Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: flames on May 14, 2010, 08:44:22 AM

Title: pulse width modulation and sharp IR sensor
Post by: flames on May 14, 2010, 08:44:22 AM

hi guys, im new in robots

can anyone help me about the very basic of the pulse width modulation and its formula?
and also, i'd like to ask about the accuracy of a sharp IR sensor. how wide does the beam of this sensor diverge?

Title: Re: pulse width modulation and sharp IR sensor
Post by: waltr on May 14, 2010, 10:50:32 AM

Look at the data sheets for the Sharp IR sensors. The beam width information is there.

Quote

pulse width modulation and its formula

In what context? Motor drive, data encoding?

Do you try googling this?

Title: Re: pulse width modulation and sharp IR sensor
Post by: GearMotion on May 14, 2010, 11:17:03 AM

Quote from: flames on May 14, 2010, 08:44:22 AM

can anyone help me about the very basic of the pulse width modulation and its formula?

Look up Pulse Width Modulation in wikipedia. Their entry page should give you enough information to have a basic understanding.

http://en.wikipedia.org/wiki/Pulse-width_modulation (http://en.wikipedia.org/wiki/Pulse-width_modulation)

Title: Re: pulse width modulation and sharp IR sensor
Post by: Webbot on May 14, 2010, 11:31:57 AM

Or even look at the member tutorial http://www.societyofrobots.com/member_tutorials/node/228 (http://www.societyofrobots.com/member_tutorials/node/228)

Title: Re: pulse width modulation and sharp IR sensor
Post by: flames on May 14, 2010, 07:23:44 PM

Quote from: waltr on May 14, 2010, 10:50:32 AM

Quote

pulse width modulation and its formula

In what context? Motor drive, data encoding?

in the context of motor drive. what i can only understand is that this PWM method is used to control the speed of the motor, but how does it really work. and is there any formula regarding to this method?

Title: Re: pulse width modulation and sharp IR sensor
Post by: corrado33 on May 14, 2010, 07:31:28 PM

It basically turns the motor on and off really fast.  Think about it, if you turn a light on and off really really really fast (faster than you could do), it would appear dimmer than if it was just on.  The more you have it on the brighter it would be, and the less you have it on the dimmer it would be.  The same thing with a motor.  The "duty cycle" determines how long it's ON and how long it's OFF.  A 50 50 duty cycle is on half of the time off half of the time.  A higher duty cycle would make the motor go faster, and a lower duty cycle would make it go slower. 

This sounds like a homework question?  If it is, you should really be doing it yourself.

Title: Re: pulse width modulation and sharp IR sensor
Post by: flames on May 15, 2010, 08:53:39 PM

thanks for the explanation.

this is a project, but we are required to know how to control the speed of the motor using PWM and the formula behind it.