Parallax Continuous Servo Motor with USB Parallax Controller

saifizi

Good Afternoon,

I want to ask some question about Parallax Continuous Servo Motor. I have problem to control Parallax Continuous Servo motor with Parallax Servo Controller (USB). I try to use the PSC software for PC to control the continuous servo motor directly from pc, but the servo motor moving without stopping. I connect the servo motor to the parallax servo controller then interface directly to the PC. I hope members forum can help me to settle down my problem.

Mike Green

The "Robotics with the BoeBot" tutorial (here: www.parallax.com/tabid/535/Default.aspx) discusses servos and how they work. Any servo responds to a control pulse approximately 0.5ms to 2.5ms in width repeated around 50 times a second. In the case of a conventional servo, the control pulse controls the position of the servo. In the case of a continuous motion servo, the control pulse controls the speed and direction of the servo movement with a 1.5ms pulse causing the servo to stop. Most continuous motion servos require adjustment of a potentiometer inside the servo to get the servo to stop with a 1.5ms pulse. The tutorial I mentioned describes this procedure. With the USB PSC, set the control for a servo position of 1500. This produces a 1.5ms pulse. You will need to adjust the servo to get it to stop exactly at the 1500 position.

Chris Savage

With the slider at the center (1500) 1.5mS position, be sure the adjustment screw on the servo is calibrated for no motion. My guess is your servo isn't calibrated for center position. If it is far enough off, it would never stop regardless of the pulse width.

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Chris Savage
Parallax Engineering