Real Motor Control
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Now that we are on this fun subject, can someone explain a really simple way
to achieve real motor control.
Yes, PWM does control an average voltage the motor sees. What is also does
is reduce the motor torque also. Thus running at lower speeds, it is a lot
easier to stall the motors.
In order to obtain real motor control you have to use a closed loop feed
back system.
I have been playing with reflective IR sensors with encoder marks on the
wheels. This has been my biggest problem. Getting a good return signal.
Anyone have a simple solution?
The motor control range I am working in is between 0.1 to 2 rpm. I am also
using a combination of PICs and Stamps for this. The PICs maintain the PWM
overhead via serial communication from the Stamp. That was the easy part.
The hard part so far has been the feed back.
Pete Miles
petem@w...
to achieve real motor control.
Yes, PWM does control an average voltage the motor sees. What is also does
is reduce the motor torque also. Thus running at lower speeds, it is a lot
easier to stall the motors.
In order to obtain real motor control you have to use a closed loop feed
back system.
I have been playing with reflective IR sensors with encoder marks on the
wheels. This has been my biggest problem. Getting a good return signal.
Anyone have a simple solution?
The motor control range I am working in is between 0.1 to 2 rpm. I am also
using a combination of PICs and Stamps for this. The PICs maintain the PWM
overhead via serial communication from the Stamp. That was the easy part.
The hard part so far has been the feed back.
Pete Miles
petem@w...
Comments
an off time under all conditions and would look at the back EMF to
determine the speed allowing a 2 wire connection to the motor and giving us
speed feedback. Not the same as an encoder but was very repeatable after
speed was set on the bench. This was done without a processor back then and
should be much easier and also more flexible with a processor in the loop.
At 09:05 AM 4/10/00 -0700, you wrote:
>Now that we are on this fun subject, can someone explain a really simple way
>to achieve real motor control.
>
>Yes, PWM does control an average voltage the motor sees. What is also does
>is reduce the motor torque also. Thus running at lower speeds, it is a lot
>easier to stall the motors.
>
>In order to obtain real motor control you have to use a closed loop feed
>back system.
>
>I have been playing with reflective IR sensors with encoder marks on the
>wheels. This has been my biggest problem. Getting a good return signal.
>Anyone have a simple solution?
>
>The motor control range I am working in is between 0.1 to 2 rpm. I am also
>using a combination of PICs and Stamps for this. The PICs maintain the PWM
>overhead via serial communication from the Stamp. That was the easy part.
>The hard part so far has been the feed back.
>
>Pete Miles
>petem@w...
>
>
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@i...
http://www.ultranet.com/~nr
> I have been playing with reflective IR sensors with encoder marks on the
> wheels. This has been my biggest problem. Getting a good return signal.
> Anyone have a simple solution?
>
> The motor control range I am working in is between 0.1 to 2 rpm. I am also
> using a combination of PICs and Stamps for this. The PICs maintain the PWM
> overhead via serial communication from the Stamp. That was the easy part.
> The hard part so far has been the feed back.
At .1 RPM you won't get any kind of decent resolution on your feedback
signal if you are reading at the wheel. I would put your optical sensor
on an earlier stage with a higher RPM, this will give you a finer feedback
resolution. There are some very tiny xmit/rec IR units that use reflective
points, I just forget the part numbers - anyone out there remember some?
have fun,
DLC