Combining haptics and inertial motion capture to enhance remote control of a dual-arm robot

High dexterity is required in tasks in which there is contact between objects, such as surface conditioning (wiping, polishing, scuffing, sanding, etc.), specially when the location of the objects involved is unknown or highly inaccurate because they are moving, like a car body in automotive industry lines. These applications require the human adaptability and the robot accuracy. However, sharing the same workspace is not possible in most cases due to safety issues. Hence, a multi-modal teleoperation system combining haptics and an inertial motion capture system is introduced in this work. The human operator gets the sense of touch thanks to haptic feedback, whereas using the motion capture device allows more naturalistic movements. Visual feedback assistance is also introduced to enhance immersion. A Baxter dual-arm robot is used to offer more flexibility and manoeuvrability, allowing to perform two independent operations simultaneously. Several tests have been carried out to assess the proposed system. As it is shown by the experimental results, the task duration is reduced and the overall performance improves thanks to the proposed teleoperation method

Design, characterisation and testing of SU8 polymer based electrothermal microgrippers

Microassembly systems are designed to combine micro-component parts with high accuracy. These micro-components are fabricated using different manufacturing processes in sizes of several micrometers. This technology is essential to produce miniaturised devices and equipment, especially those built from parts requiring different fabrication procedures. The most important task in microassembly systems is the manipulator, which should have the ability to handle and control micro-particles. Different techniques have been developed to carry out this task depending on the application, required accuracy, and cost. In this thesis, the most common methods are identified and briefly presented, and some advantages and disadvantages are outlined. A microgripper is the most important device utilized to handle micro-objects with high accuracy. However, it is a device that can be used only in sequential microassembly techniques. It has the potential to become the most important tool in the field of micro-robotics, research and development, and assembly of parts with custom requirements. Different actuation mechanisms are employed to design microgrippers such as electromagnetic force, electrostatic force, piezoelectric effect, and electrothermal expansions. Also, different materials are used to fabricate these microgrippers, for example metals, silicon, and polymers such as SU-8. To investigate the limitation and disadvantages of the conventional SU-8 electrothermal based microgrippers, different devices designed and fabricated at IMT, Romania, were studied. The results of these tests showed a small end-effector displacement and short cycling on/off (lifetime). In addition, the actuator part of these microgrippers was deformed after each operation, which results in reduced displacement and inconsistent openings at off state every time it was operated in a power ON/OFF cycle. One of these limitations was caused by the existence of conductors in arms of the end-effectors. These conductor designs have two disadvantages: firstly, it raises temperature in the arms and causing an expansion in the opposite direction of the desired displacement. Secondly, since the conductors pass through the hinges, they should be designed wide enough to reduce the conductor resistance as much as possible. Therefore, the wider the hinges are, the higher the in-plane stiffness and the less out of plane deflection. As a result, it increases the reaction force of the arm reducing the effect of deformation. Based on these limitations a new actuatorstructure of L-shape was proposed to reduce the effects of these drawbacks. This actuator has no conductor in the hinges or the arms of the end-effectors which reduce limitation on the hinge width. . In addition, a further development of this actuator was proposed to increase the stiffness of the actuator by doubling its thickness compared with the other parts of the griper. The results of this actuator proved the improvement in performance and reduction of the actuator deformation. This new actuator structure was used to design several different microgrippers with large displacement and suitable for a wide range of applications. Demonstrations of the capabilities of the microgrippers to be used in microassembly are presented. In addition, a novel tri-directional microactuator is proposed in this thesis. This actuator’s end-effector is capable of displacements in three different directions. This actuator was used with the other designs to develop a novel three-arm (three fingers) multidirectional microgripper. To study the microgripper displacement as a function to the heater temperature, the TCR of the conductor layer of each device was measured. Because different configurations of conductor layers were studied, a significant effect of the metal layer structure on TCR was discovered. The TCR value of gold film is reduced significantly by adding the chromium layers below and about it which were used to improve the adhesion between the gold film and the SU layers. In this thesis, a new method based on a robotic system was developed to characterise these microgrippers and to study the steady state, dynamic response, and reliability (lifetime cycling on/off). An electronic interface was developed and integrated to the robotic system to control and drive the microgrippers. This new system was necessary to carry out automated testing of the microgrippers with accurate and reliable results. Four different new groups of microgrippers were designed and studied. The first group was indirectly actuated using an L-Shaped actuator and two different actuator widths. The initial opening was 120 μm for both designs. The maximum displacement was about 140 μm for both designs. However, the actuator in the wider heater width showed more stable behavior during the cycling and the dynamic tests. The second group was based on direct actuation approach using the L-Shaped actuator. There were eight different designs based on this method with different heater conductor shape, actuator width, and arm thickness. The initial opening was 100 μm and there were different displacements for the eight designs. The study of these microgrippers proved that the actuator stiffness has a significant effect on the microgripper displacement. In addition, the shape of the heater conductor has less effect. The largest displacement achieved using this method of design was about 70 μm. The third group was designed for dual mode operation and has three different designs. The initial openings were 90 μm and 250 μm. The displacement was about 170 μm in both modes. The last microgripper design was a tri-arm design for multi-mode operation. The lifetime study of SU8 based microgrippers in this thesis was the first time such an investigation was carried out. The results of IMT designs showed that the larger is the displacement the less stable is the gripper design because of the high rection force acting on the actuators. The L-shape based microgrippers had better performance and they did not break after more than 400 cycles. In addition, the studies of static displacement and dynamic response of different designed microgripper proved that better performance of the proposed actuator can be obtained by using double thickness for the actuator as compared to the arm thickness

Numerical and experimental study of electroadhesion to enable manufacturing automation

Robotics and autonomous systems (RAS) have great potential to propel the world to future growth. Electroadhesion is a promising and potentially revolutionising material handling technology for manufacturing automation applications. There is, however, a lack of an in-depth understanding of this electrostatic adhesion phenomenon based on a confident electroadhesive pad design, manufacture, and testing platform and procedure. This Ph.D. research endeavours to obtain a more comprehensive understanding of electroadhesion based on an extensive literature review, theoretical modelling, electrostatic simulation, and experimental validation based on a repeatable pad design, manufacture, and testing platform and procedure. [Continues.

Calibration and Control of a Redundant Robotic Workcell for Milling Tasks

This article deals with the tuning of a complex robotic workcell of eight joints devoted to milling tasks. It consists of a KUKA (TM) manipulator mounted on a linear track and synchronised with a rotary table. Prior to any machining, the additional joints require an in situ calibration in an industrial environment. For this purpose, a novel planar calibration method is developed to estimate the external joint configuration parameters by means of a laser displacement sensor and avoiding direct contact with the pattern. Moreover, a redundancy resolution scheme on the joint rate level is integrated within a computer aided manufacturing system for the complete control of the workcell during the path tracking of a milling task. Finally, the whole system is tested in the prototyping of an orographic model.Andres De La Esperanza, FJ.; Gracia Calandin, LI.; Tornero Montserrat, J. (2011). Calibration and Control of a Redundant Robotic Workcell for Milling Tasks. International Journal of Computer Integrated Manufacturing. 24(6):561-573. doi:10.1080/0951192X.2011.566284S56157324

레이져 포인터를 이용한 Product-of-Exponentials 기반 직렬로봇 기구학적 보정 알고리즘

학위논문(석사)--서울대학교 대학원 :공과대학 기계항공공학부,2019. 8. 박종우.This thesis proposes a kinematic calibration algorithm for serial robots based on a minimal product of exponentials (POE) forward kinematic model. Generally, robot calibration requires the measurement of the end-effector frame (position and orientation), which typically requires special measurement equipment. To avoid using complex measurement devices and to make the calibration easy to implement for even the most general serial robots, in our approach we attach a laser pointer to the end-effector, which is then aimed at a set of fixed known reference points in the plane. Treating the laser as a prismatic joint and the reference point as the tip, kinematic calibration is then performed by minimizing the Cartesian position difference between the measured and estimated Cartesian tip position of the robot. Our method is validated via simulations and experiments involving a seven-dof industrial robot arm.위 논문은 Minimal POE (product of exponentials) 정기구학 모델에 기반한 직렬로봇 캘리브레이션 알고리즘을 제안한다. 일반적으로 로봇 캘리브레이션은 엔드이펙터 프레임의 위치와 방향을 측정하는 작업을 수행해야 하는데, 이는 특별한 측정장비를 필요로 한다. 복잡한 측정장비의 사용 회피와 다양한 형태의 직렬로봇에 쉽게 응용하기 위해, 이번 논문에서는 엔드이펙터에 레이저포인터를 부착하여 평면 위의 위치가 알려진 참조점들을 추적하여 캘리브레이션을 수행하는 방법을 제시한다. 캘리브레이션은 레이저포인터와 참조점을 각각 선형조인트와 팁으로 생각하여 로봇 팁 위치의 측정값과 추정값의 차이를 최소화하는 과정으로 진행된다. 7자유도 산업용 로봇 팔에 대해 시뮬레이션과 실제 공간에서의 실험을 통해 캘리브레이션 방식을 검증했다.1 Introduction 1 1.1 Existing Methods 2 1.2 Contributions of This Thesis 4 2 Kinematics Preliminaries 6 2.1 Geometric Background 6 2.1.1 The Lie Group Formulations 6 2.1.2 Screw Motions 8 2.1.3 Adjoint Representation 9 2.2 Forward Kinematics 9 2.2.1 The Product of Exponentials Formula 9 2.2.2 The Minimal Product of Exponentials Formula 11 2.3 Kinematic Error Model 14 2.3.1 Linearizing the Forward Kinematics 15 3 Calibration Methodology 19 3.1 The Concept of the Method 19 3.1.1 Forward Kinematics of a Robot With a Laser Pointer 19 3.1.2 The Error Model for Calibration 20 3.2 Calibration Algorithm 23 3.2.1 The Estimation Method of the Length of the Laser 24 3.2.2 Identification Process 25 4 Experiments 29 4.1 Simulation 1: 6-Dof Robot With Precise Data 29 4.2 Simulation 2: 6-Dof Robot With Noisy Data 31 4.3 Experiments on a 7-Dof Robot 34 5 Conclusion 39 A Appendix 41 A.1 Conversion From dq to dS and dSM [1] 41 Bibliography 43 Abstract 46Maste

Relative posture-based kinematic calibration of a 6-RSS parallel robot by optical coordinate measurement machine

In this article, a relative posture-based algorithm is proposed to solve the kinematic calibration problem of a 6-RSS parallel robot using the optical coordinate measurement machine system. In the research, the relative posture of robot is estimated using the detected pose with respect to the sensor frame through several reflectors which are fixed on the robot end-effector. Based on the relative posture, a calibration algorithm is proposed to determine the optimal error parameters of the robot kinematic model and external parameters introduced by the optical sensor. This method considers both the position and orientation variations and does not need the accurate location information of the detection sensor. The simulation results validate the superiority of the algorithm by comparing with the classic implicit calibration method. And the experimental results demonstrate that the proposal relative posture-based algorithm using optical coordinate measurement machine is an implementable and effective method for the parallel robot calibration

Développement d'un procédé automatisé pour la mise en forme de préformes textiles pour les matériaux composites

RÉSUMÉ Les matériaux composites sont de plus en plus présents dans les domaines de hautes performances tels que l’automobile et l’aéronautique. Depuis quelques années, les procédés de fabrication de composites à base de fibre de carbone se tournent de plus en plus vers l’utilisation de préformes textile. Ces dernières permettent de diminuer drastiquement le temps de production des pièces en composites. Cependant, la fabrication des préformes textiles souffre de plusieurs problèmes, entre autres, beaucoup d’opérations sont faites à la main et induisent ainsi de très long cycles de fabrication en plus de défauts dans le produit final. Le projet présenté par ce mémoire expose une solution robotique pour la fabrication des préformes textiles des matériaux composites à base de fibres de carbone (CFRP) telle que développée au Groupe CTT (GCTTG). En effet, l’hypothèse ici posée est que l’automatisation d’un tel procédé permet de réduire le temps de fabrication des préformes textiles en plus d’augmenter leur qualité. Plus en détail, les objectifs spécifiques sont d’optimiser les opérations de découpe, d’automatiser la manipulation des tissus et le changement des gabarits d’assemblage à l’aide d’un robot sériel industriel, à savoir un Kuka KR-100. Pour résoudre les problèmes liés à chaque opération du procédé (découpe, manipulation et assemblage), des solutions sont proposées. Tout d’abord, trois améliorations sont présentées pour résoudre les problèmes liés à la découpe : l’identification des meilleurs paramètres, le développement d’une nouvelle technique de découpe, et l’estimation de la pose optimale du robot. Puis, pour résoudre les problèmes liés à l’assemblage, une technique de calibration sans contact pour les repères de base est présentée. Enfin, la conception d’un outil pour la manipulation automatisée des préformes textiles est présentée sur la base d’un nouveau mécanisme possédant une capacité d’adaptation de forme à l’aide d’articulations passives compliantes. Les résultats expérimentaux démontrent qu’il est possible de diminuer la durée totale des opérations de fabrication de préforme textiles par rapport au procédé antérieurement fait à la main. Le type de mémoire choisi pour ce projet de recherche est par article. Le centre de ce travail est un article rédigé pour le Journal aéronautique et spatial du Canada (Canadian Aeronautics and Space Journal (CASJ)), intitulé Optimization of a Robotic Textile Preform Manufacturing Process for carbon fiber reinforced plastic (CFRP). Pour introduire cet article, une revue de littérature critique ainsi que la démarche générale du projet est présentées. Ensuite, certains aspects méthodologiques et résultats complémentaires sont élaborés pour compléter l’article. Finalement, une discussion générale et une conclusion terminent le mémoire.----------ABSTRACT Composite materials are increasingly present in areas of high performance such as automotive and aerospace. Recently the Carbon Fiber Reinforced Plastic (CFRP) manufacturing processes are turning more and more towards the use of textile preforms. Indeed, they allow to drastically reduce the time of production of composite parts. However, the manufacture of textile preforms suffer from several problems. Among these, many operations are made by hand and thus induce very long production cycle in addition to some defect in the final product. The project presented by this dissertation presents a robotic solution for the manufacturing of textile preforms of carbon fiber reinforced plastic (CFRP) as developed at CTT Group (GCTTG). Indeed, the assumption is made here that automation of such a process reduces the textile preform manufacturing time in addition to increasing their quality. In more detail, the specific objectives are to optimize the cutting, automate the handling of the fabric, and the changing of the jigs using an industrial serial robot, namely a Kuka KR-100. To solve the issues related to each of the process operations (cutting, handling and assembly), solutions are proposed in this dissertation. First, three improvements are presented which solve the problems related to the cuts: the best practice cutting parameter identification, the development of a novel cutting technique, and the estimation of the optimal robot pose. Then, to solve the issues related to assembly, a contactless base frame calibration technique is presented. Finally, the design of a tool for textile handling is also presented based on a novel mechanism using passive compliant shape adaptation. Experimental results demonstrate that it is possible to decrease the total duration of the textile preform fabrication operations compared to the process previously done by hand. The dissertation type chosen for this research project is by article. Therefore, the center of this work is an article written for the Canadian Aeronautics and Space Journal (CASJ) title Optimization of a Robotic Textile Preform Manufacturing Process for carbon fiber reinforced plastic (CFRP). To introduce this article, a literature review and the general approach of this project is presented. Then, some methodological aspects and complementary results are elaborated to complet the article. Finally, a general discussion and a conclusion complete the dissertation