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Über dieses Buch

This volume contains the Proceedings of the First International Conference of IFToMM Italy (IFIT2016), held at the University of Padova, Vicenza, Italy, on December 1-2, 2016. The book contains contributions on the latest advances on Mechanism and Machine Science. The fifty-nine papers deal with such topics as biomechanical engineering, history of mechanism and machine science, linkages and mechanical controls, multi-body dynamics, reliability, robotics and mechatronics, transportation machinery, tribology, and vibrations.

Inhaltsverzeichnis

Frontmatter

Biomechanical Engineering

Frontmatter

Design and Implementation of a Low-Cost Mechatronic Shoe for Biomechanical Analysis of the Human Locomotion

In this paper the development of a low-cost and easy wearable mechatronic system for the measurement of ground reaction forces (GRF) for the biomechanical analysis of the human locomotion is presented. The system consists of an insole, a conditioning device for the signals produced by the sensors applied to the insole and a data acquisition system connected to a USB portable storage. The sensors applied to the insole can measure the reaction forces in the horizontal and vertical directions during locomotion. The prototype was validated by comparing the data from the sensors with the values obtained using a force platform.

P. Boscariol, A. Gasparetto, N. Giovanelli, S. Lazzer, L. Scalera

A Study of Feasibility for a Limb Exercising Device

This paper deals with the design of a robotic device for limb exercising. The attached problem is outlined to identify the main limb exercising features as referring to upper limbs and cable driven robotic solutions. A novel design solution is proposed as consisting in a portable low-cost user-friendly cable driven manipulator. Numerical models and simulations are carried out to verify the feasibility of the proposed solution in terms of operation and motion ranges.

G. Carbone, C. Aróstegui Cavero, M. Ceccarelli, O. Altuzarra

DARTAGNAN a Self-balanced Rehabilitation Robot Able to Work in Active and Passive Modes on Both Sides of Upper and Lower Limbs

The article deals with a new six degrees of freedom system for rehabilitation, able to work, in active or passive modes, on upper and lower, left and rights limbs. This robot has an hybrid serial parallel structure, mechanically self-balanced thanks to the particular joints configuration. Performing a simple manual operation it’s possible to change configuration of the robot, depending on the patient side on which the operator would act. The system is controlled by a multiprocessor distributed control system connected via CAN bus protocol. The control unit will also able to detect the force interactions between patient and manipulator, so that the system might behave as a 3D haptic system. Patents have been applied on this device [3–5].

M. Perrelli, P. Nudo, M. Iocco, G. Danieli

Dynamic Analysis of Handcycling: Mathematical Modelling and Experimental Tests

The handbike is an upper body-powered vehicle used for sports and rehabilitation purposes. The advantages include improving patients physical activities and fitness level, as well as promoting an active lifestyle after rehabilitation duration. In this research the torques in shoulder and elbow joints have been determined during handbike motion from dynamic output and kinematics information. Therefore, a 2D model was presented. Data have been collected based on the output of experimental results obtained by sensors inserted on the handles of a cycle ergometer and by marker coordinates acquired by a vision system.

G. Azizpour, A. Ousdad, G. Legnani, G. Incerti, M. Lancini, P. Gaffurini

A Kinematic Solution of a Novel Leg Mechanism with Parallel Architecture

In this paper, a novel parallel mechanism for a biped robot leg is presented with the designed structure and its characteristics. The synthesis of the kinematic chain of the mechanism is described and the kinematic problem is solved.

Matteo Russo, Marco Ceccarelli

Multi-target Planar Needle Steering with a Bio-inspired Needle Design

Percutaneous intervention is common practice in many diagnostic and therapeutic surgical procedures. Needle steering research aims to extend these by enabling therapies that are not possible with a straight rigid needle. Being able to address multiple targets in one insertion is an example of such a therapy, which would result in reduced overall trauma to the patient and surgery time. However, needle steering remains challenging, as soft tissue is highly compliant and deformable, and thus difficult to interact with. In this work, we develop a new biologically inspired needle design (4 mm outside diameter) and show its capabilities in multiple moving target scenarios. In vitro results in gelatin demonstrate accurate 2D tracking of two virtual targets over 3 target movement rates.

Christopher Burrows, Fangde Liu, Alexander Leibinger, Riccardo Secoli, Ferdinando Rodriguez y Baena

Development of an Active Force Plate for Testing Lower-Limb Prostheses

In the recent past, lower-limb prostheses technological advancement mostly concerned the possibility of integrating ever smaller and more powerful electronic components instead of new materials and topologies. Although sophisticated, products currently on the market do not guarantee the same opportunities of their biological counterpart. According to authors’ opinion this deficiency is principally due to the lack of suitable development and verification methods. As a consequence, our research group is developing a bench for testing transfemoral prostheses. The setup is briefly recalled in this paper. Then, attention is focused on the subsystem designed for reproducing the loads acting on the foot due to reaction with the ground.

Cristiano Marinelli, Hermes Giberti, Ferruccio Resta

Determination of the Human Arm Stiffness Efficiency with a Two Antagonist Muscles Model

In the last years, due the working age increase, more and more attention was given to the use of exoskeleton for industrial applications, such to reduce fatigue and the operator effort. Since in industrial practice, stiffening the joint is a requested action for those operations in which precision is needed, an exoskeleton whose stiffness could be controlled by the operator would reduce the operator discomfort. In this paper we attempt to study the stiffness of the elbow on which two muscles act as agonist-antagonist and we proposed an estimation of the efficiency.

Daniele Borzelli, Stefano Pastorelli, Laura Gastaldi

Design of a Miniaturized Safety Clamping Device for Portable Kidney Replacement Systems

In this paper the design of a miniaturized safety clamp to be used in portable/wearable kidney replacement systems and/or ultrafiltration devices is dealt with. These devices can be used to treat patients with renal deficiency by filtering the blood drawn through a specific vascular access, and by reinfusing it after the purification. A clamping device is essential to guarantee the safety of these devices, since it allows to occlude the external body blood circulation in case of a safety hazard, such as the formation of air bubbles, clots, and blood backflow. The clamp must be designed to provide adequate clamping force, while minimizing space occupation, weight and power consumption, since it is meant to be housed in a portable/wearable and battery-operated device. The novel design proposed is based on an articulated mechanism, whose dimensions have been optimized to meet the required specifications. The estimated power consumption constitutes a sensible improvement over commercially available devices.

P. Boscariol, G. Boschetti, R. Caracciolo, M. Neri, D. Richiedei, C. Ronco, A. Trevisani

Conceptual Design of a Mechatronic Biomedical Wearable Device for Blood Ultrafiltration

The industrialization of a wearable, mechatronic, biomedical device for blood ultrafiltration would represent an important step toward the achievement of tailored and improved care for kidney disease and congestive heart failure patients. In this article, the conceptual design of a novel and portable device is proposed. The necessary components are identified, and the most suitable technologies for pumps, sensors and control systems are selected, taking into account the basic requirement of minimizing the size and weight of the device in order to make it actually portable and wearable. The selection has also been driven by the results of a thorough risk analysis from a clinical point of view. Most components have been considered as disposables in order to ensure aseptic conditions and easy restoring operations for the device, which is believed to be essential to promote the use of wearable devices for blood purification in clinical practice.

G. Boschetti, A. Dalla Via, N. De Rossi, F. Garzotto, M. Neri, L. Pamato, C. Ronco, A. Trevisani

Design of an Underactuated Hand Exoskeleton with Joint Estimation

In this study, we present an underactuated hand exoskeleton with the adaptation for the shape and the size of the objects during grasping tasks. The realism of the grasping tasks are improved by allowing only the normal transmission of the forces on the finger phalanges. The absence of the tangential forces allows the device to be attached to the user’s finger in an easy and comfortable manner for the operation. Furthermore, the finger size adjustability can be ensured by the linkage-based design. Underactuation assures the automatic adjustability of the device for the grasping objects, while preventing the posture control of the finger phalanges. The undersensing disadvantage of the underactuation approach is suggested to be overcome by utilizing an additional potentiometer on the device in order to estimate the finger joints and the pose analysis of the mechanism during operation.

Mine Sarac, Massimiliano Solazzi, Daniele Leonardis, Edoardo Sotgiu, Massimo Bergamasco, Antonio Frisoli

Standard and Natural Motion Protocols for the Kinetic Measurements of the Squat

Two motion protocols that describe the sequence of movements to be complied with by a subject to perform a controlled squat are presented. The protocols are intended to be used in gait analysis to obtain repeatable and reproducible results that can be compared among different studies. The first protocol (“standard”) is closer to other studies in the literature, in order to improve comparison with previous experimental results. The second protocol (“natural”) reproduces a squat movement more similar to natural conditions, also allowing a deeper knee flexion. The two motion protocols are tested by a volunteer on a gait lab. Results of experimental tests in terms of joint and foot-ground angles, ground reaction force and centre of pressure show the characteristics of the standard and natural squat, and the repeatability of the tests.

Nicola Sancisi, Marco Cocconcelli, Riccardo Rubini, Vincenzo Parenti-Castelli

Design and Simulation of an Assisting Mechanism for Arm Exercises

A conceptual design of a novel mechanism is proposed to assist the training exercises for the human arm. The proposed mechanism is based on a mechanism of 2 degrees of freedom whose workspace has been amplified by using a pantograph mechanism. The proposed assisting mechanism can reproduce any trajectory for arm exercise within a large suitable space in a horizontal plane. Two configurations of the mechanism are presented with the conceptual features. Analysis of the displacement, velocities, accelerations and torques are worked out to compare two possible configurations and to characterize the mechanism solution as the feasible one for future developments.

B. Chaparro-Rico, D. Cafolla, M. Ceccarelli, E. Castillo-Castaneda

History of Mechanism and Machine Science

Frontmatter

Role of Scientific-Technical Museums in the Future of Mechanical

This paper deals with a red wire which connects the mechanisms and the historical museums and collections. Starting from the collection of mechanisms of the Politecnico di Milano, an application is described of an informatics method developed by the authors. Such method, based on neurological consideration about the management of knowledge by the human brain, realize a comparison between the interest of the potential user of museums or collections and the correspondent characteristics of the objects of the collection. The result is a classification of the exposed objects in relation to the interest of the user and, consequently, a criteria of visit.

Alberto Rovetta, Edoardo Rovida

An Analysis of the Hydraulic Saw of Hierapolis

A mechanical analysis of the hydraulic saw of Hierapolis is presented. The device is the oldest example of saw moved by a water wheel and using a crank and rod mechanism. A bas relief representing the machine was found in Hierapolis, Phrygia, now Turkey, and was studied by the Italian Archaeological Mission in Hierapolis. The bas relief was dated III Century A.D. The paper starts from the archaeological studies of the find and from the early reconstructions that were proposed and presents a new pictorial reconstruction, a mechanical model and a model made by means of WM 2D™; the latter permitted to easily obtain the mechanical behavior of the machine. The water wheel was also modeled starting from archaeological relict found at Venafro, Italy.

Cesare Rossi, Sergio Savino, Francesco Timpone

Linkages and Mechanical Controls

Frontmatter

Riccati Equation Based Nonlinear Filter: A Case Study for Hydraulic Actuators in the Presence of Dead-Zone

One of the most common hard nonlinearities in hydraulic actuator is the dead-zone. More specifically, dead-zone characterizes hydraulic control valves when its spool occludes the orifice with an overlap, so that for a range of spool positions there is no fluid flow. This paper focuses on an alternative nonlinear estimation method that is able to fully take into account dead-zone hard nonlinearity and measurement noise. The estimator is based on the State-Dependent-Riccati-Equation (SDRE).

Salvatore Strano, Mario Terzo

Trajectories Generation with Constant Extrusion Rate for Experimentations on AM Techniques and Extrusion Based Technologies

AM techniques based on material extrusion are currently under experiments in the pursuance of printing new materials related with new printing techniques. For these studies it would be helpful a trajectory with constant feed rate, in order to guarantee a uniform distribution of material with a constant extrusion feed rate. For this purpose a model for trajectories generation is developed exploiting Bézier curves. This model can be helpful for AM experiments and technologies where a uniform material deposition is needed as painting, gluing and sealing. At the end of the paper an example is presented.

H. Giberti, L. Sbaglia, M. Parabiaghi

Preliminary Design of a Simplified Pneumatic Actuator

A major topic of soft robotics is the design of pneumatic actuators made of hyperelastic materials, such as silicone rubber. So far, many efforts have been made in the creation of prototypes, exploiting commercial silicone rubber, mainly to perform manipulation tasks or locomotion. However, there is a lack of methods for the design of such actuators. In this paper, we present the results of a preliminary work, aimed at the development of a method for the synthesis of a single chamber pneumatic actuator. The work is based on the use of finite elements and exploits two different algorithms to find the optimal shape of the actuator such that a prescribed deformation is obtained.

G. A. Naselli, M. Zoppi, R. Molfino

Multi-Body Dynamics

Frontmatter

Multibody Model of Under-Actuated Tendon Driven Finger to Study the Antagonist Tendon

In this paper is presented a study on the antagonist tendon of an underactuated finger that is actuated by means of a traction tendon. The study is carried out developing a multibody model in which are applied the force that the tendons exert. The study and the model are part of a research activity to develop a mechanical hand with prosthetic purposes. The different types of antagonists tendons, that achieve different dynamic behaviours of the finger, are shown and described in the paper.

Sergio Savino

A Model Reduction Strategy for Flexible-Link Multibody Systems

In this paper a novel strategy is presented to perform the reduction at system level of flexible-link multibody models based on the equivalent rigid-link system modeling approach. Such a strategy is aimed at obtaining reduced models ensuring an accurate description of the full-order model dynamics in a frequency range of interest and in a wide subset of the workspace. Starting from the well-known Craig-Bampton reduction technique, and the interior mode ranking method a configuration-dependent reduction transformation is formulated, which allows obtaining a minimum-size reduced model, accurately describing the dynamics of interest. The proposed strategy has been validated by applying it to the model of a flexible-link planar manipulator driven by three motors.

Ilaria Palomba, Dario Richiedei, Alberto Trevisani

Reliability

Frontmatter

Topology Optimization and Analysis of Static Transmission Error in Lightweight Gears

In this paper, the influence of gear-body lightweighting on the static transmission error (STE) for a pair of spur gears is investigated by using the Finite Element (FE) method. The transmission error, in fact, is recognized as one of the main internal excitation sources in a mechanical transmission and the minimization of its variability along the meshing cycle is considered as a design target to improve the N&V behaviour of the full transmission. The case study analysed in this paper is derived from a gearbox typically used in helicopter transmissions. The FE model of three different variants of the same gear pair, one solid model and two lightweight models, are generated and analysed by non-linear FE static simulations. By deriving the STE curves for each of the gear pairs, the impact of the increased flexibility caused by material removal in the two lightweight models is investigated.

Jakub Korta, Domenico Mundo, Giuseppina Ambrogio, Barbara Folino, Shadi Shweiki, Luigino Filice

A Strategy for Moving Cable Driven Robots Safely in Case of Cable Failure

Cable driven robots are often suggested for applications in which they operate close to, or even in contact with, human operators. The well known broadcasting and rehabilitation use are just two representative examples. Safety is therefore a critical issue. The aim of this paper is to introduce a motion planning strategy for leading a cable robot to a safe position of the workspace in case one or more cables brake or become slack during the motion. The strategy is addressed to redundant cable robots and guarantees that the tensions of the unbroken cables are kept positive and bounded along the whole path toward a safe position. The strategy is then applied to a point-mass planar cable robot, with two translational degrees of freedom to prove its effectiveness.

Giovani Boschetti, Chiara Passarini, Alberto Trevisani

Approaches to the Detectability of Faults in Railway Pantograph Mechanism

Vibration-based condition monitoring is a leading field in both research and industrial world. Systems features and boundary conditions makes detectability highly case-sensitive and hence each application demands for a specific strategy. In this paper we introduce a project meant to develop a robotic tool for the assessment of railway pantographs health under strong customer requirements, such as limited frequency bandwidth and few sensors allowed. The lack of historical data and the unavailability of specimens make the case-study particularly challenging. Considerations were hence derived through numerical simulations. We took into account leakage in dashpot and clearance in a joint to investigate how faults afflict both global and local modes. The way specifications limit the suitability of frequency domain methods is pursued using the extended Modal Assurance Criterion (MACX). Phase plots shapes alteration were observed collecting responses of two points to a cosine chirp force with the aim to compare the effectiveness of this simple method with MACX performance. Structural damage is identified by both techniques but only the latter detects the leakage in the dashpot. Phase plots use needs to be delved deeper to test the suitability for the real application.

G. Santamato, M. Gabardi, M. Solazzi, A. Frisoli

Behaviour of Tilting-Pad Journal Bearings in Case of Large Manufacturing Errors

The behavior of five-pad tilting-pad journal bearings in case of large manufacturing errors, is investigated by means of a parametric analysis in this paper. The sensitivity analysis was performed for several combinations of pad thickness in both load-on-pad (LOP) and load-between-pad (LBP) configuration using a TEHD model. Pad thickness machining errors cause different preload factor or clearance for each pad. Several cases of thickness variation and different rotational speed were studied. Numerical results show that machining errors have a strong influence on the dynamic coefficients and on the static behaviour.

Steven Chatterton, Phuoc Vinh Dang, Paolo Pennacchi, Andrea Vania

Robotics and Mechatronics

Frontmatter

A New Automated 2 DOFs 3D Desktop Optical Scanner

The goal of this research work was to create a completely automated desktop 3D optical measuring system for parts having freeform and complex surfaces, with high and certifiable resolution, precision and accuracy to be suitable for metrology. The proposed device is based on the principle of structured light active triangulation. The hardware system consists of an optical system, with a 2 degrees of freedom (DOFs) motorized tilt-rotational table and a framework providing fixtures for a proper location of the target specimen. The software module is able to synchronize the optical and mechanical systems after optical and mechanical calibrations. The mesh representing the measured object is registered automatically by stitching together all the single 3D data sets acquired at each movement of the positioning system. The quality of the result is evaluated by checking the difference between a certified reference model and the measured data.

Maria Cristina Valigi, Silvia Logozzo, Gabriele Canella

Adam’s Hand: An Underactuated Robotic End-Effector

This paper describes recent efforts by the authors in the development of a robotic hand, referred to as the Adam’s hand. The end-effector is underactuated through a multiple bevel-gear differential system that is used to operate all five fingers, resulting in 15 degrees of freedom actuated by just 1 degree of actuation. Special focus is devoted to the transmission ratios and gear dimensions of the system to maintain the kinematic behaviour and the dimensions of the prototype as close as possible to that of human hand.

Giovanni Antonio Zappatore, Giulio Reina, Arcangelo Messina

Automatic System for Fibers Extraction from Brooms

This paper presents an automatic system for fibers extraction from brooms, realized by Calabrian High Tech S.r.l. in the framework of PON MATRECO. Base of this system is a suspended rail from which a series of hoists are hanging, pulled by a chain. Six work stations are devoted to perform each a specific task, from hanging the plants manually to bars, placing them in position and pushing a button, to immerge them in a maceration bath held at 80° where the plants must be kept for about 20 min, to lift them, then rinse, detach fibers and finally discard the plants to restart the process. The entire cycle, controlled by a PC, will need only one person in operation, even if at the moment, being yet in an experimental phase, more people are involved. Broom is an endemic plant in Calabria, with good mechanical properties and long fibers, but fibers extraction was up to now extremely labor intensive, thus too expensive. Other fibers extraction, such as those of hemp or flax, require simpler treatments, even if the sequence of operations described in this paper, with minor modifications, could be adopted to treat all of them, obtaining long fibers. A patent application has been filed on this plant scheme, taking into account a number of possible variations [7], and a second patent is about to be deposited.

P. F. Greco, G. La Greca, G. Larocca, S. Meduri, B. Sinopoli, D. Battaglia, A. Caseti, A. Aloise, G. Chidichimo, G. Danieli

Functional Design of a Robotic Gripper for Adaptive Robotic Assembly

Nowadays, automated production systems are rapidly changing to increase flexibility. However, robot end effectors are usually designed to accomplish specific tasks and to handle a limited family of parts, and flexibility can only be obtained by using tool changing systems. The main drawbacks of such systems are increased cost of automation and reduced productivity. This paper presents the functional design of a flexible robotic gripper, capable of adaptively changing its aperture (grasp width) to different handling demands, without affecting the cycle time of the production system, as it can be actuated in hidden time. The solution proposed consists of (1) an electrically-actuated mechanism for adapting aperture, which allows to satisfy the flexibility requirements; (2) a pneumatically-actuated mechanism for open/close operations, which ensures comparably fast motion of jaws if compared to traditional, non-adaptive robotic grippers.

F. Oscari, S. Minto, G. Rosati

Optimal Design of a Reconfigurable End-Effector for Cable-Suspended Parallel Robots

In this paper, a new cable-suspended parallel robot (CSPR) with reconfigurable end-effector is presented. The system has been conceived for pick and place operations in industrial environments where the ability to avoid obstacles and to maximize the performance are the main requirements. The proposed system has the capability of dynamically modifying the configuration of the cable anchor points on the end-effector to avoid collisions with obstacles in the approaching/departing phases, while reducing the movement time in the rest of the trajectory. Kinematic and dynamic models of the reconfigurable CSPR are derived and an optimal design of the end-effector is presented. The optimization aims at minimizing the force required by the linear actuator to modify the position of the cable anchor points during a pick and place task. The results reveal the predominant effect of the end-effector mass distribution on the force exerted by the linear actuator.

Luca Barbazza, Damiano Zanotto, Giulio Rosati, Sunil K. Agrawal

Kinematic Optimization of a 2DoF PRRRP Manipulator

Parallel Kinematic Machines (PKM) are interesting in industrial field because of their ability to ensure high dynamic performance, stiffness, accuracy and precision. One of the options in the design of a manipulator is the opportunity to ensure isotropy performance within the workspace. Generally each PKM has a limited number of isotropy configurations. This paper shows that some 2 DoF PKMs may be designed to have an infinite numbers of kinematic configurations that constitute one or more continuous loci. These machines have the possibility to work at (or near) their ideal kinematic conditions in a large part of their working area. The paper presents a methodology to graphically identify the points of isotropy of a planar manipulator and defines the geometrical conditions to maximize their number.

Simone Cinquemani, Hermes Giberti, Giovanni Legnani

Optimized Trajectory Planning of Pick and Place Operations to Be Performed by Cable-Driven Parallel Robots

Cable driven parallel robots (CDPRs) have large workspace and versatile layouts which make them an interesting solution for high speed manipulation tasks. On the other hand, the available wrench set varies widely among the workspace, thus hardly affecting the performance of the system. For this reason, trajectory planning is a crucial aspect in CDPRs, and motion performance can be optimized only by considering the variability of wrench all along the path. In this paper, an optimized trajectory planning algorithm for CDPRs is proposed, which implements a pick and place task in the operational space. The algorithm, based on the calculation of the effective wrench capabilities of the robot in a set of control points along the path, allows to find the trajectory with the optimal trade-off between movement time and smoothness. The algorithm was tested in the case of an under-constrained suspended CDPR with 3-DOF and 4 cables conceived for pick and place applications. Results show that the optimal trajectory allows the CDPR to achieve values of acceleration and velocity near to the maximum allowable values defined by the polytopes of the CDPR.

Luca Barbazza, Fabio Oscari, Simone Minto, Giulio Rosati

An Innovative Method for Sizing Actuating Systems of Manipulators with Generic Tasks

This paper describes an innovative method for the design of the driving system for manipulators whose task is a generic handling within a workspace, in particular robotic simulators. For those mechanisms the choice of an actuating system of the correct size is particularly arduous. As a matter of fact, tipically the requirements for the machine are described in the workspace, but the intrinsically complex kinematics make difficult to understand which is the case that requires the highest dynamic performances. Analyzing all the possible combinations of the parameters that characterize the motion of the end-effector would require an incredible computational burden, and that’s the reason why a statistical method is taken into account: in particular the sizing process described in this paper relies on the Monte Carlo Method. In order to show the its effectiveness, its implementation in a particular application is presented.

E. Fiore, H. Giberti, G. Bonomi

Experimentally Based Design of a Manually Operated Baler for Straw Bale Construction

Straw bale construction is considered an appropriate technique for improving housing condition in developing Countries and for rebuilding in emergency condition. However, balers suitable for this purpose are not available nowadays. This paper presents a method for functional design of a human powered baler for straw bale building, based on the straw mechanical characteristic, experimentally measured. A prototype has been realized and tested.

Walter Franco, Giuseppe Quaglia, Carlo Ferraresi

Transportation Machinery

Frontmatter

Fast Calibration Procedure of the Dynamic Model of an Autonomous Underwater Vehicle from a Reduced Set of Experimental Data

AUVs (Autonomous Underwater Vehicles) represent an interesting industrial product with applications ranging from the monitoring of cultural and natural heritage to the inspection of underwater plants for the Oil and Gas industry. Development of AUVs also represents an interesting challenge for researchers and engineers involving a melting of different competences of robotics, mechanics and mechatronics. In particular, this paper is focused on the simulation, identification and validation of simplified hydrodynamic models that can be used for the overall verification and simulation of vehicle performances including aspects related to manoeuvrability and controllability of the system. The identification and validation process described in this work is based on past experiences with the Typhoon AUV built by the MDM Lab (Mechatronics and Dynamic Modelling Laboratory) of the University of Florence, Italy.

Benedetto Allotta, Riccardo Costanzi, Luca Pugi, Alessandro Ridolfi, Andrea Rindi

Braking Energy Recovery in High Speed Trains: An Innovative Model

Modern railway development trend is pushing towards a strong enhancement of the energy efficiency of lines and vehicles, with particular attention to braking energy recovery. In this research work the authors have developed an innovative and numerically efficient vehicle-line coupled model, using the object oriented Simscape language: the model has been validated considering a set of experimental measurements concerning the Italian High Speed train ETR 1000 and has then be used to analyze the feasibility of the application of energy storage systems in high speed application. This analysis has shown that the use of stationary energy storage devices can provide significant energy savings even in high speed applications.

Amedeo Frilli, Enrico Meli, Daniele Nocciolini, Simone Panconi, Luca Pugi, Andrea Rindi

Dynamic Model and Instability Evaluation of an Articulated Mobile Agri-Robot

Stability, in particular in outdoor sloped conditions, is one of the most important requirements for design safe and effective future mobile robotic platforms. In this work, the authors’ recent results on the study and development of an articulated mobile robot for agricultural and forestry activities in hilly/mountain environments are presented. First of all, a dynamic model for the stability analysis of a generic articulated platform has been designed and implemented. Then, different practical working conditions have been simulated to assess the stability of the system; possible stabilizing actions when travelling on a sloped surface on the steering angle, velocity and central joint have been finally evaluated and discussed.

G. Carabin, R. Vidoni, F. Mazzetto, A. Gasparetto

NVH Analysis of Automotive Components: A Carbon Fiber Suspension System Case

This paper presents the application of a modal parameter estimation technique, namely the Linear Identification by Polynomial Expansion in the Z-domain (LIPEZ) method, to automotive carbon fibre components. In particular, a leaf spring was chosen for its simple geometry and a door panel of an electric vehicle for its high influence in global NVH characteristics of vehicles. Both elements were experimentally tested with free-free boundary conditions under a random input force; the same test is reproduced at simulation level in order to perform a results correlation.

Alessandro Fasana, Massimiliana Carello, Alessandro Ferraris, Andrea Airale, Davide Berti Polato

Dynamics of a Tethered Rover on Rough Terrain

The deployment of a complex modular cable robot is investigated. The act is performed by a supporting rover that drives on rough terrain while pulling—and unwinding—one of the tethers. In order to avoid rebounds and stress spikes, the cable must be kept in tension by the feeding mechanism. In this work, a constant torque control system is evaluated. A numerical simulation is carried out by direct time-integration of the dynamics equation of the cable and the drive. Results show that a constant torque applied by the motor unit is able to produce a tension in the cable that is well within the cable’s yield limits, while at the same time being consistently larger than zero. This shows the viability of this technology for the deployment of cable structures by rovers in extreme environments.

Stefano Seriani, Paolo Gallina, Armin Wedler

Wind Propulsion for Robot Surface Mobility

This paper investigates new solutions for robot mobility based on wind propulsion. Different wind energy-conversion configurations are presented that can be employed to propel a land vehicle. The proposed system is based on a vertical multi-wing solution that can be mechanically configured to work as either a wind mill or a sail. The model of a three-wheel robot in wind-sail mode is also recalled showing the influence of wind intensity and direction on the vehicle’s performance.

Mario Foglia, Giulio Reina, Giovanni Boschetti

Anti-dive Front Suspension for Agricultural Tractors: Dynamic Model and Validation

Off-highway market has recently shown the introduction of agricultural tractors equipped with a suspended front axle, whose benefits in term of improvement of dynamic performance might be disrupted by their tendency to increase the chassis pitch motion. Being agricultural tractors potentially loaded with many configurations and operating in a variety of terrain conditions, analysis of kinematics and dynamics performances, both numerical and experimental, is of paramount importance for system design and optimisation. The contributions of this study are mainly two: derivation of a set of analytical formulas to design an anti-dive suspension and of a validated model of the in-plane dynamics of an agricultural tractor fitted with an hydraulic semi-active front suspension.

Francesco Biral, Riccardo Pelanda, Alberto Cis

Dynamic Model of an Independent Carts System

This paper focuses on the dynamic modelling of a recent mechatronic device called independent carts system. Different companies gave different commercial names, but the mechanics behind is the same: different linear motors on a closed loop, controlled individually to increase the flexibility but keeping the speed of dedicated solutions, such as mechanical cams or chains. The proposed model covers both the mechanical and control parts of the systems. In this paper the preliminary results are shown, and the model is validated on a real independent carts system by Rockwell Automation. The mechanical model is assumed to be a planar model and the moving carts are supposed to be rigid bodies moving along a rail. Friction and gravity effect are taken into account. The electrical model comprises three PID control loops. The aim of this model is to simulate the behavior of the system in order to evaluate different scenarios and architectures of new machines, decreasing the cost of development and the time to market.

Jacopo Cavalaglio Camargo Molano, Stefano Rossi, Marco Cocconcelli, Riccardo Rubini

Tyre-Road Adherence Conditions Estimation for Intelligent Vehicle Safety Applications

It is well recognized in the automotive research community that knowledge of the real-time tyre-road friction conditions can be extremely valuable for intelligent safety applications, including design of braking, traction, and stability control systems. This paper presents a new development of an on-line tyre-road adherence estimation methodology and its implementation using both Burckhardt and LuGre tyre-road friction models. The proposed strategy first employs the recursive least squares to identify the linear parameterization (LP) form of Burckhardt model. The identified parameters provide through a Takagi-Sugeno (T-S) fuzzy system the initial values for the LuGre model. Then, it is presented a new large-scale optimization based estimation algorithm using the steady state solution of the partial differential equation (PDE) form of LuGre to obtain its parameters. Finally, real-time simulations in various conditions are provided to demonstrate the efficacy of the algorithm.

Mojtaba Sharifzadeh, Francesco Timpone, Arash Farnam, Adolfo Senatore, Ahmad Akbari

Tribology

Frontmatter

Tilting Pad Journal Bearing TEHD Analysis: An Innovative Model

Tilting Pad Journal Bearings (TPJBs) are widely used in the turbomachinery field due to their superior dynamical performances, but their operation involves several different physical phenomena. In this research work the authors propose an innovative 3D ThermoElastoHydroDynamic (TEHD) model for the analysis of TPJBs behaviour developed and experimentally validated in cooperation with General Electric Nuovo Pignone: the model is able to perform a nonlinear transient coupled analysis taking into account fluid dynamical, thermal and elastic effects and reaches a good compromise between the accuracy of the results and the computational efficiency.

Amedeo Frilli, Enrico Meli, Daniele Nocciolini, Simone Panconi, Luca Pugi, Andrea Rindi, Stefano Rossin

Thermo-Hydrodynamic Analysis of Tilting Pad Journal Bearing with General Purpose CFD Software

This paper presents a prediction model for tilting pad journal bearings (TPJB), based on a general-purpose CFD software. Currently, the industrial manufacturers use ad-hoc proprietary codes for the design of TPJB and the prediction of their performance. However, apart from the input parameters defined by the code developer, the user can not modify the model. On the contrary, with a general-purpose software the user can implement modifications and exploit well developed toolboxes. In particular one can adopt up-to-date turbulence models and study fluid structure interaction with specific tools. A procedure was developed, based on ANSYS-CFX, to predict the static characteristic of a TPJB, such as load capacity, film temperature, flow rate and friction torque. A thermohydrodynamic model is presented and results, obtained with different boundary conditions, are compared.

Marco Del Chiaro, Paola Forte, Francesco Torrigiani, Enrico Ciulli

Multiple Holes Rectangular Gas Thrust Bearing: Dynamic Stiffness Calculation with Lumped Parameters Approach

A lumped parameters model of a rectangular air pad is developed for dynamic analysis. The model is valid for different geometries of the pad, which is supplied through multiples orifices positioned on a supply rectangle. The dynamic stiffness is analytically obtained by linearizing the system around the steady equilibrium condition. In this paper the model is validated with a distributed parameters model in static conditions.

Federico Colombo, Mona Moradi, Terenziano Raparelli, Andrea Trivella, Vladimir Viktorov

Theoretical and Experimental Study of a Rectangular Grooved Pocketed Air Pad

In this work, a numerical lumped model is developed to simulate static characteristics of an externally pressurized grooved air pad. In addition, an experimental study is performed with one sample pad to evaluate the accuracy of the model.

Federico Colombo, Danial Ghodsiyeh, Terenziano Raparelli, Andrea Trivella, Vladimir Viktorov

Experimental Identification of an Aerostatic Thrust Bearing

Conventional approaches to design aerostatic bearings are based on their static characteristics. However, dynamic predictions are fundamental in order to obtain very precise positioning since air bearings are frequently subjected to dynamic load variations. This paper presents a simple linear time invariant model for aerostatic thrust bearings and the related experimental identification procedure. The experimental procedure identifies the stiffness and damping coefficients of the air gap model. The model validation was obtained comparing the experimental and theoretical bode diagrams of the studied system. The comparison demonstrates that the model leads to good results when neighbours of equilibrium conditions are considered.

Federico Colombo, Luigi Lentini, Terenziano Raparelli, Vladimir Viktorov

Experimental Analysis of the Influence of the Electrical Arc on the Wear Rate of Contact Strip and Contact Wire in a.c. System

The transfer of electrical power from the overhead line to the train is carried out through the sliding contact between the pantograph’s contact strip and the overhead line’s contact wire. The state of the contact is defined by the current collection quality, where electrical arcs play a predominant role. Indeed, electrical arcs are generated when, during current collection, contact losses occur due to the dynamics of pantograph-catenary interaction. The main effects of the electrical arcs are electromagnetic disturbances and high values of local temperature on the strip and on the wire, which in turn cause an increase of wear rate on contact strip and contact wire. The aim of this paper is to analyze, by means of laboratory tests, the effect of electrical arc occurrence on the wear of strip and wire. Two different kinds of carbon based strip are considered: plain carbon strip and copper impregnated carbon strip. The contact wire considered in this work is a pure copper wire.

Giuseppe Bucca, Andrea Collina, Ezio Tanzi

Vibrations

Frontmatter

Low-Cost Experimental Assessment of Forces in the Contact Bridge-Soundboard of Stringed Musical Instruments

The paper describes the main results of an unconventional and non-industrial application of mechanics oriented to the experimental detection and monitoring of static and dynamic forces generated in the contact between bridge and soundboard in stringed musical instruments. Forces in bridge-soundboard contact are validated by low-cost experimental procedures, acquiring forces along the normal to the contact surfaces by means non-invasive thin film micro-sensors, interfaced to PC. Consequently, friction forces can be estimated, through the friction factor depending on the soundboard and bridge materials.

Enrico Ravina

Vibration Modes of Piezoelectric Bimorphs: A Sensitivity Analysis

The paper presents a sensitivity study on the first five vibration modes of a bimorph piezoelectric beam. More in detail, the analysis focuses on the kinematic response of these kind of strips to uncertainties in the identification of electric, piezoelectric and mechanical parameters. The study defines these uncertainties as input errors in the identification process of the first five natural frequencies. The free vibration problem for bimorph piezoelectric beam constrained by simple supports has been solved, and results have been compared with the exact two-dimensional solution. Numerical simulations have also been implemented and data analyzed according to the Weibull distribution theory; eventually, high order functions have been identified, enabling to foresight the final frequency identification error.

Alberto Borboni, Cinzia Amici, Valter Cappellini, Rodolfo Faglia

Concurrent Active Control and Dynamic Structural Modification in the Design and the Optimization of Vibrating Systems

The simultaneous optimization of the mechanical design and of the controller in vibrating systems is of great importance in order to improve the system dynamic performances. Due to the mutual interaction, the two tasks should be performed in a concurrent way. In order to overcome the limitations of traditional decoupled approaches, this paper proposes a method for the simultaneous synthesis of the state feedback controller and of the modifications of the inertial and elastic parameters. The performance optimization is obtained by assigning some desired eigenvectors and eigenvalues to the controlled systems, so that a desired dynamic behaviour is featured. Indeed, the eigenvalues determine damping and speed of response, while the eigenvectors set the sensitivity of the eigenvalues and the spatial shape of the vibration. By properly combining active control and structural modification, the capability to assign the desired eigenpairs is enlarged since passive control shapes the allowable subspace so that the desired eigenpairs can be assigned through active control. The numerical results show the effectiveness of the proposed method and the great potential advantages of the concurrent use of structural modification and active control over traditional design methods.

Roberto Belotti, Roberto Caracciolo, Dario Richiedei

A Vibration Isolator Based on Magneto-Rheological Elastomer

The paper presents an investigation about a magneto-rheological elastomeric (MRE) pad to be adopted as seismic semi-active isolator for lightweight structures. MRE pad may change its stiffness if immersed in a magnetic field. This characteristic allows to real time shift the fundamental frequency of the isolated structure. In this way it is possible to drive away the structure fundamental frequency from the exciting frequencies and therefore to reduce accelerations induced by the ground motion. The isolator includes a ball transfer unit (BTU) to sustain the vertical load so that MRE pad must only exert horizontal restoring forces and it may have a slender geometry without concern regarding buckling.

Renato Brancati, Giandomenico Di Massa, Stefano Pagano

A Physical Analytical Model to Study the Elasto-Kinematic Behaviour of a MacPherson Suspension

This paper describes a physical analytical model able to characterize the elasto-kinematic behaviour of a MacPherson suspension for automotive applications. The presented model allows to determine the position and the orientation of the wheel upright as a function of the generalized three-dimensional loads applied to the center of the tire-road contact patch, and consequently to determine the variation of the characteristic suspension parameters of main interest: wheel base, track, camber and toe. All the steps carried out to build the model are described, starting from the kinematic analysis, ongoing with the static and finally with the elasto-kinematic ones, describing how compliance has been taken into account in equilibrium conditions. The kinematic and static analyses have been validated by comparing the results with the ones of a multibody model. In order to obtain the desired elasto-kinematic curves it is possible to act both on the geometry of the suspension, and on the stiffness of the bushings and of the arms, which cause compliance, modifying the positions of the various elements of the suspension and ultimately of the hub. By means of the proposed model it is possible to rapidly evaluate the effects of these variations. Numerical examples relative to a suspension for the front axle of a vehicle are presented.

Francesco Timpone

A Smart System for Shock and Vibration Isolation of Sensitive Electronic Devices On-Board a Vehicle

The paper presents an innovative system for shock and vibration isolation of a set of racks on-board vehicles containing equipment sensitive to accelerations. The suspension system is composed of air springs so that the isolation efficiency and the rack attitude do not vary if some devices are replaced with other ones having different inertial characteristics. As the air springs have a low level of damping, the suspension system is equipped with four magnetorheological dampers whose damping may be adjusted in real time to minimize rack accelerations. The suspension system also includes stabilizers in order to contain roll and pitch motions of the racks.

M. De Michele, G. Di Massa, G. Frisella, S. Lippolis, S. Pagano, G. Pisani, S. Strano

Wavelet Analysis of Gear Rattle Induced by a Multi-harmonic Excitation

The paper reports a feasibility study for the detection of automotive gear rattle induced by multi-harmonic excitation through the use of a wavelet multi-resolution analysis. The analysis adopts experimental data coming from a helical gear pair under unloaded conditions. The excitation of gear rattle is of periodic type with two harmonic components, which is similar to the excitation of an actual automotive I.C. engine. The dynamic behavior of the gear pair has been analyzed by varying the second order harmonic amplitude of the excitation, for two mean speed values. The analysis gives useful information to develop an index of performances based on the wavelet theory that could be adopted for comparative analyses with respect to the severity of the tooth impacts occurring during the rattle phenomenon.

Renato Brancati, Ernesto Rocca, Sergio Savino, Francesco Timpone

Special Session in Honor of Prof. Aldo Rossi for his 70th Birthday

Frontmatter

Analytical and Multibody Modelling of a Quick-Release Hook Mechanism

Quick-Release Hooks (QRH) are particular accessories for connecting chains or metal ropes, that can be remotely unfastened under full-load conditions via application of an external force with limited magnitude. Despite their widespread use, and aside from a number of patents, the scientific literature related to QRH performance is rather limited. This paper reports about the modelling of a class of QRH, which relies on the use of a four-bar linkage mechanism operating in the proximity of a singularity configuration. Design graphs depicting the main functional parameters are reported. At last, a multibody model of the system is developed, which validates the analytical results while providing an insight of the frictional forces effect on the device modelling and performance.

Luca Bruzzone, Davide Bonatti, Giovanni Berselli, Pietro Fanghella

Evolution of a Dynamic Model for Flexible Multibody Systems

In this paper the evolution of a dynamic model for flexible multibody systems is presented. This model is based on an equivalent rigid-link system (ERLS) and, in the first formulation, has been exploited together with a FEM approach for the modeling of planar flexible-link mechanisms. Subsequently, the model has been linearized in order to be applied for control purposes and then it has been extended to the three-dimensional case. In the last years, a modal approach has been developed and the ERLS concept has been applied in order to formulate the dynamics of spatial flexible mechanisms with a component mode synthesis (CMS) technique.

P. Boscariol, P. Gallina, A. Gasparetto, M. Giovagnoni, L. Scalera, R. Vidoni

Anti-hedonistic Mechatronic Systems

In this paper the concept of anti-hedonistic mechatronic systems interacting with humans is discussed. Up to this time, people have used their creativity to design machines which could reduce human efforts (i.e. robots) or enhance the perceived pleasure (i.e. entertainment tools and virtual reality systems). Nowadays, new machines designed to prevent people from doing something are emerging. Examples are: intragastric balloons to prevent people from eating, timed cigarettes boxes to prevent people from smoking, bracelets to prevent people from nail biting, alcohol-testers connected to car starter to avoid driving under alcohol influence. The aim of this work is to present a survey about anti-hedonistic machines, providing general definitions and a possible classification. In particular a mechatronic system designed to motivate users to do push-ups exercises, by controlling the television energy supply, is presented.

Lorenzo Scalera, Paolo Gallina, Alessandro Gasparetto, Marco Giovagnoni

On the Use of Cable-Driven Robots in Early Inpatient Stroke Rehabilitation

Cable-driven robots are a special class of manipulators in which the end-effector is actuated by cables, rather than by actuators connected to rigid links. Their use in early inpatient stroke rehabilitation has been extensively investigated by the research group led by Prof. Aldo Rossi at University of Padua, Italy. Both cable suspended solutions (NeReBot, MariBot) and planar designs (Sophia-3) have been considered. Among them the NeReBot, a prototype underactuated cable suspended robot, has been clinically tested in early upper-limb rehabilitation of severely impaired stroke survivors. Results were encouraging, both with additional and with substitutive robotic treatment protocols, in comparison to standard stroke rehabilitation therapy. This paper presents the concept, results and benefits provided by the use of cable robot technology in stroke rehabilitation.

G. Rosati, S. Masiero, A. Rossi
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