David Gonsalez

Division Manager: Computer, Control and PowerDivision

Course 400D

Report: stepper motor testing and evaluation

Stepper motor testing.

Purpose and general plan:

The principal purposes of this exercise are to test the following:

  1. No load current
  2. Stall current
  3. Stall torque
  4. Current due to different load.
  5. Change in current due to change in torque
  6. Change in rpm due to change to input frequency.

Equipment:

  1. One PC running Matlab (any version)
  2. One function generator capable of creating a square wave from 1 Hz – 2k Hz
  3. One power supply with a supply voltage of 12v at 3 amps.
  4. One oscilloscope capable of measuring a 5 volt signal pk-pk at 2k Hz.
  5. One Toshiba TB6560 stepper control board.
  6. One multimeter with a current rating of 10Amp
  7. One Arduinouno
  8. One USB flash drive
  9. One C-clamp
  1. One Fish scale
  2. One set of Gram weights 20 – 200 grams

Connecting the 4-wire bipolar stepper motor to the Toshiba TB6560 stepper control board.

First determing which wire pairs go with each other (i.e. B+ and B-) this can be found in the data sheet for the particular stepper that you are using, the pairing will be color coded. Also locate these values from the data sheet. Operating Voltage ______Operating Current______Coil INDUCTANCE______Dimensions______

Internal resistance______HOLDING TORQUE______STEP ANGLE______WEIGHT_____

Once you know the wire pairing you can connect all 4 wires from the stepper motor to the terminals on the control board labeled B+ B- A+ A-. Now from your power supply connect +5 volts, operating voltage and ground to board terminals, +5V, +24V and G, respectively.

Setting up the oscilloscope and function generator:

Set the function generator to 5 V Pk-Pk , duty cycle of 50% , DC offset of 2.5V and frequency sweep from 100-2K Hz (do not turn ON the output yet). Connect the output of the function generator to the terminal labeledstep on the Toshiba TB6560 stepper control board.

Connect Channel 1 of the oscilloscope across terminals A+ A-

Connect Channel 2 of the oscilloscope across terminals B+ B-

of the Toshiba TB6560 stepper control board.

Turn on the output of the function generator and record the data from the Oscilloscope to a USB flash drive with file name Data1. (you are now done with the function generator)

Attach stepper shoe to stepper shaft, tighten set screw, attach C-clamp.

Hooking up The Arduino to the Toshiba TB6560 stepper control board:

This set up will rotate the stepper in a sweeping motion from 0 – 90 degrees this will be used to test a verity of loads on the stepper shaft.

Connect pin 13 of the Arduino Uno to the Terminal labeled step and pin 6 to the terminal labeled Enable on the Toshiba TB6560 stepper control board

Now run code below

/*

Stepper sweep

*/

//

//

int step = 9;

int enable = 8;

intvar;

int var1;

// the setup routine runs once when you press reset:

void setup() {

// initialize the digital pin as an output.

pinMode(step, OUTPUT);

pinMode(enable, OUTPUT);

}

// the loop routine runs over and over again forever:

void loop()

{

digitalWrite(enable,HIGH); //clockwise

var = 0;

while(var < 100) // 100 steps

{

digitalWrite(step, HIGH); // Take a step

delay(1); // input frequency

digitalWrite(step, LOW); // Take a step

delay(1);

var++;

}

digitalWrite(enable,LOW); //counterclockwise

var1 = 0;

while(var1 < 100)//100 steps

{

digitalWrite(step, HIGH); // Take a step

delay(1); // input frequency

digitalWrite(step, LOW); // Take a step

delay(1);

var1++;

}

}

Testing current and Torque:

  1. Stall torque

Connect a multimeter in series with the power supply set the meter to read current (Warning: the current pulled by a stepper motor can be between .5 – 3 amps make sure your multimeter is adequate).

Attach the fish scale at the end of the stepper shoe. Let the stepper motor pull the fish scale until it stops. The reading on the fishing scale will be Force, torque = force x distance

Stall torque______Stall Current______

  1. Divide the total weight that caused stall by 10 this new fraction of weight will be used to test the change in current due to the change in load.

Actual weight used / Current / Torque

Import Data1 and this data table into MATLAB system identification tool box. Generate graphs for

1.Current due to different load.

2.Change in current due to change in torque

3.Change in rpm due to change to input frequency.

%%% stepper motor test

%%@ 12 volts

NoLoad = [.354 ] ;

%% .41 lbs

current1= [ .403 .393 ] ;%% first number is hold current second number is ave. continuous

%% .7 lbs

current2 = [ .401 .393]; % ''

%%.9 lbs

current3 = [.404 .394];

%% stall torque 1.12 lbs * inch

StallCurrent= [ .406 .399];

%% fails > 40 rpm

%% @ 9 volts

StallCurrent2= [ .218 ] ; %%.5 lbs

current11 = [ .3 .217]; %% .26 lbs

Transfer Function Estimate

(-0.03976 )

------

s^2 + (3.486 ) s + (0.04942 )

Conclusion: Stepper motor, SM-42BYGO11-25

MAX hold torque, 1.12 lb*in. MAX RPM < 40 rpm.

Current very stable with different loads.