Line following zig zag

[ahmedragia21]

Hi, im trying to follow a line using 6 sensors and it does not follow the line smooth and the motors are so fast really ... and one motor is faster than the other .. how do i solve that problem ? also when the robot is positioned like figure 2 and make it to follow the line it doesnt ... it just cross it as it and doesnt follow it !!

 

[Krumlink]

Try just hooking the motors up to the same power source (no circuitry, just direct power). If they drive straight, then it is the circuitry's fault.

 

[ahmedragia21]

i did that , it still deviates to right ...

but why that zig zag happens ? also how do i slove the second figure problem ?

thanks

 

[blueroomelectronics]

Friction in the gear train.

 

[Hank Fletcher]

Friction in the gear train.

I'm glad you brought that up. I've noticed that depending on their orientation, the Tamiya gearboxes can get noisy. I've yet to determine the source of the noise, though. Maybe it's the crown gear on the motor? Any thoughts and/or solutions?

 

[blueroomelectronics]

I tried cementing the bushings on one unit, didn't notice any real difference in noise and probably just simply increased the friction.
12000RPM is going to be noisy with a plastic open frame gearbox & motor. The crown gear & tiny pinion gear would be my guess too.
I did find sometimes the motor presses too hard on the crown gear, I've added thin foam shims to the Mongoose manual and this helps alot.

 

[jpanhalt]

i did that , it still deviates to right ...

but why that zig zag happens ? also how do i slove the second figure problem ?

thanks

I don't know whether robots do this, but if you want to stabilize a vehicle and help it go straight, put a little toe-in to the front wheels. That way, if it deviates to the right, the left wheel will be more crossed to the direction of travel (i.e., create more drag) and device will tend to self-correct. A neutral setting is OK, but if you have any toe-out, it can become quite unstable.

Maybe your robot has toe-out on just one wheel? One thing you can check is whether with the motors disconnected does the robot coast in a straight line?

John

 

[NightFalcon90909]

"I'm glad you brought that up. I've noticed that depending on their orientation, the Tamiya gearboxes can get noisy. I've yet to determine the source of the noise, though. Maybe it's the crown gear on the motor? Any thoughts and/or solutions?"

Know what you mean... I got a double, and one of them makes a racket to wake the dead, the other one is nice and cooperative. I can only assume it is a due to minute differences in positions of the gears... no amount of grease helps...