Motor Shield; Not enough power

Hi, I am planning to make a small robot that just moves around. In order to control the motors I bought a Motor Shield from LadyAda. All seems fine and the motor spins when required (it does it really fast aswell) however once I put the robot on the ground the motor stops. I can hear buzzing but it does not move. When I lift the body it resumes spinning as normal. I am using two general motors (they didn't have any specifications) that I bought from Kitronik.

Why can't the motor manage to push the robot forward? Is there any other type of motor I should use that you recommend? (from eBay please).

Note: the robot consists of two motors, Arduino Uno, Motor Shield, 4xAA batteries and a Acrylic base that everything is mounted on.

Thanks Jakub

We need numbers to deduce anything useful - spec’s of the motors and the batteries and the motor shield (which one exactly - that means a weblink to the page/datasheet)

What’s obvious is that something is underpowered - but it could be motor, shield or batteries or any combination thereof…

Certainly, here are the details:

Motor: http://www.kitronik.co.uk/products/motors-and-motor-accessories/motors-gearbox-and-mounting-clips/medium-torque-dc-motor-single/ Shield: http://www.ladyada.net/make/mshield/

As to the batteries I use siple energizer AA batteries. Four of them.

Measure and report the voltage of the batteries when the robot isn't on the ground and then when it is.

Here are the readings:

Total Power Supplied to the Shield: 5.55v Total Power when the Wheel is not touching the ground: 1.70v Total Power when the Wheel is touching the ground: 0.37v

janiemiec20: Total Power when the Wheel is not touching the ground: 1.70v

Your batteries are dead or not able to supply enough current even when they aren't being loaded.

Have you thought that maybe you need a gearbox between the motor and the wheel to increase the torque?

Your batteries are dead or not able to supply enough current even when they aren't being loaded.

The output that I have provided is the output that the board gives off. It varied greatly when I tried a different motor however with the same result.

majenko: Have you thought that maybe you need a gearbox between the motor and the wheel to increase the torque?

I have not considered that, I am a newbie, what kind of gearbox would you suggest? The robot is not too heavy. (if that helps)

Thanks :)

janiemiec20:

majenko: Have you thought that maybe you need a gearbox between the motor and the wheel to increase the torque?

I have not considered that, I am a newbie, what kind of gearbox would you suggest? The robot is not too heavy. (if that helps)

Thanks :)

One that reduces the speed of the motor to a normal sort of driving speed. I'm sure the website that you got the motor from has some suggestions...

Do you think that something like this would suffice? http://www.ebay.co.uk/itm/390520476859?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

janiemiec20:

Your batteries are dead or not able to supply enough current even when they aren’t being loaded.

The output that I have provided is the output that the board gives off. It varied greatly when I tried a different motor however with the same result.

You were suppose to be measuring the batteries. You want to see if the supplies voltage is dropping. If so, it isn’t able to supply enough current

Where did those measured values come from?

The values that I have provided came from the output from the motor shield. These were the values that the Arduino + Shield give out on the terminal. The supplied voltage is the power to the board. I have wired it this way following the instruction on the Motor Board Manufacturer's Website.

janiemiec20: The values that I have provided came from the output from the motor shield. These were the values that the Arduino + Shield give out on the terminal.

As I said: You were suppose to be measuring the batteries. You want to see if the supplies voltage is dropping. If so, it isn't able to supply enough current

So what is the battery's voltage doing?

janiemiec20: The supplied voltage is the power to the board. I have wired it this way following the instruction on the Motor Board Manufacturer's Website.

That's not clear. Are you supplying the battery power directly to the EXT_PWR connection on the shield or through the barrel jack on the Arduino?

Hey I have the same sort of issue with that shield using 4 motors where forward and backward are fine but stalls on turning. So I suspect it's not drawing enough current so I plan to try a higher current driver module.