I'm building a robot that weighs ard 60kg and can climb stairs.
However, i'm having some problems with finding the right motors for it.
I suppose i need to calculate the amount of force needed to move the robot up the stairs.
(Please correct me if i'm wrong)
To make calculations easier, this is wad i did:
Assume the flight of stairs to be a slope of the same gradient(gradient of stairs is taken to be gradient of a line drawn from the edge-to-edge of 2 steps).
Take angel of elevation = 40 degrees
weight of robot = 600N
Then, force needed to move robot up the "slope" (assuming "slope" is smooth):
Sin40 / 600 = 1600N
However, since internal resistance of the the system and resistance due to the "uneven-ness" of the stairs cannot be ignore, thus, i assume the total resistive force to the motion to be 400N.
thus, the total force needed = 2000N
to have the robot moving up the stairs at a speed of 1.2m/s,
power need: 2000 X 1.2 = 2400J/s
~ 3.3 hp
i'm looking for a motor that is 40mm or less in diameter and ard 10 cm in length.
I'll be using 4 motors on the robot, meaning i'll need each motor to have the out put of 3/4 - 1 hp.
Does anyone have anything to recommend?
I've checked out many catalogs, i realized there's 2 different torques given, on is the torque at max. efficiency and the other is the stall torque.
Using the formula, (torque X rpm) / 5252 = horsepower,
i realized that if i used the stall torque in the calculation, many motors can provide the hp i need.
but if i were to use the torque at max. efficiency, no motor in the size i need have the amt of power i need.
Am i supposed to use the stall torque or torque at max. efficiency in my calculation to choose the motor i need?