Alberto Borboni

Stochastic Evaluation and Analysis of Free Vibrations in Simply Supported Piezoelectric Bimorphs

Piezoelectric bimorph benders are a particular class of piezoelectric devices, which are characterized by the ability to produce flexural deformation greatly larger than the length or thickness deformation of a single piezoelectric layer. Due to extensive dimensional reduction of devices and to the high accuracy and repeatability requested, the effect of erroneous parameter estimation and the fluctuation of parameters due to external reasons, sometimes, cannot be omitted. As such, we consider mechanical, electrical and piezoelectric parameters as uniformly distributed around a nominal value and we calculate the distribution of natural frequencies of the device. We consider an analytical model for the piezoelectric bimorph proposed in literature. The results show how the parameters errors are reflected on the natural frequencies and how an increment of the error is able to change the shape of the frequencies distribution. [DOI: 10.1115/1.4007721]

Movement Optimization of a Redundant Serial Robot for High-Quality Pipe Cutting

The subject of this research concerns an innovative serial robot developed to introducethe laser ray technology in the on-line pipes cutting in a continuous process of produc-tion. The presence of different cutting constraints and the necessity of avoiding any robotcollisions suggested the insertion of a redundant degree of freedom allowing infiniteinverse kinematics solutions for the motion planning as well as for the movement opti-mization. The inverse kinematics requires to evaluate the pseudo-inverse matrix of thekinematical system in several trajectory points while the optimization is performed withan opportune weighting variable assigned for each joint degree of freedom. The super-vision of the machine dynamic behavior is obtained through the change of these weightsduring the motion. As a consequence, a suitable multi-objective genetic algorithm(MOGA) has been adopted to reduce vibration effects and to improve the quality of therobot motion with optimal motion profiles. In comparison with the traditional cuttingtechniques, the proposed one allows, as a result of the optimal motion of the robot, anincreased quality improvement and a reduced cutting cycle time. Premised a brief de-scription of the technological context, this paper presents the kinematical analysis of themachine and its optimization with the implemented MOGA. The proposed algorithm hasbeen implemented on a working laser pipe cutting machine and exhibits a behavior reallysimilar to the forecasted one.

Conflicting results of robot-assisted versus usual gait training during postacute rehabilitation of stroke patients: a randomized clinical trial.

Robot gait training has the potential to increase the effectiveness of walking therapy. Clinical outcomes after robotic training are often not superior to conventional therapy. We evaluated the effectiveness of a robot training compared with a usual gait training physiotherapy during a standardized rehabilitation protocol in inpatient participants with poststroke hemiparesis. This was a randomized double-blind clinical trial in a postacute physical and rehabilitation medicine hospital. Twenty-eight patients, 39.3% women (72±6 years), with hemiparesis (<6 months after stroke) receiving a conventional treatment according to the Bobath approach were assigned randomly to an experimental or a control intervention of robot gait training to improve walking (five sessions a week for 5 weeks). Outcome measures included the 6-min walk test, the 10 m walk test, Functional Independence Measure, SF-36 physical functioning and the Tinetti scale. Outcomes were collected at baseline, immediately following the intervention period and 3 months following the end of the intervention. The experimental group showed a significant increase in functional independence and gait speed (10 m walk test) at the end of the treatment and follow-up, higher than the minimal detectable change. The control group showed a significant increase in the gait endurance (6-min walk test) at the follow-up, higher than the minimal detectable change. Both treatments were effective in the improvement of gait performances, although the statistical analysis of functional independence showed a significant improvement in the experimental group, indicating possible advantages during generic activities of daily living compared with overground treatment.

Multimodal Treatment of Distal Sensorimotor Polyneuropathy in Diabetic Patients: A Randomized Clinical Trial

OBJECTIVE The purpose of this study was to evaluate the effectiveness of the application of analyzing treadmill, muscle strengthening, and balance training compared with a standard care intervention in patients with diabetic neuropathy. METHODS Twenty-seven patients, 63% female (mean ± standard deviations age, 72 ±9 years), with diabetic neuropathy randomly assigned to receive a multimodal manual treatment approach including analyzing treadmill with feedback focused, isokinetic dynamometric muscle strengthening, and balance retraining on dynamic balance platform or a standard care intervention for activities targeted to improve endurance, manual exercises of muscle strengthening, stretching exercises, gait, and balance exercises (5 weekly over 4 weeks). This study was designed as a double-blind, randomized clinical trial. Measures were assessed at pretreatment, 4 weeks posttreatment, and 2-month follow-up. RESULTS No important baseline differences were observed between groups. At the end of the treatment period, the experimental group showed a significant increase in gait endurance in a 6-minute walk test, 65.6 m (F[2.0] = 9.636; P = .001). In addition, the 6-minute walk test increased after the intervention, and an even greater difference was found at follow-up (P = .005) for the standard care group. The Functional Independence Measure in both groups increased (P < .01) and continued until the follow-up in the standard care group (P = .003). CONCLUSIONS The results suggest that the experimental rehabilitation program showed positive effects on the gait endurance after 4 weeks of treatment, whereas it did not produce significant improvements of the gait speed. Both the treatments produced significant improvement of functionalities of the patient.

Reliability Roadmap for Mechatronic Systems

This paper aims at proposing a structured approach in reliability design and analysis for mechatronic devices. Mechatronic systems are a complex integration of extremely advanced technological components able to perform tasks with high accuracy and flexibility. This complexity at all levels increases the risks of malfunction, failures and issues. The definition of an effective roadmap is necessary to provide prompt solutions in terms of product performances and duration. This study presents a set of reliability activities to be integrated in the product process development and during its cycle life. This approach may contribute to improve the mechatronic product functionalities and duration.

Design and Analysis of a Fibre-Shaped Micro-Actuator for Robotic Gripping

A prototype of an automatic micropositioning system was developed. This prototype uses a shape memory alloy (SMA) actuator, a dedicated PI controller and a piece of software to command a desired motion profile for the actuator. The proposed micropositioning system is characterized by a 4 mm stroke, a 1 μm resolution and a 70 g nominal force and can be commanded directly from a personal computer and without human retroaction. The closed loop positioning resolution (1 μm) is obtained in spite of inaccurate system behaviour during its movement.

Machine Tools Thermostabilization Using Passive Control Strategies

The aim of this study is to investigate passive control strategies using Phase Change Materials in Machine Tools (MTs) thermostabilization. By considering the main issues related to the thermal stability, authors presented the application of novel multifunctional materials to Machine Tools structures. A set of advanced materials are considered: aluminium foams, corrugate-core sandwich panels and polymeric concrete beds. The adopted solutions have been infiltrated by phase change materials (PCMs) in order to maintain the thermal stability of MTs when the environmental temperature is perturbed. The paper shows the results of simulative and experimental tests.

Innovative Modular SMA Actuator

A modular design for a shape memory actuator is proposed. The actuator is able to perform linear movements, while the modularity allows force and/or stroke improvements. Experimental results show how the behavior of the proposed implementation is sufficient for a wide class of problems and can be improved with proper developments.

Precision Positioning Systems: An Overview of the State of Art

In the industrial world the interest in Precision Positioning Systems is exponentially increasing in relation to the rapid growth of Ultra High Precision (UHP) machining. A greater attention is given to traditional techniques and developing of innovative solutions. This paper intends to present a review of the actual state of art in precision positioning system based on flexure hinge related to industrial machines, showing a comparison between different techniques.

Precision Point Design of a Cam Indexing Mechanism

This work regards on the design of a cylindrical cam indexing mechanism with a motion law that passes through a positional precision point. A numerical algorithm is proposed to solve this problem and, particularly, a genetic algorithm. The algorithm and the encoding of the problem are described.