PhD Thesis: Methodology for implementation of Synchronization Strategies for Wireless Sensor Networks

On July 16, 2020, our colleague Francisco Tirado-Andrés read and defended his PhD Thesis entitled “Methodology for implementation of Synchronization Strategies for Wireless Sensor Networks” under the direction of Dr. Alvaro Araujo Pinto.

This work was defended in an unusual way. Half of the tribunal was in person, but the other half of the tribunal was evaluating it via video conference. Even with this new form of presentation, the Thesis work was valued very positively by the entire tribunal, giving it the highest score: outstanding.
In addition, the entire tribunal issued a confidential and secret vote, which unanimously allowed the work to be awarded the mention of “cum laude”.

We leave you some links where you can find more information about this PhD:

List of publications:

  • F. Tirado-Andrés, A. Rozas, and A. Araujo, “A Methodology for Choosing Time Synchronization Strategies for Wireless IoT Networks,” Sensors, vol. 19, iss. 16, 2019
  • F. Tirado-Andrés and A. Araujo, “Performance of clock sources and their influence on time synchronization in wireless sensor networks,” International Journal of Distributed Sensor Networks, vol. 15, iss. 9, 2019.
  • J. H. García-Palacios, I. M. Díaz, J. C. Mosquera, J. M. Soria, and F. Tirado-Andres, “Learning dynamic analysis of structures using handy and affordable equipment. On the way of smart structures,” in IV International Conference on Structural Engineering. Education Without Borders, 2018, pp. 134-142.
  • R. Rodriguez-Zurrunero, F. Tirado-Andres, and A. Araujo, “YetiOS: an Adaptive Operating System for Wireless Sensor Networks,” in 2018 IEEE 43rd Conference on Local Computer Networks Workshops (LCN Workshops), 2018, pp. 16-22.
  • J. García-Palacios, J. M. Soria, I. M. Díaz, and F. Tirado-Andres, “Modal tracking with only a few of sensors: application to a residential building,” in 8th European Workshop On Structural Health Monitoring (EWSHM 2016), 2016.
  • J. García-Palacios, J. M. Soria, I. M. Díaz, and F. Tirado-Andres, “Ambient modal testing of a double-arch dam: the experimental campaign and model updating,” in 13th International Conference on Motion and Vibration Control (MoViC 2016), 2016.
  • J. García-Palacios, F. Tirado-Andres, J. M. Soria, I. M. Díaz, and A. Araujo, “Effects of time synchronization on operational modal analysis,” in 6th International Operational Modal Analysis Conference (IOMAC 2015), 2015.
  • A. Araujo, J. García-Palacios, J. Blesa, F. Tirado, E. Romero, A. Samartín, and O. Nieto-Taladriz, “Wireless Measurement System for Structural Health Monitoring With High Time-Synchronization Accuracy,” IEEE Transactions on Instrumentation and Measurement, vol. 61, iss. 3, pp. 801-810, 2012.
  • A. Araujo, F. Tirado-Andres, J. García-Palacios, and J. Blesa, “High precision structural health monitoring system using wireless sensor networks,” in 3rd International Symposium on Life-Cycle Civil Engineering (IALCCE 2012), 2012, p. 1093–1101.
  • J. García-Palacios, A. Samartín, R. Ortega, F. Tirado-Andres, A. Araujo, O. Nieto-Taladriz, J. Blesa, E. Romero, E. Reynders, G. D. Roeck, L. He, and F. Percivale, “Some advances in extensive bridge monitoring using low cost dynamic characterization,” in International Conference on Experimental Vibration Analysis for Civil Engineering Structures (EVACES 2011), 2011, pp. 417-424.

TFG: Design and development of synchronization protocols for wireless EMG devices

Clock Synchronization

Electromyography is the technique used to check the health of muscles and the nerve cells that control them. Muscle data is normally collected through non-intrusive surface electrodes, which are placed on the skin. One of the problems that this technique has traditionally presented is the number of wires that are needed to connect the electrodes to the device that processes the information.

In the B105 Electronic Systems Lab there is a line of research focused on the development of a platform that removes these wires. The proposed solution is a platform with wireless sensors that allows the collection of EMG data.
The design and development of the synchronization and data transfer protocols are essential and will be covered in this project. This work is a fundamental piece along with the detection of EMG signals, the encapsulation of the device and the representation of the data to create a final wireless EMG product.

In this project the objective is to design and develop at least one synchronization protocol and one data transfer protocol that allow the specific activities of an EMG platform to be carried out. A previous study of the EMG technique, as well as the available hardware and software have been conducted. Subsequently, two synchronization protocols and one data transfer protocol have been designed and implemented.

Finally, tests have been carried out to evaluate the operation of the protocols, verifying that they work properly.

TFM: Design and implementation of a neuromuscular stimulator based on electromagnetic induction

In recent years, the development of medical devices has become a key element in order to face the research of new treatments and diagnosis of different diseases. These devices are designed to reduce the negative effects of some pathologies in which traditional pharmacologic treatments are not effective. An example of these pathologies are those that are produced due to a nervous system deterioration. Dysfunction of the human nervous system can be caused by situations such as a stroke or an accident in which the spinal cord is injured. This deterioration can lead to signal transmission disorders to the muscles, which are responsible for the movement of the body, and lead to muscle weakness or paralysis. The pathologies affecting the spinal cord, such as paraplegia, block communication between the central nervous system and the nerves, responsible for transmitting signals to the muscles. Therefore, these signals which are sent to the muscle from the brain can not be propagated, preventing the contraction and relaxation of muscles that give rise to movement. For all these reasons, different techniques of functional electrical stimulation (FES) have been developed and their use has been growing during these years. They are based on the concept of induction of the muscle contraction through the generation of electrical stimulus in the nerve. This technique produces skin damage and pain sensation. On the other hand, artificial stimulation by electromagnetic induction has been barely studied. Magnetic stimulation is based on the induction of a time-varying magnetic field that causes a current into the tissue and therefore, into the nerve. In this End of Master Project a prototype is designed to work on this less common technique.

Model of the generation and propagation of the signal that produces the muscle contraction.

This required a first stage of research on the state of the art in applying electromagnetic induction in neuromuscular stimulation techniques and understanding the main characteristics of the devices used in them. From this study, the advantages and disadvantages are established, and at the end, the characteristics to be considered in the design of the prototype. The prototype is based on a modular solution called modular multilevel converter, which allows to obtain the desired voltage and current to generate a time-varying magnetic field that induces the stimulating current in the nerve.

The device designed in this project is composed by a hardware part and by a software part. In the hardware part of this modular multilevel converter, the microtopology is established, based on the modules as a unit, and the macrotopology, based on the combination of the modules. The different modules and their components are implemented on a printed circuit board (PCB) that will serve as support and connection of the modules. The software part defines the control signals that allow each of the modules to define their working states, and therefore their contribution to the signal that generates the time-varying magnetic field. The designed software allows the modules to work in a synchronized relationship in the macrotopology of the system.

The results obtained on this project allows establishing some first conclusions about the use of modular multilvel converters focused on magnetic stimulation. The control signals of the modules are a great challenge for the implementation of a system composed of more modules than those presented in the prototype. In addition, the size of the system with a larger number of modules, necessary to cause an effective stimulation that leads to muscle contraction, must be considered in successive design iterations. This prototype establishes the first milestones towards the development of a platform that allows the magnetic stimulation of the motor nerves.

TFG: Design and development of wireless sensorization system of a low-cost robotic arm

In the past the last few years, we have observed that new technologies have been improving the quality of life of all people, especially those who have difficulties in their daily lives. An example of this is prosthesis, which offers autonomy to those who need it, recovering part of the lost mobility.

This End of Degree project intends to carry out the sensorization of a wireless robotic arm. The objective of this project is to obtain information on the movement of the prosthesis and to analyse its behavior to improve the functioning of future prostheses, in such a way that it is as similar as possible to a human arm. We have specially focused on the movement of the wrist and the pressure exerted by the index finger and thumb.

Firstly, a previous study was carried out where we analysed the different angles of wrist rotation and their amplitude. Also, we studied the different ways that the hand makes to apply pressure to an object. On the other hand, we made a study of the different prostheses that exist today, separating them according to their mobility, to choose which was the robotic arm that better adapted to our study. Then, all the pieces of that arm were printed in a 3D printer to make its assembly.

Once the previous study has been carried out, the selection of sensors has been made. To do this, we made a small analysis of the different procedures that use these sensors to obtain the desired measurement. After this, a software has been created to obtain these measurements with the aim of being able to be interpreted by the user, through a graphic interface. A demo represents the movement of a human arm through the data provided by the sensor, as you can see in the figure above. The other demo is in charge of symbolizing through colors the different force exerted by the thumb and index finger.

Finally, different tests have been carried out to analyse the movement of the wrist and the pressure  exerted  by  the  fingers  according  to  the  different  positions  of  the  arm  and  using different forces.

TFG: Development of algorithms for monitoring physiological parameters to assist drivers

One of the main problems that we face today is traffic accidents. In recent years there have been more than 1000 deaths per year in Spain due to this reason, however, it is extremely difficult to find products on the market that assist the driver to deal with this problem.

In order to provide a solution to the problem outlined, at the B105 Electronic Systems Lab, a bracelet wearable was designed, which monitors the driver’s body temperature, stress level, heart rate, blood pressure, and the level of alcohol in the air.  This device is intended to provide a tool for the drivers to assist them to check if they are physically good and mentally ready to drive. However, the reliability expected in this device was not achieved, to use it as an end system in a user, due to a lack of time. For this reason, the main objective of this TFG has been to achieve the greatest performance of the electronic device designed in the previous project.

The first step has been to carry out a study of other similar products that can be found in the market, as well as the design of the device.

Then, an analysis of the parameters obtained with the bracelet has been conducted, to understand what aspects need to be known about them to measure them, and the different methods that exist to obtain them. In addition, the measurement method used by the device for each of them has been analysed in further detail, focusing on what problems it could present, and which factors could affect them.

Afterwards, tests have been carried out in all the modules in a separate way, in which the previous analysis has been considered. Different measurements have been performed on all the sensors during the tests, to calibrate them and to check their behaviour towards the factors that affect them.Through these tests, it has been concluded which is the optimal method to obtain each one of the parameters, the design problems that the device presents, and how it could be improved.

Lastly, the integration of all the modules has been carried out, in which besides obtaining all the parameters considering the conclusions obtained from the tests, an alarm system has been carried out. This system warns the user by the vibration of the bracelet, if a value out of a healthy range is detected in any of the measurements on the parameters. This integration has also been tested and depurated using the debugger.

Finally, it can be concluded that the main objective of the project has been achieved, although some changes would be necessary to improve its functionality, in order to be used as an end device.