Mobility Motors:
Deciding the motor to be used for mobility must take into account the voltage input, the power output, the torque output, the weight of the motor, the reliability of the motor, the safety of the motor, the ability for the motor to be attached to wheels and the chassis, and, debatably most importantly, the cost efficiency of the motor.
There are two main types of motors that are in the main market for combat robots today: brushed motors and brushless motors. Brushed motors usually have a higher torque, while brushless motors usually apply less torque, but are much cheaper.[1] Based on our criteria, we selected the following motor:
We will be using the same motors as our attack motor,
Propdrive v2 4248 650KV motors
Cost: $~40 [x2]
Gearbox:
Originally, a gearbox selection is very important to add to the motor to see how much more torque we want on our motors. With the motor selection we have, they have built in motors. We will need a gearbox for both wheels going forward. Gears are surprisingly expensive
Possible Cost: $300 [X2]
Wheels:
Because we are opting for only 2 wheels instead of 4 wheels on our bot, we want to invest in durable wheels, have good protection, and have a good sized radius. We expect our bot to be about 6 inches thick or more to account for the batteries and the motors so our wheel should be at least 6.5 inches in diameter. We also expect very good traction on the wheels as with 2 wheels, we expect the front of the bot to drag on the ground. We want a wheel that has an 8″ diameter and also has a ball barring with inside diameter of .5 inches. Overall a good wheel and most of these wheels are similar in price. We will need likely 4 or more wheels as wheels are the most common object to be damaged or completely ripped apart or off the robot. If this happens, and the robot is incapable of movement, this is called an official KO and we lost the battle.[3] This means that protecting the wheels and having strong and sturdy wheels is very important.
Cost: $200
Total Mobility Cost: $~1000
Sources:
[1] [MET2019_Giese_Justin]
[2] https://www.instructables.com/Phoenix-30-lb-Combat-Robot/
[3] https://battlebots.com/wp-content/uploads/2019/12/BattleBots-Tournament-Rules.Rev.2020.0.pdf