Giuseppe Di Gironimo

Alternative supply chains for logging residues under access constraints

We conducted a comparative study of chipping logging residues at the roadside landing or at the yarder pad, the latter inaccessible to heavy road vehicles. Field data was collected from real operations in the Italian mountain, and it was used for building a simulation model that could generalize the results of the study. The model was built with Arena 14 and carefully reflected interaction delays between individual units along the chain. Chipping at the pad with a chipper and two shuttles was the best compromise solution of low supply cost and fuel consumption. At a mean cost of €22.7 per fresh tonne, this solution was 10% cheaper than chipping at the landing. Using three chip shuttles did not allow a meaningful reduction of supply cost over a two-shuttle chain, but resulted in a 7% increase of fuel consumption. The distance between the pad and the roadside landing was by far the most important factor in determining supply cost, and accounted for 80% of the variability in the data, for both systems. Under these circumstances, the higher speed and payload of the chip shuttles made it preferable to chip at the pad, provided enough shuttles are available.

A Top-Down Approach for Virtual Redesign and Ergonomic Optimization of an Agricultural Tractor’s Driver Cab

Nowadays, economical, technical and ergonomic factors have a great importance on the design of the agricultural tractors. The paper illustrates the use and the management of heterogeneous product information (manual measurements and drafts, 2D drawings, technical documentation, photos), advanced CAD modeling tools and digital human models, for the redesign and the ergonomic optimization of an agricultural tractor’s driver cab. The project development has been organized using a top–down approach in a collaborative environment. At first, a manual measurement with gauges allowed to realize a technical draft of the whole agricultural tractor and of each component part of the driver cab. Then a main skeleton has been created in Catia V5 environment in order to specify all the datum elements necessary to model each sub-assembly of the tractor. Cabin, platform, engine, tires, seat, dashboard and controls have been organized separately and modeled considering the details related to the manual measurements and to the technical standards. Once obtained the 3D CAD model of the tractor, an opportune questionnaire was prepared and a test campaign was carried out with real operators in order to define the more critical control devices within the driver cab, as regards to usability and ergonomic issues. An “Ergonomics’ Evaluation Index” (EEI) was defined taking into account the posture angles of the operator and the Rapid Upper Limb Assessment analysis tool available in the “Ergonomics Design & Analysis” module of Catia V5 based on the use of a digital human model. The index was validated comparing the results of tests carried out using virtual manikins of different percentiles performing a specific driving task, with the results of tests carried out by real operators, of the same percentiles, performing the same driving task. Critical values of the EEI obtained during some driving tasks in virtual environment, suggested to modify the shape and the position of some control devices in order to optimize the ergonomics of the driver cab. The adoption of the top-down modeling based approach allowed each change on a singular component part to be automatically propagated on the whole assembly, making easy the changes on the virtual prototype.Copyright

A Virtual-Reality-based evaluation environment for wheelchair-mounted manipulators

The design of solutions for robotic extenders of wheelchairs must take into account both objective and subjective metrics for everyday activities in human environments. Virtual Reality (VR) constitutes a useful tool to effectively test design ideas and to verify performance criteria. This paper presents the development of a simulation environment, where three different manipulators to be mounted on a commercially available wheelchair have been considered. Experimental results are discussed in a significant case study, based upon users’ feedback.

Multiple-Point Kinematic Control of a Humanoid Robot

Robots designed to operate in everyday domains have to move in environments designed for the humans. Therefore, they will often have a humanoid kinematic structure. Simple and efficient kinematic models are needed for motion control of this class of robots. An algorithm is presented to solve the inverse kinematics problem in the presence of a number of control points arbitrarily located on the whole robot body, using an augmented Jacobian approach and including posture control. Simulation experiments are reported, showing the effectiveness of the proposed approach.

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.

Virtual environments and prototyping for human health and safety

The chapter focuses on virtual environments and virtual prototyping methods and techniques, whose application in the design of products, manufacturing processes, assistive devices, medical tools and treatments, can improve the human condition both in industry, and in everyday life. Human beings can benefit from experiments, carried out on digital human models, in order to evaluate their performances on the work, their interaction with automated mechanical systems and their feedback about innovative medical treatments. Virtual Ergonomics and Virtual Safety are more and more recognised as crucial aspects of the life cycle management of industrial products. Indeed, it is understood that digital humans simulations can be very useful to evaluate the Workplace Health and Safety. Moreover, both in industrial and in non-industrial contexts, reliability and safety are of great importance when human beings and robots need to share their workspaces to collaboratively perform a specific task.

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.

Interactive Tools for Safety 4.0: Virtual Ergonomics and Serious Games in Tower Automotive

This work focuses on an innovative training methodology based on the use of Virtual ergonomics and “serious games” in the field of occupational safety. Virtual Ergonomics was chosen as an effective and convincing tool for disseminating the culture of safety among the workers, while a “serious game” was developed to train operators on specific safety procedures and to verify their skills. The results of the experimentation in a real industrial case study showed that, compared to the traditional training methodology, multimedia contents and quantitative ergonomic analyses improve the level of attention and the awareness of the operators about their safety. On the other hand, Serious games turned out as promising tools to train the workers about safe operating procedures that are difficult to implement in a real working environment.

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.

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, ...).