불확실성을 포함하는 조립작업을 위한 컴플라이언스 기반 펙인홀 전략

학위논문 (박사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(지능형융합시스템전공), 2020. 8. 박재흥.The peg-in-hole assembly is a representative robotic task that involves physical contact with the external environment. The strategies generally involve performing the assembly task by estimating the contact state between the peg and the hole. The contact forces and moments, measured using force sensors, are primarily used to estimate the contact state. In this paper, in contrast to past research in the area, which has involved the utilization of such expensive devices as force/torque sensors or remote compliance mechanisms, an inexpensive method is proposed for peg-in-hole assembly without force feedback or passive compliance mechanisms. The method consists of an analysis of the state of contact between the peg and the hole as well as a strategy to overcome the inevitable positional uncertainty of the hole incurred in the recognition process. A control scheme was developed to yield compliant behavior from the robot with physical contact under the condition of hybrid position/force control. Proposed peg-in-hole strategy is based on compliance characteristics and generating the force and moment. The peg is inserted into the hole as it adapts to the external environment. The effectiveness of the proposed method was experimentally verified using a humanoid upper body robot with fifty degrees of freedom and a peg-in-hole apparatus with a small clearance (0.1 mm). Three cases of experiments were conducted; Assembling the peg attached to the arm in the hole fixed in the external environment, grasping a peg with an anthropomorphic hand and assembling it into a fixed hole, and grasping both peg and hole with both hands and assembling each other. In order to assemble the peg-in-hole through the proposed strategy by the humanoid upper body robot, I present a method of gripping an object, estimating the kinematics of the gripped object, and manipulating the gripped object. In addition to the cost aspect, which is the fundamental motivation for the proposed strategy, the experimental results show that the proposed strategy has advantages such as fast assembly time and high success rate, but has the disadvantage of unpredictable elapsed time. The reason for having a high variance value for the success time is that the spiral trajectory, which is most commonly used, is used. In this study, I analyze the efficiency of spiral force trajectory and propose an improved force trajectory. The proposed force trajectory reduces the distribution of elapsed time by eliminating the uncertainty in the time required to find a hole. The efficiency of the force trajectory is analyzed numerically, verified through repeated simulations, and verified by the actual experiment with humanoid upper body robot developed by Korea institute of industrial technology.펙인홀 조립은 로봇의 접촉 작업을 대표하는 작업으로, 펙인홀 조립 전략을 연구함으로써 산업 생산 분야의 조립작업에 적용할 수 있다. 펙인홀 조립작업은 일반적으로 펙과 홀 간의 접촉상태를 추정함으로써 이루어진다. 접촉상태를 추정하기 위해 가장 널리 쓰이는 방법은 힘 센서를 사용하는 것인데, 접촉 힘과 모멘트를 측정하여 접촉상태를 추정하는 방식이다. 만약 이러한 센서를 사용하지 않을 수 있다면, 하드웨어 비용과 소프트웨어 연산량 감소 등의 장점이 있음은 자명하다. 본 논문에서는 힘 센서 혹은 수동 컴플라이언스 장치를 사용하지 않는 펙인홀 전략을 제안한다. 홀에 대한 인식 오차 혹은 로봇의 제어 오차를 극복하기 위하여 먼저 펙과 홀의 접촉 가능 상태를 분석하고 로봇의 컴플라이언스 모션을 위한 제어 프레임워크를 디자인한다. 전략은 컴플라이언스 특징에 기반하며 펙에 힘과 모멘트를 생성시킴으로써 조립작업을 수행한다. 펙은 외부환경에 순응함으로써 홀에 삽입된다. 제안한 전략은 낮은 공차를 갖는 펙인홀 실험을 통해서 그 유효성이 검증된다. 펙과 홀을 로봇팔과 외부환경에 각각 고정된 환경에서의 실험, 인간형 로봇핸드를 이용하여 펙을 잡아서 고정된 홀에 삽입하는 실험, 그리고 테이블에 놓인 펙과 홀을 각각 로봇핸드로 파지하여 조립하는 총 세 가지의 실험을 수행하였다. 핸드로 펙을 파지하고 조작하기 위하여, 파지 방법과 핸드를 이용한 물체 조작 알고리즘을 간략히 소개하였다. 제안한 전략의 성능을 실험적으로 분석한 결과, 높은 조립 성공률을 갖는 대신 조립시간이 예측할 수 없는 단점이 나타나 이를 보완하기 위해서 렌치 궤적 또한 제안하였다. 먼저 가장 일반적으로 사용되는 나선 힘 궤적을 이용했을 때 조립 성공시간의 분산이 큰 이유를 확률개념을 이용해 분석하고, 이를 보완하기 위한 부분적 나선 힘 궤적을 제안한다. 제안한 힘 궤적이 나선 힘 궤적에 비해 갖는 성능의 우수성을 증명하기 위하여 수치적 분석, 반복적 시뮬레이션, 그리고 로봇을 이용한 실험을 수행하였다.1 INTRODUCTION 1 1.1 Motivation: Peg-in-Hole Assembly 1 1.2 Contributions of Thesis 2 1.3 Overview of Thesis 3 2 COMPLIANCE BASED STRATEGY 5 2.1 Background & Related Works 5 2.2 Analysis of Peg-in-Hole Procedure 6 2.2.1 Contact Analysis 7 2.2.2 Basic Idea 9 2.3 Peg-in-Hole Strategy 12 2.3.1 Unit Motions 12 2.3.2 State of Strategy 13 2.3.3 Conditions for State Transition 15 2.4 Control Frameworks 18 2.4.1 Control for Compliant Behavior 18 2.4.2 Friction Compensate 20 2.4.3 Control Input for the Strategy 25 2.5 Experiment 29 2.5.1 Experiment Environment 29 2.5.2 Fixed Peg and Fixed Hole 31 2.5.2.1 Experiment Results 31 2.5.2.2 Analysis of Force and Control Gain 36 2.5.3 Peg-in-Hole with Multi Finger Hand 41 2.5.3.1 Object Grasping 42 2.5.3.2 Object In-Hand Manipulation 44 2.5.3.3 Experiment Results 49 2.5.4 With Upper Body Robot 50 2.5.4.1 Peg-in-Hole Procedure 52 2.5.4.2 Kinematics of Grasped Object 54 2.5.4.3 Control Frameworks 54 2.5.4.4 Experiment Results 56 2.6 Discussion 59 2.6.1 Peg-in-Hole Transition 59 2.6.2 Influential Issues 59 3 WRENCH TRAJECTORY 63 3.1 Problem Statement 64 3.1.1 Hole Search Process 64 3.1.2 Spiral Force Trajectory Analysis 66 3.2 Partial Spiral Force Trajectory 70 3.2.1 Force Trajectory with Tilted Posture 70 3.2.2 Probability to Three-point Contact 76 3.3 SIMULATION & EXPERIMENT 78 3.3.1 Simulation 78 3.3.2 Experiment 83 4 CONCLUSIONS 90 Abstract (In Korean) 102Docto

Synthesis of Manufacturing Systems Using Co-Platforming

Modern manufacturing environment is characterized by frequent changes within product design in order to satisfy evolving customer requirements. Various strategies are implemented in order to efficiently manage the consequences arising from the product design changes starting from design of the product, planning, manufacturing…etc. This dissertation focuses mainly on the manufacturing phase in which a new concept in manufacturing system synthesis is proposed. A new concept in manufacturing system synthesis has been introduced and coined as “Co-platforming”. Co-platforming is the synthesis of manufacturing systems through mapping product platform features and components to platform machines on one side, and non-platform product features and components to non-platform machines on the other side, in order to reduce the manufacturing system investment cost and prolong the manufacturing system useful life as product variants evolve and change. Tools and methods are developed to synthesize the manufacturing system based on Co-platforming within functional and physical levels. At the functional level, the group of platform and non-platform machines and the number of each machine type are determined. A new matrix based mapping model is proposed to determine the platform and non-platform machines candidates. A ranking coefficient is formulated which ranks the platform machines according to their machining capabilities in order to assist manufacturing firms in decision making concerning which type of platform machine to choose. Furthermore, a new mathematical programming optimization model is proposed in order to provide the optimum selection of machine types among machine candidates and their numbers. Moreover, a new mathematical programming model is proposed which synthesizes manufacturing systems taking into consideration machine level and system level changes based on co-platforming. At the physical level, the manufacturing system configuration is determined which is concerned with determining the number of stages, types of machines in each stage and the number of machines in each stage. A new mathematical programming optimization model is proposed which determines, in addition to the type and number of each machine, the optimal manufacturing system configuration based on co-platforming. The Co-platforming methodology is being applied in two case studies from automotive industry. The first case study is concerned with machining of automotive cylinder blocks taken from Mitsubishi Heavy Industries and the second case study is concerned with the assembly of automotive cylinder heads taken from ABB flexible automation. The results obtained from the co-platforming methodology indicate that cost reduction can be achieved when synthesizing the manufacturing system based on co-platforming

Cuttings transport and hydraulics optimisation for underbalanced drilling (UBD) operations in concentric and eccentric, directional and extended reach wells.

Underbalanced drilling facilitates the effective control of wellbore pressures - amongst several other important advantages - when compared to conventional drilling technology. However, this involves the flow of multiphase fluids, which introduces additional complexities due to highly transient flow patterns, unpredictable wellbore hydraulics and increased tendency for the settling of drilled cuttings in the wellbore. An accurate prediction of fluid dynamics and cutting transport efficiency is required to achieve an effective pressure-management hole-cleaning operation. In this research, a theoretical, numerical and experimental study was performed to analyse and investigate cutting transport dynamics and wellbore hydraulics. The analytical study involved the development of several mechanistic models, which are valid for both single phase and two-phase flows in the concentric and eccentric annuli, both with and without inner pipe rotation. The study derives and presents Reynolds number and effective viscosity equations valid for annuli flow of both Newtonian and non-Newtonian Power law, Bingham plastic and Yield power law fluids. The study also used the solution of the continuity equation of motion for axial steady-state flows to formulate new Laminar and turbulent friction geometry parameter and friction factor equations, which take into account the combined effect of the fluid rheology, fluid circulation rate, pipe eccentricity and inner pipe rotation speed for the evaluation of the flow dynamics and pressure losses in the annuli. In addition, the study developed new flow gas-liquid pattern-dependent multi-layered models for the different cuttings transport mechanisms, valid for both horizontal and inclined annuli flows. Numerical computational fluid dynamics simulations were performed to discretise and solve the governing equations for fluid flow, using a finite volume mathematical approach to obtain velocity, viscosity and pressure fields for different input conditions. Furthermore, an experimental study was carried out to evaluate the interplay between the two-phase gas-liquid flow patterns and the major drilling parameters, and to investigate the influence on the cuttings and fluid flow dynamics in a horizontal and inclined drilling wellbore. Results showed that the effect of the drillpipe rotation on cuttings transport in the annuli is highly dependent on the fluid rheological properties, the drillpipe eccentricity, the wellbore inclination and fluid flow pattern. The annuli pressure gradient was found to be dependent on the fluid flow pattern and the prevailing cutting transport mechanism. The minimum requirements to clean an eccentric annulus is higher than that required for the concentric annulus. Furthermore, the local mixture properties and gas-liquid flow pattern of the fluid is strongly influenced by the inclination angle of the wellbore, which consequently influences annuli pressure losses and cutting transport dynamics. Although drillpipe rotation can improve cuttings transport through the annuli, the influence of drillpipe rotation on the cutting's movement in the two-phase gas-liquid drilling fluid is much less than that of the single-phase drilling fluid. Overall, a good match was found when the mathematical models were compared to the experimental data. The output of this research is very useful for implementing an efficient cutting transport operation, hydraulic program optimisation and effective wellbore control, particularly for managed pressure drilling operations

Smart Technologies for Precision Assembly

This open access book constitutes the refereed post-conference proceedings of the 9th IFIP WG 5.5 International Precision Assembly Seminar, IPAS 2020, held virtually in December 2020. The 16 revised full papers and 10 revised short papers presented together with 1 keynote paper were carefully reviewed and selected from numerous submissions. The papers address topics such as assembly design and planning; assembly operations; assembly cells and systems; human centred assembly; and assistance methods in assembly

Plasmonic nanopores for single molecule spectroscopy towards sequencing applications

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Organic thin films as active materials in field effect transistors and electrochemical sensing

This PhD thesis is focused on Organic Electronics, an emerging field where different disciplines converge to gain insights into the properties of organic materials and their applications. Under the present work different organic materials have been realized and analysed for application both in Organic Field Effect Transistors and electrochemical sensing with Organic Electrochemical Transistors. An overview about Organic Electronic is reported with the most recent advancement of the last years: a state of the art of research about Organic Field Effect Transistors (OFETs) and Organic Electrochemical Transistors (OECTs) is given, with an overview on the emerging Organic Bioelectronics. The main motifs of the research performed are reported along the discussion. In the application of the supersonic molecular beam epitaxy method, thin films of Copper Phthalocyanine have been grown, reaching an unprecedented order in the crystalline structure, as the characterization by Raman spectroscopy and AFM have shown. A modified-pentacene molecule (2,3-CN2-TIPS-Pn films) has been used as active layer for the building of an OFET device, which showed an ambipolar behaviour with balanced electrons and holes mobility on the order of 2⋅10-3cm2/Vs. The charge transport properties of 2,3-CN2-TIPS-Pn films show the effectiveness of TIPS-Pn functionalization with cyano e− withdrawing groups to promote e- transport while maintaining equivalent h− transport. A second OFET device has been realized with tetracene organic thin films deposited on different dielectrics substrates: the devices have been characterized and the mobility measured. For the tetracene film deposited on the polystyrene substrate, we have found a mobility of 2⋅10-1 cm2/Vs, the highest retrieved up to now in literature for tetracene. The molecular structures of all the organic molecules used, have been deeply investigated by means AFM analysis and XRD-advanced algorithm tools. For the films made with the TIPS molecule, the GIXRD analysis revealed a favourable arrangement of the molecules in the TFT channel. The XRD analysis performed on the tetracene films revealed interesting correlation between the mobility of the film and the AFM and structural parameters: in particular the polystyrene film shows the best surface coverage and the highest alpha phase percentage of the molecular structure. New insights into the device physics of OECT have been discovered: in the sensing experiments with OECTs, the role of the gate electrode has been investigated. This clarified the two working principles an OECT can operate (faradaic or non-faradaic mode). We found that an OECT can switch between these two modes of operation simply changing the metal wire acting as gate electrode. In particular the faradaic operational mode lead to the possibility to exploit the transistor as a halide sensor, able to detect Na+ ions in solution with a sensibility up to 10μM. Then the role of electrolyte has been studied with micellar structures, which open unexplored horizons for the application of OECT with a new class of electrolytes. The ability of micelles to dope/dedope efficiently the PEDOT:PSS permitted to investigate the doping process of the polymer, that is one of the main issue today in organic electronics. The modulation signals have been correlated with the surface charge of the micelles, measured by the zeta-potential techniques and the injection of micelles into the polymer structure has been probed by an optical spectroscopy measurement, performed in-situ during the OECT current acquisition. As a consequence of the micelle experiment, bilayer structure, like liposomes, have been tested and detected for the first time with an OECT. Although this experiment is currently in progress, it seems particularly promising, mainly because the opportunity to exploit the ability of liposomes to trap and release drugs in a controlled way. A new nanoparticles-based sensor has been developed, able to detect the presence in solution of iron-oxide magnetic nanoparticles functionalised with different polymeric coatings: we provide the ability of OECTs to detect and monitor selectively, with an appropriate choice of the electrolyte, different nanosystems. We demonstrate an on-line sensing based on OECTs, with an easy sampling/sample preparation, for the detection of functionalized magnetic nanoparticles. OECTs have promising applications in bioelectronics as well as in nanomedicine or neuroscience. They are becoming an ideal platform for both in-vitro and in-vivo biomedical applications, as well as for the development of protocells inside miniaturized electro-chemical laboratory