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21
Mechanics and Construction / Linear Actuator with feedback
« Last post by nabberuk on November 21, 2014, 06:23:29 AM »
Hi,

I'm creating an autonomous sailing boat. In order to control the main sail and rudder i would like to use linear actuators instead of servos as they have a hold position that will use minimum power.

These actuators will be controlled by a raspberri pi/arduino. The mail sail will need to be able to cope with a higher force due to the wind pulling on it.

My question is, can i create a screw threaded linear actuator fairly cheaply and be able tell it the position to be set to?

I've never really tried to build my own actuator with feedback before?
22
Software / Super fast obstacle maze solving. How?
« Last post by EXCodeX on November 20, 2014, 09:48:54 PM »
Hi guys!

I just want to get some idea about fast obstacle maze solving robot. Recently I saw a super fast maze solving robot at the Micro mouse competition.  Please refer the following link.

https://www.youtube.com/watch?v=_9Y4ODmweYA

I am wondering how they have achieved this much of stability and accuracy at this very high speed level.

What kind of obstacle a detecting sensors suitable for this ? any special motor controller? motors? and what kind of algorithms should be used  for noise filtering etc.

I searched a lot and tried to find those information and some sample code. by still i couldn't.


Your ideas are really appreciated . Thanks! :)
23
Misc / Super fast obstacle maze solving. How?
« Last post by EXCodeX on November 20, 2014, 09:19:31 PM »
Hi guys!

I just want to get some idea about fast obstacle maze solving robot. Recently I saw a super fast maze solving robot at the Micro mouse competition.  Please refer the following link.

https://www.youtube.com/watch?v=_9Y4ODmweYA

I am wondering how they have achieved this much of stability and accuracy at this very high speed level.

What kind of obstacle a detecting sensors suitable for this ? any special motor controller? motors? and what kind of algorithms should be used  for noise filtering etc.

I searched a lot and tried to find those information and some sample code. by still i couldn't.


Your ideas are really appreciated . Thanks! :)

24
Electronics / Re: 50 dollar robot question
« Last post by jkerns on November 20, 2014, 06:07:04 PM »
Hmmm. I would have bet money that would have worked.

You've covered the obvious things.

Odd things that I have seen include a chip not 100% pressed into the chip socket (did you use a socket or solder directly to the ATMEGA8?) or a chip that has been damaged.
25
Electronics / Re: 50 dollar robot question
« Last post by Zevoo on November 20, 2014, 04:20:50 PM »
Set it to 125 and I still get the same error.
26
Electronics / Re: 50 dollar robot question
« Last post by jkerns on November 20, 2014, 03:19:32 PM »
1/4 clock frequency (250 kHz) is too fast.
It needs to be LESS than 1/4 and you have to consider that the clocks are not going to run EXACTLY at the rated speed.

Set your ISP clock to 125 KHz.
27
Electronics / Re: 50 dollar robot question
« Last post by Zevoo on November 20, 2014, 03:10:01 PM »
Okay I made the schematic again (3rd attempt) there is no room for wiring errors!  I have checked and no problem everything works just fine. When I go to program the robot it comes up with this error (check message and console).
I have put the programmer on 1/4 the micro's frequency. What am I doing wrong now? I don't believe it is wiring again....
28
Electronics / Re: H Bridge
« Last post by jkerns on November 20, 2014, 07:57:58 AM »
The link you provided doesn't work, but in general: Yes, the idea of building a MOSFET H bridge using 6V for the motor power supply and the Arduino for the control is sound.
29
Electronics / Re: H Bridge
« Last post by gkiverm123 on November 19, 2014, 08:57:35 PM »
Sorry, I realized my original post was wrong. Since this is a school project, we can't use the I/O pin of the servo. In fact, I think the servos are modified so there isn't a wire leading out of the I/O pin from the motor anyways. I didn't realize until this now, so the data sheet isn't all that useful. So basically the servo more like a typical DC motor with a V_DD and ground. I found some H Bridges online http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-002-discrete-h-bridge-circuit-for-enhanced-vibration-motor-control-haptic-feedback.

Not sure how good they will work. Since my arduino will be used to power a bunch of other sensors, I plan on powering the motor, V_DD with 6 V. The MOSFET voltages will be controlled with the arduino. Does this sound like a reasonable plan?
30
Electronics / 50 $ robot modifying the servos
« Last post by pedromatias on November 19, 2014, 05:13:49 PM »
So I started building the 50$ robot and I'm in the beginning, where it says I should modify the servos. So, I read the servo modifying tutorial but I was confused by the part where it said I should upload the .hex file to the microcontroller.  I think I need to build the board first, right? I checked the posts here and there was no answer I could understand, maybe because I'm not a native English speaker. So, am I supposed to do the electronics first or am I missing something? Also, I can't order things from radioshack because they don't ship to my country, is this board good for the job: http://www.amazon.co.uk/gp/product/B00491C26Q/sr=8-3-fkmr0/qid=1416438882/ref=olp_product_details?ie=UTF8&me=&qid=1416438882&sr=8-3-fkmr0 If not, can someone tell me where I can buy one? And can this photoresistors do the trick, again I can't order things from radioshack. http://www.amazon.co.uk/Sensitive-Resistor-Photoelectric-Photoresistor-GL5549/dp/B00GIFDWOC/ref=sr_1_1?ie=UTF8&qid=1416439239&sr=8-1&keywords=cds+photoresistor Sorry for long post and for asking many questions in one thread, but I figured that someone who could answer one could also answer all of the others.
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