FRC #2 Climb Motor Decision
Based on the design and other constraints of our robot, we can likely ONLY use one motor for the robot climb. The FRC legal motors we would choose between are a 775 motor, Neo motor, CIM, or mini CIM motor. Below are the motor curves.
Towards the end of the match, our battery tends to "brown" or supply lower voltage and therefore pulling too many amps during the climbing sequence could result in a failure. We want to pull around 50 amps maximum while climbing. Math wise, our robot will be 140 pounds but for the purposes of calculating the force needed to pull up our robot we will use a weight if 165 pounds. Lets look at how much Power each motor will output if it mechanically will operate at 50amps.
NEO brushless motor- 433 watts
775 brushed motor- 323 watts
CIM motor- 313 watts
mini CIM- 214 watts.
From this data it looks like the two best options for this application are a NEO brushless motor and a 775 motor as they output the most watts, and therefore will supply more RPM and torque. Here's some reasons why we chose the NEO over the 775.
1) The NEO would operate at a 73% efficiency rate while the 775 would operate at 53%. This means we wouldn't be optimizing our power.
2) The 775 operates at a free speed of 18,000 RPMs and the NEO operates at 5500-To get a proper reduction for the 775 to get enough torque to climb, the gearbox would have to be much larger than a NEO.
The next step is to calculate the reduction we would need in the gearbox we need to pull our robot up, and to find the speed at which we can climb.