MAGRITTE - L'Information scientifique au service de la recherche - CEA

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For this application, MAGRITTE was an essential component in the remote control system ... The experiment made on the ITER fusion reactor mockup in ENEA's ...
ASTRA 2004, Nordwijk, Pays-bas, 2-4 novembre 2004

MAGRITTE: a graphic supervisor for remote handling interventions Christophe Leroux(1), Martine Guerrand(1), Christophe Leroy(1), Yvan Méasson(1) , Bachir Boukarri(2) CEA LIST CEA –FAR, 18 route du panorama BP6 92265 Fontenay Aux Roses cedex- France [email protected], [email protected], [email protected], [email protected] CYBERNETIX, 4 , Rue rené Razel / Bat. Apollo/ Domaine Technologique de Saclay,91892 –ORSAY CEDEX [email protected] ABSTRACT In this paper we present the MAGRITTE 3D graphic supervisor. MAGRITTE is dedicated to assist an operator in remote handling tasks. It is designed to be intuitive to reduce the stress of operators involved in complex operations. MAGRITTE is especially made to adapt to on line interventions. It relies on the usage of 3D graphic representation and programming. It attempts to hide the complexity of a robotic system to the operator to let him focus his attention on tasks to achieve. The software has been used in several remote handling applications like decommissioning, maintenance, intervention in hazardous environments, remote surgery and under water applications. 1 INTRODUCTION For several years robotics makes a large use of 3D graphic to facilitate supervision. Graphic representations can be used in supervision to prepare mission and control their execution through the usage of more or less sophisticated models of the robot and of the environment. Robotics environments are however not structured. They are partially known from operators and their evolution is unpredictable. This makes usage of computer graphics quite delicate. Another difficulty with graphics representation comes from the variety of tasks. In this respect graphic must offer generic services. Common command strategies can be classified in manual remote control still much in practice; computer assisted remote handling [1] [11] where the command is shared between the operator and some assistances provided by computer, remote programming [8] [9] where tasks are executed sequentially following a program defined on line and supervisory control [2] [13] where the robot has some decisional autonomy. This paper presents the 3D graphic supervisor for remote handling MAGRITTE1. We will start explaining MAGRITTE's functions and describing then some applications focusing on the intuitive use of the system and the wide variety of tasks addressed. 2 WHAT IS MAGRITTE? MAGRITTE is a 3D graphic supervisor for remote handling applications such as intervention in hazardous environment, undersea operations and surgery. Such applications are very stressful for an operator since he must interact in real time with the environment dealing with complex systems. Frequently, these systems include one or several robots, specific tools and sensors. Remote tasks are not repetitive, often undefined since work depends on observations during the interventions. Most of the time, the operator does not have direct vision on the operation workplace. Sometimes he does not even have video feedback. Robots are not always very accurate and the operator must compensate for this inaccuracy to execute tasks in the safest way preserving the environment and the equipment. Often operators involved in these tasks have the profile of technicians with no special knowledge in robotics. MAGRITTE has been developed to ease operator's task when performing an intervention. The principles chosen consist in letting the operator interact with the environment through a 3D graphic representation of the workspace. Through this interface operators elaborate robot programs, simulate them and control their execution in an intuitive way. MAGRITTE offers graphic assistances, making easy robots programming and control. It interfaces to robots and tools through an execution controller, allowing updating model state according to the real situation. In MAGRITTE, specific processes functions (welding, ultrasounds inspection, grinding) are gathered in dedicated trade modules. 3 DIFFERENCES BETWEEN REMOTE HANDLING SUPERVISION AND CAD ROBOTICS CAD robotic software (DELMIA™, ROBCAD™, ACT™) are powerful for industrial missions simulation. These software provide functions to design robotized cell, to simulate tasks and test collisions. They are specially designed for off line programming. Elaborated programs are then carried out by robots. These software offer however poor means for task execution control and when an unforeseen situation occurs during execution. In interventions in hazardous environment, programs cannot be elaborated entirely off line and more assistance than simple task monitoring is required. 4 MAGRITTE GRAPHIC LANGUAGE, GRAPHIC PROGRAMMING, AND FUNCTIONS The basic MAGRITTE function is 3D visualization and manipulation of robots, obstacles, tools, and virtual objects in a scene. MAGRITTE includes a simplified 3D modeler with interface to CAD modeler. It allows simulation of robot movements, programs and processes to finely foresee robots behaviour. Interface to various robot controllers for on line 1

Module d'Assistance Graphique à la Réalisation Interactive de Tâches TéléopéréEs

ASTRA 2004, Nordwijk, Pays-bas, 2-4 novembre 2004

program triggering, monitoring and execution control. It provides collision detection, optional stop on collision and adjustment of security distance. Joint limits and collisions are indicated graphically or with an audio signal. Path planning in joint or Cartesian mode with obstacle avoidance and TCL text robot programming functions are available. MAGRITTE specially features a 3D graphic language and 3D robot graphic programming. Graphic language enables easily specifying tasks and triggering actions using intuitive interfaces (mouse, SPACEMOUSE™). Graphic language attempts to hide robotics complexity letting the operator focus his attention on tasks to realize and processes to tune. Commands like joint or Cartesian motion, tool or object grasping or path following can be triggered down by interactions in the 3D model with the mouse. 3D graphic programming is a feature complementary to the 3D graphic language. The idea is to represent robot programs into the graphic 3D window. Program execution control is displayed in the 3D graphic window. Graphic programming is an alternative to textual programming. Graphic programming in MAGRITTE differs from 2D graphic iconic programming in the way that programs have their representation in the 3D scene representation. Therefore, the operator has a very clear view of what robot will actually do. Operators can very easily follow and control tasks execution. At any time, they can predict what mechanism behaviors will be. MAGRITTE graphic language and graphic programming relies on an extensive use of 3D graphic features and widgets. View points, robot poses, path to follow are represented by 3D graphic widgets with specific behavior and mechanisms allowing an easy and intuitive use and navigation in the 3D virtual scene for a non computer processing and non robotics specialists. 5 MAGRITTE APPLICATIONS 5.1 Hazardous environment 2003: Nuclear decommissioning of CEA installations Hydraulic technology provides manipulators with interesting payload/weight ratio in relatively small volumes when compared to other standard technologies (electrical technology for example). For that reason and because of its capacities to operate in constrained area, MAESTRO arm [5] has been chosen for nuclear dismantling operations by CEA. In these applications, the operator does not have direct vision on the system. Cameras and microphones do not give him enough information. MAGRITTE has been used to answer these problems. 3D MMI allows the Fig 2: Maestro arm an operator to easily program the robot, using the mouse. He can also be warned of any problem on the system including collision proximity. embedded controller The system used for dismantling consists in: a MAESTRO slave arm, the force feedback VIRTUOSE™ master arm, the tools and the radiation hardened embedded control unit. The operator prepares, simulates and executes tasks and trajectories from the control room with MAGRITTE. The supervisor provides a protection for the elements of the system, warning Fig 1: Maestro in the operator when the robot or tool comes too close to the obstacles. 2002:Nuclear reactor underwater maintenance with a 7 degrees of freedom robotic arm MAGRITTE has been used to supervise nuclear pressure vessel repairing with MAESTRO hydraulic robot. In the experiment, the robot and its tool mast were inserted into the vessel under 20 meters depth of water for inspection and repair tasks. The operator could see the robot environment through 2 pan and tilt cameras, and 2 steady cameras. Using virtual views supplied by MAGRITTE, the operator could safely manage operations. MAGRITTE high level 3D graphic functions allowed the operator to program, process and supervise deployment trajectories and repairing tasks. The operation was made in 3 major steps: Deployment step: It consisted in moving the arm from start position to tool grasping position close to Fig 3: Controller, the tool mast, and from this position to the workspace in front of the vessel. During preparation, deployment trajectories avoiding obstacle were simulated and then executed. arm and mast Grasping/Releasing tool step: In this is a manual mode step, MAGRITTE was used to give additional and relevant 3D views to allow the operator to localize correctly the tool with respect to the gripper, to approach without collision, and to grasp the tool without force constraint. Tool attachment and detachment was realized in an intuitive way by clicking the 3D objects. Processing task step: After grasping the tool, deployment trajectory was executed to reach the workspace. A non-destructive inspection was then executed, followed by an accurate machining, and a welding. With MAGRITTE, the operator was managing the task process, adjusting tool parameters and programming the trajectories with “teach and repeat” function. The operator could control the real execution of the task through the video camera. He could also use MAGRITTE to supervise the task operations through a status windows and 3D representation. For this application, MAGRITTE was an essential component in the remote control system to Fig 4: VT inspection execute after simulation, the deployment and work tasks with a high safety degree. The system has been tested in industrial and intensive conditions during 1000 hours in Y2002 and Y2003.

ASTRA 2004, Nordwijk, Pays-bas, 2-4 novembre 2004

2001: Maintenance of ITER fusion reactor, in Brasimone in Italy The experiment made on the ITER fusion reactor mockup in ENEA’s Research Centre [7], aimed at demonstrating a maintenance operation with a hydraulic robot arm. One of the major difficulties to operate a manipulator inside the reactor is the degradation of video feedback due to the level of radiation. The demonstration was made with a master slave system consisting in a MAESTRO [5] arm, an MA23 force-reflecting master arm both under supervision of MAGRITTE software. The arm was mounted on a sliding table at the top of a Cassette Toroïdal Mover (CTM). Main task consisted in locking/unlocking the Divertor Cassettes bolted to the Vacuum Vessel. The arm was used to place a bolt tool and to apply a required force. Position of the arm in regard to the cassette was estimated from data given by the robot touch probe. MAGRITTE was used afterwards to generate trajectories for the CTM, the sliding table and the manipulator and to manipulate tools in the working area. The experiment proved the relevance of a virtual model supervision to provide visual feedback and to support high-level task oriented motions for “blind” remote handling operations. A long distance locking/unlocking task has also been demonstrated in CEA Fontenay. Commands and feedbacks between MAGRITTE and the robot controller TAO2000 [6] were sent via an Internet connection forced to pass via CEA Cadarache (1500km trip). The experienced varying delays precluded the use of force-reflecting master-slave modes. The whole procedure was successfully completed using automatic and rate-control modes plus SPACEMOUSE™ for visual force feedback control, despite a significant Fig 5: CTM in Magritte Fig 6: ITER general view execution time penalty. 2000: Inspection of chemical cell with a 10 degrees of freedom flexible robot PAC (Porteur Articulé en Cellule, Cell Articulated Carrier) is is a 6 meters long robot with 5 segments used in COGEMA La Hague hot cells for the nuclear building inspection, repair or modification [12]. It is used as a decision support in case of cell incident, clearing operations and control before and during decommissioning and dismantling. Neither classical Cartesian nor joint control of PAC would have been possible without MAGRITTE software. MAGRITTE is used to control a simulated robot Fig 8: PAC in cell (using VORTEX software) to generate speed orders for the real robot. Operator control the robot applying forces on the head or on segments, using a SPACE MOUSE™, without having to care of robot's configuration, nor to think about collision avoidance. Fig 7: PAC mission

1997: Maintenance of nuclear cell windows with a Staübli robot (RX90™ STÄUBLI industrial robot) MAGRITTE has been applied to perform various maintenance and decontamination tasks in COGEMA facilities with an RX90 [4]. MAGRITTE provides the overall supervision functions necessary to perform remote handling maintenance using: force-feedback master-slave control, computerassisted remote handling; trajectory programming as well as graphical modelling of working environment, simulation, automatic path planning with Fig 10: Radiation Fig 9: Magritte obstacle avoidance, man-machine interface for tasks programming and shielding window execution. MAGRITTE closely matches the task management level and allows the operator to execute elementary commands, as well as programs describing a complete mission. The supervision module supports on-line man-machine interactions and controls the execution of mission programs. Its real time performances match human response time (100ms). 5.2 Under water vehicle 2002-2003: Inspection and maintenance with the Autonomous Undersea Vehicle (AUV) (European project ALIVE2) ALIVE [10] is an AUV with a hydraulic manipulator able to execute remote handling tasks on sub-sea facilities supervised with MAGRITTE [11]. It has been designed for interventions, recovery and delivery and observation missions down to 3000 meters depth [14]. MAGRITTE is used to create, simulate and execute in safe conditions ALIVE manipulator trajectories. ALIVE test mission, consisted in setting first the vehicle in front of an undersea panel. Afterwards, the Fig 11: ALIVE operator initiated a docking phase. This phase involved the remote-handling of two grabbers and of a manipulator arm. Grabber grippers were then closed to ensure firm positioning on docking bars. Once rigidly docked, the supervisor was updated with the correct alignment of the vehicle on the panel. Trajectories simulated in MAGRITTE were then downloaded to the vehicle’s arm controller for execution and monitoring. In this test experiment, MAGRITTE was fundamental to compensate for bad vision conditions and long data transmission 2

Autonomous Light Intervention Vehicle

ASTRA 2004, Nordwijk, Pays-bas, 2-4 novembre 2004

delay making manual control impossible. It allowed as well, achieving a predictable and safe remote control of the robot arm and of the grabbers. Following a series of tank and shallow water tests carried out in 2003, sea trials of ALIVE have been successfully performed near Marseille. These trials have been performed in difficult conditions of sea state and wind which left very short time for operations. Despite this, the system has performed extremely well. On-line software simulation features provided by MAGRITTE proved to be efficient: allowing the crew to be perfectly trained before the final sea trials and to react in an efficient way when facing unexpected situations. The pertinence of MAGRITTE was reinforced by the fact that the trials could be successfully achieved despite of unreliable video feedback. Fig 0: Video and graphic view 5.3 Remote surgery operation 1999: Supervision of remote surgery operations (European project MIDSTEP) MIDSTEP (Multimedia Interactive Demonstrator Telepresence) objective was to build two demonstrators for remote surgery operations: one for remote scanning exams and one for Minimal Invasive Surgery. The remote scanning demonstrator allowed a clinician away from his patient, to access a number of facilities for a biopsy with an ultrasound system. The Laparoscopic Ultrasound Telemanipulation demonstrator allowed performing an experiment with surgeons in the operating theatre and a radiologist situated in remote place [15]. For laparoscopic surgery, MAGRITTE was used to provide the surgeon with facilities for perception of the remote environment and ergonomic man machine interface to achieve remote robot control. 6 CONCLUSION In these experiments, MAGRITTE has shown its intuitive use for non robotics specialists. Robotics complexity is hidden to the operator to help him focus his attention on tasks to realize. The graphic representation provides the same tools to simulate and control the execution of the tasks. The operator has a precise idea of the robot's behaviour before executing the tasks. Possibilities to create path in free space from a list of points obtained on line, manipulate frames and trajectories and triggering of movement on predefined path with the mouse appeared to be very relevant. Graphic functions provided to assist on line execution control are as well much appreciated to compensate for the deficiencies of direct vision on the scene. Graphic representation of robots programs is of great help when the situation becomes stressful. For example when the arm has to move very close to the obstacles (for example welding) or when it is needed to manage a contact with the environment (drilling, bolting, polishing, grinding). MAGRITTE makes use of the 3D model elaborated to fulfil a task. It can happen however that differences occur between the 3D model and the real scene. Developments are conducted to take into account sensor information during task execution to compensate for errors in the model. Elaboration of the 3D model of the scene is time consuming. Progress has to be made to enable fast and interactive elaboration of models. MAGRITTE has been developed by CEA-LIST. The software is transferred to CYBERNETIX Company. 7 BIBLIOGRAPHIE [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

André G, Fournier R, Generalized end-effector control in a computer aided teleoperation system, Int. Conf. on Advanced Robotics, Tokyo, 1985. Anderson R, Autonomous Teleoperated and Shared Control of Robot Systems, Int. Conf. On Robotics and Automation, 1996. Burdea G, The Synergy Between Virtual Reality and Robotics, IEEE Trans. On Robotics and Automation, vol. 15 n°3, 1999. Desbats P , Andriot C,Gicquel P,Viallesoubranne JP,Souche, Force Feedback Teleoperation of Industrial Robots – A cost effective solution for decontamination of nuclear plants, RECOD’98 conference, 1998, Nice, France. Fournier R., Gravez P., Foncuberta P. Volle C. , “Maestro hydraulic manipulator and its TAO2000 control system”, Proc. ANS 7th Topical Meeting on Robotics and Remote Systems, Augusta, pp. 840-847, 1997. P. Gicquel, C. Andriot, F. Lauture, Y. Measson, P. Desbats, “TAO2000: a generic control architecture for advanced computer aided teleoperation systems,” Proc. ANS 9th Topical Meeting on Robotics and Remote Systems, Seattle, 2001. Gravez P., Leroux C., Irving M., Galbiati L., Raneda A., Siuko M., Maisonnier D. , Palmer J. D., “Model-based remote handling with the Maestro hydraulic manipulator”, “22nd Symp. on Fusion Technology”, Helsinki, Finland, Sept. 2002. Hirzinger G., Brunner B., Dietrich J., Heindl J., ROTEX – the first remotely controlled robot in space, IEEE Int. Conf. on Robotics and Automation, San Diego, 1994. Lin Q, Kuo C, Virtual Teleoperation of Underwater Robots, IEEE Int. Conf. On Rob. and Automation, New Mexico, 1997. Marty P., “ALIVE : An autonomous Light Intervention Vehicle”, Deep Offshore Technology Conf., France, Nov. 2003. Masson Y, Gravez P, Fournier R, A graphical supervision concept for telerobotics, Int. Symp. on Robotics, 1998. Perrot Y, et al. Scale One Field Test of a Long Reach Articulated Carrier for Inspection in Spent Fuel Management Facilities, ANS 10th Int Meet on Robotics and Remote Systems for Hazardous Environments, USA 2004 Sheridan T. B., Supervisory control of remote manipulators, vehicles and dynamic processes, Advances in man-machine systems Vol. 1, pp. 49-137, JAI Press, 1984. ALIVE http://europa.eu.int/comm/research/transport/news/article_747_en.html MIDSTEP http://www.cordis.lu/infowin/acts/rus/projects/ac214.htm