Liquid Transfer Project

The purpose of this project update the Engineering Physics 4A04 Project designed by former students Michael Bulk, Parsian Katal Mohseni, Rachel Poupore, and Andrew Rabeau. By updating the project, the project can be cleaned up and can be used in the future provide a representation of the some of the type of work that students in Engineering Physics complete during their time at McMaster.

In September 2005, the 4A04 students were given the task of designing and constructing a device capable of competing to win four “pouring” races. The races were conducted in groups of two, with the first two races taking place approximately 7 months after the project began, and the final two races being completely a week later. The objective was to fabricate a device that has a minimal cost function, while maintaining maximum fluid transfer from the source to the container. On top of this the task was to be completed in the shortest amount of time possible. The fluid transfer was defined as “removing the contents from the source container and relocating them into the destination container” [1].

The device was constructed such that it was capable of opening either a 351 mL can of pop, a 500 mL bottle of water, or a 591 mL bottle of pop, and transferring the contents into a 1 L plastic container. The device operates on 4 feet by 4 feet and half an inch thick piece of particleboard, which is divided into four quadrants where the source and detection containers can be placed.

The source and detection containers were randomly placed on the playing field, and the purpose of the device was to locate the source container and transfer its contents into the destination container without any assistance, (except for throwing a single switch). The source container needed to be removed from the destination container ensuring that the transfer is complete. The end of the process is noted by the illumination of an LED.

When approaching this project, the first part was to locate the device the group had constructed previously as well as their final report. The device was setup using a clamp instead of screwing it into the particleboard. The report was read such that we became familiar with the project. It was apparent that several pieces of the project were missing, but the main concern was does it function properly using the circuit diagrams the project was inspected, in search for broken or missing connections and parts. Notably there was a missing connection going from an h-bridge to the elevator motor, but this was left as it was for a period of time. The reasoning was the wire looked like it had been intentionally cut and perhaps it was meant to be that way. There were also many open connections and places for the circuit to short, despite the use of electrical tape. All of the electrical tape was removed and heat shrink tubing was used in its place to maintain a more professional look. The motors, LEDs and lasers needed to be checked make sure the entire system was still working. If certain motors are not working, they would need to be replaced, which would be an unwanted hassle. One of the lasers used for detection was missing, and needed to be replaced.

After applying heat shrink tubing to the wires and inspection of the project, the power sources needed to be found and hooked up. These consisted of a 12V DC, 800mA power supply, a 5V DC power supply, two 9V batteries and six 1.5V alkaline cells. The sources were connected in the respective places and the device was turned on. Using the single laser, the rotating motor moved the arm and stopped moving when the bottle broke the signal with the detector. When this occurred the sliding arm moved and stopped when the whisker switch was pressed. This should have enabled the elevator arm to go down and grab the can, however it did not. At this point the circuit had to be revaluated to determine the problem. The wire that we left cut seemed to be the problem, so it was soldered together and the device was tested again. All of the motors worked and none of them needed to be replaced. The main problem now was the missing laser and the alignment of the lasers. Once lasers were acquired they were placed in the holders and aligned. The alignment was difficult and tedious; sometimes when they appeared to be aligned they still would not be detected. Two LEDs were added to the laser detection circuit to verify when the lasers are properly aligned. When the laser is aligned the LED emits red light, and when the beam is broken the LED turns off, this gives a precise indication of what is going on during the device operation.

At this point the device runs off 6 separate power supplies, the 12V source, the 5V source, the two 9V batteries, and the several 1.5V batteries inside each laser. The power supplies are to be integrated so that only one supply is used. This process was began be integrating the lasers. The lasers were taken apart by cutting off the outer metal shell. The batteries were removed, and the positive and negative terminals of the lasers were determined. A ribbon cable was used to connect the lasers to each of the 9V batteries in the detection circuits. The first laser that this was tried with did not work. The laser had over heated and such that the optics inside the laser were damaged and could not be repaired. The second and third lasers tried worked well initially. However, there was a noticeable decrease in intensity from the time the laser turned on, caused by excess current resulting in the lasers to overheat. Current limiting resistors were added in series to the lasers to provide a more luminescent output. The lasers now brightly illuminate the two detectors.

The next step in the project update was to get rid of the two 9V batteries which now provide power to both detectors and both lasers. The 9V going into these circuits first goes through a 5V regulator, which seemed odd at the time but ended up being useful for our purposes. The batteries and connectors were simply removed and the 12V from the power supply was connected to the circuits. They grounds were all commonly connected.

The device now operates off of two separate power supplies; the 5V and the 12V. In order to integrate these two power supplies we had to ensure there was enough current going to each of the motors during the device operation. The current across each motor was measured multiple times.

Since only one motor is running at a single time and for a certain period of time, it was decided that the 12V, 800mA power supply would suffice as the current is close enough for the drill motor. The 5V source was removed. A 5V adjustable regulator was created using the 3-terminal adjustable regulator LM117. It was set to an output of 5V. The 12V source was connected to the regulator which was connected to the 5V line (where the source was removed).

The voltage regulator consisted of the LM117 3-terminal adjustable regulator, a 0.1uF capacitor, a 1uF electrolytic capacitor, a 240 ohm resistor and a 5 kilo ohm potentiometer. The capacitors were added to improve transient response and as an additional input bypass. The system was then checked to make sure all the motors still work and the device performs properly with the use of only one power supply. The results were good and the switch did not seem to have any negative results.

The next step was to replace the circuit box with a newer box. This box would incorporate the use of several switches and LEDs so that motors can be turned on and off as necessary. Two DPDT switches, several SPST, several fuses and a fuse holder were purchased to be used. The box was modified to hold these items as well as some LEDs to give it a good appearance.

The size of the components needed to fit in the box were measured and mapped out on the project box. To create the holes for the components, a soldering iron was first used to burn a sizeable hole into the box, followed by using drill bits by hand to create a neater finished look. This was an alternative to just using a drill. The holes were adjusted in size until all the components fit properly.

Now that there was a functioning project box, wires were soldered to each of the switches, LEDs and the fuse box. The components were placed in the box and secured. The circuit boards were removed from the old project box and place in the new one. Several wires were cut, so they could be attached to the switches to add on/off functionality. The auto/manual function was also implemented for the elevator motor. In the manual function there exist two options: move elevator up or down.

The old box is now completely replaced. The LEDs are held in place using silicon concealer. The project is almost complete. The input jack used is not the one preferred so it is left outside of the project box, as the system is tested and the lid is put back on. The LEDs used to indicate when the project has completed its cycle are now also placed on the box, as they were previously neglected. All of the parts of the project are complete and the project update is done. The only change would be to change the 750mA fuse to a 1A fuse to prevent it from blowing. The drill motor typically draws 1A of current.

This procedure has be taken and updated from the Engineering Physics 4A04 – Design and Synthesis Project Report from Section 5.0 – Operating Instructions. The following instructions are to be followed prior to the activation of the device. They are to be followed to properly prepare and setup the system

1. Align four holes in the base of the central arm with the four holes in the center of the playing field. Alternatively, a clamp can be used to hold the base of the central arm in place if the actual playing field is unavailable.
   1. Insert one ¼” bolt into each hole and fasten from underneath the playing surface using one ¼” washer and one ¼” nut.
2. Ensure that the elevator arm is 10.25” above the playing surface. If the arm is not in this position, then its height can be manually adjusted using the switch:
   1. Turn the elevator switch to the manual position. This ensures that there is no current being drawn back to the main circuit box and that the transistors are not charged.
   2. Using the UP/DOWN switch the elevator arm will move accordingly. Adjust the switch until the arm is at a height of 10.25.”
   3. Returning the switch to the middle position stops the arm from moving.
3. Plug in the 12V adapter to the wall socket and connect to 12V plug on the circuit box.
4. Ensure all motors are in the OFF position.
5. Turn the power switch on. The ON LED should also turn on. If not, the fuse has been blown and needs to be replaced.
6. Turn the laser/detector switch ON. Make sure the lasers are aligned by breaking each beam and observing the change in LEDs. The LEDs should be on when the switch is on and the lasers are hitting the detectors and off when there is an obstruction.
7. Return the on switch to OFF for the rest of the setup.
8. Ensure that the elevator arm is as close to the center of the playing surface as possible. If this is not the case, it can be manually pushed back along the boom arm.
9. Turn the elevator switch to the AUTO position.
10. Prepare the source container for detection as follows:
    1. If the source is a pop, then attach the longer of the two detection rods to the top of th can with Velcro. Place source container on the playing surface.
    2. If the source is a water bottle, then attach the shorter of two detection rods to the top of the bottle with Velcro. Also, wrap 12” of duct tape around the center of the bottle to ensure that the plunger can grip the bottle and not allow it to fall through when raised. Place source container on the playing surface.
    3. If the source is a pop bottle, then spread liquid soap along the thickest part of the bottle above the label. This will reduce friction as the plunger is lowered onto the bottle. Dish soap is used instead of an oil based lubricant so that the plunger can be wiped off and not lubricated for subsequent trials. No detection rod is required as the pop bottle is tall enough to break the signal on its own. Place source container on the playing surface.
11. Prepare the destination container for detection by placing the destination detection rod inside the container. Place destination container on the playing surface.
12. Ensure that the drill is secured into the plastic tube by screwing the threaded rod at the end of the drill motor into the plastic tube. One revolution into the tube will suffice.
13. Turn the saw motor ON.
14. Turn the rotation motor ON.
15. At this point all systems are prepared and the device can be activated by turning the main switch on the circuit box to the ON position.
16. Once the trial is complete, indicated by the illumination of the LEDs on top of the circuit box, the main switch can be turned to the off position thereby deactivating the device.

• Will be uploaded at another date.