Weekly Progress

Week 1.

This was the first week of lab and the group met for the first time. Everyone met and discussed various ideas about the project. The dominant idea was regenerative braking which required the group to design a prototype that shows how energy could be conserved from a moving car as well as slow the car down.

Week 2. 
The group came up with a rough sketch of how the project design was going to look like. Daniel sketched the diagram below as how the final design will look like with the bike wheel acting as a car tire, the generator to convert the energy, gears to increase the rotational speed and how the mounts are going to look.

Week 3

The group had a meeting outside of the class times and duties were assigned. With the following tasks set out as the major tasks to be achieved by the end of the week.

1) Choose the type of generator.

2) Design supportive mounts for which the wheel & axle will rest upon.

3) Design a brake pedal that springs back into its original place after pressing on it.

4) Supportive mount for the generator and how the generator will be attached to the to wheels to get the most efficiency.

6) Incorporate  compact gear case that will withstand high rotation.

Week 4

The group met in the lab to take measurements of the inner wheel hub(9/16 inch) in order to order the appropriate bearings and machine the axle shaft to these specifications. The group spent a few hours in the machine shop learning how to use various machines like a lathe, drill press, and press to machine and assemble the shaft and its components into the finished assembly below.

Shaft being machined to fit in bike wheel

Bike wheel and axle with bearings 

Week 5

The group decided which generator was going to be used in this week. This came as a challenge being that we tested both alternating current (AC) and direct current (DC) motors and the AC generator worked when plugged into a socket but did not produce electricity when spinning it with an external force. The DC motor worked as a motor and a generator so the group decided to go with a DC motor to use as their generator.

Week 6

After doing research, the team agreed the initial design would be more efficient if modified to the new design below because of how a DC generator works. Instead of having a break pedal that joins the inner and out part of the generator together with a circuit drawing current, the group learned that this was not necessary as the generator would not produce a force against the rotation until the current is being drawn. in order to simplify this, the group decided to put a switch in the circuit that would act as the break. 

Week 7

In this week the mechanical prototype of the design was completed. The bike wheel, axle, bearings and their supportive mounts were completed and combined as shown.

Bike wheel, axle, bearings and supportive mounts 

The group spun the wheel using their hands and it rotated with low frictional resistance. Not to forget the wheel represented a car wheel and the axle a car axle. The DC generator at the end was also connected the the axle and while spinning the wheel the generator spun. A multi-meter was used to measure voltage and current of the generator at various revolutions per minute (rpm). The group decided to incorporate a circuit which when closing should draw a current on the generator creating electricity and slowing the wheel down. The closing of the circuit signified the engagement of a break and disengagement when opened.

Week 8

This week the group finalized the circuit design and the final deliverable was complete. The circuit incorporated a potentiometer and multiple resistors in order to control the current produced by the generator.

3 535-ohm resistors and a potentiometer

The design was finished with the circuit completed and added to the prototype:

Final design with components of the circuit incorporated

The circuit consisting of 7 680 ohm resistors, 2 switches, a generator, and a potentiometer

The group decided to run some tests to prove their concept that when generator is incorporated to a wheel, electricity can be produced as well as slow down the wheel, reducing the speed of the car.

Below were the steps and tests done:

·      Rotated the wheel at the highest speed possible by hand and measured the maximum amount of current passed when connected to only the potentiometer (0.440ohms).
·      Rotated the wheel again with the potentiometer while the circuit was open then closed the circuit and made observations.
·      Rotated the wheel as fast as possible by hand and this time added 4 680 ohm resistors (connected in parallel) to the circuit and measured the maximum current
     Rotated the wheel again with the added resistors when the circuit was open, closed the circuit and made observations.
·      Rotated the wheel again this time adding 3 more 680 ohms resistors to the original resistors and noted the maximum current.
·      Rotated the wheel to its maximum speed with the circuit above and close the circuit and note the observation.

 Week 9
This week the group members tested the prototype to determine how fast the wheel could stop under certain demands: no circuit attached, the switch for the first 4 680 ohm resistors closed and the other open, and finally both switches for the 4 680 and 3 additional 680 ohm resistors closed. The test was conducted by mounting the prototype to the bench top and dropping a hammer that was affixed to a string around a pulley on the axle shaft to spin the wheel at a measurable rate. Once the hammer hit the ground, the timed measurements were taken. The system without any resistance slowed down the slowest while the system with the most resistance slowed down the quickest.
Week 10
This week the group did the same tests as the previous week. However in this case a different weight was used. The weight was 3 kg which is more than the hammer. One of the noted observations was that the voltage produced was greater than before as shown below.