### Author Topic: stepper motors and basic stamp  (Read 1640 times)

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#### dmehling

• Full Member
• Posts: 62
##### stepper motors and basic stamp
« on: August 26, 2007, 03:56:02 PM »
I have just about decided to use a basic stamp for my robot, and now I am trying to determine what kind of motor driver I need for my stepper motors.  I will be using two of these motors; one to raise and lower a platform weighing 15 to 20 pounds and the other motor to slide that same platform forwards and backwards.  Both of these motors will be using a screw thread drive to accomplish this linear movement.  I am not sure how powerful of a stepper motor I need as well as the type of driver/controller I need.

#### hazzer123

• Supreme Robot
• Posts: 460
##### Re: stepper motors and basic stamp
« Reply #1 on: August 27, 2007, 03:46:42 PM »
There are a couple of unknowns in the equation for torque needed for your application. Screw pitch and efficiency.

But anyway, for example-

screw pitch = 2mm = 2x10-3m
efficiency = 70%
mass of platform = 10kg (i like metric )

work in x efficiency = work out

torque x 2pi x efficiency = mass of platform x acceleration due to gravity x screw pitch

torque x 2pi x 0.7= 10 x 9.8 x 2x10-3

torque = (98 x 10-3) / (pi x 0.7) = 0.044unipolar and bip6Nm = 4.46Ncm

The driver you want to choose depends on 2 things - unipolar or bipolar motor? and how much are you willing to pay?

unipolar motors have 5,6 or 8 leads and require a different driver to a bipolar which have 4 leads.
If you wanna keep costs down, then you can build your own driver - http://aaroncake.net/circuits/stepper.asp
otherwise there are plenty of commercial drivers out there to suit your needs.

Harry
Imperial College Robotics Society
www.icrobotics.co.uk