31
May, 2019

Best Paper Award at IEEE I2MTC 2019

Congratulations to our team for winning the Best Paper Award for the paper “Qualification of Additive Manufactured Trabecular Structures Using a Multi-Insutrumental Approach” presented at the 2019 IEEE International Instrumentation and Measurment Technology Conference!

This research is part of a Progetto di Ricerca di Interesse Nazionale (PRIN) carried out in collaboration with the University of Brescia, the University of Perugia, the Polytechnic University of Marche and the University of Messina.

To read more about the project, check out this page!

31
May, 2019

Optical analysis of Trabecular structures

Rapid prototyping, known as 3D printing or Additive Manufacturing, is a process that allows the creation of 3D objects by depositing material layer by layer. The materials used vary: plastic polymers, metals, ceramics or glass, depending on the principle used by the machine for prototyping, such as the deposit of the molten material or the welding of dust particles of the material itself by means of high-power lasers. This technique allows the creation of particular objects of extreme complexity including the so-called “trabecular structures“, structures that have very advantageous mechanical and physical properties (Fig. 1). They are in fact lightweight structures and at the same time very resistant and these characteristics have led them, in recent years, to be increasingly studied and used in application areas such as biomedical and automotive research fields.

Despite the high flexibility of prototyping machines, the complexity of these structures often generates differences between the designed structure and the final result of 3D printing. It is therefore necessary to design and build measuring benches that can detect such differences. The study of these differences is the subject of a Progetto di Ricerca di Interesse Nazionale (PRIN Prot. 2015BNWJZT), which provides a multi-competence and multidisciplinary approach, through the collaboration of various universities: the University of Brescia, the University of Perugia, the Polytechnic University of Marche and the University of Messina. 

The aim of this thesis was to study the possible measurement set-ups involving both 2D and 3D vision. The solutions identified for the superficial dimensioning of the prototyped object (shown in Fig. 2) are:

  1. a 3D measurement set-up with a light profile sensor;
  2. a 2D measurement set-up with cameras, telecentric optics and collimated backlight.

In addition, a dimensional survey of the internal structure of the object was carried out thanks to to a tomographic scan of the structure made by a selected company.

Fig. 1 - Example of a Trabecular Structure.
Fig. 2 - The prototyped object studied in this thesis.

The 3D measurment set-up

The experimental set-up created involved a light profile sensor WENGLOR MLWL132. The object has been mounted on a micrometric slide to better perform the acquisitions (Fig. 3).
The point cloud is acquired by the sensor using a custom made LabView software. The whole object is scanned and the point cloud is then analyzed by using PolyWorks. Fig. 4 shows an example of acquisition, while Fig. 5 shows the errors between the point cloud obtained and the CAD model of the object.
Fig. 3 - 3D experimental set-up.
Fig. 4 - Example of acquisition using the light profile sensor.
Fig. 5 - Errors between the measured point cloud and the CAD model.

The 2D measurment set-up

The experimental set-up involving telecentric lenses is shown in Fig. 6. Telecentric lenses are fundamental to avoid camera distorsion especially when high resolution for low dimension measurments are required. The camera used is a iDS UI-1460SE, the telecentric lenses are an OPTO-ENGINEERING TC23036 and finally the retro-illuminator is an OPTO-ENGINEERING LTCLHP036-R (red light). In this set-up a spot was also dedicated to the calibration master required for the calibration of the camera.
The acquisitions obtained have some differences according to the use of the the retro-illuminator. Fig. 7, 8 and 9 show some examples of the acquisitions conducted.
Finally, the measured object was then compared to the tomography obtained from a selected company, resulting in the error map in Fig. 10.

 

Fig. 6 - 2D experimental set-up.
Fig. 10 - Error map obtained comparing the measured object to the tomography.

If you are interested in the project and want to read more about the procedure carried out in this thesis work, as well as the resulting measurments, download the presentation below.

DOWNLOAD THE PRESENTATION
13
Jan, 2017

The Smart Gym Concept

Goals

Subjects with complete spinal cord injury (SCI) experience several limitations in their daily activities. Rehabilitative gait training by means of powered gait orthosis (PGO) has been shown to decrease the risk of secondary pathologies (e.g. skin injuries, osteoporosis, cardiovascular issues) and can significantly improve the quality of life, provided that they are used on a regular basis and in the correct way.
The traditional training is based on three steps: gait trial, data analysis, and gait correction. Gait is monitored using force platforms and dedicated instrumentation directly applied to the patient (EMGs, IMUs, markers). These devices require time to be positioned and care by the patient while walking.
Data analysis and gait correction are totally dependent on the therapist experience. The process must be performed in specialized centers and is very time consuming. This leads to a high cost for the community health services.

Costs and efforts needed for longer training sessions could be reduced by the availability of a SMART GYM environment to:

  1. provide real-time feedback directly to the patient about his/her gait performance;
  2. provide information to clinicians and therapists to remotely monitor the patient;
  3. involve the patient in personalized gait exercises depending on his/her performance in time;
  4. allow the patient to train on his/her own, along paths longer than those permitted by the limited room available in gait laboratories.
Figure 1 - The smart gym objectives.

The SMART GYM components

  • BMM (BioMechanical Model): this component evaluates patient posture and motion in real time. The BMM is fed with (i) the spatiotemporal gait parameters, (ii) the kinematics of the lower limbs, and (iii) the kinematics of the upper limbs;
  • IC (Instrumented Crutches): this system is specifically designed measure the kinematics of the lower limbs and the spatiotemporal gait parameters;
  • OMT (Optical Motion Tracking): this system estimates the upper limb kinematics using a suitable set of Kinect devices;
  • VR (Virtual Reality): this system carries out the self-training of the patient;
  • TD (Therapist Dashboard): a dedicated software service that collects the data from BMM and allows the therapist to follow the patient progress remotely, an to plan new train patterns.
Figure 2 - The SMART GYM components.
Figure 3 - The therapist dashboard architecture.

Novelty of the Project

  • The IC system, based on “A Vision System that walks with the patient” (challenging, but very promising);
  • The OMT based on multiple Kinect devices is new with respect to state of the art, since most applications are performed using a single device.
  • The combination of the OMT in the VR system will lead to the realization of a novel human machine interface, able to accurately render the posture of the whole body.
  • The paradigm of adaptiveness that lays under the BMM system is novel, as it requires new approaches to the estimate of the gait and posture indices.
  • The smart gym project is highly interdisciplinary: knowledge and expertise from the mechanical and the electronic measurement community will allow the development of either sensors (both contact and contact-less), models (both in the biomechanics and in the artificial vision contexts), measurement procedures, virtual reality scenarios and clinical experimentation, which will be fused together and integrated using ICT technologies. This aspect well fits one of the most significant Horizon 2020 priority, i.e., transversality.

Impact of the Project

  • The SMART GYM represents a new environment where the patient can practice autonomously and yet under the therapist control;
  • The SMART GYM will reduce community costs;
  • The SMART GYM will be valuable for elderly people;
  • The SMART GYM will be valuable even for healthy people.
11
Jan, 2017

MAPSS: Multimaterial Additive Production for Structural Sustainability Applications

This project focuses on the e-manufacturing of complex parts by integrating smart additive manufacturing technologies to more traditional manufacturing processes, in view of obtaining sustainable, flexible, completely automatic and fast manufacturing (SMART MANUFACTURING).

The project is funded by the POR FESR 2014-2020: Linea R&S per Aggregazioni 2015 Regione Lombardia, and involves SMEs and Research Laboratories in strong cooperation to demonstrate the feasibility of producing industrial manufacts in the automotive industry.

The role of the laboratory is the study and the implementation of vision tools for the on-line control of the manufacturing process based on the additive approach.

27
Dec, 2016

Evaluation of morphological characteristics of retinal vessels

The accurate and timely monitoring of hypertension-related diseases is important for a population screening and follow up, to prevent the onset and to assure proper treatment. The evaluation of morphological characteristics of small resistance arteries in human beings in not easy. The gold standard is generally considered the evaluation of the media to lumen ratio of subcutaneous small vessels obtained by local biopsies and measured by wire or pressure micromyography. 

However, non-invasive techniques for evaluation of retinal arterioles were proposed, in particular two approaches seem to provide interesting information: scanning laser Doppler flowmetry and adaptive optics; both of them provide an estimation of the wall to lumen ratio (WLR) of retinal arterioles.

The Laboratory is involved in the assessment of the efficiency and efficacy of a recently developed non invasive diagnostic instrument, able to provide high-quality images of the retina, by means of adaptive optics. In collaboration with the Chair of Internal Medicine of the University (Prof. D. Rizzoni), the instrument and its software are tested for accuracy and repeatability on artificial vessel models, and on a database of subjects.

Based on the data collected so far, the instrument performs in a quite satisfactory way as compared to the previously used techniques.

Related publications

Ciuceis, C.; Caletti, S.; Coschignano, M. A.; Rossini, C.; Duse, S.; Docchio, F.; Pasinetti, S.; Zambonardi, F.; Semeraro, F.; Sansoni, G.; Agabiti Rosei, C.; Pileri, P.; Agabiti Rosei, E.; Rizzoni, D. “Comparison between techniques of evaluation microvascular morphology: The gold-standard locally invasive micromyography vs. three non-invasive techniques. Preliminary data.” Artery Research, Vol 20, pp 95-96. 2017

Rizzoni, D.; Agabiti Rosei, C.; De Ciuceis, C.; Semeraro, F.; Rizzoni, M.; Docchio, F. “New Methods to Study the Microcirculation“, American Journal of Hypertension, Vol 31, Issue 3, pp 265–273. 2018

Nardin, M.; Coschignano, M. A.; Rossini, C.; De Ciuceis, C.; Caletti, S.; Rizzoni, M.; Docchio, F.; Porteri, E.; Rizzoni, D. “Methods of evaluation of microvascular structure: state of the art“, European Journal of Translational and Clinical Medicine, Vol 1, pp 7-17. 2018

16
Aug, 2016

A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination

Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, able to work in harsh environments and at high rolling speeds. We have developed a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a Laboratory test bench.

3D macro-topgraphy and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The operate with very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens.

Related Publications

Bodini, I.; Sansoni, G.; Lancini, M.; Pasinetti, S.; Docchio, F. “A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination“, Review of Scientific Instruments, Vol 87. 2016

Bodini, I.; Sansoni, G.; Lancini, M., Pasinetti, S.; Docchio, F. “Feasibility study of a vision system for on-line monitoring of rolling contact fatigue tests“, Journal of Physiscs: Conference Series, Vol 778. 2017

Bodini, I.; Petrogalli, C.; Mazzù, A.; Faccoli, M.; Lancini, M.; Pasinetti, S.; Sansoni, G.; Docchio, F. “On-line 2D monitoring of rolling contact fatigue/wear phenomena in dry tests“, Journal of Physics: Conference Series, Vol. 882. 2017

16
Aug, 2016

Innovative, fast autofocusing system with liquid lens objective

Vision-based measurement techniques have become very important in the biomedical field, especially for macro applications such as fingerprints detection, retinal measurements and melanomas analysis. These applications usually require fast and accurate focusing systems to rapidly acquire the optimal image for the successive elaborations. Applications in macro regions also need a stable focus to systems that suffer from low frequency vibrations due to the natural oscillations of the human body.

Liquid lens objectives have become popular in the last years thanks to their small dimensions (apertures goes from 3 mm to 10 mm), low power consumption (less than 0.1 mW) and fast response time (about 15 ms) [1]. These characteristics make the liquid lens objectives suitable for autofocusing systems, which require high velocity, good accuracy and good stability. The high-speed control of liquid lens objectives requires smart algorithms for the autofocusing procedure, especially in macro regions.

We developed a new system for biomedical macro applications. It uses a liquid lens objective, which implements a voltage control of the focal length, and an autofocus algorithm. The algorithm finds the best focus position using a two-stage search: a coarse searching and a fine searching. This approach combines high accuracy and high speed of convergence.

Figure 1 - Scheme of the autofocus algorithm.

The control variable of the algorithm is the clearness of the acquired image. Various indexes of clearness have been studied to implement the algorithm. Among these, two indexes have been selected, based on the absolute and on the squared values of the image derivatives respectively [2]. 

The black curve in figure 2 is the image clearness within the focal length range. The blue and the green areas represent the range in which the algorithm performs a coarse search and a fine search respectively. The red dots correspond to the values of clearness at different focal lengths, at each iteration of the algorithm. As a first step, a coarse search of the best focus position is carried out by varying the focal length from point (1) to subsequent points, until the green region is reached: in the figure, this process is performed in two steps, from point (1) to point (3). Then, the fine search is carried out: here, small increments of the focal length are considered, and the corresponding values of clearness are computed. A suitable threshold based algorithm is used to evaluate both the sign and the entity of the corresponding variations, and to choose the correct convergence direction. In the figure, this process is schematically represented by the path from point (3) to point (5), which corresponds to the best focus position.

Figure 2 - Algorithm approach using a template image.

The algorithm shows good performances in terms of speed of execution and accuracy and exhibits good results in real macro applications such as fingerprints, retinal and melanomas analysis. The algorithm has a good focus stability also with hand-held systems.

Related Publications

Pasinetti, S.; Bodini, I.; Sansoni, G.; Docchio, F.; Tinelli, M.; Lancini, M. “A fast autofocus setup using a liquid lens objective for in-focus imaging in the macro range“, AIP Conference Proceedings, Vol. 1740. 2016

Pasinetti, S.; Bodini, I.; Lancini, M.; Docchio, F.; Sansoni, G. “A Depth From Defocus Measurement System Using a Liquid Lens Objective for Extended Depth Range“, IEEE Transactions on Instrumentation and Measurement, Vol. 66, no. 3, pp. 441-450. 2017

Pasinetti, S.; Bodini, I.; Lancini, M.; Docchio, F.; Sansoni, G. “Experimental characterization of an autofocus algorithm based on liquid lens objective for in-focus imaging in the macro range“, 2017 7th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), pp. 195-200. 2017

Pasinetti, S.; Bodini, I.; Lancini, M.; Docchio, F.; Sansoni, G. “Automatic selection of focal lengths in a Depth From Defocus measurement system based on liquid lenses“, Optics and Lasers in Engineering, Vol. 96, pp. 68-74. 2017

10
Sep, 2015

LASER ALLUMINIO: Real-time acquisition for laser welding monitoring

The objective of this project was to develop a vision system for the real-time acquisition and saving of images produced in laser welding processes. This activity represents an initial step in the context of a research project aimed at studying the relation among the welding parameters and the quality of the welds, as they are captured by the vision system, for the feedback of the welding parameters during the welding.

The Laboratory worked in collaboration with TubeTech Machinery srl (Cazzago San Martino, Brescia, Italy), that was the company interested into this study.
The hardware used to devop this application is the Embedded Vision System (National Instruments) with LabVIEW 8.6.1, the IMAQ Vision libraries and the Real Time module for LabView. The vision system is based on the cooperation between a Host PC (PCS), and the NI EVS 1464 device. The acquisition campaigns have been done on one of the welding machines  available at TubeTech Machinery.

Suitable image elaboration tools have been developed to extract information from the videos captured by the system.

9
Sep, 2015

SMART BREAK – Bialetti REstoration Adaptive Kit

SMART BREAK is a project funded by Regione Lombardia thanks to a grant in the field of “Smart cities and communities”, for ambient assisted living. Nine companies (Bialetti Industrie Spa, Connexxalife Srl, Elemaster Spa, Lampia Srl, Gualtiero Marchesi Srl, Synergie CAD Instruments Srl, SAEF Srl, Sait Srl, and Signal Srl), two universities (UniBS and UniBG) and one hospital (San Raffaele) have joined the SMART BREAK project, and Bialetti Industrie is the leading partner.

SMART BREAK will be a modular system: food will be heated, hot and cold drinks will be provided as well as smoothies and users will be profiled, to create a food diary.

The Laboratory contributes to the project and works on a vision system, based on a smart camera (VisionCam XS – Imago Technologies), which communicates by means of an HMI, via a Modbus Ethernet Protocol. The developed vision system is capable of reading EAN barcodes, for the food diary and of recognizing lunch boxes of known weight.

The machine under development. Ileana is working at the vision system.
Food containers and barcodes that have to be recognized.
present_photogrammetry.jpg
Examples of bar code detection.
18
Aug, 2012

The MICE Project

This activity has been accomplished in collaboration with the dept. of Physics of the Politecnico of Milan. The objective was to develop and test specific image processing algorithms based on piece-wise linear histogram transformation to assist tumor detection by means of a time-gated fluorescence imaging technique. The developed procedures have been designed to improve, in real time, the quality of the images taken by means of an intensified video camera. Smart optimization criteria have been followed for the automatic choice of the enhancement parameters. An example applied to the detection of experimental tumors induced in mice is shown in the figures below.