Scientific degrees, institution, year: Assoc. Prof., Institute of Mechanics- 1998; Ph.D., Bulgarian Academy of Sciences, 1994
Fields of Research: Mechatronics and Robotics
Membership: Senior Member of IEEE (Robotics and Automation Society) - since 1999, Member of American – Romanian Academy of Arts and Science - since 2002; Member of Managing Board of Bulgarian Robotics Society and founder, 1991; Member of Bulgarian Biomechanics Society and founder; Member of Bulgarian Union of Scientists - since 2004;
Abstract: The paper presents implementation of CD technology in injection moulding of micro-pattern polymer substrates for application in microfluidic device used for cell immobilization, manipulation and subsequent investigation. The paper aims to develop a design concept of the micro-pattern polymer substrates with specially located thin-sections. Microstructure for positioning of cells is located in the thin sections and is consistent with the possibility the substrate to be produced by injection molding. For this purpose an appropriate microstructure and the thickness of the substrate thin-sections are chosen according the impact of geometrical parameters and the location of microstructure. They are optimized by study their dependence on the parameters of the gate system and the substrate thickness on the process of mould filling. By the CD-based models developed a series of values of microstructure parameters and thin-section parameters were obtained. Relevant versions of the substrate design with cell-grooves are achieved. Results obtained states that the reduction the cell-grooves size and increasing the number of the thin-sections makes the mould filling difficult or impossible. In this case, it is advisable, the polymer substrate and thin-sections to be molded by injection molding, then cell-grooves can be further shaped by hot embossing.
Abstract: The paper presents the design concept of automatic CD-based polymer microfluidic device for single cell immobilization applicable for use in robotic system for microinjection of substances into cells. The device is also provided for use as a standalone system for cell immobilization for their research and to carry out various micro- manipulations with cells. Key role in the functioning of the device plays a CD-based polymer substrate, on whose surface is specifically located microstructure in the form of micro-grooves for immobilization of cells. At the bottom of the micro-grooves are made suction holes. Immobilization of cells is achieved through the subatmospheric pressure provided by micro pump, connected to the micro-grooves by suction holes. The structure of the substrate is provided to be produced by injection molding. A possibility of using CD-based technology in injection moulding of the micro-patterned substrate is discussed. An approach to study the substrate through computer simulation by the finite element method is presented. In order to achieve an appropriate location and size of microstructure on the polymer substrate, impact of geometrical parameters of the gating system and the size, dimensions and location of the microstructure of the substrate on the mold filling is investigated. By means of iterative steps in the frame of the simulation codes, a series of values of the microstructure parameters are obtained and relevant versions of the substrate design with the deployment of cell-grooves are achieved.
The present design of the CD-based substrate and the approach for investigation of substrate can find applications in the construction of CD-based devices for immobilization of biological cells for research or micro-injection of cells.
Abstract: The paper presents some Computer Assisted Engineering (CAE) aspects concerning the achievement of a hybrid actuated micro-nano robot. Starting from a unitary concept Control - Design, different kinematic solutions were developed and compared, before a decision upon the structure was selected. Multiple closed loop simulations were performed via MATLAB/Simulink, Solid Dynamics and ANSYS software. The experimental results for the nano-stages/actors were run for two XY orientations with a range of 240 arcsec while and for translation in Z direction in a stroke range of 65 microm, and system resolution of 10 nm. Additional identification and reconstruction of the hysteresis curves were obtained and implemented in the model by using a Neuro-Fuzzy technique. Two hardware systems were developed for the micro and nano robot respectively. Corresponding software HMI capable also of joy-stick telemanipulation was developed.
Abstract: The work is concerned with the determination of the mechanical behaviour of cell membranes under uniform hydrostatic pressure subject to microâinjections. For that purpose, assuming that the shape of the deformed cell membrane is axisymmetric a variational statement of the problem is developed on the ground of the soâcalled spontaneous curvature model. In this setting, the cell membrane is regarded as an axisymmetric surface in the threeâdimensional Euclidean space providing a stationary value of the shape energy functional under the constraint of fixed total area and fixed enclosed volume. The corresponding EulerâLagrange equations and natural boundary conditions are derived, analyzed and used to express the forces and moments in the membrane. Several examples of such surfaces representing possible shapes of cell membranes under pressure subjected to micro injection are determined numerically.
Abstract: This paper describes how the web technologies are utilized for a robot system synthesis. A web application is created for automation of the synthesis of closed structures for micro- and nano-applications, utilizing the advantages tense piezo-actuators and closed robot kinematical structures. The algorithm, integrated into the developed web based application, offers a synthesis of robot kinematic chains without extensive knowledge in this domain. The aim is to facilitate synthesis of such kind of kinematic chains from specialists who will generate optimal solutions for automation and robotisation of the requested micro- and nano-process.
Notes: Kostadinov K., R. Kasper, T. Tiankov, M. Al-Wahab, D. Chakarov, D. Gotseva,, Unified Approach For Functional Task Formulation In Domain Of Micro/Nano Handling Manipulations, in W. Menz and St. Dimov (Eds.), 4M2005 Second Int. conference on Multi- Material Micro Manufacture (Grenoble, 20.09.-22.09.2006), Elsevier ISBN-13: 978-0-08-045263-9, ISBN â 0: 0-08-045263-0, pp. 255-258.
Abstract: The combination of robots for macro and micro operations is necessary for performing a large number of technological operations where macro motions precede finishing high accuracy motions. The basic difference between the two manipulation systems (MS) is the type of actuations used. The present study offers algorithms for solving inverse problem of kinematics (IPK) related to a macro MS without linearizations and IPK for a micro MS which is redundant, having two extra degrees of freedom. Conditions for unidirectionality of the basic links of a micro MS are assumed. A virtual model of a robotized system is developed and presented on the basis of the algorithms designed for solving the IPK. The robotized technical solution can be useful for cell manipulations where high precision and high speed of cell injection are required.
Abstract: This study focuses on problems of structural synthesis and optimization, referring predominantly to macro-robots with closed kinematic chains (CKC), but theory is valid for the structures of micro-robots as well. In addition to the known structural dependencies, the authors have reached two new ones, whereby the synthesis turns from formal permutation of the connection of links with kinematic pairs (ÐP) into a purposeful creation of KC and the extraction of isomorphic structures. Through the introduction of restrictions and optimum criteria, sets of structures are selected, which are suitable for robot manipulation systems.
Abstract: Polymer injection moulding is very suitable for mass fabrication of high
precision micro- and nanostructures. The optical disc information structures are
both in the micro and nanometer range and being in the form of pits they are
moulded into the disc through injection moulding. The key reason for the success of
optical discs (CD) as storage media is the fact that injection molding makes
possible the transfer of Gbytes of data points (surface pits) in a few seconds onto a
cheap polymer carrier. The experience gained up to now in the field of injection
moulding of optical disc substrates has shown that the mould and the sprue system
design occupy a central place in the production process.
A design concept and integrated 3D CAD models of the sprue system of an
optical disc mould and the optical disc substrate are developed. The sprue system is
known as a system, in which the central hole of the polymer substrate is formed by
direct punching of the circle gate from the polymer substrate. In the process of the
investigation a modified variant of the sprue system is developed, in which the melt
distribution area with symmetrical shape is formed. The proposed models allow
easy change of the geometric shape and dimensions of the sprue system and
polymer substrate. The gate size, the polymer substrate thickness and the draft
angle of the sprue are defined as variable parameters with three variants of the
processing conditions in mould filling simulation. The results obtained show that
small changes of the gate size and substrate thickness cause significant impact on
the ability to fill the mould cavity. By means of iterative steps within the frame of
the simulation program, a series of values of the polymer substrate thickness and
the gate size are attained, in which easy mould cavity filling is obtained for all
variants of processing conditions.
Abstract: Conceptual design approach for mechatronic systems (MS) with dynamic interaction with technological environment (TE) has been presented in this paper. It is based on the exploitation of impedance control method with its 3 known approaches to perform the reference task function. By analyzing the dynamic interaction of MS with TE ideas and design approach are generated to design either some subsystemsâ drive, mechanic, sensor, control and information or the whole MS. This allows the desired quality parameters and functionality to be achieved. Applying this approach some MS have been designed, such as positioning robot for feeding operations, MS for monomolecular films deposition, Robot for micro & nano manipulations, etc. Experimental results obtained from those typical examples illustrate the effectiveness of the proposed conceptual design approach for MS dynamically interacting with TE.
Abstract: Impedance scaling approach presented in this paper is specially developed for teleoperation robot control to meet requirements to control robots and mechatronic systems with completely different dimensions and mechanic characteristics than the human operator. It is applied to the developed Ro-TeMiNa robot system with 6 DOF and to the mechatronic handling device with 3 DOF for micro and nano operations. The hybrid approach transferring operator motion and manipulation skills for control of the robot system for cell micro and nano manipulations is based on visual/haptic interface.
Abstract: This paper considers a new method for integration of piezo-electric actuators and motion amplification elements (MAE) into one component, subjected here to be telecontrolled as micro/nano manipulator. In this case development of a control approach for such micro and nano manipulators is the object of this paper. The used piezo-ceramic disc is segmented according the desired task space. It is characterized with non-linear behavior while the segments are controlled either separately or in combination. The main problems concerning the integrated structure-control design optimization approach is defined and considered in order to realize a telemanipulation control of the desired micro/nano operations. An appropriate hybrid telemanipulation approach is developed to improve the efficiency of any micro- and nano manipulation and operation for which the operator has neither experience nor knowledge. It combines the advantages of the known two teleoperated control approaches â direct and task-oriented teleoperation.
Abstract: Pick-and-place of micro/nano sized objects means handling of very tiny and very different in properties objects having specific behavior. Besides formal requirements of assembly processes, the tools for controllable manipulation with these objects should not affect the examined micro/nano environment, i.e. should be âsmall and passiveâ in any sense. Despite of the recent progress, most available micro-grippers are still suffering of high voltage power supply required, short lifetime, low detection sensitivity and high price.
Prototypes of a newly designed micro-gripper, having advantages over the existing analogues, have been developed, experimentally studied, and presented in this paper. The envisaged microgripper is of normally-closed type with thermo-mechanically driven actuator and piezoresistive arm-displacement feedback. The thermo actuator is placed between gripperâs arms and consists of double-folded highly-doped compliant silicon beam. As low average voltage vs. arm displacement value as 1V/μm, was experimentally measured.
Notes: Book overview
This book constitutes the refereed proceedings of the 5th International Precision Assembly Seminar, IPAS 2010, in Chamonix, France, in February 2010.The 39 revised full papers were carefully reviewed and selected from numerous submissions. The papers are organized in four parts: design of micro products; micro-assembly processes; positioning and manipulation for micro-assembly; and development of micro-assembly production.
Abstract: The challenge in the development of ultraprecise manipulating systems is to combine
the unique features of piezoactuators with appropriate mechanics and sensor/
control electronics in order to achieve the requirements of the micro and nano
worlds.
The RoTeMiNa robotic system utilizes a teleoperated control approach with
impedance scaling and was developed for cell micromanipulations and nanomanipulations,
as a result of an optimized design process. Giving the perception to the human operator allows effectiveness of the robot teleoperation and control for
microcell and nano-cell manipulations.
The equations of motion of the micro-nano robot have been generated based on
oriented edge graphs with multiple cycles. The concept of a matroid, applied to independency
of columns, is a novel approach for generating equations of motion.
The experimental results for the hysteresis curve of the linear axes are obtained
and compared with the results for the piezoactuator as a single unit. The results confirmed
that the hysteresis of the piezoactuator is reduced by roughly 40% for a
closed-loop structure robot. The identification of the structure is made in MATLAB
using the obtained experimental results for the x-, y-, and z-axes for different identification
methods and two different types of input signal: sinusoidal and triangular.
The transfer functions of these three axes have been obtained for control research of
the piezoactuated microrobot.
A control schema was proposed in order to compensate the hysteresis of piezoactuators
included in micro-nano robotics. The schema uses a neuro-fuzzy inverse
model with a PID/PI error mapping compensator. We adopted an originally mixed
algorithm in order to tune the PID/PID parameters using the GEATbx toolbox. The
results of simulation proved that the method is very effective, with very good linearization of the hysteresis curve. The MSE was below 0.005 in all of the tested
cases. The control schema is based on an inverse neuro-fuzzy model in a feed-forward
connection. The piezoactuator is modeled by a modified mathematical model
in order to be simulated and to be tested in a mixed analog-discrete schema. The
mapping errors due to the dynamic fuzzy model are compensated by PID/PI controllers.
The PID/PI parameters are found using genetic algorithms applied to global
optimization problems with two objectives. The Pareto front that describes the optimal
solutions is found using a rank-based selection for local points. The proposed
method improved noticeably the linearization of the hysteresis and the performance
of the piezoactuator.
Abstract: The telemanipulation control approach is widely used in micro/nano manipulation where complex handling tasks are to be completed in very small spaces unnatural for humans. Visual, tactile, position or force feedbacks are used assisting the operator to see, sense and control the manipulation process. Without any of these feedbacks it is very difficult to work into the unknown micro/nano world. It is possible to create virtual working environment
using the impedance parameters spring, damping and inertia to follow its dynamics. To improve operatorâs skills for handling the micro/nano operations, an impedance scaling approach is used herein. The development of a telemanipulation approach for mechatronic handling devices employed for micro/nano operations with three
degrees of freedom (DoF) is presented. A virtual environment is created and sensed accounting for spring and damping virtual force effects. The effectiveness of the teleoperation control is experimentally investigated on a 3 DoF robot for scanning operation and a mechatronic handling device for biological investigations, using an
inverted microscope and digital cameras.
Abstract: In the present work a methodology is developed for synthesis of closed structures for micro- and nano-applications, utilizing the advantages of structured piezo-ceramics, tense piezo-actuators and closed robot kinematics structures. The synthesis of closed kinematic structure with piezo- ceramic actuators is investigated for three case studies:
Ð) Synthesis for parallel structures in which the basic links are connected in between, only by means of driving chains of the piezo- ceramic actuators.
B) Synthesis for parallel structures in which the basic links are connected in between in a serial chain. The driving chains of the piezo- ceramic actuators are attached parallel to the links of the basic serial chain.
C) Synthesis for parallel structures in which the basic links are connected in between in a parallel chain. The driving chains of the piezo- ceramic actuators are attached parallel to the links of these chain.
A synthesis of kinematics schemes with definite degrees of mobility based on the synthesised structures is developed in the paper. The class of the kinematic couples of the links and the immovable link are selected. Examples and graphic interpretation of the solutions are presented in the paper.
Abstract: A unified approach for functional task formulation is developed that allows communication between user and team of mechatronic engineers developing the mechatronic handling devices for requested task function. All-important parameters are set for realization of mechanics and control of desired process for automation. 3D variants are modeled in SDS 2004+ and simulated, making interactive closed loop with the user and better communication between different research and industrial domains for achievement of good results. The possibilities of the developed iterative program for the task function formulation are illustrated with the results obtained for the case of micro/nano manipulations necessary for measurement of electrochemical impedance.
Abstract: This paper presents an investigation and development of mechatronic handling devices (MHD) based on a structured piezo ceramic with (3, 1)-piezoelectric effect for manipulation and processing of micro/nano operations. Following the synthesis of kinematic structure for micro- and nano-manipulation tasks based on structured piezo ceramics and closed kinematic structures, a specific multilayer design of piezo actuated MHD for micro-and nano-operations was developed. The MHD was mathematically modelled and a FEâmodel was created and simulated with the program system ANSYS. Comparison study of the MHD prototypes was performed using obtained experimental results. An experimental set up was created that aimed to verify the mathematical and simulation models measuring system behaviour like force, displacement and stiffness.
Abstract: This paper presents enabling robot technologies for innovative hybrid assembly approach subject of European integrated FP6 project #026622 Hydromel. This hybrid assembly approach combines the self-assembly technology with high performance robotic tools such as precise manipulators with submicron resolution and mechatronic handling or feeding devices, innovative vision to detect either the micro objects or the tip of the technological end-effector, force sensing and robot system control. The enabling robot technologies includes web application for automation of the closed structures synthesis for micro- and nano-applications, utilizing the advantages tense piezo-actuators and closed robot kinematical structures. Automated and teleoperated robot control approaches are developed based on the different scaling approaches and techniques and real time control applications utilizing optical sensing approach providing pipette tip detection and tracking with 0,1µm resolution. Hydro-MiNa robot with 7 DoF for cell injection with force sensing is presented as an example utilizing the enabling robot technologies developed.
Abstract: In this paper piezo actuated micromanipulators are considered with serial-parallel structure including elastic joints. Such structure allows a preliminary tension of the mechanical system in order to eliminate backlashes and to improve the performance of the piezo-actuators. A kinematics model of a serial-parallel structure for local micro manipulators is build here. A pseudo rigid body approach is used, where elastic joints are modelled as revolute joints. A stiffness model is created to estimate the general stiffness of the manipulator by means of reduction the stiffness of all elastic joints. Two approaches are presented here for preliminary tension of parallel manipulator structure: - deflection from the initial manipulator state by introducing of a driving joints motion during the assembly; - preliminary tensioning of the separate elastic joints. The two approaches considered are experimented on the manipulator for cell injection. The values of the mechanical parameters obtained by preliminary tension of the manipulator are pointed out.
Abstract: A prototype mould for micro- and nanostructure replication on polymer substrates is designed. Novelty of the mould is the ability to be used two types of the moulding process: conventional injection and injection-compression moulding. Advantage of the mould is also a design concept which allows mounting various types of sprue systems in the mould by replacing some of the sprue system elements. 3D CAD models of the polymer substrate and the sprue systems are developed. The substrate thickness, the sprue system parameters and the gate size are defined as variable parameters, which are combined with process conditions. By means of iterative steps in the frame of the simulation code, a series of values of the variable parameters and of the aspect ratio between the substrate radius and thickness are obtained. The maximum value of the aspect ratio of the substrates for all types of the sprue system is obtained. On the basis of the results a comparative analysis between the sprue systems is considered. The proposed mould and the obtained results can be used both for experimental work and for mass-production of polymer substrates with micro- and nanostructures replicated on their surfaces such as optical discs (CD, DVD and Blu-ray discs) and also CD micro fluidic devices for medical diagnostic and applications, CD micro fluidics for BioMEMS applications, Lab-on-a-CD and CD microfluidic chips.
Abstract: The total force Ftot=(T, μ, L) between the plates of a gripper, which working arms are separated at a distance L from each other, depends on the environmental conditions in which it is working characterized, among the others, via the temperature T and the chemical potential of the fluid in which it is immersed. In the current study on the
basis of a model of a gripper immersed in a nonpolar fluid, which can be liquid or gas, we calculate the dependence of the F tot=(T, μ, L) on T, μ and L, using a suitable mathematical program that solves a set of (L / a) coupled nonlinear equations for the order parameter profile of the fluid between the plates of the gripper. Here a is the
characteristic distance between the molecules of the fluid. In our approach we take into account the direct substrate-substrate van der Waals interaction ~ J.exp(s), the van der Waals interactions between the molecules of the fluid with the other molecules of the fluid ~ J.exp(l) , as well as with the constituent elements of the substrate, which is proportional
to J.exp(l , s), and the interaction between the plates generated by the fluctuations of the density of the fluid (i.e., the Casimir force). We suppose that both arms of the gripper are made out of the same material which strongly prefers the liquid phase of the fluid. We conclude that Ftot=(T, μ, L ) strongly depends on the contrast, at given fixed T and μ , between the physical properties of the fluid and the material of the arms of the gripper and
is proportional to J.exp(l)[Ïl â Ïs J.exp(l,s)/ J.exp(l)], where Ï(T, μ) is the number density of the fluid, and Ïs is the number density of the substrate. Our approach can be applied to any nonpolar fluid. We present, as example, results for4He and 3He considering the working arms of the gripper being made of Au.
Abstract: This paper presents the development of a methodology and technology for the appropriate selection and creation of mechatronic handling devices (MHD) able to accomplish certain micro- and/or nano-operation task. As basis actuator, piezo ceramic structures integrated into the mechatronic device are utilized and developed here. Two applications, in bioscience and electrochemistry are foreseen for a demonstration phase. Specific multilayer design approach of piezo-actuated mechatronic handling devices for micro- and nano-operations was proposed based on the method for piezo structures synthesis. Comparison study of the developed mechatronic handling device prototypes is performed based on the obtained simulation and experimental results. Teleoperated control approach is developed based on the impedance scaling technique.
Abstract: In this paper is presented a developed robotic system for cell micro/nano manipulation and penetration, based on the visual/haptic interface. The operator's motion and manipulations skills are transferred to the robot control system by direct teleoperation. The robot's regional structure has three translational joints and one passive rotational joint for the nano robot adjustment. The three-d.o.f piezo actuated nano robot has a compact and stiff structure, to guarantee the three-dimensional nano motion and control for sample manipulation or injection. The closed kinematics structure with three fundamental chains has been chosen for the required working space, high speed, and precision. The digraph-matroid approach is used for the model's kinematics, and the SDS software for the robot's simulation.
