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pcmguy
Joined: 24 Oct 2005
Posts: 5
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| Hitecc 422 servo control |
 Posted: Thu Oct 27, 2005 3:14 am |
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Hi, I purchased a biped robot from www.lynxmotion.com and I want to use PIC16F876 to control the robot (instead of using their control card).
But I found out one problem. All the servos are 'reversable' means when we are not triggering the servo, so the robot leg will fall down due to gravity.
So, I just want to know a way to control all the servo motors 'anti reversable' when I not changing the motor angle.
Thanks...
pcmguy, |
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Harry Mueller
Joined: 17 Oct 2005
Posts: 116
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| Posted: Thu Oct 27, 2005 5:09 am |
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Just keep sending their most recent pulse to all the servos, that way they'll hold their position.
Harry |
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rnielsen
Joined: 23 Sep 2003
Posts: 852
Location: Utah
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| Posted: Thu Oct 27, 2005 8:19 am |
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You'll need to apply a 'holding voltage' to the servo in order for it to stay in position. Pulsing it will make it rotate but, with any servo, if you simply remove voltage from it it will 'free wheel' and move to where gravity will take it. All servo and stepper controllers apply a holding voltage when it is not moving the motor.
Ronald |
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RobM
Joined: 29 Apr 2005
Posts: 13
Location: Santa Cruz, CA
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| Posted: Thu Oct 27, 2005 12:15 pm |
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| rnielsen wrote: | You'll need to apply a 'holding voltage' to the servo in order for it to stay in position. Pulsing it will make it rotate but, with any servo, if you simply remove voltage from it it will 'free wheel' and move to where gravity will take it. All servo and stepper controllers apply a holding voltage when it is not moving the motor.
Ronald |
This is not correct. RC servos require a continuouse pulse to hold position:
http://www.geocities.com/BourbonStreet/3220/servobasics.html
They set a position that is a function of the "on" time of the pulse, where 1ms is 0 and 2mSec is full scale out.
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Rob
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