Robot climbing times

[ToddF]

Running some quick numbers to put a lower bound on time:

Assume the simplest possible lifting method, winching yourself from the floor to the 90 inch bar straight vertically (yes, I know this is illegal). Power the winch by two CIM motors left over after using 4 in your drivetrain. To get max power from the motors, they run at 1/2 speed, producing 1/2 the stall torque.

For a CIM, stall torque is 21.5 in-lb and free speed is 5310 rpm.

Torque/Force used to select gear ratio:
Two CIMS running at max power produce 21.5 in-lb.
Assume a 1" diameter rod (smallest practical size, ish) to reel the cord onto.
At 1:1 gear ratio, line tension would be 43 lb.
For a 150 lb robot, need ~3.5:1 gear ratio.
Select motor pinions with 12 teeth engaging a winch gear of 40 teeth gives a robot weight of 143.3 lb

Gear ratio used to find lifting speed:
The CIMS are running at half speed = 2655 rpm
After the gear reduction, the winch speed is 796.5 rpm.
Multiplying by the rod circumferance and converting from minutes to seconds gives 41.7 inches/second.

So, with the most optimal lifting mechanism, operating at the optimal conditions, not accounting for acceleration and deceleration, lifting 80 inches, would take about 2 seconds.