bildiride, açık döngülü piezo-elektrik doğrusal sürücüler için yüksek çözünürlükte histerez telafisi gösterilmektedir. Piezo-elektrik malzemelerde yapıları gereği mevcut olan doğrusalsızlıklar, Bouc-Wen modeli kullanılarak model tabanlı bir kontrol algoritması ile telafi edilmiştir. Telafi için kullanılan yöntemin histerez davranışında zaman, değişen frekans ve farklı hareket genişliği nedenleriyle görülen değişimler altında başarılı sonuçlar verdiği gösterilmiştir. Piezo-elektrik sürücülerin yer değiştirme bilgilerini elde edebilmek için yüksek çözünürlüklü lazer interferometre sisteme entegre edilmiş ve lazer interferometreden elde edilen ölçümler döngüyü kapatmak üzere bir geri besleme olarak kullanılmıştır. Histerez döngüsünün telafisi sonucu yer değiştirme gerilimi ve gezinme aralığı arasındaki doğrusallaşma davranışını gösteren muhtelif benzetimler ve deneysel sonuçlar sunulmaktadır

Design and implementation of an enhanced framework for complex mechatronic systems software development

Mechatronics is a multidisciplinary engineering and design eld that includes a combination of mechanical engineering, electrical engineering, computer engineer- ing and control engineering. Operation of systems within this eld depends on the smooth cooperation of several layers, namely: hardware, electronics, computer, operating system and software. Regarding the realization of system operation and control, creating human-system interaction and recording information related to the operation of the system; computers and softwares are inevitable parts of the com- plex mechatronic systems. Therefore, design and development of the software can not be separated from the overall system design process. In order to incorporate the software into the system modeling process and more importantly, to modify the modeling approach in such a way that system components can be easily represented by software units; a new kind of modeling methodology has to be proposed and then supported by the related common procedure, tools and building blocks. The most basic design consideration for this methodology would be the decomposability of the whole system into lowest level building units that can be directly implementable using current software engineering methods. Based on the problem de nition and the other factors that motivated the e orts put within the context of this study, a framework is created and realized to be used for the software development of any kind of system that falls within the complex mechatronic system concept. Proposed framework is called Complex Mechatronics Systems Software Framework (CMS- FRAME). As the name implies, CMSFRAME is planned with an intention to cover all mechatronic systems with any type of components and in any level of complexity. Regarding the formulation and creation of CMSFRAME, the intention was to create a blend of the best practices taken so far and to enhance with some extra features which can not be found within the frameworks that are already developed to serve for similar purposes in mechatronics or related elds. The systems that are developed in Sabanci University MicroMechatronics Laboratory during the period of this study are all perfect examples of the so called complexity of mechatronic platforms. Thus, the proposed framework is applied for the software development of these systems, namely; Laser Assisted Micro-Machining Workstation (LAMMW) and Micro-Factory in order to evaluate applicability and performance of the frame- work components along with the methodology structured to serve as a guideline for application. As a result of experiments that were realized on both systems which were run by software developed using the proposed framework, it has been noted that both systems were fully functional and outcomes of all experiments were as targeted which can be translated to the success and the accuracy of CMSFRAME on complex mechatronic systems software development. Being the rst complex mechatronic systems framework that can serve as a system modeling tool and a software development tool at the same time with its visually representable structure that enables the creation of a system model via a graphical user interface which also allows automatic generation of source code that constitutes the system soft- ware, CMSFRAME itself stands as a substantial contribution to the related eld. Providing clear de nitions regarding the composition of packages and procedures it introduces, CMSFRAME facilitates a higher level expandability via the preparation of new packages which paves the way of covering any new functional or physical sub-component. The more it is going to be applied on di erent systems successfully, the more experience on it will be gathered based on the application notes along with the possible new components that will be implemented as additions to the initial version of the framework during these applications

Galvanometrik sistemin lazerle yüksek hassasiyette işaretleme için yapay sinir ağı tabanlı modellenmesi

Bu çalışmada bir galvanometrik (galvo) lazer ışın demeti yönlendirme sisteminin yapay sinir ağları tabanlı kinematik modeli sistemin yüksek hassasiyette işaretleme, kaynaklama ya da lehimleme işlemlerine yönelik sunulmaktadır. Galvo sistem lazer ışın demeti ile yüksek hızlarda tarama yapabildiğinden hızlı işlemler içeren uygulamalar için güçlü bir araç olma özelliği taşımaktadır. İşaretleme yapılırken kullanılması istenen 2 boyutlu desenlerin bilgisayar destekli tasarım (CAD) ile hazırlanmış çizimler olarak sağlanabilmesi sisteme kullanım kolaylığı ve esneklik kazandırmaktadır. Çizimler önce MATLAB yazılımı kullanılarak grafik olarak çözümlenmiş ve x-y referans veri noktaları şeklinde değerlenmiş, ardından ise C programlama dili kullanılarak hazırlanmış bir kod içerisinde diziler halinde kaydedilmiştir. Bu C dosyasına, sistem yazılımı içerisinde atıfta bulunularak ana rutin tarafından referans veri kaynağı olarak kullanılması sağlanmaktadır. Sistemin teorik kinematik modeli çıkarılarak benzetimleme yapıldığında, ilgilenilen bölgede sistemin neredeyse doğrusal biçimde davrandığı görülmektedir. Sistem pratikteki uygulamalar için yapay sinir ağları yaklaşımı kullanılarak modellenmiştir. Modelin, dönme uzayı ve görüntü alanı üzerindeki ölçülen konumlara göre doğrulaması yapılmıştır. Farklı biçimindeki referans şekilleri takip etmeye yönelik deney sonuçları %4 ve altında hata payları ile yüksek hassasiyetin yakalandığını göstermiştir