## Convert servo to servo motor?

Discussions regarding building a walking robot at home. Most of the robots participating at Robo-One competitions are custom fabricated.
2 postsPage 1 of 1
2 postsPage 1 of 1

### Convert servo to servo motor?

Guys

just a thought but if you disconnected the variable resistor (left in the centre position) from the output shaft of a standard (none digital) servo and removed the mechanical stop

Would this effectively give you a servo controlled motor with continuous rotation?

If this is feasible I assume a centre PW signal would make the motor stop and either side of centre would make the motor turn one way or another.

My main question is would a signal that was close to the centre pulse width frequency give a slow speed and a signal further away from the centre frequency give a higher speed or would the speed be the same regardless?

Cheers

Stu
Guys

just a thought but if you disconnected the variable resistor (left in the centre position) from the output shaft of a standard (none digital) servo and removed the mechanical stop

Would this effectively give you a servo controlled motor with continuous rotation?

If this is feasible I assume a centre PW signal would make the motor stop and either side of centre would make the motor turn one way or another.

My main question is would a signal that was close to the centre pulse width frequency give a slow speed and a signal further away from the centre frequency give a higher speed or would the speed be the same regardless?

Cheers

Stu
stuuk offline
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Posts: 44
Joined: Sun Apr 27, 2008 8:34 pm

### Re: Convert servo to servo motor?

stuuk wrote:Guys

just a thought but if you disconnected the variable resistor (left in the centre position) from the output shaft of a standard (none digital) servo and removed the mechanical stop

Would this effectively give you a servo controlled motor with continuous rotation?

Yes, it's done all the time for simple wheeled robots. You can find detailed examples with a Google search.

If this is feasible I assume a centre PW signal would make the motor stop and either side of centre would make the motor turn one way or another.

Exactly.

My main question is would a signal that was close to the centre pulse width frequency give a slow speed and a signal further away from the centre frequency give a higher speed or would the speed be the same regardless?

It depends on the servo board and characteristics like deadband, etc. In general, the cheaper servos will ramp rapidly then run at speed, You would have more control of the speed with a more expensive servo. But, it's easier to manage the effective speed on the controller end with whatever software you develop for the robot if you need slow or variable speeds. The trick is getting feedback. Optical encoders are usually a good, fairly cheap, solution.
stuuk wrote:Guys

just a thought but if you disconnected the variable resistor (left in the centre position) from the output shaft of a standard (none digital) servo and removed the mechanical stop

Would this effectively give you a servo controlled motor with continuous rotation?

Yes, it's done all the time for simple wheeled robots. You can find detailed examples with a Google search.

If this is feasible I assume a centre PW signal would make the motor stop and either side of centre would make the motor turn one way or another.

Exactly.

My main question is would a signal that was close to the centre pulse width frequency give a slow speed and a signal further away from the centre frequency give a higher speed or would the speed be the same regardless?

It depends on the servo board and characteristics like deadband, etc. In general, the cheaper servos will ramp rapidly then run at speed, You would have more control of the speed with a more expensive servo. But, it's easier to manage the effective speed on the controller end with whatever software you develop for the robot if you need slow or variable speeds. The trick is getting feedback. Optical encoders are usually a good, fairly cheap, solution.
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tempusmaster offline