Hi,

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?