Camera servos too slow, help please

Hi,
I finally got all the stuff i needed to get the camera working, and i did, using the bells and whistles, downloaded to the RC.
but the servos move too slow, and if the light is moving too fast for it (i.e the robot is moving towards the target, therefore the tilt changes) and the camera no longer finds the light, and go back to searching mode.
How can i make the servos move faster?
Plus, we are having problem with the pan servo. it clockwise and counterclockwise at hight speed (it looks as if the gear is shaking back and forth)
Any thoughts on that 2?
Thanks,
Carmel

Try loading the default (not default camera, just 2007 default) code and using the built-in one joystick drive to control the camera servos.

That’s a good way to test if it’s a hardware problem or a problem with your cam code.

If it’s still slow, try two different servos and two different PWM outputs.

Basically what I’m saying is try to isolate and test every possible cause of the problem until you can for sure identify what the cause is, then re-post, and we’ll go from there :]

-open up the tracking menu by putting ‘t’ into the “To Port ->” window of the IFI loader’s terminal window and hitting the enter key.

-you’re then going to want to change the pan gain, the tilt gain, and the delay. the menu should walk you through that process.

-once you find values that work for you, you should set them as your defaults

-open up tracking.h the values you’re going to want to change are:

SEARCH_DELAY_DEFAULT
PAN_GAIN_DEFAULT
TILT_GAIN_DEFAULT

Agreed. The cameras should not be responding slowly, especially with pretty standard code (nothing wacky) and standard hardware (no custom circuits.)
The servos usually aren’t bad unless if you fried them, so it probably is the code (just a guess.)

Another longshot. Are your servos the same brand/model as listed in the KOP? I remember reading somewhere that some of the parts could be different then listed in the KOP depending on availability in foreign countries. The the servos are different, maybe they respond differently?

More crazy ideas,
Jacob

Try these:

  • disconnect the servo linkage so the servo shaft is free and see if the unwanted motion continues. If it doesn’t, the servo shaft was probably rotated too far when you pressed the round plastic servo arm onto the shaft, and your code is trying to drive it past the internal stops.
  • try a different PWM cable
  • try a different servo
  • if your PWM cable is very long, it might be picking up electrical noise - use a clamp-on Ferrite core to solve this (similar to Digikey 445-2038-ND) http://www.tdk.co.jp/tefe02/e9a15_zcat.pdf. You might find something similar at Radio Shack.

That reminds me of how I “tared” our camera servos. I plugged them into the RC before building the camera mount, then set the pan servo to PWM=124 and the tilt servo to PWM=144. (These are the default center values in Kevin’s cam code.) I then removed them from power so they’d stay in that position and built the cam mount.

Since you already have the mount built, if you think setting resetting the servos to allow more useful angle might help, just remove the retainer screws on the servos and lift the “PT-HORN” off. Then you’ll probably want to remove the whole PT-MNT piece also. Then run code to set the PWM values I said above, remove power, and add the PT-MNT at whatever angle you want and rotate the PT-TILT-BRK however you want. Press them back onto the servos and replace the retainer screws.

(I got the “PT-HORN” type names from the official Mount Assembly instructions)

Thank you all,
I will check it out tmw at school and let you know how it worked

Well,
I’ve done that, and during the search mode it did infact moved faster.
but when it spotted the green light, its movement were so slow we could bearly move the target without the camera losing track of it
Any ideas?
Thanks,
Carmel

The servos can’t generate a lot of torque, so make sure you built the pan/tilm mechanism per the instructions and didn’t over-tighten the fasteners. You’ll need to disconnect the servo from the linkage to see how freely it moves.

-Kevin

Hi,
I don’t think so,
cause when we checked for momvment using the joystick, the servos moved great, and also in the searching mode they move great. only when it spots the light it slows down.
Carmel