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Author Topic: Build motor control cirtuits for 4 wheel robot 6V ~2A stalled current  (Read 1724 times)

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Offline RpiHackerTopic starter

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I have spent hours searching the web for project plans / DIY information on how to build 6V motor control circuit for a 4 wheel bot that is equipped with motors that have a stall current of 2A.  I am specifically looking for plans based on the L298 IC as the info I have found to date indicates the L298 is a good choice for this project.

The bot is to be Raspberry Pi controlled.

My intent is to build most of my own circuits starting with a variable power supply and NiHM battery charger in one project box to support the bot. Both circuits are in the parts purchasing stage.  It took a while to get information to build these two items; however, no where nears as long as I have already spent on trying to find DIY info on 6V motor control circuits.

Building a robot from scratch is a journey not an event; so hopefully, my journey will not be disrupted for lack of motor control plans. Therefore, I would appreciate any advice on finding a schematic and, or project plans that can be used for this application.

Regards,


Offline jkerns

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Re: Build motor control cirtuits for 4 wheel robot 6V ~2A stalled current
« Reply #1 on: October 06, 2014, 01:49:12 PM »
Start with the  data sheet for the L298, it will tell you most of what you need to know to make your motor control circuit.

The data sheet lists the logic inputs needed to make it work - basically you need enable (off - high impedance on the outputs), and two inputs to set the direction for each motor (the L298 will drive two motors). Each of these logic is typically driven by a digital output from your controller. Putting a resistor between the controller and L298 on each of the logic connections can reduce the chances of destroying the controller when you blow the L298.

The two devices will need a common ground.

Motors connect to the out 1/2 and out 3/4 pairs.

Sense A and B can go directly to ground with no resistors unless you need to measure the motor current.

There are lots of H bridge tutorials around on the web and youtube to help you along. I have some on my channel https://www.youtube.com/playlist?list=PL30C02F65B2D5C320 , but they reference a different chip and are pretty boring.

« Last Edit: October 06, 2014, 06:12:47 PM by jkerns »
I get paid to play with robots - can't beat that with a stick.

http://www.ltu.edu/engineering/mechanical/bachelor-science-robotics-engineering.asp

Offline RpiHackerTopic starter

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Re: Build motor control cirtuits for 4 wheel robot 6V ~2A stalled current
« Reply #2 on: October 07, 2014, 08:53:14 AM »
Jkerns - thank you for taking the time to help me short out H-Bridges.

Your posted advice was very helpful as were the Geoffrey Thorpe videos.

At this point I see a way forward and am confident I will be able to plan and build a functioning H-Bridge with PWM to control the bot motors, while minimizing circuit smoke!

The only piece of the planning puzzle left is learning about how to add feedback loops using encoders on the motors to ensure the motors are working together and doing what the code /sensors tells them to do.

Cheers,






Offline jkerns

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Re: Build motor control cirtuits for 4 wheel robot 6V ~2A stalled current
« Reply #3 on: October 07, 2014, 08:56:13 AM »
Jkerns - thank you for taking the time to help me short out H-Bridges.
Sorry - had to laugh!  :)
I get paid to play with robots - can't beat that with a stick.

http://www.ltu.edu/engineering/mechanical/bachelor-science-robotics-engineering.asp

Offline RpiHackerTopic starter

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Re: Build motor control cirtuits for 4 wheel robot 6V ~2A stalled current
« Reply #4 on: October 07, 2014, 10:20:41 AM »
No worries - that is very funny. Hopefully, I was not viewing the future when I typed that!

Clearly, I never learned to type and think at the same time and the sad thing is I proof read the post.

Cheers,

 


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