How to make a 5 kg war bot for Robo sumo( part 1) .....

 If you are want to make a 5 kg sumo robot for Robo war then you must have to follow some theory. I am telling you the right theory behind those bot's, and with out this theory you are not able to understand that how much power and torque will required to operate your bot.

1. Circumferential Velocity Calculation:

If you are think that at first you chose the motor and then you will find wheels for your Bot, then my friend your idea is totally wrong. At first chose your  Bot's wheel then calculate the circumferential velocity.

Now, usually in most of cases we are using 2 or 3 inch wheel for our 5 kg war bot. Consider 3 inch wheel and we will get the Circumference is 0.235 metre. Remember this one you have to convert those units in SI.

And suppose consider your motor's RPM is 300.

Now, Circumferential Velocity of your bot is Vs= (π * D *N)/60 ;        (π * D) is  Circumference of wheel

                                                                              =(0.235*300)/60  

                                                                               =1.178 metres/second (m/s)

2.Ultimate Power Calculation:

Now, Maximum power that we are need to operate our Bot, P

=(power required to run our bot) + (power required to push opponents Bot when opponents Bot trying to push our bot too me ans opponents Bot's wheels are in running condition) + (power required to push opponents Bot if opponents Bot are in stall condition)  

=( m * Vs1 * g * Cr1) + (m * Vs2 * g * Cr2) + (m * Vs3 * g * Cs) ;      here m = mass of the Bot and                                                                                                                         mass is equal for both the bots.

  =( 5 * 1.178 * 9.81 * 0.02) + (5 * 1.178 * 9.81 * 0.02) + ( 5 * 1.178 * 9.81 * 0.5);                                                                                                                                                   consider Vs1 = Vs2  are the                                                                                                                        circumferential velocity of both the    =31.2 watt power                                                                                                          Bots are same.

                                                                                                            Cr1  and Cr2  = 0.02 are the rolling frictional co-efficient of arena and the Bots wheel and Cs is the sliding frictional coefficient of arena and wheel and consider it 0.5. (0.5 frictional coefficient value is too much high usually it varies from 0.1 to 0.3 ) 

                                              

3. Torque Calculation :

Now the most important think that torque calculation, it is very easy to calculating the optimum torque 

Torque T = ( P * 60)/ ( 2 * π * N);

               =0.99 Newton metre Torque

Now, 31.2 watt and 1 N-m torque is enough for making a 5 kg war bot. No need to use excess amount of power and torque. If you are using more power and torque then your Bot's wheels are may have facing some slip in the Front to Front stall condition. That means if you don't have enough weight to push down the wheels in to the ground then the wheels getting slips and your excess power and torque will wasted.