Stanislao Grazioso

A nonlinear finite element formalism for modelling flexible and soft manipulators

This paper presents a nonlinear finite element formalism for modelling the dynamics of flexible manipulators using the special Euclidean group SE(3) framework. The method is based on a local description of the motion variables, and results in a singularity — free formulation which exhibits important advantages regarding numerical implementation. The motivation behind this work is the development of a new class of model — based control systems which may predict and thus avoid the deformations of a real flexible mechanism. Finite element methods based on the geometrically exact beam theory have been proven to be the most accurate to account for flexibility: in this paper we highlight the key aspects of this formulation deriving the equations of motion of a flexible constrained manipulator and we illustrate its potential in robotics through a simple case study, the dynamic analysis of a two-link manipulator, simulating different model assumptions in order to emphasize its real physical behavior as flexible mechanism.

From Differential Geometry of Curves to Helical Kinematics of Continuum Robots Using Exponential Mapping

Kinematic modeling of continuum robots is challenging due to the large deflections that these systems usually undergone. In this paper, we derive the kinematics of a continuum robot from the evolution of a three-dimensional curve in space. We obtain the spatial configuration of a continuum robot in terms of exponential coordinates based on Lie group theory. This kinematic framework turns out to handle robotic helical shapes, i.e. spatial configurations with constant curvature and torsion of the arm.

Towards a self-collision aware teleoperation framework for compound robots

This work lays the foundations of a self-collision aware teleoperation framework for compound robots. The need of an haptic enabled system which guarantees self-collision and joint limits avoidance for complex robots is the main motivation behind this paper. The objective of the proposed system is to constrain the user to teleoperate a slave robot inside its safe workspace region through the application of force cues on the master side of the bilateral teleoperation system. A series of simulated experiments have been performed on the Kuka KMRiiwa mobile robot; however, due to its generality, the framework is prone to be easily extended to other robots. The experiments have shown the applicability of the proposed approach to ordinary teleoperation systems without altering their stability properties. The benefits introduced by this framework enable the user to safely teleoperate whichever complex robotic system without worrying about self-collision and joint limitations.

Input predictive shaping for vibration control of flexible systems

This paper presents the foundation of a new class of input shapers, designed using a predictive approach. The method is used to control the transient and residual vibrations in flexible nonlinear systems with time-varying parameters. The motivation is the development of simple algorithms and architectures for controlling the motion in flexible nonlinear systems with minimal modeling effort. The approach trains an artificial neural network to obtain closed-form expressions used for calculating, in real time, the amplitudes and the time locations of the impulses required by a common input — shaping technique. In this work we use this idea to design a command shaper for controlling the motion of the simplest flexible nonlinear system, an overhead crane with a suspended payload. We validate the approach using simulations and experiments. The benefits of such a control system will, in the end, enable using this method for controlling the motion of complex nonlinear systems, resulting in almost zero vibrations.

Enhancing airplane boarding procedure using vision based passenger classification

This paper presents the implementation of a new boarding strategy that exploits passenger and hand-luggage detection and classification to reduce the boarding time onto an airplane. A vision system has the main purpose of providing passengers data, in terms of agility coefficient and hand-luggage size to a seat assignment algorithm. The software is able to dynamically generate the passenger seat that reduces the overall boarding time while taking into account the current airplane boarding state. The motivation behind this work is to speed up of the passenger boarding using the proposed online procedure of seat assignment based on passenger and luggage classification. This method results in an enhancement of the boarding phase, in terms of both time and passenger experience. The main goal of this work is to demonstrate the usability of the proposed system in real conditions proving its performances in terms of reliability. Using a simple hardware and software setup, we performed several experiments recreating a gate entrance mock up and comparing the measurements with ground truth data to assess the reliability of the system.

INBODY: Instant Photogrammetric 3D Body Scanner

The digital manufacturing processes initially developed in rapid prototyping centers are nowadays appearing not only in industry, but also in medicine. In particular, in orthopedics, the manufacturing of orthoses is following this trend. The digital manufacturing process of orthoses requires a scanning device for the three-dimensional (3D) digitization of the human body part whose deformity needs to be corrected. However, the slowness of acquisition phase of the recent body scanners may constitute a key issue of the overall process, especially for patients with mobility impairments. This work aims at presenting INBODY, an instant photogrammetric 3D full body scanner. The motivation behind it is to speed up the acquisition phase of 3D human models, up to make it instantaneous. INBODY provides several features of interests in 3D body scanning technologies: (i) instant acquisition of the human body model; (ii) precision and accuracy of the resulting 3D model comparable with laser systems; (iii) affordable costs. INBODY is built upon a modular and distributed architecture: in this paper we highlight its key concepts and illustrate its potential through a case study, the real time acquisition and the 3D reconstruction of a human full body and a human torso, used for the digital manufacturing process of orthoses. Moreover, INBODY can be used also in other fields, whenever body measurements and 3D human models are needed (sport, medicine, fashion, ...).