DIIGIIT ROBOTICS FORUM

You are not logged in.

#1 Re: Introduce yourself » Hello World » 2014-12-23 14:23:23

Hello Incendie,

Incendie wrote:

Don't be an asshole" because a lack of rules doesn't dictate a lack of respect.

I totally agree with you.

This is the same for life; everything is not written in laws and rules. You are always going to see people taking advantage of it for their own purpose. This is the reason why laws are so complicated.

The good news is that you should not be angry any more because you have realized sooner than other persons that such person exists and that they are ready to do anything to win.

The bad news is that those assholes can sometimes make great lives.

#2 Microbotics & Nano Robotics » Nidec Sankyo micro stepper motor » 2014-10-28 20:48:39

Odysseus
Replies: 0

Hello,

I would need some advise on my setup as i am testing the Nidec Sankyo Micro Stepper Motor that you can find here.

Here is an image of my setup.

Sankyo testing setup

I have been using an Arduino board and an L293D motor driver.

Basically, I have been using what is described in this page for the bipolar stepper motor. I have removed the rotary pot and used the modified code below that increment the stepper motor by 1 stepper every 0.1 second.

/*
 * MotorKnob
 *
 * A stepper motor follows the turns of a potentiometer
 * (or other sensor) on analog input 0.
 *
 * http://www.arduino.cc/en/Reference/Stepper
 * This example code is in the public domain.
 */

#include <Stepper.h>

// change this to the number of steps on your motor
#define STEPS 100

// create an instance of the stepper class, specifying
// the number of steps of the motor and the pins it's
// attached to
Stepper stepper(STEPS, 8, 9, 10, 11);

// the previous reading from the analog input

void setup()
{
  // set the speed of the motor to 30 RPMs
  stepper.setSpeed(30);
}

void loop()
{
  // move a number of steps equal to the change in the
  // sensor reading
  stepper.step(1);

  delay(100);
}

The motor has been working ok and its torque seems decent for such a small stepper motor. However, my main challenge was to make the connection with the motor. Pins are so small and short that I was not able to use any breadboard. I then decided to go with some hook clip as you can see on the picture. The problem is that the clips are so strong as compared to the motor pins that I broke motor pins many times.

Do you know any king of device or breadboard i could use for my testing? What would you recommend?

#3 Re: Electronics & EDA (Electronic Design Automation) » Male header with short pin » 2014-10-16 00:11:49

Thank you John.

This is probably something like that I need.

I have also found that from Toby.

The pin size is similar to the one from Digikey but body size is slightly smaller.

#4 Electronics & EDA (Electronic Design Automation) » Male header with short pin » 2014-10-14 21:31:06

Odysseus
Replies: 2

Hello,

I am looking for male-male pin header, standard 2.54 mm pin spacing but with shorter pin length that the usual 11.5 mm.

Does anybody know if I can find this product somewhere.

I have not been able to find anything like that on the internet.

More precisely, usually standard male-male header have a long and a short pin. Would need something with 2 short pins.

#5 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-09-25 13:52:04

How much does Seeedstudio charge you to create a single PCB like this?

#6 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-09-06 00:59:16

This is very impressive. Thank you for the nice pictures.

How did you learn electronics?

I read on your blog that you have a software background.

#7 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-30 13:18:57

Can you tell me more about your board like input, output, wifi, programming. It seems pretty powerful.

#8 Re: Introduce yourself » Meet guitarino » 2014-08-30 13:03:02

Hello guitarino,

Welcome to the forum. Feel free to ask any question.

Do you have a project in mind to start learning robotics?

#9 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-19 13:01:02

Are you satisfied with the quality of your 3D printer?

Do you have to sand some parts like the nosecone to make it smooth?

#10 Re: Introduce yourself » Who is SherpaDoug » 2014-08-17 02:57:52

Hello SherpaDoug,

Welcome to this forum. Your background is quite impressive!

I hope you will be able to share your experience and maybe present some of the projects you've been working on in the Underwater robotics forum.

#11 Introduce yourself » I am Odysseus » 2014-08-16 19:27:49

Odysseus
Replies: 1

Hello,

I have a background of Mechanical Engineer but spend most of my career as a scientific programmer.

I am here to improve my skills in robotics especially electronics.

I will be participating in this competition by exploring some aspect of robotics that a rarely discussed, first one being Computed Aided Design for hobbyist with FreeCAD.

I will be very happy to hear from you on the miscellaneous tutorials I'd like to write and welcome you comments.

#12 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-15 13:54:44

Well you have already done a lot (from mechanics to electronics).

I did not find any reference to your CAD system but this link to the NanoSeeker shows that you are definitely using one.

I am not sure I understand; do you mean that the NanoSeeker is not using any reduction motor since the propeller is very small?

Did you try different propeller pitch and size to see which one was best suited for your motor?

It looks like you are using an homemade (3D printed) propeller. Did you try to make different propeller to compare thrust?

Did you try any commercial propeller?

#13 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-12 01:06:12

Did you make any kind of CFD simulation to have a gut feeling of your new design?

Lot of torpido like design, have a thruster similar to this Bluefin Robotics design:

BF9M-Architecture.jpg

Your second design seems better but I am pretty sure water is not flowing smoothly in front of the thruster.

Also I am wondering if your propeller is properly located...

I am looking at this article: Gimbaled Thrust and think that maybe your thruster should be moving (inside your tail) so that you could remove the little fin on the back.

#14 Learn robotics » FreeCAD - Tutorial 3 - The sketcher » 2014-08-08 18:32:38

Odysseus
Replies: 0

There is two ways (that I know) you can access the sketcher: from the Sketcher workbench itself or from the Part Design workbench. I will try this second option.

Let's start again a fresh FreeCAD session in the Part Design workbench.

When the Part Design workbench is active, you are working in 3D unless you decide to switch temporary to a 2D view, the sketcher. It is a way to work in a specific plane of your part: (x,y), (x,z) or (y,z) or any other reference surface of the design you are working on.

At this point, I would recommend you to read the official documentation on the Sketcher. It really explains in details what you need to know when creating a sketch and adding constraints.

One more time, I am not going to repeat what is already documented. What is really important to understand at this point is the workflow between Part Design workbench and Sketcher workbench.

From the Part design workbench, you need to find out the "Create New or Edit Sketch" button. Once the button is clicked, a dialog will propose you to create (if it does not exists) a new sketch in a specific plane. Once you validate it, you enter the sketcher workbench. Notice the grid. Take time to design some kind of shape within the sketcher.

Be careful: most of the time, you will need to create a pad, revolution from your sketch so it needs to be closed. For that reason, I would suggest to create a simple square or circle sketch first.

Now press on "Close the editing of the sketch" icon. You are back to your 3D view with your sketch. If your sketch is properly closed, you will be able to create a pad or make a revolution for instance.

This is the workflow: enter "Part Design Workbench", "Create a sketch", "Close the sketch", apply some geometric transformation to your sketch. That's it.

Here is a 5 minutes design to illustrate the idea. The sketch on the right side looks like an R (for robotics!) and then a 270 degree revolution around the (y,z) axis to get my part.

tutorial3

Right now, FreeCAD 0.14 is far better than the previous release and very stable. It did not crashed at least once!!!

#15 Learn robotics » FreeCAD - Tutorial 2 - First Part Design » 2014-08-08 15:42:26

Odysseus
Replies: 0

New designers may be a bit disturbed with the miscellaneous workbenches you can find in FreeCAD. However, if your objective is to design a part, you should concentrate your attention on 3 workbenches:

  • Sketcher

  • Part Design

  • Part

Why 3 workbenches for a single task?

The best answer to this question is probably because you want to reduce the number of operations required to create your part. You save time, you keep your design simple (KISS) and you reduce the rendering processing time of your computer, especially for a large assembly.

Which workbench you should start with really depends on the part you want to design.

For instance, if your part looks like a cube with fillets on edges, you should start designing in the Part workbench. If your design is a cube with grooves, it could be a better idea to start with the part design workbench. It really depends. Your experience also will be important in that decision. So maybe you should start with a first design and scrap it if you are not satisfied. At any time you can switch from one workbench to another to find out a feature that is missing in another workbench.

  • Part workbench can be used to create boxes, cylinders, spheres and cones. These are really basic shapes. It can also be used to measure your part.

  • Part design workbench is used to create shapes that relies on a sketch like a pad, revolution. It has additional features to create fillet, chamfer, draft for instance.

  • To be honest, creating a design in 3D is not always easy especially when you have to deal with perspectives or want to know if two lines are parallel for instance. This is the reason why the sketcher workbench exists. From time to time, it's better to work in 2D.

At this step, you should be in the Part workbench and click on the "Create a new document" icon and then click on the "Create a box solid" icon for instance. Here we are, you've got a cube!

If you right click on the cube and see "Navigation style", you will see a list of 4 styles.

At this stage, you should read this: Mouse Model

This is really important that you start playing with this cube to know how to zoom in and out the part, rotate it, select an edge or face, etc ...

I use "Touchpad Navigation" but "CAD Navigation" is fine too.

Be careful not to be in "Inventor mode" when you are doing some design. You won't be able to make proper selection of your part.

You can now save your cube. Let's call it cube. The unnamed part is replaced with cube!

Being able to open a FreeCAD document and play with it is already a major step.

Next tutorial: The sketcher

#16 Learn robotics » FreeCAD - Tutorial 1 - Basic Concepts » 2014-08-08 13:24:49

Odysseus
Replies: 0

I guess CAD can be a little bit intimidating when you are using it for the first time and maybe you don't know where to start.
However, in the emerging world of 3D printing, this is an essential skill any hobbyist should have. My objective is not to provide you with a detail explanation of every feature of FreeCAD.

One more time, I am not an expert of this software. My objective is to document my learning process as well as to give you enough details to get you started in what seems to be the most logical way to start learning FreeCAD since its workflow seems to be very similar to CATIA.

Part versus Assembly

First, some essential vocabulary:

  • sketch: this is a 2D design

  • part: this is a 3D design of a real world object

  • assembly: many parts together

  • draft: a 2D view of a part or assembly

The difference between a part and an assembly is not always clear and depends on your design.

Let's take an example:

A tire and its wheel can be designed as two different parts or as a simple one. It really depends on the level of details and flexibility you need in your design. However, if you go with 2 parts, you will be interested to have both wheel and tire defined as a single entity: this is an assembly. An assembly is defined as a bunch of parts with relative positioning. Positioning can be handled by the CAD itself or by a higher level software called PDM (Product Data Manager) or PLM (Product Lifecycle Manager). Once your got you tire+wheel assembly, you can reuse it as many time as you want to create, for instance, 4 wheels in a mobile robot. The concept is really similar to code reuse; once you have a generic piece of code, you can create a library. Having a separate wheel and tire under a single assembly rather than having them together inside a single part can have advantages since you may want to try different brands of tires coming from some kind of FreeCAD tire library. When you split your design, you can also consider see many designers in a single company work on the same design.

Workbench

The second concept I should talk about is workbench. A workbench is the equivalent to a bunch of features depending on what you want to achieve. For a commercial CAD software, a workbench comes with a licence and a cost. Some generic workbench like part design for instance will be less expensive than FEM workbench for instance. The good thing with FreeCAD is that you can have all those workbenches for free!

I have installed the best so far version of FreeCAD, which is 0.14 at the time I am writing this tutorial on Ubuntu. I may say that starting FreeCAD is a bit weird. It opens a grey window with a few menus. You have to manually select Workbench menu under View menu. There is no default workbench selected.

I would suggest that you go on submenu "Preferences..." under the General tab of "Edit" menu and on the "Start up" section select a default workbench to auto load. Take "Part Design" workbench.

Close FreeCAD and start it again!

Next tutorial: First Part Design

#17 Mechanics & CAD (Computer Aided Design) » FreeCAD for a CATIA designer » 2014-08-08 01:53:55

Odysseus
Replies: 0

For years, I was lucky enough to have my computer installed with CATIA and to be able to work with it on a daily basis. No matter what I was in my mind, I was able to design it. CATIA is incredible but unless you have a lot of money, no one would ever want to purchase it. Not only that, you certainly do not want to spend that much money to have a deprecated version after a couple of years. Same thing for SolidWorks, Solid Edge, NX & co!
         
To be honest, since nearly 10 years, I have been moving to Open Source software for the same reason; when you spend money in closed source, it is not long before your software or operating system become deprecated. This been said, if you are in my situation, you have to be realistic and be ready to pay the price; Open Source CAD is not their yet!
I've been looking for an alternative for years but right now, one of them get my attention: FreeCAD

Why FreeCAD? because:

  • FreeCAD is Open source

  • FreeCAD has features and a workflow similar to CATIA: sketch to 3D modeling

  • FreeCAD community is small but seems to be growing. See FreeCAD Google trends

  • FreeCAD has a robotic workbench that seems very interesting in the context of this forum

I have tried FreeCAD 0.13 one year ago. To be honest it was really unstable.

For this tutorial, I first try version 0.14 on Ubuntu 14.04 which was very stable. However I later decided to switch to the best so far version of the software, updated daily. Here is a nice documentation to know how to do it. It can be summarized with the following command lines:

sudo add-apt-repository ppa:freecad-maintainers/freecad-daily

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install freecad freecad-doc

I will try to document my findings in this forum in what seems to be the most natural workflow for a CATIA guy and hopefully will convince you and me that FreeCAD is the way to go to design your next robotic project.

FreeCAD Tutorial 1 - Basic Concepts
FreeCAD Tutorial 2 - First Part Design
FreeCAD Tutorial 3 - The sketcher

#18 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-07 22:58:04

Hello Jon,

JonHylands wrote:

If you look at the third video above, you can see black electrical tape wrapped around the front and back of the sub - that was a quick and dirty way to get the weight & balance just right, on the first (and only) time I had it in a pool.

You've tried your Nanoseeker only once! Why so much work for a single time?

Been able to update your NanoSeeker code live is definitely a major and clear enhancement on the previous design. On the other hand, I am not clear why you have decided to change the nosecone shape and have a longer ROV vehicle especially if you have tried your NanoSeeker only once!

Did you see a major flaw in your first design?

#19 Re: Underwater Robotics » NanoSeeker (Tiny Autonomous Underwater Vehicle) » 2014-08-01 20:16:20

Hello Jon,
This is an impressive job!
I was wondering if you need to put some weight to your AUV. According to your specifications, your NanoSeeker is approximately 130 cm3. Since it is made of ABS with air inside, I guess you need to put some kind of weight to reach the 130 g necessary to make it dive. Am I right? Is weight something critical for your NanoSeeker versus engine thrust (to go up and down)?

#20 Re: Microcontrollers & Computers » Arduino Uno projects » 2014-07-10 03:20:04

There is nothing you can do with an Arduino Uno. You need at least an Arduino Mega to create your own 3D printer smile

#21 Re: Microcontrollers & Computers » GPIO control and PWM generator ? » 2014-07-10 02:21:02

ThOmAs wrote:

I can detect a person with the web cam but i don't understand how i can interface the actuators and my detection program.

Can you tell us more about that? What kind of technology are you talking about to detect a person in front of the camera? OpenCV?

#22 Electronics & EDA (Electronic Design Automation) » Small size distance sensor » 2014-07-08 02:41:51

Odysseus
Replies: 1

Do you guys know any small size distance sensor that could be used for a small (really small) quadcopter project?
The Parallax Ping)) Sensor and Maxbotix are too large. The Devantech SFR10 is slighty smaller but quite expensive.
I can see IR sensor with a sensing distance up to 80 cm probably not enough for a quadcopter.
It looks like the CrazyFly quadcopter is not using any distance sensor.
What kind of sensor would you suggest me?

Board footer