Picturing the interest of research institutions and industrial actors, the list of research and demonstration parallel cable-driven robot prototypes is growing by the day. LIRMM and Tecnalia have decided to put knowledge in common in order to develop novel concepts for cable-driven parallel robotics and demonstrate its capabilities in industrial tasks. We have developed together a reconfigurable cable robot for this purpose. The robot main characteristics, e.g. footprint, mobile platform geometry and drawing point layout can be modified at will, making it particularly suitable for studying in good conditions new configurations or novel control laws, as well as any scenario suggested by our partners. The present paper first provides an overview of the robot. Afterwards, a more specific view on the different components and the capabilities of reconfiguration are presented, as well as examples of layouts meant for various research and industrial projects.
Abstract-This paper deals with the vision-based control of cable-driven parallel robots. First, a 3D pose visual servoing is proposed, where the end-effector pose is indirectly measured and used for regulation. This method is illustrated and validated on a cable-driven parallel robot prototype. Second, to take into account the dynamics of the platform and using a Cartesian pose and velocity estimator, a vision-based computed torque control is developed and validated in simulation.
Par2 is a two-degree-of-freedom parallel robot designed for high-speed and high-accuracy industrial pick-andplace operation tasks. As a result of the high acceleration trajectories, the end-effector undergoes some undesirable vibrations after reaching the stop positions, compromising its precision and leading therefore to an increase in the operation cycle time. Accelerometer sensors placed on the end-effector and piezoelectric patch actuators wrapped around the robot arms are employed in order to actively reduce these vibrations in a non-collocated closed-loop setting. After submitting the robot to an identification procedure, the obtained nominal model is used to synthesize a reduced order controller with the H ∞ Loop Shaping technique. Performance analysis as well as simulation and experimental results exhibit that vibration reduction is achieved around the nominal operating point, but fails for some extreme operating points, due to high control efforts. An antiwindup strategy is then employed to deal with the saturation of the actuator, which allows to achieve vibration attenuation on the whole operation domain, for a given configuration of the robot at the stop point.
Abstract. MARGE is a joint project in the framework of the interdisciplinary national program in Robotics, called ROBEA, launched by the French National Research Center (CNRS) in 2001. The focus is on the development of design methodologies and on the control of high mobility and dexterity assistive devices for complex gesture assistance in minimally invasive surgery, especially for coronary artery bypass grafting. This paper presents the main results of this two-year project.
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