Matrix user forums

I've added a continuous servo to a project.
I used the general servo controller component to the 2d dashboard.

But unlike a normal servo this doesn't need to be positioned to a certain position.
I want to use the servo to drive a shaft and the only thing I need is to control the speed, direction and duration of the movement.

What is the best practice to get this done?

I want to divide a revolution of the servo in smaller parts and control the amount of parts of this revolution.
So I can control the servo to do 3 1/8th of a revolution by changing these parameters.

Hi,

So 'continuous servo' is actually an oxymoron if you are referring to a RC type servo. The way they make the 'continuous' part is to bypass the feedback (usually) a pot. Technically this nullifies the "servo" description and makes it just a pwm speed controlled motor.

Because the motor no longer has any feedback there is no way to know or predict the motor position, or know 3 and 1/8th rotations.
It sounds like a stepper would be a much better choice here.

Please correct me if I am wrong..

Chad

chad wrote:Hi,

So 'continuous servo' is actually an oxymoron if you are referring to a RC type servo. The way they make the 'continuous' part is to bypass the feedback (usually) a pot. Technically this nullifies the "servo" description and makes it just a pwm speed controlled motor.

Because the motor no longer has any feedback there is no way to know or predict the motor position, or know 3 and 1/8th rotations.
It sounds like a stepper would be a much better choice here.

Please correct me if I am wrong..

Chad

Thanks Chad, you are right that a continuous servo isn't what servo's are meant for.
But they are commonly used apparently and they are sold that way.

I will try to find a PWM kind of way to control the servo. Too bad all my PWM channel pins are used for other purposes.
I will manage.

Hello,

I have made little robots like this in the past by modding standard servo motors.

Using the servo controller component you can control a continuous servo by outputting 128 as the mid point this will give you 0 speed in either direction.

Dropping the position from 128 to say 100 will give you movement in one direction.

Upping the position from 128 to say 156 will give you equal movement in the opposite direction.

I found that moving from say 100 to 0 will not give much additional speed so it's worth playing in the 128 to 100 range to see the various speeds you can achieve and where exactly the cut off is.

As you've lost the feedback you no longer have any positional accuracy or speed accuracy it's all dead reckoning and can vary from motor to motor. As Chad says if you need either of these then a stepper might be better or you could maybe use an encoder.