Science Buddies: "Ask an Expert"

Ok so basically when I turn on my robot the wheels just don stop moving i've triple checked the breadboard and nothing is wrong with it the motion sensor lights uo when it sees motion but the wheels NEVER STOP MOVING... HELP PLS!

-Thx

Hi GG2002,

Quick question - did you purchase the "BlueBot" kit from Science Buddies or did you buy all the parts separately?

Next question - when you're operating the robot, are you holding it so it's facing away from you or anything else that might move (people or animals)? The motion sensor is very sensitive and will detect even a tiny bit of motion, which will cause the wheels to keep spinning. It also has a pretty wide field of view, so will detect things that are off to the side and not in front of the robot. Sometimes the sensor can even be set off by sunlight (which contains some infrared light), so try using it away from any open windows.

You can also try partially or completely covering the sensor with cardboard and/or tape, as described later in the procedure of the project, and see if that helps.

Finally - I know you said you triple checked the breadboard - but it just takes ONE misplaced wire to mess things up. Are you sure you have the jumper wire connections to the motion sensor correct?

-Ben

I am having the same issue with my robot. The wheels keep spinning and do not stop. Please let me know how to fix this.

also, my sensor looks different than the one you have as a sample on the website... was I sent the wrong sensor???

Hi Lilibean1,

Did you purchase the kit from Science Buddies? If so, email us a picture of your sensor at [email protected] (mention that you spoke to Ben on the Ask an Expert forums) and I can check. If you include several clear pictures of your breadboard then I can also help you troubleshoot your circuit. Be sure to take a few pictures from different angles and make sure they're in focus so I can clearly see where all the wires are plugged in. Tall parts like the MOSFETs tend to obscure some of the wires if you only take a picture from one angle.

Thanks,

Ben

Hello Ben,

Thanks for replying. Yes, I purchased the kit from Science buddies. I emailed you the sensor and breadboard for your review. Please advise asap what I can do.

Thanks!
Yvonne

Hi Lilibean1,

It turns out you are correct that you received the wrong sensor. I checked your breadboard diagram and it looks like everything is wired correctly. I believe we are going to send you the correct sensor but I wanted to get you an answer ASAP for how to get the current one working, if you want to move forward anyway. There are two steps you need to follow:

1. The + and - pins on this sensor are reversed from the one in our directions. So, switch the red and black wires that are plugged into the sensor.

2. There are two small orange knobs on one side of the sensor that you can adjust with a small Philips head screwdriver. Turn these knobs all the way counterclockwise.

If you get a chance, try that and let me know if your robot works. If you prefer, you can just wait until you receive the correct sensor, then follow the directions on the project page.

Sorry about this, and thank you for catching it! This will help us correct the problem and avoid it for other users.

Thanks,

Ben