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Camera Pan and Tilt motor controller

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Posts: 2
Posted: 2011-07-25 07:38 
I'm building an RC controlled pan and tilt for my video camera and I need some quick feedback about dual motor controllers. Right now I have a Solarbotics LM298 motor controller for my brushed 12v DC motors. The issue is fine motor control. If I just run the motors full tilt everything is great, but I need to have a much smoother operation at slow speeds. The motors are geared down 50:1, so all I need is a way to just start the motors very slowly. The LM298 just cant start off slowly, it has to have a certain amount of "Kick" voltage to spin the motor. Any suggestions on a low amp dual motor controller?

Thanks,
Dave


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Admin ( offline )
Posts: 3873
Posted: 2011-07-25 09:59 
Hi DukeNukeIt,

Welcome to the RobotShop Forum. How are you controlling the L298? Did you try to modify the code for a "soft start" (i.e. ramp up quickly)? Certain motor controllers offer a "soft start" function. The "kick" is likely to overcome static friction which is then convereted to kinetic friction and requires less torque, causing the jolt. Before buying a new controller, you may try to find ways where others have controlled it using code.

Sincerely,

_________________
Coleman Benson

RobotShop inc.
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New ( offline )
Posts: 2
Posted: 2011-07-28 09:04 
I am controlling the LM298 with an Arduino, but the motor controller is just inadequate for the job. I have to push the joystick on my RC controller almost halfway before the motor will start turning (I can hear the motor winding start to sing before they move). When the motor finally starts, the speed is to fast and the camera moves to quickly for precise control. I need to make the motor literally creep along at a very slow speed at first, and this little motor controller is just not doing the job.


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Admin ( offline )
Posts: 3873
Posted: 2011-07-28 10:45 
Hi Duke,

Can you see what happens when you remove the load entirely? Does the motor start off at a lower speed? If yes, they you may want a slightly more powerful motor since it needs to "work hard" to overcome inertia. If it takes just as long to start without a load as it does with a load, you can try to program it to "jump" to the minimum speed and then ramp down, so it's overcoming kinetic rather than static friction. An alternative controller may be an option, but there are many factors at play here.

Sincerely,

_________________
Coleman Benson

RobotShop inc.
Putting Robotics at your service!™
www.robotshop.com

Lynxmotion
Imagine it. Build it. Control it.™
http://www.Lynxmotion.com


 

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