OSH Park recensione

Ciao,

Sorry but this time I’m going to write the post in my mother tongue. This is because I want to explain how to make a very easy PCB’s to young students that may not understand English.

Ci sono molte recensioni del servizio di PCB sharing chiamato OSH Park ma nessuna (ancora) è in Italiano. La scheda che ho realizzato con KiCad è davvero semplice e a scopo dimostrativo. Utilizza componenti PDIP molto comuni come l’operazionale LM324, resistori e condensatori though hole. Ovviamente i più smaliziati possono divertirsi con la tecnologia SMD(SMT) anche se molto più difficile da saldare sulla piastra.

Mi rivolgo soprattutto a studenti di istituti tecnici o professionali a cui piace sporcarsi le mani. Il nostro paese tende a scordarsi di voi e di quanto la vostra formazione sia importante per l’innovazione. Vi do un consiglio: se siete predisposti a sporcarvi le mani (come me), non sentitevi a disagio con questa vostra necessità! Siate curiori, fate pratica, errori e correzioni. Anche il mercato del lavoro ve ne darà conto perchè dimostrare di poter fare qualcosa di pratico e funzionante vi porterà tra i primi della lista.

Stay tuned!

The definitive plectrum comparison for acoustic guitar with spectrum analysis

Hello guys,
Halloween just passed and it is getting colder and colder over here. The days are becoming short and I tend to spend a lot of time with Tiia. She is my love and she let me play everything I want, of course I’m talking about my Martin OMCPA4 Rosewood.
I’m learning how to get the best sound out of her, expecially when I perform on the stage. As you know there are differences in the sound coming from the piezoelectric located under the bridge and a possible microphone placed in front of the guitar. Even though this last option is preferable, it is often impractical on the stage.
Another variable is the plectrum to use. Despite different songs should be played with different techniques and picks at some point you need to choose one kind and go on with it for the whole performance.
I though that the spectrum analysis, that shows the response at different bands, would help me and other friends to investigate better the business.I’m using the free on available at http://sevenphases.wordpress.com/
As result of this analysis I will opt for a thick plectrum as the 0.73mm from now on. At least in this song I need a greater “presence” and the thicker plectrums seem to enhance the high frequencies.

Stay tuned!

RepRap 3d printer

Hello guys,
I finally graduated as Diplomi-Insinööri and I made a present to myself 🙂
A kit from poland has arrived some week ago and during my job quest breaks I managed to build it up. I’m talking about the MendelMax 1.5 kit by Gadget3D. The package contained mechanics and electronics (ramps1.4) but the manual and the bolts/nuts contained didn’t mach the most of the times.I often needed to find some work-around and for this reason be aware that the word “kit” doesn’t mean a kids play 😦
I have to report that the ramps 1.4 electronics board had a broken track that didn’t allow the change of direction in the z axis. They will send a working one from Poland but in the meanwhile I had to solder a wire to bring the logical level from the Arduino board to the Pololu stepper driver.
It took quite a long time to get into the RepRap issues, checking on internet and inventing some solution.
The process of calibration is slightly complex in the beginning but it becomes routine quickly.

Thanks for the attention and stay tuned!

Altitude control system for indoor airship

Hello guys,

It has been a while..! I have been writing my MSc thesis and I completely forgot about the blog. Any case I have some good update. The thesis is complete and I suggest you to read it through to understand the techniques used to rule the altitude.

The whole thesis is available at the link http://urn.fi/URN:NBN:fi:tty-201408221388

Fiber optic gyro

Hi,
It is quite a long time that I don’t post anything!Sorry I have been busy with thesis, gigs and girls(good moment indeed) 😉
I’m having my last course in Tampere University of Technology and it happpened to me(once in a lifetime) to have this very precise sensor to test.
This short video shows the calibration procedure of a fiber optic gyro(fog).
This initial phase is used to estimate the bias in the measurements. The bias instability must be taken into account but for short periods the sensor can be extremely accurate. This FOG is so sentitive to measure the Earth rotation rate and it can be used to identify the geographic north. High accuracy = high price. In about one month the department has to give it back to the producer and I’m always afraid to brake it 😦

Nyton motor test

Today I did some voltage limiter with just two zener and a resistor to both motors.
Now they can work with the voltage provided by the battery pack without problems.
The video shows a sequence of orientations while the motor are spinning with a PWM modulation.It produces a noise that is a kind of irritating but I’m really glad that the things start working.
Nyton will be soon ready to fly!

Nyton beta payload test

Well.It seems that Nyton can load 135g!This is the effective load that make the baloon reach the equilibrium(almost).
This test is done with a box that weights 98g(screws included) and some nails that weights about 4,6g each.
I needed 8 nails + the box that is about 135g of load.
It means that the lifting force is equal to 0.135*g so about 1.3Netwon

 

 

Nyton beta test

Hello,

I have been busy and I didn’t write for a while.I’m ending the semester and I have been studying really hard.

Here in Tampere(Finland) days are getting shorter and shorter and the snow is covering the landscape.Santa is getting ready with the presents for all the good kids.

Anyway…my friend Juha Koljonen gave me the first present for Christmas.He has a great, home-made 3d printer and he managed to print some parts I designed with Solidworks.

I eventually found the time to glue the parts and proceed with some test.Well…I needed to fix the tollarances with a file but it seems to work as expected!

Here there is a video that shows how the attidute of the thrust can be chanded.It follows the simulation done with Solidworks.

Simulation becomes reality 🙂

Stay tuned!

WCF vs LS

Hi,

I have been doing an exercise at the university that turned to be pretty complicated and interesting to explain here.

It is about the estimation of the user position exploiting the received signal strength(RSS) from different wlan access points.

For the purpose I’m considering a weighted centroid function and the least square method.The trilateration can be used but it assumes the intersection of the pseuseranges corresponding to the RSS. Unfortunatelly this is a contition hard to find.

The Centroid Function is explained at this page on Wikipedia http://en.wikipedia.org/wiki/Centroid and has been implemented for positioning purposes by a team of researcher on this paper here

For every instant you have consider the 3 most powerful access points. The RSS is then conversed to an expenced distance from the access point through a path loss model. You assign a weight that is invertly by the distance from it. A g factor is used to optimize the weight.

g=1;
weight=1./(dist.^g);
sum_weight=sum(weight);
x=sum(weight*pos(:,1))/sum_weight;
y=sum(weight*pos(:,2))/sum_weight;

The Least square method tries to find an estimation that minimize the sum of the square distances.

It is used in GNSS receivers in order to obtain the best estimation using 4 or more presudoranges. You can find a better explaination of the use of it for indoor positioning at this link here 
H=[pos(1,1) pos(1,2) dist(1);pos(2,1) pos(2,2) dist(2);pos(3,1) pos(3,2) dist(3)];
d=-0.5*[dist(1)^2-(pos(1,1)^2+pos(1,2)^2);dist(2)^2-(pos(2,1)^2+pos(2,2)^2);dist(3)^2-(pos(3,1)^2+pos(3,2)^2)];
X=inv(H’*H)*H’*d;
x=X(1);
y=X(2);

I don’t feel like sharing the full matlab code i wrote.

Here you can find an animation that is the result of the script.

Stay tuned!

Bill of materials

Hi!

It took a long time but eventually I have everything I ordered from the web.

The items I ordered are:

1)Balloon (Blimp, Silver)- 52″x37″  – 1X

2)Motor-7mm 3.3 Ohm – 2X

3)Propeller – 65mm – 2X

(from Plantraco Canada)

4)Pololu USB AVR Programmer – 1X

5)Baby Orangutan B-328 – 1X

6)Battery LiPo 2S/1P 7,4V 350 mAh 25C – 1X

7)Battery LiPo 2S/1P 7,4V 550 mAh 20C – 1X

8)Battery charge LiPo PolyCharge 12V – 1X

9)Ultrasonice range finder XL MaxSonar EZ2 – MB1220 – 1X

10)Micro Servo Hitec HS 55 – 1X

(from RobotStore.it)

11)Pan / tilt SPT50 mechanics – 1X

(from RobotShop.eu)

I wrote the number of items needed for the project but actually there are some backup parts.

There is the Helium misssing from the list because I’m working to find it to some local dealer.

Most likely I will have to buy some other small electrical components and find some wire.Anycase these are the main stuff I will need.

I received my stuff here in Tampere(FI) without problems from the european stores.I had to cope with some burocracy about the envelope coming from Canada.

In fact Tulli(finnish import agency) wanted me to provide: Evidence of my study activity, list of components in the package, declaration from the university department about my need of those parts and of course they checked my ID.

Maybe next time I will ask to a finnish friend to go in case of me.I may understand that a long black beard italian, with a deep voice and a Fonzie’s black leather jacket may look suspicious 🙂

After twice I have been at that office(lost in the industrial side of Tampere) I have been able to receive my package at home.

Now I’m working on it.

Stay tuned!