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Author Topic: $50 robot with differrent MCU, motors and sensors  (Read 2294 times)

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Offline ajax spray n wipeTopic starter

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$50 robot with differrent MCU, motors and sensors
« on: March 01, 2008, 08:59:40 PM »
I'm thinking of making the $50 robot, and I was wondering about making a few changes, such as:
  • Using a sonar rangefinder instead of the sharp IR rangefinder. The reason behind this is that the sonar rangefinder that I am looking at ,Maxbotix MaxSonar-EZ0 High Performance Sonar Module (http://www.robotshop.ca/home/products/robot-parts/sensors/ultrasonic-range-finders/maxbotix-ez0-ultrasonic-ranger.htm) has a 6.45 metre range , whereas the sharp rangefinders that I've seen only have 80 cm. I was wondering what kind of changes I would have to apply to the code so that it has the same function as the sharp, and whether I can mount this on a servo as well.
  • Using a Pololu Orangutan LV-168 Robot Controller With USB Programmer as the MCU. This MCU has 2 DC motor servos, which is useful for me, as I live outside the U.S., and it is about 10$ cheaper for a motor than for a servo. It includes the USB programmer, but I am hopeless at code  ??? so I'm wondering whether it will use the same .hex files etc. as the original $50 robot. Here's the site:http://www.robotshop.ca/home/suppliers/pololu-en/pololu-orangutan-lv168-controller-usb.html

Also, with the DC motors, they need 6-12V, and (with no load) a current of 0.3 A. Their speed is 18,400 RPM and they have 69.2g.-cm torque (at 12V). The MCU has an input voltage of 2-5V (step-up regulator makes it 5V) so will I need another power source for the motors?
If anybody can help, your advice is very much appreciated.

Offline airman00

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #1 on: March 01, 2008, 09:01:45 PM »
those things will require A LOT of program changes

what is your experience with programming?

also, the orangutan is AVR based, rite?
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

www.Narobo.com

Offline ajax spray n wipeTopic starter

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #2 on: March 01, 2008, 09:17:37 PM »
The Orangutan LV-168 is based on Atmel's mega168 AVR microcontroller. I have no previous experience in anything short of html programming. Do you think I could build this from the beginning, or will I have to build the $50 robot with the normal components, and then buy the extras and add them later. I would prefer the first option, as otherwise my $50 robot, already around $200 will be about $300.
« Last Edit: March 01, 2008, 09:20:22 PM by ajax spray n wipe »

Offline airman00

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #3 on: March 02, 2008, 06:47:30 AM »
you'll need to change the code slightly if you use sonar  since sonar needs a trigger pulse for it to send out a sonar beam

please combine your related posts

i posted another answer for your questions over there
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

www.Narobo.com

Offline airman00

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #4 on: March 02, 2008, 08:08:10 AM »
In the 50 dollar robot tutorial  you make the MCU board yourself



the Orangutan is also an MCU board , but what I would do is just add H bridges, etc. to the 50 dollar robot MCU board that you already made
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

www.Narobo.com

Offline Soeren

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #5 on: March 02, 2008, 08:21:19 AM »
Hi,

I'm thinking of making the $50 robot, and I was wondering about making a few changes
You want to make so radical changes (Sort of like "I wanna build a Ford and I wanna use the motor from a Toyota and the chassis from a VW") that you should look at something else, like building from the ground up.


Also, with the DC motors, they need 6-12V, and (with no load) a current of 0.3 A. Their speed is 18,400 RPM and they have 69.2g.-cm torque (at 12V).
You will need substantial gear reduction to use these motors.


The MCU has an input voltage of 2-5V (step-up regulator makes it 5V) so will I need another power source for the motors?
You'd need a power source supplying the 12V for the motors, but you can use a regulator (switch mode preferably) to get the lower voltage for the Ácontroller and what else needs it.


If anyone could reccomend another similar MCU (based on ATmega168 chip, motor drivers/H-bridges, I/O ports for sonar.
You won't find a Ácontroller with build in H-bridge (as you asked in another post).
As long as a ÁC has enough I/O's etc. you just add whatever is needed to control motors, read sensors etc., but judging from your questions, I'd guess, you aren't capable of making so radical changes as you seem to want.

Readjust your expectations and you'll have a lot of fun, but as it stands, I foresee a lot of disappointment coming to you.
Regards,
S°ren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

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Re: $50 robot with differrent MCU, motors and sensors
« Reply #6 on: March 09, 2008, 10:52:26 AM »
The sonar will work without any code changes (if you use the sonar analog pin). Also, the accuracy will be much much lower.

Quote
it is about 10$ cheaper for a motor than for a servo

http://www.societyofrobots.com/robot_faq.shtml#servo_motor

And it wouldn't really be the $50 Robot if you replace everything in the tutorial :P
Remember, keep your first robot simple, and worry about all those neat ideas you have for your 2nd robot. ;D

As for using the Orangutan, you'd have to change the pinouts that are in my code to match the schematic.

 


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