Talmai Oliveira

I finally implemented a gesture recognition using Crossbow’s TelosB sensors coupled with an Arduino ADXL3xx accelerometer. The accelerometer is placed on a glove, and given the X, Y and Z axis readings, the sensor identifies the position of the hand of the user. Additionally, I have incorporated the gesture recognition into a racing game called HoloRacer. As the user pretends to hold a steering wheel, the car goes left or right. The usage of another sensor as the throttle allows to speed up the car. Fuzzy logic was used to help express the uncertainty behind any kind of classification and linguistic values where utilized such as “very low” or “very high”, which helped facilitate the expression of rules and facts, contrary to variables in mathematics that usually take numerical values. The extreme values of each one of the axis are divided into 5 groups. Each group is given a linguistic value which are “low”, “medium-low”, “medium”, “medium-high”, and “high”. For each hand position hat we plan on classifying, we measure the average values and identify in which linguistic group it belongs. If anyone is interested, this is the report I handed in for the class project.

What did I learn from this? I will need to put in a little more effort before getting something really good, but the way it is is actually pretty remarkable.

For one of my classes I had to write a survey on time synch. protocols for ad-hoc networks. As stated in the abstract, in wireless sensor networks (WSN) there is no global clock or common memory. Each wireless node has its own internal clock and its own localized notion of time. In practical scenarios, clocks can easily drift apart by several seconds per day, accumulating large amounts of error over time. Furthermore, since different clocks “tick” at different frequencies, they will most likely not remain always synchronized, even if they start synchronized. This clearly poses a serious problem to applications that depend on a synchronized notion of time. Time synchronization is therefore of the upmost importance for WSN and has a significant effect on fault diagnostics and recovery problems, secure systems, and scheduled and synchronized operations. However, many of the successful time synchronization protocols for wired networks are unsuitable for WSN due to the many different challenges that are not considered.

In this report, then I discussed about the time synchronization protocols for WSN, with special focus on randomized node deployment scenarios. Additionally, since in a real-world scenario the WSN may be deployed in an un-friendly environment, especially considering the promising prospect of battlefield deployment, security becomes essential in time synchronization scheme design. A section is then dedicated to secure time-synchronization protocols.

The pdf file is available in the publications/research page.

End of quarter woes for me include grading a lot of homework resubmissions. Call me soft, but I think that school is made to help the students learn, so as long as there is time, I’ll accept resubmissions. Sadly, that means that on the last week students will resubmit almost all of their assignments. The only good news out of all of this is that I accidently found out that hitting F7 will get a complete list of commands that you executed. It’s similar to the linux command ‘history’, but it’s more visual as it brings up a popup! Use the arrow keys to highlight the command you want to run again or just hit the number key corresponding to the command that you want to execute.

F7 is also what I use to compile code in Visual Studio…