Ultimate Robot Kit won't make turns

#1

We have built the Ultimate Robot and all seems to work fine except for the fact that it wont make turns. Not for sure the problem. The wheels cannot be tightened to much or they wont work. If not tight enough, they fall off. Even when the robot is working well, it will only go forward and backwards. M1 and M2 will not work in a manner that will allow the robot to make turns. The robot is for competition and requires the ability to turn in order to pick up objects. One motor on the back wheel will stop working and has to be wiggled and shook to make work again.

#2

Without having a picture to see how your wheels are put together I would check to see how your bearings are mounted on the wheels. On the free spinning wheels they should be inserted in such a way that the plastic ring collar and the shaft collar are only touching the bearings and not the wheels. If you can not push all of these together and firmly tighten the set screw with the wheel freely turning have another look at it.If they are you might want to check to see that the bearing are turning freely. It was important that the plastic collar was being used on mine to provide the proper spacing. On the motor mount check to see that the collar of the motor is slightly longer than the plate it goes through so the shaft will turn freely. I had to pull my motor mounted wheel slightly away from the plate for good clearance, but if you use two set screws instead of one it should hold firmly. Mine worked fine until I put the tracks on it at which point it behaved like your, only going back and forth. I think one of my tracks was tighter than the other. Before I investigated further I took it apart to work on another issue. I built a test bed for all of the motors and sensors to make it easier to check out and observe it in action. When working correctly the motors moved forward and in reverse at the same time unless you were turning in which case one went forward and the other in reverse causing it to turn. It sounds like you might have a bad connection on one of the motors and again with out seeing it I can’t tell if it is repairable. Look for a bad pin or solder joint.

#3

Thank you for the help. I was able to fix the tire falling off issue. BUT, it still will not make turns. So very frustrating.

#4

There have been reports that weak motors were causing some of the turning problems. You might want to check into that. There was a program from the factory addressing this issue.

#5

Like redkcir suggested, it could be a known problem with the motors or something.What are you using to control the robot? I have tested my starter tank robot with the motor test sketch (repeats going forward and backward with pauses in between) and the android app using BT.

I am not sure how many transport motors your robot uses; the starter tank uses two–one on the left and one on the right (both with tank tracks to pull the non-motorized wheels).

After I first built it, it was totally problematic; so I did lots of testing–including a motor test with an extra motor I picked up (nothing else connected). I discovered my 6 AA rechargeable batteries couldn’t provide sufficient power for the motor. I tried a 1 amp center positive wall-wart and the motor worked. In fact it worked on all setting from 3v to 12v. If you have the robot off the ground, when you make turns the wheels should spin at different speeds. I found the robot worked with fresh non-rechargeable AA batteries.

With the android app, I created a control surface that not only has the built-in N/NE/E/SE/S/SW/W/NW directional arrows, but I also set up two robot arm bidirectional gadgets to control M1 and M2. This let me control the left and right tracks independently.

If you haven’t done so yet, get your robot off the ground and see if you can tweak the Test DC Motor sketch to make one motor go forward and one go backwards (assuming your transport is similar to the tank robot). If that works, hard code a sketch to do a circle–one motor at something like 45 to 65% of the other motor. Again, of the ground the motors should cause the wheels to spin at different rates. (Does your robot use more than2 motors for the transport? If so, you would have to adapt the sketch differently depending on how the motors function as a team.)

Anyhow, I hope some of these observations help.

Steve

#6

@iSteve I am having the same problem that @StacieA has noted where the robot will move forward and backward, but will not turn… If I pick the robot up, I can see all the motors moving in the proper directions, but when I put it down on the ground, the motors just stop and make a whining noise… I plugged in a 1 amp wall-wart and I can see much improvement in the turning, but it still does not spin about when the direction of the motors is reversed.

I constructed the robot as instructed. Any other suggestions?

#7

My 8 year old grandson and I just built the starter tank and it will not turn on a smooth surface or climb over even a small object like a pencil or up onto the carpet.
He was very disappointed. I changed the batteries twice and checked each battery’s voltage before installing them.

#8