Human machine interaction via the transfer of power and information signals

Robot manipulators are designed to perform tasks which would otherwise be executed by a human operator. No manipulator can even approach the speed and accuracy with which humans execute these tasks. But manipulators have the capability to exceed human ability in one particular area: strength. Through any reasonable observation and experience, the human's ability to perform a variety of physical tasks is limited not by his intelligence, but by his physical strength. If, in the appropriate environment, we can more closely integrate the mechanical power of a machine with intellectually driven human hand under the supervisory control of the human's intellect, we will then have a system which is superior to a loosely-integrated combination of a human and his fully automated robot as in the present day robotic systems. We must therefore develop a fundamental approach to the problem of this extending human mechanical power in certain environments. Extenders will be a class of robots worn by humans to increase human mechanical ability, while the wearer's intellect remains the central intelligent control system for manipulating the extender. The human body, in physical contact with the extender, exchanges information signals and power with the extender. Commands are transferred to the extender via the contact forces between the wearer and the extender as opposed to use of joystick (master arm), push-button or key-board to execute such commands that were used in previous man amplifiers. Instead, the operator becomes an integral part of the extender while executing the task. In this unique configuration the mechanical power transfer between the human and extender occurs in addition to information signal transfer. When the wearer uses the extender to touch and manipulate an object, the extender transfers to the wearer's hand, in feedback fashion, a scaled-down value of the actual external load which the extender is manipulating. This natural feedback force on the wearer's hand allows him to feel the scaled-down value of the external forces in the manipulations. Extenders can be utilized to maneuver very heavy loads in factories, shipyards, airports, and construction sites. In some instances, for example, extenders can replace forklifts. The experimental results for a prototype extender are discussed

Planificación automática y supervisión de operaciones de montaje mediante robots

One of the main topics to be solved in order to fully automate a robotized assembly task is the automatic determination of the movements to be done by the robot to properly perform the tasks when the existing uncertainty is not negligible. This problem is of particular theoretical and practical interest when rotational degrees of freedom and friction forces are taken into account. In this thesis, an automatic movement planner that considers these aspects is proposed, including the description of how to execute the plan and supervise the evolution of the task. In order to generate the plan, the task is represented by a finite number of states, which are associated to the nodes of a graph with the links connecting contiguous states. Then, using uncertainty models developed in the thesis, the domains of the possible configurations and reaction forces that can be measured by the corresponding sensors in each task state are determined. From the existing initial conditions of the task and the desired final conditions, an initial and a goal state are determined, and, using the state graph, a sequence of contiguous states joining them is searched. At the same time, state transition operators (movement directions of the robot) that may allow the transition from one state to the next in the sequence are also determined.The execution of the task according to the plan basically consist in the estimation of the current state by matching the sensorial information obtained on-line with the domains of configuration and force of each state, and then, the application of the proper state transition operator to proceed in the state sequence towards the goal state.The main contributions of the thesis are the following: on one side, as a general contribution, the proposed planning procedure that allows the simultaneous consideration of friction forces, rotational degrees of freedom, and the different uncertainty sources that affect a robotized task; on the other side, as more specific contributions, the proposal of task states as the occurrence of a set of basic contacts, and, for movements on a plane, the fusion of the uncertainty models and the determination of the reaction forces possible in any contact situation by using the dual representation of the force lines. The thesis includes the application of the developed concepts to a simple assembly task (the block in the corner problem) considering movements on a plane. Although the implementation is not a general application prototype, it contributes to the validation of the theoretical results of the work.Uno de los principales problemas a resolver en la automatización total de una tarea de montaje robotizada, es la determinación automática de los movimientos que debe realizar el robot para llevar a cabo la tarea cuando la incertidumbre que le afecta es significativa. Este problema es de especial interés teórico y práctico cuando se consideran grados de libertad de rotación y fuerzas de fricción. En la tesis se propone un planificador automático de movimientos que tiene en cuenta estos aspectos. Se describe también cómo llevar a cabo la ejecución del plan y supervisar la evolución de la tarea.Para llevar a cabo la planificación, la tarea se representa mediante un conjunto finito de estados. Considerando la incertidumbre mediante modelos desarrollados en la tesis, se determinan los dominios de observación de configuraciones y de fuerzas de reacción que pueden ser indicadas por los sensores cuando tiene lugar cada estado de la tarea. Los estados de la tarea se representan como nodos de un grafo en el que los arcos unen los estados contiguos.A partir de las condiciones iniciales de la tarea y condiciones finales deseadas se establecen sendos estados inicial y final, y, utilizando el grafo de estados, se determina una secuencia de estados contiguos que los ligue. Paralelamente, se determinan operadores de cambio de estado (direcciones de movimiento del robot) que pueden permitir la transición de un estado a otro de la secuencia.La ejecución de la tarea acorde al plan consiste básicamente en estimar el estado en curso contrastando la información sensorial obtenida en-línea con los dominios de observación de configuración y fuerza, para aplicar entonces el operador de cambio de estado que corresponda, y así sucesivamente hasta alcanzar el estado final.Las principales aportaciones de la tesis son las siguientes. Por un lado, desde un punto de vista general, cabe destacar el procedimiento de planificación propuesto, que permite considerar simultáneamente fuerzas de fricción, grados de libertad de rotación y las incertidumbres que afectan a una tarea de montaje robotizada. Por otra parte, pueden mencionarse como aportaciones particulares, la introducción del concepto de estados de la tarea como ocurrencia de un determinado conjunto de contactos básicos y, para el caso de movimientos en un plano, el modelado y fusión de incertidumbre de una forma más precisa que las descritas en trabajos previos, así como la determinación de las fuerzas de reacción que pueden tener lugar en cualquier contacto mediante el uso de la representación dual de sus rectas de acción. La tesis incluye la aplicación de los conceptos teóricos desarrollados a una tarea de montaje (bloque en la esquina) considerando movimientos de los objetos en un plano. Aunque la implementación no pretende ser un prototipo de aplicación general, contribuye a la validación de los resultados del trabajo

Robotic machining evaluation of the positioning accuracy and the machined surface quality

Due to the importance of the surface quality of machined parts, many research works have been devoted to the surface irregularities and their generating mechanisms. However, the surface quality of the robotic machining operations has not been sufficiently investigated. Indeed, the relative works are restricted to the finishing operations such as grinding and deburring. In this work, the surface quality of the slot milling operation which is executed by an industrial robot on an aluminum block is investigated. For this purpose, several slots at different directions are machined on the block by applying various cutting parameters. In order to investigate the surface quality of the slots, the machined surfaces are evaluated by a mechanical profiler, and then the results are analyzed using the power spectrum density method. Moreover, to monitor the machining conditions, the machining forces are measured with a dynamometer table. To identify the generating factors of the irregularities, both the kinematic and the dynamic properties of the robot are experimentally examined. The kinematic properties of the robot are investigated by measuring its straightness using a laser tracker, and the dynamic properties are evaluated by applying the impact test. Lack of accuracy is one of the difficulties restricting the usage of robotic machining. Indeed, the poor accuracy of industrial robots makes the off-line programming uneffective. Consequently, the operators are forced to use on-line method which is a time consuming approach. However, if a robot is calibrated properly, the off-line method could be effectively applied. To this end, before analyzing the surface quality, the accuracy of the robot is investigated and improved using a hybrid calibration model considering both the geometric errors and the joint compliances

Modelagem, controle e emprego de robôs em processos de usinagem

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2010Atualmente os robôs são majoritariamente empregados em operações que não impõem restrições ao movimento de seus efetuadores. É o caso das tarefas envolvendo manipulação de materiais, pintura e soldagem. Na presença de restrições, como nas tarefas de usinagem, seu emprego é bem reduzido, decorrente das limitações científico-tecnológicas ainda existentes. Neste caso, além de realizar um movimento com restrição, o robô aplicará uma força originada pelo corte do material. O robô deverá ser capaz de realizar a remoção do material, dentro das especificações de projeto, sem que a força aplicada ultrapasse os limites físicos da ferramenta e do robô. Buscando atender a estas exigências operacionais, desenvolve-se neste trabalho um modelo matemático de caráter inédito, representativo das forças de interação que se manifestam entre o robô e o meio, que, trabalhando em conjunto com algumas estratégias de controle pré-selecionadas, garanta o cumprimento da tarefa requisitada. O modelo matemático desenvolvido é válido para uma diversidade de ferramentas cortantes que possuam as três componentes ortogonais de força definidas no espaço cartesiano. Como exemplos destas ferramentas têm-se o rebolo, a fresa de disco de dentes retos e a fresa de topo com haste cilíndrica, todas consideradas ao longo do texto no intuito de auxiliar no desenvolvimento do modelo. Os objetivos desta tese são a síntese deste modelo, assim como das estratégias de controle de rigidez e por impedância, além da análise de estabilidade do sistema em malha fechada com cada uma destas estratégias de controle.Nowadays the robots are currently employed in operations that do not impose constraints to the displacement of their end effectors. It is the case of tasks involving material handling, painting and welding. In the presence of constraints, such as those on machining tasks, they are rarely used, because of the still existing scientific-technological limitations. In this case, in addition to performing a constrained displacement, the robot will apply a force originated by the cut of the material. The robot should be able to perform the removal of material, within the design specifications, without allowing the applied force to exceed the physical limits of the tool and the robot. Looking to meet these operational demands, a novel mathematical model, representative of the interaction forces that arise between the robot and the environment, is developed, which, working in conjunction with some pre-selected control strategies, ensures the achievement of the requested task. The mathematical model developed is valid for a diversity of cutting tools that have the three orthogonal components of force defined in Cartesian space. As examples of these tools one has the grinding wheel, the peripheral mill and the endmill with cylindrical shank, all considered throughout the text in order to assist in the development of the model. The goals of this thesis are the synthesis of this model, as well as the control strategies of compliance and impedance, beyond the stability analysis of the closed loop system with each of these control strategies

Proceedings of the NASA Conference on Space Telerobotics, volume 2

These proceedings contain papers presented at the NASA Conference on Space Telerobotics held in Pasadena, January 31 to February 2, 1989. The theme of the Conference was man-machine collaboration in space. The Conference provided a forum for researchers and engineers to exchange ideas on the research and development required for application of telerobotics technology to the space systems planned for the 1990s and beyond. The Conference: (1) provided a view of current NASA telerobotic research and development; (2) stimulated technical exchange on man-machine systems, manipulator control, machine sensing, machine intelligence, concurrent computation, and system architectures; and (3) identified important unsolved problems of current interest which can be dealt with by future research

An intelligent robot control system for physiotherapic applications

An intelligent robot control system for physiotherapic applications has been developed. The intelligent robot control system consists of a specially designed robotic hand with built-in sensors, an interfacing module between the robot system and the computer, an intelligent path planning module and a fuzzy logic based intelligent control module. The robotic hand with the integrated palm and two fingers has been used to perform the padding and kneading opeartions. The sensory information of the robotic hand have been used in the intelligent control process. The intelligent path planning and control modules have been constructed with the knowledge bases (KBS) and the fuzzy logic based inference mechanism, which are able to deal with uncertainties by manipulating the fuzzy terms. Thus, with the fuzzy/linguistic input terms, the required parameters can be generated for the path planning module. The massaging path can be planned by using the KBS in the intelligent path planning module. While the task execution is monitored by the intelligent control module. The intelligent control module allows error-correction strategies to be formulated. The required corrections can be carried out by using the on-line KBS and fuzzy inference mechanism in the intelligent control module. Experimental results are presented, which show the feasibility and the effectiveness of the designed intelligent control system