Parallel Robots with Configurable Platforms

Vitreo-retinal surgery encompasses the surgical procedures performed on the vitreous humor and the retina. A procedure typically consists of the removal of the vitreous humor, the peeling of a membrane and/or the repair of a retinal detachment. Operations are performed with needle shaped instruments which enter the eye through surgeon made scleral openings. An instrument is moved by hand in four degrees of freedom (three rotations and one translation) through this opening. Two rotations (? and ? ) are for a lateral instrument tip movement. The other two DoFs (z and ?) are the translation and rotation along the instrument axis. Actuation of for example a forceps can be considered as a fifth DoF. Characteristically, the manipulation of delicate, micrometer range thick intraocular tissue is required. Today, eye surgery is performed with a maximum of two instruments simultaneously. The surgeon relies on visual feedback only, since instrument forces are below the human detection limit. A microscope provides the visual feedback. It forces the surgeon to work in a static and non ergonomic body posture. Although the surgeon’s proficiency improves throughout his career, hand tremor may become a problem around his mid-fifties. Robotically assisted surgery with a master-slave system enhances dexterity. The slave with instrument manipulators is placed over the eye. The surgeon controls the instrument manipulators via haptic interfaces at the master. The master and slave are connected by electronic hardware and control software. Implementation of tremor filtering in the control software and downscaling of the hand motion allow prolongation of the surgeon’s career. Furthermore, it becomes possible to do tasks like intraocular cannulation which can not be done by manually performed surgery. This thesis focusses on the master console. Eye surgery procedures are observed in the operating room of different hospitals to gain insight in the requirements for the master. The master console as designed has an adjustable frame, a 3D display and two haptic interfaces with a coarse adjustment arm each. The console is mounted at the head of the operating table and is combined with the slave. It is compact, easy to place and allows the surgeon to have a direct view on and a physical contact with the patient. Furthermore, it fits in today’s manual surgery arrangement. Each haptic interface has the same five degrees of freedom as the instrument inside the eye. Through these interfaces, the surgeon can feel the augmented instrument forces. Downscaling of the hand motion results in a more accurate instrument movement compared to manually performed surgery. Together with the visual feedback, it is like the surgeon grasps the instrument near the tip inside the eye. The similarity between hand motion and motion of the instrument tip as seen on the display results in an intuitive manipulation. Pre-adjustment of the interface is done via the coarse adjustment arm. Mode switching enables to control three or more instruments manipulators with only two interfaces. Two one degree of freedom master-slave systems with force feedback are built to derive the requirements for the haptic interface. Hardware in the loop testing provides valuable insights and shows the possibility of force feedback without the use of force sensors. Two five DoF haptic interfaces are realized for bimanual operation. Each DoF has a position encoder and a force feedback motor. A correct representation of the upscaled instrument forces is only possible if the disturbance forces are low. Actuators are therefore mounted to the fixed world or in the neighborhood of the pivoting point for a low contribution to the inertia. The use of direct drive for ' and and low geared, backdriveable transmissions for the other three DoFs gives a minimum of friction. Disturbance forces are further minimized by a proper cable layout and actuator-amplifier combinations without torque ripple. The similarity in DoFs between vitreo-retinal eye surgery and minimally invasive surgery (MIS) enables the system to be used for MIS as well. Experiments in combination with a slave robot for laparoscopic and thoracoscopic surgery show that an instrument can be manipulated in a comfortable and intuitive way. User experience of surgeons and others is utilized to improve the haptic interface further. A parallel instead of a serial actuation concept for the ' and DoFs reduces the inertia, eliminates the flexible cable connection between frame and motor and allows that the heat of the motor is transferred directly to the frame. A newly designed z-?? module combines the actuation and suspension of the hand held part of the interface and has a three times larger z range than in the first design of the haptic interface.

Error handling in multimodal voice-enabled interfaces of tour-guide robots using graphical models

At present, parallel robots show a great progress in their development due to their behaviour in multiple applications. In this sense, the Stewart-Gough platform with proper mechanical adaptations could be used for a climbing parallel robot. A climbing parallel robot with 6 degrees of freedom has been proposed and analysed. Parallel robots have great advantages compared to serial robots with legs using as climbing robots. Some advantages can be cited as the high weight payload capacity, robustness, simplicity of its mechanical design, etc. However, some difficulties have to be resolve too as the adaptation to the structure meanwhile the robot accomplishes the task or the singularities that can be produced in the movement on the structure. In this paper several options of a climbing parallel robot based in the S-G platform have been presented and analysed. First of all, an initial prototype to climb along tubular structures as pipes or palm trunks has been shown. The main features of this robot are the pneumatic actuators and the external control loop that allows centring the robot to the tubular structure. Taking into account this first prototype, another parallel robot to resolve the problem of displacement and climbing along metallic structures has been presented. The main features of this robot are the electrical actuators and the clamping device developed with the purpose of reducing possible collisions between the movement ring of the robot and the environment. The results achieved with both prototypes show the validity of these platforms to undertake tasks in which are necessary to climb on. In short, this paper tries to show the big potential of using parallel robots as climbing robots. Also, we are working in introducing teleoperation techniques to manage these parallel robots. So, the robots will be controlled in a semi-automatic way when it displaces along the tubular or metallic structures.

The re is a growing need for robot control interfaces that allow a single user to effe ctively control a large number of mostly-autonomous robots. The ch allenges in controlling such a collection of robots are very similar to the challenges of controlling characters in some genres of video games. In this paper, we argue that interfaces based on elements from computer video games are effe ctive tools for the control of large robot teams. We present RIDE, the Robot Interactive Display Environment, an example of such an interface, and give the results of initial user studies with the interface, which lend support to our claim. Follow this and additional works at: htt p://openscholarship.wustl.edu/cse_research Part of the Computer Engineering Commons, and the Computer Sciences Commons

The topic of this paper concentrates on robots and their new role in the architectural process from the early stage of conceptualization to the final stage of its materialization.By presenting a theoretical framework and an applied case study, this paper tries to initiate the discussion of redefining the status of the robotic machine in architecture.Besides being a regular tool among other digital fabrication tools, the robot and the ability of the architect to technically manipulate them, bears the potential of further reconnecting and intertwining the process behind design and fabrication.Operational and structural processes are being modified and points of focus shifted.Digital design connected by customized robotic machines to digital fabrication has the capability to result in a new type of architecture.

By combining the investigation of the biomechanics and behavior of elephant trunk in the performance of a wide range of dexterous manipulations, a novel approach in the design and kinematics modeling of a fruit harvesting continuum manipulator was proposed. By comparing the structure of two different species of elephant trunk, a new continuum structure which matched the key features of elephant trunk was designed. Based on analysis of the underlying elephant trunk’s grasping mode, a novel kinematics model was proposed. Contrast to traditional robot kinematics which focused on end effector’s position and posture, the proposed continuum manipulator kinematics focus on the center of manipulator’s position and posture, which is more effective when trunk robot realizing grasp and establishes the foundation for its application. Finally, three typical grasping experiments were implemented. The experiment results showed that the manipulator could conduct wrap/pinch manipulations effectively for both small objects and bigger ones. DOI: 10.3965/j.ijabe.20150801.008 Citation: Shao T, Zhang L B, Du M Y, Bao G J, Yang Q H. Fruit harvesting continuum manipulator inspired by elephant trunk. Int J Agric & Biol Eng, 2015; 8(1): 57－63.

Robogami structures are employed for many purposes, including miniature parallel manipulators. Parallel manipulators require accurate joint position feedback, underlining the open problem in robogami structures for providing sophisticated feedback with 2D, fully embeddable, down-scalable, flexible sensors. Existing studies include only on-off control applications, excluding any parallel mechanism implementations and continuous proportional control signals. We implement silver inkjet printed angle sensors for the first time into a robogami structure and use this class of sensors for control. For the first time, a parallel manipulator is controlled with a 2D sensor, and printed sensors are tested for continuous control. Performances are analyzed with set-point and tracking control tasks using a paper Delta mechanism, compared with on-off control and encoder feedback control cases for better evaluation. A detailed comparison with the existing studies both for robogami parallel mechanisms and other sensor-embedded flexible hinges is provided. Encoder-like control performances are achieved in a wide range of the joint space and down to ~1 mm. RMS task space accuracy is recorded. Sources and potential improvements for the less accurate regions are stated. We conclude that printed sensors are promising for parallel mechanisms and continuous signal control applications.

In this paper, a novel three degree of freedom configuration platform is presented based on the 2UPS/RU parallel mechanism, which serves as an end-effector for industrial robots, enhancing their workspace and flexibility in confined areas. Utilizing mechanism topology theory and screw theory, we calculate the degrees of freedom and coupling of the 2UPS/RU parallel mechanism. Additionally, the inverse kinematics equations and the velocity Jacobian matrix for the platform are also established. The correlation between the workspace and the structural parameters of the mechanism is expounded, and the dexterity performance index within the workspace is characterized based on the Jacobian matrix. Furthermore, a compactness index is devised to evaluate the relationship between the workspace of the 2UPS/RU parallel mechanism and its structural dimensions by analyzing the platform’s motion characteristics. The structural parameters of the 2UPS/RU parallel mechanism are optimized using the genetic algorithm, with the compactness index parameter and the global dexterity index serving as the objective functions. This optimization results in a 116.92% increase in the compactness index of the configuration platform and an 11.14% improvement in the global dexterity index.

Agriculture and horticulture depend heavily on human labor to perform tasks that are often dirty, hazardous, and highly repetitive. One reason for the lack of automation of these tasks is the absence of suitable robotic handling equipment. Rigid robotic manipulators are typically incapable of performing dexterous manipulation tasks such as harvesting apples as they lack the ability to adapt to objects of various shapes and sizes. Such robotic manipulators need a large number of sensors and actuators to overcome these challenges, making them overly complex and not very robust. Therefore, the development of robotic manipulators for dexterous manipulation tasks has begun to focus on morphological computation, in which at least some aspects of the control are outsourced to the body of the robot. Taking inspiration from grasping mechanisms in natural systems, the field of soft robotics attempts to address this problem by constructing robots from soft materials. Although soft robotics may be the key to realizing automation of dexterous manipulation tasks, the current commercially available soft robotic grippers are only capable of performing simple pick-and-place tasks with open-loop control. This limited capability is in large part due to a lack of techniques to endow these manipulators with a sense of self-movement and body position, known as proprioception. Proprioception is a simple problem for conventional robots with rigid members and discrete joints, as the body position can be easily reconstructed using the information from encoders in the robots’ joints. However, it is a highly challenging problem for soft robots with virtually infinite degrees of freedom and above all, no suitable off-the-shelf sensors…

Parallel Manipulators with Configurable Platforms (PMCPs) have platforms with internal degrees of freedom and form a class of manipulators that is not covered by existing type synthesis methods. Because the minimum number of legs for a PMCP is three, fully parallel 3DOF PMCPs may be considered an elementary subset of PMCPs. To support the extension of type synthesis methods to PMCPs, this paper presents the first kinematic designs of manipulators from this subset. A structured design method has led to the kinematic design of two spatial manipulators that are both capable of independently performing one translation, one rotation and one internal platform motion.

The integration of independently-developed applications into an efficient system, particularly in a distributed setting, is the core issue addressed in this work. Cooperation between researchers across various field boundaries in order to solve complex problems has become commonplace. Due to the multidisciplinary nature of such efforts, individual applications are developed independent of the integration process. The integration of individual applications into a fully-functioning architecture is a complex and multifaceted task. This thesis extends a component-based architecture, previously developed by the authors, to allow the integration of various software applications which are deployed in a distributed setting. The test bed for the framework is the EU project XPERO, the goal of which is robot learning by experimentation. The task at hand is the integration of the required applications, such as planning of experiments, perception of parametrized features, robot motion control and knowledge-based learning, into a coherent cognitive architecture. This allows a mobile robot to use the methods involved in experimentation in order to learn about its environment. To meet the challenge of developing this architecture within a distributed, heterogeneous environment, the authors specified, defined, developed, implemented and tested a component-based architecture called XPERSIF. The architecture comprises loosely-coupled, autonomous components that offer services through their well-defined interfaces and form a service-oriented architecture. The Ice middleware is used in the communication layer. Its deployment facilitates the necessary refactoring of concepts. One fully specified and detailed use case is the successful integration of the XPERSim simulator which constitutes one of the kernel components of XPERO.The results of this work demonstrate that the proposed architecture is robust and flexible, and can be successfully scaled to allow the complete integration of the necessary applications, thus enabling robot learning by experimentation. The design supports composability, thus allowing components to be grouped together in order to provide an aggregate service. Distributed simulation enabled real time tele-observation of the simulated experiment. Results show that incorporating the XPERSim simulator has substantially enhanced the speed of research and the information flow within the cognitive learning loop.

A parallel spherical manipulator can provide three degrees of freedom of pure rotation around the virtual center of its platform. Parallel manipulators, where all actuators are fixed to the base of the manipulator, provide better load-carrying capacity and better dynamic properties. This advantage makes it possible to use a parallel spherical manipulator as an additional tool for rotating the end-effector in robots with an incomplete set of degrees of freedom or compensate rotation/position error of the master robot. This solution can be used in precise machining operations and other problems where external forces have great influence or other sources of position errors are significant.Under the influence of external forces robot's end-effector could have an offset in the positioning. In this work, we propose to use a specially designed parallel robot that mounted on the master robot flange between the master robot and its tool. In order to compensate position errors following steps is performed: 1) Estimation of master robot stiffness model; 2) Estimation of spherical parallel robot stiffness model; 3) Estimation of external forces; 4) Estimation of compliance errors for both robots; 5) Trajectory modification for spherical parallel robot; 6) Trajectory execution.In this way, the overall accuracy of the system could be greatly improved, without any modification to the master robot program.

Bidirectional Human-Robot Learning: Imitation and Skill Improvement

This paper reviews the state of the art of using Brain-Computer Interfaces (BCIs) in combination with Augmented Reality (AR). First it introduces the field of AR and its main concepts. Second, it describes the various systems designed so far combining AR and BCI categorized by their application field: medicine, robotics, home automation and brain activity visualization. Finally, it summarizes and discusses the results of the study.

In this paper, an explicit dynamic model for the 6-DOF Stewart platform parallel manipulator is established using a new formulation. The main principle of this formulation is to provide the final form of dynamic models based on a direct and systematic procedure; in more detail, the analytical expression of each term due to the dynamic effects, that is, the system inertia tensor, centrifugal/Coriolis tensor and the environment forces are developed according to only the physical parameters of the system (i.e., mass, inertia tensor, position of the center of mass and geometrical parameters) and generalized coordinates without the need for any complicated intermediate calculations such as the potential, kinetic and acceleration energy development. In this approach, the parallel manipulator is first opened into six serial legs and a free platform. Next, the dynamic models of each sub-structure can be easily obtained based on the new formulation in their own local space. The Jacobian and Hessian matrices of the constraint equations, resulting from the closed-loop chains, are then used to combine the substructure dynamics. Finally, a detailed dynamics model of the entire robot with respect to the workspace or the actuation space is developed. After that, a simulation of the suggested methodology is investigated and analyzed in comparison to the more established dynamic modeling techniques provided in the literature; the efficiency and correctness of our approach are then verified. It is shown that our method requires a lower computational cost and even competes with the implicit form of dynamic models. Finally, a trajectory-tracking problem using model-based control is presented. It is shown that our approach can be totally and efficiently computed online without the need for symbolic form of equations of motion, which is highly challenging for parallel manipulators.