Hello,
Im making an arduino controlled rc car. A problem Im having is that the car will not move forward unless given a push. It uses a DC motor for going forward and reverse and it uses the canakit hbridge to control the DC motor. How can I fix this problem?
Supply more power.
dxw00d:
Supply more power.
...and before you do that (what does that even -mean-?) you should provide us with a complete schematic of what you are trying to do (and perhaps your code, too). Likely, though, you need to increase the size of your motor's power supply (you don't mention what you are using, what the motor is, etc - but likely, if you have your voltage correct, your battery can't supply enough current to drive the motor; that, or the motor is over-sized for your motor controller, and -it- can't supply the current needed by the motor, even if the battery can). So, what we need:
It was a deliberately vague answer to an equally vague question.
Ive included a picture of our setup
we use : L298 H-Bridge Dual Bidirectional Motor Driver (2 x 2A)
link: 4A Dual Bi-Directional Motor Driver (L298 H-Bridge)
We are able to get the wheels to turn when they are off the ground but when the car is on the ground, the wheels do not turn.
we also posted a video on youtube to see if it would help show our problem: RC arduino car dc motor fail - YouTube
nezietoon:
Ive included a picture of our setup
Did you read the part about batteries? Are you trying to run the car on that 9V battery? That's unlikely to give you more than 0.2 amps or so. While it may turn the wheels when they're unloaded, it likely won't propel the car forward when it's loaded.
For comparison, my Arduino RC car draws over 5A when starting (it hits the 5A current limit on my power supply -- gotta try to bridge it up to 10A to see how much it really wants)
And, yes, that's a wired power supply, so the car won't get very far until I put in a real battery pack 
If the car came with re-chargeable batteries, I would wire those to the power connector, instead of the 9V battery, and see if that helps, as my first troubleshooting step. My second step would be to take a better (mains power based) power supply, and use that instead of the 9V battery.
We are using the 9v battery for the arduino board. We have a 7.2 volt 6 cell 1800mAH rechargeable battery connected to the motor driver/h-bridge. And yea when the wheels are in the air and moving the dc motor is getting about 2.5 volts while on the ground with the wheels stopped its getting about .2 volts. So we dont know how to figure out why the hbridge is limiting power to the dc motor and we dont know how to solve the problem
Do you have access to a bench power supply? You could wire that up instead of the batteries, and see how much current it really draws.
I use one of these: http://www.amazon.com/Mastech-TRIPLE-LINEAR-SUPPLY-HY3005F-3/dp/B004ISD7T6/ref=sr_1_7?ie=UTF8&qid=1335468360&sr=8-7
It can actually be bridged up to 10A of capacity. (Most affordable banana plug wire is not suitable for long-term use at those currents, though.)
Other than that... are the batteries charged? Are there more control wires than the plus/minus power? Is there one, two or four motors?
nezietoon:
We are using the 9v battery for the arduino board. We have a 7.2 volt 6 cell 1800mAH rechargeable battery connected to the motor driver/h-bridge. And yea when the wheels are in the air and moving the dc motor is getting about 2.5 volts while on the ground with the wheels stopped its getting about .2 volts. So we dont know how to figure out why the hbridge is limiting power to the dc motor and we dont know how to solve the problem
Have you tested this without the Arduino in the loop; that is, applying a 5V signal directly to the necessary pins on the motor driver board?
Also, realize that the L298 can only source 2 amps max; beyond that it will go into "overload" mode. Do you know what your motor is rated at (stall vs running amps)? If you don't, then you need to find that out.
I just see the battery hooked up to the motor driver and 3 pins to the arduino. No common ground visible between the motor driver and the arduino.
I was wondering if the attached picture would help answer some questions. Its a crude diagram of how the hardware is connected
Doesn't show any grounds, so doesn't really help.
we have the gnd pin connected to a (-) railing of the breadboard and then have the gnd pin of the arduino also connected to a (-) railing of the breadboard. We have a wire connecting the two (-) railings
Draw a schematic that shows all the electrical connections. The modular block diagram doesn't really help.
