Modeling and motion analysis of autonomous paragliders

This report describes a preliminary study on modeling and control of parafoil and payload systems with the twofold objective of developing tools for automatic testing and classification of parafoils and of devising autonomous paragliders able to accomplish long-range delivery or monitoring tasks. Three different models of decreasing complexity are derived and their accuracy compared by simulation

Repeatable Motion Planning for Redundant Robots over Cyclic Tasks

We consider the problem of repeatable motion planning for redundant robotic systems performing cyclic tasks in the presence of obstacles. For this open problem, we present a control-based randomized planner, which produces closed collision-free paths in configuration space and guarantees continuous satisfaction of the task constraints. The proposed algorithm, which relies on bidirectional search and loop closure in the task-constrained configuration space, is shown to be probabilistically complete. A modified version of the planner is also devised for the case in which configuration-space paths are required to be smooth. Finally, we present planning results in various scenarios involving both free-flying and nonholonomic robots to show the effectiveness of the proposed method

A CoppeliaSim Dynamic Simulator for the Da Vinci Research Kit

The design of a physics-based dynamic simulator of a robot requires to properly integrate the robot kinematic and dynamic properties in a virtual environment. Naturally, the closer is the integrated information to the real robot properties, the more accurate the simulator predicts the real robot behaviour. A reliable robot simulator is a valuable asset for developing new research ideas; its use dramatically reduces the costs and it is available to all researchers. This letter presents a dynamic simulator of the da Vinci Research Kit (dVRK) patient-side manipulator (PSM). The kinematic and dynamic properties of the simulator rely on the parameters identified in Wang et al. With respect to the kinematic simulator previously developed by some of the authors, this work: (i) redefines the kinematic architecture and the actuation model by modeling the double parallelogram and the counterweight mechanism, to reflect the structure of the real robot; (ii) integrates the identified dynamic parameters in the simulation model. The obtained simulator enables the design and validation of control strategies relying on the robot dynamic model, including interaction force estimation and control, that are fundamental to guarantee safety in many surgical tasks

Humanoid odometric localization integrating kinematic, inertial and visual information

We present a method for odometric localization of humanoid robots using standard sensing equipment, i.e., a monocular camera, an inertial measurement unit (IMU), joint encoders and foot pressure sensors. Data from all these sources are integrated using the prediction-correction paradigm of the Extended Kalman Filter. Position and orientation of the torso, defined as the representative body of the robot, are predicted through kinematic computations based on joint encoder readings; an asynchronous mechanism triggered by the pressure sensors is used to update the placement of the support foot. The correction step of the filter uses as measurements the torso orientation, provided by the IMU, and the head pose, reconstructed by a VSLAM algorithm. The proposed method is validated on the humanoid NAO through two sets of experiments: open-loop motions aimed at assessing the accuracy of localization with respect to a ground truth, and closed-loop motions where the humanoid pose estimates are used in real-time as feedback signals for trajectory control

Decidability in robot manipulation planning

Consider the problem of planning collision-free motion of n objects movable through contact with a robot that can autonomously translate in the plane and that can move a maximum of m ≤ n objects simultaneously. This represents the abstract formulation of a general class of manipulation planning problems that are proven to be decidable in this paper. The tools used for proving decidability of this simplified manipulation planning problem are, in fact, general enough to handle the decidability problem for the wider class of systems characterized by a stratified configuration space. These include, e.g., problems of legged and multi-contact locomotion, bi-manual manipulation. In addition, the approach described does not restrict the dynamics of the manipulation system modeled

Field Model Identification and Control of a Mobile Electromagnet for Remote Actuation of Soft Robots

The actuation of miniaturized robots through external magnetic fields has great potential for medical applications. The controllability properties of the miniaturized robots are affected by magnetic field generation modality. In this work, the magnetic field of a mobile electromagnet, notably capable to generate a desired magnetic field in large 3D workspaces, has been identified first. Then, a control model of the field generation system has been developed to produce a desired magnetic field designed to generate a locomotion gait in a legged miniaturized robot. Preliminary experiments prove the viability of the approach.</p

Impact of Segmented Magnetization on the Flagellar Propulsion of Sperm-Templated Microrobots

Technical design features for improving the way a passive elastic filament produces propulsive thrust can be understood by analyzing the deformation of sperm‐templated microrobots with segmented magnetization. Magnetic nanoparticles are electrostatically self‐assembled on bovine sperm cells with nonuniform surface charge, producing different categories of sperm‐templated microrobots. Depending on the amount and location of the nanoparticles on each cellular segment, magnetoelastic and viscous forces determine the wave pattern of each category during flagellar motion. Passively propagating waves are induced along the length of these microrobots using external rotating magnetic fields and the resultant wave patterns are measured. The response of the microrobots to the external field reveals distinct flow fields, propulsive thrust, and frequency responses during flagellar propulsion. This work allows predictions for optimizing the design and propulsion of flexible magnetic microrobots with segmented magnetization

Interventional radiology

This contribution focuses on the problem of needle-tissue interaction force reconstruction, one of the main challenges to fully exploiting robotics potentialities in percutaneous procedures