Inverse Kinematics-Based Trajectory Generation For Robot-Assisted 3D Surface Machining

Machining and tracking of 3D surfaces using industrial robot is not a newmethod, but the new in this paper is the use of simple trigonometric relations inthe calculations of robots joints variables by using the inverse kinematicsapproach rather than the previous conventional methods like forward kinematics,decoupling, and sensor based machining. Calculations of the joints variables aremainly based on knowing the robot reference point (origin point) and thecoordinates of the tip of the end effectors which is the cutter contact point (CC-P)at the surface. The coordinate of the cutter location point (CL-P) is the coordinateof the normal vector that passing through the intended cutter contact point. Thejoints variables are calculated based on simple trigonometric relationships. Theresults of the proposed method are verified based on hand-made simulationprograms organized for this purpose. The simulation results explore the highaccuracy and efficiency of the proposed method and its high speed in prediction ofjoints variables

Design and Optimization of a Robot for Abrasive Waterjet Polishing of Hydraulic Turbine Blades

RÉSUMÉ Dans l’industrie de fabrication de turbine hydraulique, toutes les surfaces de turbines qui sont en contact avec de l’eau devraient être polies afin d’obtenir la qualité et l’efficacité maximales. Pour cela, il est nécessaire d’utiliser une méthode de polissage qui peut avoir accès à toutes les surfaces des turbines incluant leurs bords, leurs zones restreintes et leurs courbures serrées. En raison des propriétés particulières qu’offre la technique de polissage par jet d’eau abrasif, celle-ci peut être utilisée pour accomplir cette tâche. Par conséquent, dans cette recherche, les propriétés de cette méthode non-conventionnelle sont examinées dans un premier temps et les principaux paramètres affectant ses performances sont alors déterminés. Ensuite, les conditions nécessaires de manipulations de la buse de pulvérisation vis-à-vis des surfaces courbes sont étudiées et les propriétés d’un bras robotisé pour manipuler celle-ci sont obtenues afin de réaliser cette tâche d’une manière appropriée. Par après, plusieurs mécanismes robotiques tels que des mécanismes sériels, parallèles à membrures, parallèles à câbles, et des robots hybrides sont considérés et leurs capacités à être utilisé dans ce processus sont analysées. Il est alors démontré qu’une l’architecture hybride est le meilleur candidat à retenir pour le design d’un robot de polissage par jet d’eau abrasif. Ensuite, l’architecture conceptuelle d’un robot hybride à 5 DDL est proposée. La structure du robot est constituée d’un mécanisme parallèle à câbles à 3 DDL et d’un poignet sériel à 2 DDL. Afin d’améliorer les propriétés cinématiques du mécanisme à câbles tout en minimisant le nombre d’actionneurs nécessaires, il est proposé d’utiliser des différentiels pour guider ce robot manipulateur. Aussi, la rigidité et la compacité du mécanisme sont améliorées en utilisant une liaison prismatique. Par la suite, les systèmes à câbles différentiels sont examinés et les différences entre leurs propriétés cinématiques et celles de systèmes actionnés indépendamment pour chaque câble sont décrites. Il est démontré que la force résultante de tous les câbles d’un différentiel à câbles doit être prise en compte dans son analyse cinématique. En effet, dans un système différentiel planaire, la direction de la force résultante n’est pas fixée vers un point particulier. Mais plutôt, elle se déplace dans le plan de ce système différentiel. Cette propriété peut être bénéfique pour les propriétés cinématiques des robots à câbles. En comparant deux types d’espace de travail de plusieurs robots planaires actionnés par des mécanismes différentiels par rapport à leurs équivalents pleinement actionnés, il est alors montré qu’en utilisant ces mécanismes, les espaces de travail des robots planaires à câbles peuvent être améliorés. Cependant, cette même propriété qui augmente la plage de variation de la direction de la force résultante dans un câble différentiel, diminue aussi son amplitude. Ainsi, le design optimal d’un différentiel à câble résulte d’un compromis entre ces deux propriétés.----------ABSTRACT In hydraulic turbine manufacturing, all surfaces of the turbines which are in contact with the water flow should be polished to obtain the desired quality and maximal efficiency. For this, it is needed to use an effective polishing method which can have access to all surfaces of the turbines including edges, narrow areas and tight bends. Because of the particular properties of the abrasive waterjet polishing technique, it can be used to accomplish this task. Therefore, in this research, the properties of this non-conventional method are first investigated and the main parameters affecting its performance are then determined. Next, the manipulation requirements of the jet nozzle over free-form surfaces are studied and the properties of a robotic arm to appropriately perform this task are obtained. Afterwards, several robotic mechanisms, e.g., serial, linkage-driven parallel, cabledriven parallel, and hybrid robots are considered and their abilities to be used in this process are investigated. It is then shown that a hybrid architecture is the best candidate for the design of an abrasive waterjet polishing robot. Next, the conceptual design of a 5-DOF hybrid robot is proposed. The structure of this robot is made of a 3-DOF cable-driven parallel mechanism and a 2-DOF serial wrist. To improve the kinematic properties of the cable-driven mechanism while the number of required actuators is kept at a minimum, it is proposed to use cable differentials to drive this manipulator. Also, the rigidity and compactness of the mechanism is improved through the use of a prismatic joint in its structure. Afterwards, differentially driven cable systems are investigated and the differences between their kinematic properties and these of independently actuated cables are described. It is shown that the resultant force of all cables of a cable differential should be taken into account in its kinematic analysis. Indeed, in a planar differential, the direction of the resultant force is not fixed toward a particular point. Instead, it moves within the plane of that differential. This property can be beneficial in the kinematic properties of differentially driven cable robots. By comparing two types of workspaces of several planar robots actuated by differentials with their fully actuated counterparts, it is then shown that using these mechanisms, these workspaces of planar cable robots can be improved. However, the same property that increases the range of variation of the resultant force direction in a cable differential, decreases its magnitude. Thus, the optimal design of a cable differential is a trade-off between these two properties. Next, a synthesis method is presented to find all possible arrangements of the cable differentials to generalize the idea of using such mechanisms in the design of planar cable robots. Additionally, the application of differentials in spatial robots is also investigated and it is shown that they have properties similar to the planar types

Robot tool use: A survey

Using human tools can significantly benefit robots in many application domains. Such ability would allow robots to solve problems that they were unable to without tools. However, robot tool use is a challenging task. Tool use was initially considered to be the ability that distinguishes human beings from other animals. We identify three skills required for robot tool use: perception, manipulation, and high-level cognition skills. While both general manipulation tasks and tool use tasks require the same level of perception accuracy, there are unique manipulation and cognition challenges in robot tool use. In this survey, we first define robot tool use. The definition highlighted the skills required for robot tool use. The skills coincide with an affordance model which defined a three-way relation between actions, objects, and effects. We also compile a taxonomy of robot tool use with insights from animal tool use literature. Our definition and taxonomy lay a theoretical foundation for future robot tool use studies and also serve as practical guidelines for robot tool use applications. We first categorize tool use based on the context of the task. The contexts are highly similar for the same task (e.g., cutting) in non-causal tool use, while the contexts for causal tool use are diverse. We further categorize causal tool use based on the task complexity suggested in animal tool use studies into single-manipulation tool use and multiple-manipulation tool use. Single-manipulation tool use are sub-categorized based on tool features and prior experiences of tool use. This type of tool may be considered as building blocks of causal tool use. Multiple-manipulation tool use combines these building blocks in different ways. The different combinations categorize multiple-manipulation tool use. Moreover, we identify different skills required in each sub-type in the taxonomy. We then review previous studies on robot tool use based on the taxonomy and describe how the relations are learned in these studies. We conclude with a discussion of the current applications of robot tool use and open questions to address future robot tool use

Design Transactions

Design Transactions presents the outcome of new research to emerge from ‘Innochain’, a consortium of six leading European architectural and engineering-focused institutions and their industry partners. The book presents new advances in digital design tooling that challenge established building cultures and systems. It offers new sustainable and materially smart design solutions with a strong focus on changing the way the industry thinks, designs, and builds our physical environment. Divided into sections exploring communication, simulation and materialisation, Design Transactions explores digital and physical prototyping and testing that challenges the traditional linear construction methods of incremental refinement. This novel research investigates ‘the digital chain’ between phases as an opportunity for extended interdisciplinary design collaboration. The highly illustrated book features work from 15 early-stage researchers alongside chapters from world-leading industry collaborators and academics

Design Transactions: Rethinking Information for a New Material Age

Design Transactions presents the outcome of new research to emerge from ‘Innochain’, a consortium of six leading European architectural and engineering-focused institutions and their industry partners. The book presents new advances in digital design tooling that challenge established building cultures and systems. It offers new sustainable and materially smart design solutions with a strong focus on changing the way the industry thinks, designs, and builds our physical environment. Divided into sections exploring communication, simulation and materialisation, Design Transactions explores digital and physical prototyping and testing that challenges the traditional linear construction methods of incremental refinement. This novel research investigates ‘the digital chain’ between phases as an opportunity for extended interdisciplinary design collaboration. The highly illustrated book features work from 15 early-stage researchers alongside chapters from world-leading industry collaborators and academics