Let's Make Robots!

The planning of a tiny autonomous SHR type robot.

I have built a SHR robot using an arduino and a L298N. Everything works fine although the motor driver is junk. However, I want to build another. One that is really small, and cheap to build. I have not bought any parts so everything I am saying is just thoughts in my head right now.

Remember that all these parts were (mentally) chosen due to their small size and cost.

 

Arduino Nano - $8  eBay  (Has PWM pins which would be used for servo, etc.)

HG7881 Motor Driver Board - $2  eBay  (Not sure about this board, the price scares me. I'll try it before ordering anything else.)

Small 3V DC Motors - $3  eBay  (2 of these would put you at 6V; meaning they could be powered with 4 AAA or AA.)

Bottle Caps - Free  (Used for wheels; electrical tape around them for traction)

4 AA or AAA Battery Pack w/ Switch - $2 eBay

4 AA or AAA Batteries - $2  (Can find these anywhere)

HC-SR04 Distance Sensor - $2  eBay  (These work great, and are cheap.)

SG90 Servo - $3  eBay  (Cheap 180 degree servo; works good for price and is VERY small.)

Jumpers - $2  eBay  (Can get 40 stuck together for $2)

 

The body would just be made of some small piece of plastic and everything would be secured with hot glue or double sided foam tape. Standoffs may be used depending on how everything is placed on the plastic.

 

Again, this whole plan is hypothetical. Everything seems like it would work out okay though. Then again I am very inexperienced with this kind of thing. If you see something wrong with my plan please let me know. I just think it would be cool if it was really small because after completing mine I thought it didn't look right. Yeah it's really cool moving around by itself, but it looks to big to be doing something simple like that.

 

 

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Thank you for the feedback. The board I found did have 2 chips and gave out an 800mA load. I just ordered one and will do some testing when it arrives.(slow boat from China)

I looked at the HG7881 motor driver data sheet. The chip will only drive 1 motor so hopefully the PCB you ordered has 2 chips on it. The DIP package has a maximum rating of 1.1A continuous and the SMD version is rated for 800mA cont. Peak current can be as high as 1.5A but you would need some serious heatsinking.

The datasheet specifies that with an 800mA load at 6V you will have at least 1.7V drop. This voltage drop should get better with lighter loads.

Basically for a small start here bot where normal motor current is going to be less than 800mA they will work fine.

 

Thank you for the feedback. The board I found did have 2 chips and gave out an 800mA load. I just ordered one and will do some testing when it arrives.(slow boat from China)