Hello everyone, my name is Luc, new to arduino unfortunately, but have a bit of experience in electronics. My biggest challenge is to combine sketches. I mean once in a while I combined them following the clues, but looks like other parts of the void loop doesn't work. Long story short, I want to use the new cytron dual motor shield for less little wires, lol. I bout 2 of the powerwheels gear motor 12v everything on amazon, I have two arduino uno already, and a shift register 74hc595 in case of additional pins, LCD shield with button pad that I want to print my own message like " NelmowE likes Nelsons" lol agin, 4IR for edge avoidance, and 4Ultrasonic sensors for obstacle. Also want to make it safe for my children, I want to be able to stop the cutting blade if they are too close of it. Please let me know what to do, use the shift register or two unos? But how? That would be another complication for me to know how to run this code inside the other ones, man! What is best please? since I will run out pin I already tried with an l298n lol, amp too low, gets hot. Got it work a bit just with the ultrasonic s only, but again new to it. PLEASE, PLEASE help me someone with the programming, will be really appreciated. I migh use a higher voltage just for the cutting blade
Not a good idea to post your email address.
"Robotic lawnmower" is a popular project, and several have been described in some detail on the web, and have also been discussed in this forum.
Have your searches turned up nothing useful?
Not going to happen.
I'll be blunt with my opinion this time.
My guess the reason you have trouble combining sketches is you have not learned what the code does.
The reason I'm so blunt (which is not my style) is because you mentioned children and safety in the same post. To even have a prayer to accomplish this you must know the code very very well.
My suggestion is you backup and lean the code you have and then layout what your code needs to do and create that code.
Spinning blades and humans is not a good combination.
I apologize if I have offended you, it was not my intention 
I'm not offended at all cause I want help. spinning the blade safety, I can handle that part with a totally different circuit. I'm just looking for better ideas bro. Again I'm new, don't know much about the codes, why "{ or }" when to use }
} ok bro. The hint that i'm looking for it's only what links the 3 structures of two or more codes in oder to run all commands. i combined two sketches without realize it, but I need to know why this or that. I follow videos and some tutorials, but you'll never really know the keys or what you exactly want to know. got me man? for instance if I want to know after you wire a 74hc595 then i won't be able to find how to integrate it in my project cause all i found it's about LEDs.
I recommend you abandon this project for the safety of your kids and there appendages. If you must do this start with a flywheel on the motor and stop it in 1/2 revolution or less, that is just a starting point. You and yours would be much safer if you start with a vacuum cleaner, much less complicated.