i made a lifehacked rc car with normal household items.
the plan is to make simple a car which move forwards or backwards and steer it a little bit with an arduino board for better understanding.
i am new in this area and need help.
My rc car looks like this:( i know its look a little bit horrible but it is a prototype )
i build my rc car with two dc engines from an old cd drive connected with the back wheels.
I dont know the voltage or the torque and so on but i see lots of videos where it was possible.
my wheels are from a bottle cover. For testing i connect the engines with the arduino with the digitalPins(set to HIGH) and with GND. I know that it is better to take an motor shield or with L293D and so on. But i want to test if it is generlly possible to move it forward.
So here start my knowledge limit and i have a problem:
If i hold the car in the air the wheels are normally spinning. But if i put down it on the table or on the ground it didnt not move.
So i noticed that i need a little bit mechanic knowledge too for this little project.
I dont know what the problem is.
There is such of variants what it can be i think:
the edges of the wheels are little bit higher than the rest of the wheel ( see picture )
the torque of the engines are to low so its not enough to move ( if i put the arduino on top of the car it is little bit more heavy )
the connection to the arduino must be with a motor shield ( i dont know enough about motor shields or L293D , i must test it )
HaShLo:
What is at this point your recommandations?
Don't do anything more with it connected straight off a digital pin, is my suggestion. Apart from the lack of current (or rather the chance of drawing too much (edit: for the Arduino, that is)) without a flyback diode you're going to get some nice spikes. Your Arduino is at risk....
kenwood120s:
Don't do anything more with it connected straight off a digital pin, is my suggestion. Apart from the lack of current (or rather the chance of drawing too much) without a flyback diode you're going to get some nice spikes. Your Arduino is at risk....
thanks for this recommend. i will connect it through the L293D or motor shield.
Have you any idea why my car dont move ? are the engines to weak ?
Whatever torque the motor can supply, and I doubt it's very much to begin with, is going to result in diminished driving force with your fairly big wheels.
Torque = force x distance so force = torque/distance.
For a given torque, which is a characteristic of the motor, dividing by a largish number means a small force at the rim of the wheel.
HaShLo:
Have you any idea why my car dont move ? are the engines to weak ?
I think it is because you were powering the motors from the arduino which is incapable of providing the needed current.
Get yourself some batteries to power the motors. Maybe some AA batteries in a 4 pack holder.
Apply the power directly to the motor and see if it turns with more power.
Warning - you are using motors with unknown voltage limits and unknown torque.
You are guessing on the voltage to apply.
If you stall the motor testing it out, you might pull much more current that expected and do some damage.
kenwood120s:
Whatever torque the motor can supply, and I doubt it's very much to begin with, is going to result in diminished driving force with your fairly big wheels.
Torque = force x distance so force = torque/distance.
For a given torque, which is a characteristic of the motor, dividing by a largish number means a small force at the rim of the wheel.
Thank you, but i dont know what to with the formula or rather what is distance ?
vinceherman:
I think it is because you were powering the motors from the arduino which is incapable of providing the needed current.
Get yourself some batteries to power the motors. Maybe some AA batteries in a 4 pack holder.
Apply the power directly to the motor and see if it turns with more power.
Warning - you are using motors with unknown voltage limits and unknown torque.
You are guessing on the voltage to apply.
If you stall the motor testing it out, you might pull much more current that expected and do some damage.
Thx i will try it.
Can you say me how to connect the batteries with the motors through the arduino ?
HaShLo:
Can you say me how to connect the batteries with the motors through the arduino ?
You already know one answer to that: you mentioned a shield in your original post.
edit: Adafruit shows how to do it with a transistor here although they power the motor off the Arduino which is a dangerous idea. Heed their warning about current in the red box.
Hi,
I think one of your problems is the type of motor you are using.
They look like small hobby motors that are only happy running at 1000rpm or higher.
You will not get sufficient torque because you are trying to get drive directly from the motor shaft.
If you lift the chassis off the bench so it freewheels, you will see how fast the motor wants to go, but has little torque.
TomGeorge:
Hi,
I think one of your problems is the type of motor you are using.
They look like small hobby motors that are only happy running at 1000rpm or higher.
You will not get sufficient torque because you are trying to get drive directly from the motor shaft.
If you lift the chassis off the bench so it freewheels, you will see how fast the motor wants to go, but has little torque.
Tom...
Yes i think you are right. They are actually hobby motors or the motors from a cd drive. Its the same with the hobby motors. What is your suggestion what should i do ? Buy motors with more torque? Thx
I want more tips about how i can modify my car bring it to move with maybe motors with more torque. and so on. the tips from the previous users was very useful i think. I will test it later and report it, but the last one is not that one i not want really do, because i said it at my first post too. I want do it with household items not with bought things.
Hi,
Try smaller drive wheels, angle the motors so they point down at 45Deg.
This will allow smaller wheel diameters than the diameter of the motor casing.
Sorry for half diagram, its late here and got hayfever.
TomGeorge:
Hi,
Try smaller drive wheels, angle the motors so they point down at 45Deg.
This will allow smaller wheel diameters than the diameter of the motor casing.
Sorry for half diagram, its late here and got hayfever.
Tom....
Hi Tom i dont really understand that with 45 degrees. Can you explain it more in detail please
HaShLo:
i dont really understand that with 45 degrees.
He just means that if you go for a smaller wheel, and the wheel's diameter is smaller than the motor's, the wheel won't touch the ground unless you put it at an angle.
