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16  Using Arduino / Project Guidance / feasibility question: turning dc motor to servo? on: October 04, 2012, 08:07:15 am
I installed 2 dc motors, one vertically to ground for left-right and the other on top of it horizontally, for up-down movement. My circuit is an Arduino and L298. I put one pot per motor, so I have the position. What I need is that when I break the motor (LOW-LOW), not only get it stopped right at the moment (which is done ok), but also to have it not to move, so if this is an arm that lifted something, it won't fall down!

Is there any hardware(electronics) / software solution, or such a thing must only be done mechanically?

17  Using Arduino / General Electronics / Re: debounce problem on: October 02, 2012, 11:16:00 am
Thank you all, like always my mind got clear by refering to Arduino Forums!
18  Using Arduino / General Electronics / Re: debounce problem on: October 01, 2012, 01:13:06 pm
True, can't do software debounce for I'm on ISR, no delay() !

I drew what I call 'standard', sorry if not very clean drawing, and yes, I made a mistake, 10uF for sure!

Sorry for I forgot: the resistor is connected to +5v.
19  Using Arduino / General Electronics / debounce problem on: September 30, 2012, 04:18:04 pm
I have a plan to install a bumper switch in the neck of the robot and just set it up on breadboard to test. I used standard hardware debouncing by using an SN74AC04 hex inverter and 10k resistor and 10mf capacitor and a microswitch.

For test program I attached the zero interrupt of pin 2 and it works, but not well enough: it sometimes makes a mistake. Seems to me not a fast enough debouncing. If I press the switch repeatedly around 2 times a second, it makes mistakes sometimes.

My question: is there any way I could guarantee its operation, or a better way of implementing such a limiting switch, as it is to sit with a dc motor and just imagine if the bot is turning the neck and limiting switch won't work!
20  Using Arduino / Project Guidance / Re: packet loss on: September 10, 2012, 02:33:42 pm
Thank you, you made my mind clear, I shan't state a fault of wifi when I still did not trace the path.

I implemented over TCP/IP. Based on your kind information I will simply put away my own software and implement over ROS and TCP/IP, then if I'd again get pocket loss, I will first trace and if not solve it ask help back here.

Thank you again, :-)
21  Using Arduino / Project Guidance / Re: pocket loss on: September 09, 2012, 10:33:57 am
Thank you for response, my hardware:
bot: router (OpenWRT) <--> ethernet (enc28j60) <--> Arduino

A notebook is added to the wifi network of the router, then a wii bluetooth joystick pairs with notebook, sending commands to a java-program on the notebook which receives and sends commands to a C++ program on the router via socket, then from there the command is being sent to Arduino.

I actually did this long ago (a year at least) and had this problem of pocket losing, i.e. sometimes I'm pressing buttons of the joystick and the bot is not moving, or I'm trying to stop it and it goes on to hit head to wall.

Now I'm investigating to setup a new implementation using ROSjava (Android), router (spec. for security) and Arduino, where connections on the bot are all on ethernet EJ45 and the bot is teleoperated via wifi. I don't want to have packet losing this time! I'm going to send this one outdoor to meet people, don't want to heart anyone!

I passed the hello world tutorial of ROS between Arduino and Ubuntu (publisher, subscriber, hello world printing) and now opening way toward ROSjava, but first decided to write here to know why I was losing packets (if I'm referring to the problem with the right name), and implement the new design so that not to repeat mistakes.

Will appreciate greatly your suggestions,

22  Using Arduino / Project Guidance / packet loss on: September 07, 2012, 01:17:21 pm
I experimented with router<-->arduino but suffer enough from pocket loss, is there any recommendation of implementation so that to minimize them, or just get rid of?)

For example, from commands I send from keyboard over wifi to the router, to move arduino->L293->motors, some are lost and make false behaviors.

Would appreciate suggestions,


Moderator edit: Thread title corrected.
23  Using Arduino / Project Guidance / ROS, Ethernet, messaging reliability on: September 01, 2012, 02:04:48 pm
Recently, going for cheap camera pushed me to something new to me, called ROS. I can put two cameras on a router with usb port (hub) and connect Arduino to the router over Ethernet (Enc28J60).

I've just finished some ROS tutorials for Arduino and now thinking about setup. My question is about best practice that Gurus could suggest for such a scenario:

User gets to pc and sends commands (pressing keyboard keys) to move Arduino robot. Using ROS or not, what is the most reliable way of delivering messages over internet to Arduino please?

I have completed hello world packages for Arduino<->Enc28J60<->pc, but that was simply turning led on/off. Here the robot is going to sense the environment and feedback the data and user sends actuator commands back to Arduino. If my packages are lost over wifi somewhere and not to be resent, or their order of delivery is wrong, the robot may hurt self or others in the environment!

What could create a least guarantee please?(with or without ROS, any answer very welcome)

Thank you,
24  Using Arduino / Project Guidance / Re: spy-camera, hack? on: August 28, 2012, 02:49:11 am
I assume arduino can handle the file-management of moving files from sd to somewhere else. 

This would likely require "sharing" an sd card between 2 devices.  That would definitely require some soldering, and likely some checks to make sure they're playing nice and taking turns.

Well all of above is theoretically obvious (imagination). The problem is how to implement them practically because these are not too simple to do:
1. sharing that SD card, where Arduino is effectively a spy for the file created by original device
2. video streaming: my end goal is the cheapest system to study stereo vision!

I already obtained an IP cam for 50$ and yes, could be much less by using a cheap router, usb-hub and 2 web-cam each for 20$, but anyway the design this post is questioning will be much cheaper.

The work there is to put an Arduino that:
1. Starts the camera
2. "Senses" the avi file made by the camera
3. reads and sends the file to the specified destination* and removes each sent byte.

*. destination: say, via Ethernet to Android, where the vision algorithm is working (Android 1.5GHz)

Open question is, if there is similar project to obtain practical skill about:
1. sharing SD of another device with Arduino synchronously
2. sensing strategy: how to find out that the main device created a file

Please help to reach to the cheapest Arduino stereo vision system smiley
25  Using Arduino / Project Guidance / spy-camera, hack? on: August 26, 2012, 08:46:32 am
After a while, back to Arduino! Just found ROS and very eager to try it but with some more serious projects like vision, but then I need stereo camera first. Before, I completed this project successfully:
pc <--> google cloud <--> wifi <-->android<--> enc28j60<-->arduino

now my question is how to obtain cheap cameras to add there so that I can get pictures with Arduino (not Android for it has only 1 camera, I need stereo), give it to Android and back to cloud for processing. I need to learn all the way compressing images, making avi files.

I thought may be simply get 2 spy-cameras for cheap off ebay (this, I can do, I got once 1 for some 6$ only) and then hack them (this, I can't do yet  smiley) so when they write video files to their microSD cards, each of 1GB, I just read them from there and send over ethernet/usb from arduino to android and to cloud. Then also I must empty files so that it can write camera on and on, but this perhaps is a hack to FAT there and too much work (for my skill level).

I'm not sure but I hope that people did that before and I can learn from their projects.

The camera seems to be calles also as "808 key-chain" camera, as shown here:
Could you please suggest similar projects or alternative cheap way of camera hack to get a stereo system please, any idea?
26  Using Arduino / Project Guidance / Re: touch response on: July 19, 2012, 11:50:04 am
Thank you very much, exactly what I need!
27  Using Arduino / Motors, Mechanics, and Power / Re: servo motor init pos set problem on: July 14, 2012, 02:19:11 am
Well, then stepper motors, but with pots for that accidental shut down, right?

28  Using Arduino / Project Guidance / Re: touch response on: July 14, 2012, 02:02:43 am
The pen is very practical to make by my cnc machine out of corian dupont stone.

Any link on similar project of using this darlington pair transistors please?
29  Using Arduino / Motors, Mechanics, and Power / Re: servo motor init pos set problem on: July 13, 2012, 01:58:07 pm
Thank you, nice post on Lynxmotion, I also have 2 ssc-32 controllers.

In summary, I think that it is easier to go with a dc, get the h-bridge out of some L293, an encoder and voila!
Thanks again!
30  Using Arduino / Project Guidance / touch response on: July 13, 2012, 05:27:25 am
My desktop monitor could be turn on by touching the turn-on place of it. I want to embed Arduino in a pen, so that when one takes the pen and fingers sit at regular place on pen (no matter the style of person in keeping it), the lights on pen go on.

What could be the best element to realize it please? Any example project I could get as starting point?
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