Status: STARTED 09/15/2007 ***
| On some occasions you may not know the speed (RPM or Revolutions per minute) so you a platform to test out the motor and get the RPMs compared to the Voltage supplied to the motor to start to work with it. This project uses a VEX platform with a VEX Optical Encoder to create a Dynamometer to display the RPMs of a motor. |
| Hardware | |||||
| Chasis | |||||
| Encoder Gearing | |||||
| Software | |||||
| Colors: | No Work | Started | Completed | Canceled | |
(10/20/2007) [phase:Software]
The optical encoder was attached to Interupt 3.
Coding was set to:
Start the interupt 3
Repeat Loop
Wait 1 second
Get interupt value and save
Reset interupt value
compute RPMs (value * 60 seconds * 15:1 gear reduction)/90 pulses per revolution
Display result of Terminal
The motor I connected RPMs were tested and computed at 5940 RPMs.
(9/15/2007) [phase:Hardware-Chasis]
The chasis must contain the motor and the encoder and gears. To stop the play in the encoder, darlin bearings are used with gears and collars. Once the assembly was put together little play could be observed. The rotation from where the motor attaches was tested to make sure it was free on snags.
(9/15/2007) [phase:Hardware-Encoder Gearing]
The optical encoder from VEX is capable of 90 (4 degrees) pulses per revolution. The problem is that you cannot just hook a motor up to it, too much play and at higher speed too much drag. Gearing resolves this. By gearing down speed from the motor to the encoder, this will overcome the drag issues. It does however add some force to the motor so it is actually not a no-load test, but close enough since a motor will probably have a minimum load anyways in my projects.
end
