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106  Topics / Robotics / Re: Wheel Placement on Robot on: September 14, 2013, 07:57:12 am
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Is there a reason to keep the center from moving much?

I wold like to keep the turning as accurate as possible.


Quote
you would just have some (maybe a lot) of wheel drag

that would make my turned less exact and decrease the life of the motors. (I'm mostly concerned with the turning) Right?

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I fail to see how that would be better than just a single pair of wheels in the center, and a caster on the front and back?

That was my original plan, but two motors do not have enough torque to push the robot. It was cheeper to buy another two wheels/motors  then to buy better ones. I assume that by adding two more motors/wheels I doubled my torque. Right?

Quote
wheels mounted on shafts riding on bearings

They are.


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A large, heavy frame will tip over if not properly balanced.

If the wheels are  towards the middle of the robot It will tip over, but the caster wheels will help balance it. Maybe tip is not the right word. Think of a seesaw. If the wheels are in the middle of the robot it will pivot and the back & front could hit the ground.


Thanks! Would my idea work? I can't test it out because I don't have the two caster wheels.
107  Topics / Robotics / Re: How to make wall/obstacle avoiding robot with arduino uno atmega 328 on: September 13, 2013, 10:21:39 pm
Start with one thing at a time. Lets get the wheels rolling before we add in the obstacle avoidance.


I found this http://www.geekonfire.com/wiki/index.php?title=Dual_H-Bridge_Motor_Driver on the link you gave me. It pretty much explains how to get your motor driver up and running. It even gives you the code!


Once you have your car zipping around come back to this thread you started and we can help you with the object avoidance.

Best of luck!



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Not true. We'll right the code, if it's wrong. But, we won't write the code.

Thanks. I fixed my bad grammar smiley
108  Community / Bar Sport / Re: Best digital multimeter? on: September 13, 2013, 06:54:00 pm
I would like to keep the price below $300. I will buy a logic analyzer, but that has no effect on the price of the multimeter. Any FLUKE you recommend? I looked on their web sight and they have a lot of them.

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BEST is at best a relative term. It depends on the real need.

Needs…

1 Arduino projects

2 EE School. As i'm not there yet I have no idea what the classes will be like. I would love to attend a school like MIT were you get lots of practical, hands on experience, so I hope to use it a lot. I plan on centering most of my classes on DC if possible because I'm not a big fan of AC.

3. General AC use for home troubleshooting. smiley 

4. A data logging one might be a good idea.

Thanks!
109  Topics / Robotics / Re: How to make wall/obstacle avoiding robot with arduino uno atmega 328 on: September 13, 2013, 06:30:53 pm
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Gee, I don't think anyone has ever done that.
LOL.


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Hi genius  
   I'm going to build (assemble) ultrasonic obstacle avoiding robot and I have Arduino Uno - Atmel Atmega 328-PU board and Arduino Compatible H-Bridge Motor Driver board (photo's attached) and Ultrasonic Module HC-SR04 Arduino. I'm looking for a way to attach cable from motor,ultrasonic module and within uno and motor control board and also suitable  program/code for it...

1st off pictures are of little value. Give us links to data sheet or the products page… I don't plan on hunting them down. You bought the stuff!

2. No body is going to wright your code for you… you would never learn. However, I will give you some examples.

Analog read example… chances are your sensor is analog… now way to tell with out data sheet.
Code:
/*
  AnalogReadSerial
  Reads an analog input on pin 0, prints the result to the serial monitor.
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.
 
 This example code is in the public domain.
 */

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}

// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // print out the value you read:
  Serial.println(sensorValue);
  delay(700);        // delay in between reads for stability
}



Thats it for now  until you post the data sheets or product page. No point wasting my time giving you code that might/might not apply.

Best of luck!
110  Topics / Robotics / Re: Wheel Placement on Robot on: September 13, 2013, 06:05:34 pm
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I would assume you would burn the higher speed motors as they will try to drag the lower speed motors forward.


I was able to get 4 of the same motors. It took some time as the motors are not officially for sale, but parallax worked with me and sold me 4 new ones. I had 2 older ones, but they are slightly slower and you said I could not use two fast motors and two slow motors. So it took some time for me to convince them that I need 4 sets as they don't have many ready. 

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Think about it a bit: We are talking 4 wheels here. If you moved the wheels in the front back, and the ones in back forward, until they were near the center (but still spaced opposite each other), then yes, it would be easier to turn. Heck - if the wheels "merged", then you have the classic differential steered robot (add some casters on the front and back to balance).


I was thinking about putting one wheel/motor on each corner of the robot but you explained how that would screw up the turning.
What if I slid the wheels from the corner down towards the middle of the robot so that they were almost touching and then put a caster wheel on each end of the robot. It would be like putting two, three wheel robots back to back.  That way the driver wheels are like .5in apart making the turning easy yet the caster wheels will help support the front/end.

http://www.geology.smu.edu/dpa-www/robo/trux/n06.jpg

Would that work? I think it would yet I have never seen a robot like that.
111  Community / Bar Sport / Re: Which is your favorite programming font? on: September 12, 2013, 07:05:22 pm
Can you change the font of the Arduino IDE on a mac?
112  Using Arduino / Programming Questions / Re: Library issues on: September 12, 2013, 04:07:43 pm
That did the trick. Thank you so much for confirming that the example had an error.
113  Using Arduino / Programming Questions / Re: Library issues on: September 12, 2013, 03:21:24 pm
I tested it and it is way off… Its saying hot water is 59 degrees while room temperature 82. My thermometer says room temperature is around 75 and the water is over 110 degrees.


What could be wrong?


Edit:
I'm going to switch the leads of the wire and see if that helps.
114  Using Arduino / Programming Questions / Re: Library issues on: September 12, 2013, 03:11:57 pm
The code below complies correctly. Do you think it will work?


Code:
/*
  Single_Temp.pde - Example using the MAX6675 Library.
  Created by Ryan McLaughlin <ryanjmclaughlin@gmail.com>

  This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
  http://creativecommons.org/licenses/by-sa/3.0/
*/

#include <MAX6675.h>

int LED1 = 9;             // Status LED Pin
int CS = 10;             // CS pin on MAX6675
int SO = 12;              // SO pin of MAX6675
int SCK2 = 13;             // SCK pin of MAX6675
int units = 2;            // Units to readout temp (0 = raw, 1 = ˚C, 2 = ˚F)
float temperature = 0.0;  // Temperature output variable


// Initialize the MAX6675 Library for our chip
MAX6675 temp(CS,SO,SCK2,units);


// Setup Serial output and LED Pin 
// MAX6675 Library already sets pin modes for MAX6675 chip!
void setup() {
  Serial.begin(9600);
  pinMode(LED1, OUTPUT);
}

void loop() {
// Read the temp from the MAX6675
temperature = temp.read_temp();

if(temperature < 0) {                   
// If there is an error with the TC, temperature will be < 0
Serial.print("Thermocouple Error on CS");
Serial.println( temperature );
digitalWrite(LED1, HIGH);
} else {
Serial.print("Current Temperature: ");
Serial.println( temperature );
digitalWrite(LED1, LOW);
}
 
// Wait one second before reading again
delay(1000);
}
115  Using Arduino / Programming Questions / Re: Library issues on: September 12, 2013, 02:59:46 pm
I was just using the example code provided. I did not make that code up. Does the example have an error in it?
116  Using Arduino / Programming Questions / Library issues on: September 12, 2013, 11:24:33 am
I'm trying to get the MAX6675 library to work. The example had serval errors originally but after editing the file MAX6675.h to include Arduino.h that solved most of the problems. There is one error code left that I can't figure out how to resolve.

read_temp:14: error: conflicting declaration 'int SCK'
/Users/Drew/Documents/Arduino/Arduino.app/Contents/Resources/Java/hardware/arduino/variants/standard/pins_arduino.h:43: error: 'SCK' has a previous declaration as 'const uint8_t SCK'

Example:

Code:
/*
  Single_Temp.pde - Example using the MAX6675 Library.
  Created by Ryan McLaughlin <ryanjmclaughlin@gmail.com>

  This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
  http://creativecommons.org/licenses/by-sa/3.0/
*/

#include <MAX6675.h>

int LED1 = 9;             // Status LED Pin
int CS = 10;             // CS pin on MAX6675
int SO = 12;              // SO pin of MAX6675
int SCK = 13;             // SCK pin of MAX6675
int units = 2;            // Units to readout temp (0 = raw, 1 = ˚C, 2 = ˚F)
float temperature = 0.0;  // Temperature output variable


// Initialize the MAX6675 Library for our chip
MAX6675 temp(CS,SO,SCK,units);


// Setup Serial output and LED Pin 
// MAX6675 Library already sets pin modes for MAX6675 chip!
void setup() {
  Serial.begin(9600);
  pinMode(LED1, OUTPUT);
}

void loop() {
// Read the temp from the MAX6675
temperature = temp.read_temp();

if(temperature < 0) {                   
// If there is an error with the TC, temperature will be < 0
Serial.print("Thermocouple Error on CS");
Serial.println( temperature );
digitalWrite(LED1, HIGH);
} else {
Serial.print("Current Temperature: ");
Serial.println( temperature );
digitalWrite(LED1, LOW);
}
 
// Wait one second before reading again
delay(1000);
}



MAX6675.h:
Code:
/*
  MAX6675.h - Library for reading temperature from a MAX6675.
 
  This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
  http://creativecommons.org/licenses/by-sa/3.0/
*/

#ifndef MAX6675_h
#define MAX6675_h


#include "Arduino.h"

class MAX6675
{
  public:
    MAX6675(int CS_pin, int SO_pin, int SCK_pin, int units);
    float read_temp();
  private:
    int _CS_pin;
    int _SO_pin;
    int _SCK_pin;
    int _units;
int chip_read( int CS_pin, int &error_tc );
};

#endif


Any ideas?

http://playground.arduino.cc/Main/MAX6675Library
117  Using Arduino / Motors, Mechanics, and Power / Re: HB-25 Motor Controller will not work on: September 12, 2013, 08:38:03 am
Quote
this is   1000 microseconds, 1500 microseconds and 2000 microseconds.
Tom.

Thank you. That fixed the problem. I was thinking that ms stood for microseconds. The motor driver operates correctly now.
118  Using Arduino / Motors, Mechanics, and Power / Re: HB-25 Motor Controller will not work on: September 11, 2013, 07:54:26 pm
I tried modifying your code, but I still don't get any voltage on the output pins on the motor driver (m1/m2)

Code:
String readString;
#include <Servo.h>
Servo myservo;  // create servo object to control a servo



void setup() {
  myservo.attach(7, 0, 3);  //the pin for the servo control, and range if desired
}

void loop() {

  myservo.writeMicroseconds(1);
  delay(500);
}

Any ideas?
119  Using Arduino / Motors, Mechanics, and Power / HB-25 Motor Controller will not work on: September 11, 2013, 07:16:07 pm
I bought the HB-25 Motor Controller from Parallax (link below) but I'm unable to get it working. I have attached it just as it explained in the data sheet but  it is not outputting any voltage.  Its not the power supply as the motor controller is getting 12v in. The program is extremely short as I'm just trying to get this working, however, perhaps my program is not properly controlling the motor driver. It's a strange motor driver because it acts like a servo. Any pointers on how to get it working would be awesome.



Code:
#include <Servo.h>

Servo servo1;


void setup() {

  servo1.attach(3);


}

void loop() {
 
servo1.writeMicroseconds(2); 
delay(500);

}




http://www.parallax.com/sites/default/files/downloads/29144-HB-25-Motor-Controller-V1.2.pdf
http://www.parallax.com/product/29144
120  Using Arduino / Motors, Mechanics, and Power / Re: Power Supply Question on: September 11, 2013, 02:11:21 pm
I would not go over the max Voltage! Although not extremely common 6v power supplies can be found. Look at this one

http://www.alibaba.com/product-gs/970152463/6V_20A_High_frequency_lab_power.html?s=p

The other option would be to use a 6v BEC. The biggest problem you have is the amperage. 6v is easy to supply at 1-5 amps. 6v at 12amps is not so easy supply. Most BEC's stop before 5amps.
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