Lightweight design and encoderless control of a miniature direct drive linear delta robot

This paper presents the design, integration and experimental validation of a miniature light-weight delta robot targeted to be used for a variety of applications including the pick-place operations, high speed precise positioning and haptic implementations. The improvements brought by the new design contain; the use of a novel light-weight joint type replacing the conventional and heavy bearing structures and realization of encoderless position measurement algorithm based on hall effect sensor outputs of direct drive linear motors. The description of mechanical, electrical and software based improvements are followed by the derivation of a sliding mode controller to handle tracking of planar closed curves represented by elliptic fourier descriptors (EFDs). The new robot is tested in experiments and the validity of the improvements are verified for practical implementation

Microfactory concept with bilevel modularity

There has been an increasing demand for miniaturization of products in the last decades. As a result of that, miniaturization and micro systems have become an important topic of research. As the technologies of micro manufacturing improve and are gradually started to be used, new devices have started to emerge in to the market. However, the miniaturization of the products is not paralleled to the sizes of the equipment used for their production. The conventional equipment for production of microparts is comparable in size and energy consumption to their counterparts in the macro world. The miniaturization of products and parts is slowly paving the way to the miniaturization of the production equipment and facilities, enabling efficient use of energy for production, improvement in material resource utilization and high speed and precision which in turn will lead to an increase in the amount of products produced more precisely. These led to the introduction of the microfactory concept which involves the miniaturization of the conventional production systems with all their features trying to facilitate the advantages that are given above. The aim of this thesis is to develop a module structure for production and assembly which can be cascaded with other modules in order to form a layout for the production of a specific product. The layout can also be changed in order to configure the microfactory for the production of another product. This feature brings flexibility to the system in the sense of product design and customization of products. Each module having its own control system, is able to perform its duty with the equipment placed into it. In order to form different layouts using the modules to build up a complete production chain, each module is equipped with necessary interface modules for the interaction and communication with the other process modules. In this work, the concept of process oriented modules with bilevel modularity is introduced for the development of microfactory modules. The first phase of the project is defined to be the realization of an assembly module and forms the content of this thesis. The assembly module contains parallel kinematics robots as manipulators which performs the assigned operations. One of the most important part here is to configure the structure of the module (control system/interface and communication units, etc.) which will in the future enable the easy integration of different process modules in order to form a whole microfactory which will have the ability to perform all phases of production necessary for the manufacturing of a product. The assembly module is a miniaturized version of the conventional factories (i.e. an assembly line) in such a way that the existing industrial standards are imitated within the modules of the microfactory. So that one who is familiar with the conventional systems can also be familiar with the construction of the realized miniature system and can easily setup the system according to the needs of the application. Thus, this is an important step towards the come in to use of the miniaturized production units in the industry. In order to achieve that kind of structure, necessary control hardware and software architecture are implemented which allows easy configuration of the system according to the processes. The modularity and reconfigurability in the software structure also have significant importance besides the modularity of the mechanical structure. The miniaturization process for the assembly cell includes the miniaturization of the parallel manipulators, transportation system in between the assembly nodes or in between different modules and the control system hardware. Visual sensor utilization for the visual feedback is enabled for the assembly process at the necessary nodes. The assembly module is developed and experiments are realized in order to test the performance of the module

COMPARATIVE STUDY OF HAPTIC AND VISUAL FEEDBACK FOR KINESTHETIC TRAINING TASKS

Haptics is the sense of simulating and applying the sense of human touch. Application of touch sensations is done with haptic interface devices. The past few years has seen the development of several haptic interface devices with a wide variety of technologies used in their design. This thesis introduces haptic technologies and includes a survey of haptic interface devices and technologies. An improvement in simulating and applying touch sensation when using the Quanser Haptic Wand with proSense is suggested in this work using a novel five degree-of-freedom algorithm. This approach uses two additional torques to enhance the three degree-of-freedom of force feedback currently available with these products. Modern surgical trainers for performing laparoscopic surgery are incorporating haptic feedback in addition to visual feedback for training. This work presents a quantitative comparison of haptic versus visual training. One of the key results of the study is that haptic feedback is better than visual feedback for kinesthetic navigation tasks

Software framework for high precision motion control applications

Developing a motion control system requires much effort in different domains. Namely control, electronics and software engineering. In addition to these, there are the system requirements which may be completely different to these spanning from biomedical engineering to psychology. Collaboration between these fields is vital, however these fields should be involved only as much as they are needed to be in the fields of expertise of the others. Several software frameworks exist for the creation of robotics applications. But currently there is no standard for the creation of mechatronics systems nor is there a complete software package that can deal with all aspects in the programming of such systems. Existing frameworks each have their advantages and disadvantages, however they generally have limited or no dedicated structure for the development of the motion control aspect of the problem and deal extensively with the robotenvironment interactions and inter mechanism communications. Dealing with the higher levels of the problem, they are usually not well suited for hard realtime; since the interactions can run on soft realtime constraints. The software framework proposed in this study aims to achieve a level of abstraction between the different domains utilized within a system. The aim in using the framework is to achieve a sustainable software structure for the system. Sustainability is an important part of systems, as it permits a system to evolve with changing requirements and variable hardware, with the ultimate goal of having robust software that can be utilized on different platforms and with other systems using an abstraction layer between the hardware and the software. This ensures that the system can be migrated from a processing platform to any other platform and also from one set of hardware to another. The framework was tested on several systems that have precision motion control requirements such as a 10 degree of freedom micro assembly workstation, a modular micro factory and a haptic system with time delay. Each of the systems works in di erent processing platforms and have different motion control requirements. The achieved results from the implementations show that the software framework is an important tool for the development of motion control software

Uzaktan lazer cerrahi için kısıtlı sistem tabanlı efendi köle denetleyicisi

Bu bildiri, uzaktan lazer ameliyatlarında kullanılmak üzere kısıtlı sistem tabanlı efendi-köle denetleyicisi tasarımını ve gerçek bir sisteme uyarlanışını sunmaktadır. Önerilen denetleyici şeması, sisteme beslenen bir resimden elde edilen gezinge üzerinde zamandan bağımsız bir kısıtlama yaratıp efendi robotun hareketini bu gezingeyle sınırlayan bir algoritmanın türetimini içermektedir. Efendi robot üzerine uyarlanan bu kısıtlama, cerrahın hareketini gezinge tanjantı doğrultusunda serbest bırakıp diğer doğrultularda engellemek üzere kuvvet yaratmaktadır. İlaveten ikinci bir denetleyici, gezinge doğrultusunda cerrahın yaptığı hareketi uzaktaki bir köle sistemine transfer ederek hareket senkronizasyonunu sağlamaktadır. Bu sayede, efendi sistemi kullanan cerrahın, uzakta duran köle sistemin altındaki bir dokuyu istediği derinlikte ve gezinge dışına çıkmadan lazerle kesmesini mümkün kılan bir sistem ortaya çıkarılmıştır. Önerilen yöntem, her biri üç serbestlik derecesine sahip olan efendi ve köle robotlar içeren bir deney düzeneğinde test edilmiştir. Deneylerden elde edilen başarılı sonuçlar, önerilen yöntemin robotik cerrahide kullanılabilirliğini kanıtlamakta ve lazer ameliyatlarının geleceğine dair yeni bir kapı açmaktadır

FUNDAMENTAL UNDERSTANDING OF THE CYCLOIDAL-ROTOR CONCEPT FOR MICRO AIR VEHICLE APPLICATIONS

The cycloidal-rotor (cyclorotor) is a revolutionary flying concept which has not been systematically studied in the past. Therefore, in the current research, the viability of the cyclorotor concept for powering a hover-capable micro-air-vehicle (MAV) was examined through both experiments and analysis. Experimental study included both performance and flow field measurements on a cyclorotor of span and diameter equal to 6 inches. The analysis developed was an unsteady large deformation aeroelastic analysis to predict the blade loads and average aerodynamic performance of the cyclorotor. The flightworthiness of the cyclorotor concept was also demonstrated through two cyclocopters capable of tethered hover. Systematic performance measurements have been conducted to understand the effect of the rotational speed, blade airfoil profile, blade flexibility, blade pitching amplitude (symmetric and asymmetric blade pitching), pitching axis location, number of blades with constant chord (varying solidity), and number of blades at same rotor solidity (varying blade chord) on the aerodynamic performance of the cyclorotor. Force measurements showed the presence of a significant sideward force on the cyclorotor (along with the vertical force), analogous to that found on a spinning circular cylinder. Particle image velocimetry (PIV) measurements made in the wake of the cyclorotor provided evidence of a significant wake skewness, which was produced by the sideward force. PIV measurements also captured the blade tip vortices and a large region of rotational flow inside the rotor. The thrust produced by the cyclorotor was found to increase until a blade pitch amplitude of 45 was reached without showing any signs of blade stall. This behavior was also explained using the PIV measurements, which indicated evidence of a stall delay as well as possible increase in lift on the blades from the presence of a leading edge vortex. Higher blade pitch amplitudes also improved the power loading (thrust/power) of the cyclorotor. When compared to the flat-plate blades, the NACA 0010 blades produced the highest values of thrust at all blade pitching amplitudes. The NACA blades also produced higher power loading than the flat plate blades. However, the reverse NACA 0010 blades produced better power loadings at lower pitching amplitudes, even though at high pitch amplitudes, regular NACA blades performed better. Among the three NACA sections (NACA 0006, NACA 0010 and NACA 0015) tested on the cyclorotor, NACA 0015 had the highest power loading followed by NACA 0010 and then NACA 0006. The power loading also increased when using more blades with constant chord (increasing solidity); this observation was found over a wide range of blade pitching amplitudes. Asymmetric pitching with higher pitch angle at the top of the blade trajectory than at the bottom produced better power loading. The chordwise optimum pitching axis location was approximately 25-35% of the blade chord. For a constant solidity, the rotor with fewer number of blades produced higher thrust and the 2-bladed rotor had the best power loading. Any significant bending and torsional flexibility of the blades had a deleterious effect on performance. The optimized cyclorotor had slightly higher power loading when compared to a conventional micro-rotor when operated at the same disk loading. The optimum configuration based on all the tests was a 4-bladed rotor using 1.3 inch chord NACA 0015 blade section with an asymmetric pitching of 45 at top and 25 at bottom with the pitching axis at 25% chord. The aeroelastic analysis was performed using two approaches, one using a second-order non-linear beam FEM analysis for moderately flexible blades and second using a multibody based large-deformation analysis (especially applicable for extremely flexible blades) incorporating a geometrically exact beam model. An unsteady aerodynamic model is included in the analysis with two different inflow models, single streamtube and a double-multiple streamtube inflow model. For the cycloidal rotors using moderately flexible blades, the aeroelastic analysis was able to predict the average thrust with sufficient accuracy over a wide range of rotational speeds, pitching amplitudes and number of blades. However, for the extremely flexible blades, the thrust was underpredicted at higher rotational speeds and this may be because of the overprediction of blade deformations. The inclusion of the actual blade pitch kinematics and unsteady aerodynamics was found crucial in the accurate sideward force prediction

Assistive control for non-contact machining of random shaped contours

Recent achievements in robotics and automation technology has opened the door towards different machining methodologies based on material removal. Considering the non force feedback nature of non-contact machining methods, careful attention on motion control design is a primary requirement for successful achievement of precise cutting both in machining and in surgery processes. This thesis is concerned with the design of pre-processing methods and motion control techniques to provide both automated and human-assistive non-contact machining of random and complex shaped contours. In that sense, the first part of the thesis focuses on extraction of contours and generation of reference trajectories or constraints for the machining system. Based on generated trajectories, two different control schemes are utilized for high precision automated machining. In the first scheme, preview control is adopted for enhancing the tracking performance. In the second scheme, control action is generated based on direct computation of contouring error in the operational space by introducing a new coordinate frame moving with the reference contour. Further, non-contact machining is extended for realization in a master/slave telerobotic framework to enable manual remote cutting by a human operator. With the proposed approach, the human operator (i.e. a surgeon) is limited to conduct motion within a desired virtual constraint and is equipped with the ability of adjusting the cutting depth over a that contour providing advantage for laser surgery applications. The proposed framework is experimentally tested and results of the experiments prove the applicability of proposed motion control schemes and show the validity of contributions made in the context of thesis

Optimized state feedback regulation of 3DOF helicopter system via extremum seeking

In this paper, an optimized state feedback regulation of a 3 degree of freedom (DOF) helicopter is designed via extremum seeking (ES) technique. Multi-parameter ES is applied to optimize the tracking performance via tuning State Vector Feedback with Integration of the Control Error (SVFBICE). Discrete multivariable version of ES is developed to minimize a cost function that measures the performance of the controller. The cost function is a function of the error between the actual and desired axis positions. The controller parameters are updated online as the optimization takes place. This method significantly decreases the time in obtaining optimal controller parameters. Simulations were conducted for the online optimization under both fixed and varying operating conditions. The results demonstrate the usefulness of using ES for preserving the maximum attainable performance

Parallel Manipulators

In recent years, parallel kinematics mechanisms have attracted a lot of attention from the academic and industrial communities due to potential applications not only as robot manipulators but also as machine tools. Generally, the criteria used to compare the performance of traditional serial robots and parallel robots are the workspace, the ratio between the payload and the robot mass, accuracy, and dynamic behaviour. In addition to the reduced coupling effect between joints, parallel robots bring the benefits of much higher payload-robot mass ratios, superior accuracy and greater stiffness; qualities which lead to better dynamic performance. The main drawback with parallel robots is the relatively small workspace. A great deal of research on parallel robots has been carried out worldwide, and a large number of parallel mechanism systems have been built for various applications, such as remote handling, machine tools, medical robots, simulators, micro-robots, and humanoid robots. This book opens a window to exceptional research and development work on parallel mechanisms contributed by authors from around the world. Through this window the reader can get a good view of current parallel robot research and applications