how to use the 3th motor

[Martijn]

i have a limit of 3 motors.
2 are already used , one for the left side and one for the right.
im using a elektromagnet for our weapon so there's one motor left for me to use.
can someone help me how to use the 3th motor too switch in when pushing the other sumo-robot, so i would have a better traction.

 

[dknguyen]

You mean like a button on the front of the robot that turns on the extra motor when it pushes against another robot?

 

[Martijn]

the stearing of the 3th motor won't be a problem because we have to work with remote controle. the problem we have is we have a rotating movement but we dont know how to give our robot more tration with it.

 

[dknguyen]

You'd need to have a strange transmission that lets the power from the 3rd motor drive both wheels at the same time as the left and right motors. Which is beyond practicality...THe only other thing to do is to use the motor to drive a vacuum fan to grip the floor but this is illegal in almost every sumo competition (and it's complicated to pull off).

About your magnet...
Magnets have a few problems especially with small sumo robots.

1.Sumo bots push. Magnets pull. HOw is this going to help you? If it's to stop the other robot from escaping see the remaining points

2. You need 100% contact for the magnetic to do anything. It's attraction strength decreases with the exponentially with distance.

3. Even strongest magnet can still be removed by sliding it off.

4. A magnet strong enough to do anything pull uses much more power than a motor and in this case doesn't even make a difference because of the things mentioned about pushing/pulling and sliding.

5. Many materials used in robots are not magnetic...especially small ones where strength is not needed like plastic, rubber, and wood than metal. Even the metals used tend to not be magnetic because steel is only used when strength is needed and other metals are too expensive and are only mixed in to alloy. Aluminum for example is very common and completely non-magnetic. You rarely find steel on smaller robots

A motor-driven clamp is much more effective to catch other robots and to stop the other robot from escaping which is something you could use the 3rd motor for. You don't even need a motor clamp. Just a V-shaped structure at the front will stop the other robot from escaping to the side as it's being pushed.