Weekly Update 2007-07-26
This Week’s Goals:
1) attach the optical encoders to the cart
a) Completed See Figure 3 Below
b) I have hooked up the distance measurement encoder to the free wheel so we can measure distance directly. Dr. Oh do you want me to move it to the pivot point of the cart-pendulum system?
2) attach the pendulum to the cart
a) Completed See Figure 2 Below
3) attach the arm to the cart
a) Completed See Figure 4 Below
4) finish the analog motor driver
a) NOT Completed, See “Goals For Next Week” below
5) get into contact with Kathie Donahue in regards to weekly payment because I have not heard back since her last email last week.
This week I completed the construction of the cart. Please see the pictures below for the description of each part.
Pendulum Free Wheel
Figure 1 (Front of the cart)
Figure 1 above shows the front of the cart-pendulum system. The wheel to the right is the drive wheel and the wheel to the left is able to spin freely. The wheel to the left is also used to measure the distance traveled from the origin, aka the starting position.
Screw into Shaft
Screw into Shaft
Figure 2 (Top of the cart)
In Figure 2 above you can see the top of the cart system. The pendulum is a threaded rod that screws into the shaft, thus it can be easily removed for transportation and storage.
Position Encoder Angel Encoder
Figure 3 (Back of the cart)
In Figure 3 above you can see the two encoders that are used to make measurements of the system. The one on the top, connected to the pendulum, is used to measure the angel that the pendulum is at. The other encoder, on the bottom right, is connected to the free wheel in Figure 1 above and is used to measure the distance traveled from the starting position.
Pendulum Wheels Encoders
Wheels Encoders Arm Pivot
Figure 4 (Whole Cart)
Figure 4 shows the cart attached to the arm which is attached to the pivot point. The pivot point can be attached to a heavy object or a suction cup to act as solid point for the cart to spin around. In the future this point will have the motor and encoder wires attached through it via a slip ring type setup to allow for 360 degree rotation around the pivot.
Figure 5 (Pendulum’s mass)
Figure 5 shows the top of the pendulum and it’s mass. The mass is attached by two small screws on the threaded rod, the pendulum’s arm, and is able to be moved up and down. This will allow us to change the dynamics of the system by changing the center of mass instead of adding more mass.
Please click on the two images below for a video of the cart-pendulum system working with Labview and the NI-USB6211 DAQ. Please click here for the Labview code used in the videos below.
Please note that the videos below are on the DASL servers but I do not have a public folder yet so it will ask you to log in, my user name as password is still the default dlofaro:daslftp
I have been having problems making a working analog motor controller with analog output. I have built multiple different designs, most notable the servo controller from the servo controller directly from the LM675’s datasheet and one of my own design. See last weeks weekly update for the schematic for the design directly from the LM675’s data sheet. The latter design worked on a smaller less powerful motor but did not work when I connected the motor that we are using for this project, the Maxx EPU10. I also tried my own design which did work in one direction with the Maxx EPU10 but not in the other direction. I have talked to Bryan about my problem and we came up with a possible solution to my problem. I am going to us the same LM675 opamp that I was using before to drive the system but only in the directly that it is able to drive the motor. I will then have logic that will switch an added H-bridge from forward to reverse. For the H-bridge I plan on using the TIP-122 Darlington which I can procure form the ECE parts window for testing.
Goals For Next Week:
My goals for next week are as follows: