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Author Topic: is the servo really slow?  (Read 1314 times)

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Offline robakerTopic starter

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is the servo really slow?
« on: March 08, 2010, 06:34:31 AM »
i have a servo which can be seen here-http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_5&products_id=187. after modification I found that it is rotating so slowly that it will take hours for robot to complete the smallest track.
Is it really slow? or still there is someway to get a good speed out of it.

Offline jka

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Re: is the servo really slow?
« Reply #1 on: March 08, 2010, 07:41:46 AM »
What code are you using to test it? If you set the servo pulse to 1.5ms, the servo should stop. If you want to travel full speed in either direction, use .75ms or 2.25ms, which is the extreme position in either direction on a normal servo. If you specify a pulse that is close to 1.5ms, the servo will rotate slowly, because it thinks it's near the destination.

Offline HDA

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Re: is the servo really slow?
« Reply #2 on: March 08, 2010, 07:43:43 AM »
No a typical servo (after modification) is able to have a convenient rotating speed.
Are you sure you replace all the gearwheel in the right order ?  

Offline robakerTopic starter

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Re: is the servo really slow?
« Reply #3 on: March 08, 2010, 08:02:35 AM »
if the gear wheels fit in one another in only one way,  it seems gearwheels are correctly placed.
and about the code ---
declarations ----->

void servo_right(signed long int speed)
   {
   PORT_ON(PORTD, 1);
   delay_cycles(speed);      
   PORT_OFF(PORTD, 1);//keep off
   delay_cycles(200);
   }
then in main() function --- after port configurations-->

while (1)
      {
      // Place your code here
             servo_right(23);  //(44)

      }

Offline BEAMer

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Re: is the servo really slow?
« Reply #4 on: March 08, 2010, 08:35:12 AM »
Check the current that you are providing to the servo. A typical servo may absorb from 300mA to 500mA. I faced this sort of an issue in an unmodified servo.

BEAMer 

Offline BEAMer

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Re: is the servo really slow?
« Reply #5 on: March 08, 2010, 08:40:04 AM »
hey i am from India and I use the same servo from robokits  :)

Offline robakerTopic starter

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Re: is the servo really slow?
« Reply #6 on: March 08, 2010, 09:38:13 AM »
oh ok. but current doesn't seem to be a problem i think. may be it is to to with pulse width-- does any one know about how to speed it up ?

Offline robakerTopic starter

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Re: is the servo really slow?
« Reply #7 on: March 08, 2010, 09:47:48 AM »
--- @ BEAMer ---

May be you can help by giving the code that suited for your servos....

Offline BEAMer

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Re: is the servo really slow?
« Reply #8 on: March 08, 2010, 09:21:32 PM »
I use PIC16F877A and a demo version of mikroC form mikroelektronika.
This code will make a servo connected to RC2/CCP1 pin to rotate to one extreme -> wait for 1 second -> rotate to another extreme -> wait for 1 second and repeats this action.

void main()
{
    PORTC=0;
    TRISC=0;

    Pwm1_Init(250);
    Pwm1_Start();
    Pwm2_Init(250);
    Pwm2_Start();
   
    while(1)
    {
            Pwm1_Change_Duty(40);
            Delay_ms(1000);

            Pwm1_Change_Duty(150);
            Delay_ms(1000);
    }
}

Offline BEAMer

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Re: is the servo really slow?
« Reply #9 on: March 08, 2010, 09:22:58 PM »
Generally a servo expects a pulse every 20ms. try reducing this...

BEAMer

 


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