Chief Delphi - Search Servo Initialization Caution

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Keith Watson

08-02-2006 14:25

Search Servo Initialization Caution

The default search code initializes the camera pan/tilt servos with this code.

Code:

    if(new_search == 1)

    {

        new_search = 0;

        temp_pan_servo = 0;

        temp_tilt_servo = Tracking_Config_Data.Tilt_Center_PWM;

                            

    }

    else

    {

        // search code

    }

    PAN_SERVO = (unsigned char)temp_pan_servo;

    TILT_SERVO = (unsigned char)temp_tilt_servo;

Note that the pan servo pwm is hardcoded to zero. If you have changed PAN_MIN_PWM_DEFAULT from zero to something else then hardcoding to zero is incorrect. Change the line to:

Code:

temp_pan_servo = Tracking_Config_Data.Pan_Min_PWM;

Kevin Watson

09-02-2006 01:05

Re: Search Servo Initialization Caution

Quote:

Originally Posted by Keith Watson

The default search code initializes the camera pan/tilt servos with this code.

Code:

 if(new_search == 1)

{

new_search = 0;

temp_pan_servo = 0;

temp_tilt_servo = Tracking_Config_Data.Tilt_Center_PWM;

 

}

else

{

// search code

}

PAN_SERVO = (unsigned char)temp_pan_servo;

TILT_SERVO = (unsigned char)temp_tilt_servo;

Note that the pan servo pwm is hardcoded to zero. If you have changed PAN_MIN_PWM_DEFAULT from zero to something else then hardcoding to zero is incorrect. Change the line to:

Code:

temp_pan_servo = Tracking_Config_Data.Pan_Min_PWM;

Hmmm... I wonder what the heck I was thinking when I did that? Oh well, since I can't possibly explain this away as an undocumented "feature", I guess we have to call it a bug <grin>.

-Kevin

Keith Watson

09-02-2006 02:13

Re: Search Servo Initialization Caution

I found it by reading the code to understand the algorithm. The rest of the code was all nicely parameterized. :)

Donut

09-02-2006 07:49

Re: Search Servo Initialization Caution

You may want to keep temp_pan_servo or temp_tilt_servo the same for a new search as well; we ran into a problem where the camera would catch the target as it spun all the way back to 0 (as it does this the tilt angle increases, which is why it caught it on the way to the left but not the right), lose it when it got there, initialize a new search and have us repeat over and over.

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