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1  Community / Exhibition / Gallery / Re: ArduDelta - delta Robot implementation on: August 03, 2011, 07:05:33 am
Hello Zozerk and thank you.
The code is attached to my previous post.
The kinematic functions are also embedded in the project.

Just ask if you need more help, and good luck with your project.
2  Community / Exhibition / Gallery / Re: ArduDelta - delta Robot implementation on: July 10, 2011, 01:39:28 pm
Yey... feedback.  smiley-grin

So.. one at a time:

@lusian - thanks - this link should be beter.

@Knightrous - Thank you!
Welcome to the forum i guess. smiley And yes, i will make the code public, i think
that is the essence of the Arduino. Fell free to ask if something seems weird.

@marcuschan - Thank you!
And yes, future development is planned. smiley-grin The pen was mounted just to visually show what it can do.

@tinkermonkey - Thank you!
The code is posted now.

@focalist - Thank you!
Of course i know that project, at first i was simply amazed because i thought that the marker was hanging
in the air with a magnetic field. Congratulations. After i've looked closer (and listen your comments) i've
figured out what's the deal. Very nice, and very precise. And a very nice name too smiley-grin
To the chase now:
1. "How are you compensating for the difference in distances radially (in that a movement toward the center is "smaller" than a movement further away)?"
This i don't understand. If you can explain further please, i will be happy to reply.

2. It's so nice that your system is in a plane (like xyz plane, sorry for the english) so you only have x and y to mess with.
That simplifies the process. I was thinking about stretching of the wire, but you said that you use fishing line, so most
probably that isn't a problem.
3. Yes, mine is faster, but with some costs. I can actually decrease the speed, and that makes it more accurate, but..
i have a new problem: servo jitter. And that makes the drawing very not cool. The current speed is a compromise
between speed and accuracy. For the future i have in plan a dedicated servo-controller.
4. Bouncy'ness smiley-razz . I was thinking. What about my quick sketch (the second attachment)?
5. Thank you again. I worked very hard on this.



So the code is now public.
Notes:
I admit that the code is improvable. I have changed my mind several times
during the design, and that is reflected in the code.
Special thanks needed for this code go to: mzavatsky and jarkman especially.
3  Community / Exhibition / Gallery / Re: ArduDelta - delta Robot implementation on: July 06, 2011, 12:15:00 pm
Hello. Sorry for the late answer.
And yes, i will help you, you will get an email soon.

p.s. does this project suck or there isn't at least a "good job" for me on this forum?
It is quite disappointing.
4  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: July 03, 2011, 02:30:05 pm
That is probably my next step in developing the delta.
But i don't know exactly how they work. I know one thing dough - no serial. smiley-grin
Can you point out a model please?
5  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: July 03, 2011, 01:19:03 pm
Yes, they do. And yes the delta is the project.
When i support the platform, the thing twitches from time to time. (2-5s).

Thank you.
6  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: July 03, 2011, 06:31:23 am
You were right, thank you very much for your help.
I was quite busy finishing my latest project, my first serious one, which is not presented here.

Thank you!
7  Community / Exhibition / Gallery / ArduDelta - delta Robot implementation on: July 03, 2011, 06:30:39 am
Hello everyone.
I have just finished my latest project, the biggest I've done so far and now i want to share (brag about).  smiley-lol
So... I am talking about my own delta robot. For those who don't know what a delta is, i will briefly explain:
it's a parallel robot (because the lower arms use parallelograms to maintain the lower platform parallel to the
upper platform) very fast, very precise (the concept is, mine is not that good) and a bit complicated
(mathematically speaking) at first site.
I have so many things to say about this project, it took me 7 months to complete (working from time to time).

Components (i have attached a picture with the (almost) final rig).
- 3 black arms for support - made of wood, painted
- an upper platform (the light-brown thing from the top) - made of wood
- 3 standard servos (towerPro 946r) places on their sides (pivot point facing exterior) mounted 120 degrees apart.
- upper arms - made of plexiglas - connected to servo throw a plastic arm with 2 connection points (one on the
  servo pivot point and another 2.5 cm appart)
- in the exterior point of the upper arm i have 2 spacers (2 pieces of carbon-fiber tube) connected to articulated
  joints (2 pieces). One parallelogram (out of 3) is formed with 2 spacers, 4 articulated joints (2 up, 2 down),
  2 carbon-fiber tubes and, in the lower part, where the joints meet the lower platform, there is another "spacer".
  All of this is called lower arm.
- the lower platform - made of plexiglas. It's an equilateral triangle with some other pieces of plexiglas glued, for
  forming a mounting point for the lower arms.
- in the bottom part we have a working area (the light-brown thing from the top), connected to the support arms
  with a diameter of 40cm, made of wood
- the controller: made of plexiglas, it consists of an 20x4 serial lcd, an Arduino Mega2560, and a pcb that contains
  an infrared receiver, 2 rgb leds and a button.

The robot has 2 main states:
- a manual state: this state allows for independent increments of the xyz coordinates.

Delta Robot - Manual mode



- a path following state: this state allows the robot to follow a predefined path.
I have selected just a few paths and a few different modes of operation.

Delta Robot drawing - geometrical primitives



Drawing Fii logo (the logo of my faculty - UAIC Infoiasi )



Drawing Fii logo - top view (the logo of my faculty - UAIC Infoiasi )



Drawing circles - top view


I can talk about this project for days, so if anyone has a question I will more than happy to answer.
Sorry for the long post and the english screw-ups.

Bogdan.
8  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: June 25, 2011, 11:08:08 am
For my lcd. It doesn't support anything higher than 9600.
9  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: June 25, 2011, 08:05:34 am
hmm... it does jitter. But very, very little.
But why.... ?
10  Using Arduino / Motors, Mechanics, and Power / Re: Problem with servo jittering. on: June 24, 2011, 01:44:28 pm
OK, thank you for answering. So...

1. External power supply - home made stabilized 5.2 v source.
2. Servo wiring. The servo connections are: servo + to power supply +,  servo - to power supply -,
     signal to digital (pwm if makes any difference) pin of arduino. The exact pins are 5, 6 and 7.
     And yes, the grounds are conected.
3. The code. I present a simplified version.

Code:
#include <Servo.h>
#include <Servo.h>

Servo myservo1;
Servo myservo2;
Servo myservo3;

int servoCalibrationPos1 = 1100;
int servoCalibrationPos2 = 1100;
int servoCalibrationPos3 = 1100;

void setup() {
 
  myservo1.attach(5);
  myservo2.attach(6);
  myservo3.attach(7);

 
  servosGoTo(servoCalibrationPos1, servoCalibrationPos2, servoCalibrationPos3);
  delay (100);

 

}

void loop() {
for(int i = 1100; i<1300; i++)
for(int j = 1100; j<1300; j++)
servosGoTo(i, j, i);
  }
}
void servosGoTo (int a1, int a2, int a3)
{
myservo1.writeMicroseconds(a1);
myservo2.writeMicroseconds(a2);
myservo3.writeMicroseconds(a3);
}

The more complex version only has some Serial2.print for debugging. I use a 20x4 lcd screen.
The serial writing really makes the servos useless. They jitter allot.
The only mod in the code is in the loop where I have some
Code:
       Serial2.print(i);
        Serial2.print(j);
and the Serial2.begin(9600), the max baud rate.
But the problem appears event without the serial.write. Is there something
that I can do? I even tried some toroidal iron cores wrapped around the
servo cables. Doesn't work...
11  Using Arduino / Motors, Mechanics, and Power / Problem with servo jittering. on: June 24, 2011, 10:58:39 am
Hello.
        I have an Arduino MEGA2560, and 3 servo's connected to it. It jitters... allot.. smiley-sad

Details:
      - Tower Pro MG-946R servos. - standard.
      - the servos are powered from an external source.
      - the library used is <Servo.h> the one from the Arduino IDE.
      - there is no serial communication (nothing is sent via serial to produce interrupts),
        just plain old initialization and writeMicroseconds.
      - i have googled the problem allot before asking, please help me, I couldn't find
        anything useful.
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