User:N ngea/ENES100/Project 3

Project Preference
Autonomous Power Wheel - BioVest - Wind Turbine

Problem Statement
Design the electro-mechanical systems and software required to control a Power Wheel. The autonomous vehicle should be able to travel outdoor on specified paths while avoiding obstacles.

Project Plan
Following this work, we will use the following plan:

We will be focusing on the electronics for this design while incorporating mechanical from previous team. We will simulate the system as it goes. We are hoping to test the whole electronics using mock-ups carefully designed.

Week 1 Narrative
This week, we focused on discovering the entire system and reviewing previous work. As we are using a linear actuator for the steering wheel, our work this week was to find the force needed to move it. In order to do that, we used a meter stick, a spring scale and electrical tape. Here is the set up:

We will also look up how to use a wheelchair motor instead of the steering wheel for direction.

Week 2 Narrative
This week, other team members took over the steering wheel and we focused on the pedal. The former team came up with the following design:

As we got the 12VDC, 78RPM Motor with Right Angle Lead-screw motor, we realized that the two holes dimensions should be adjusted. We took some measurements: hole diameter is 0.459 in(11.65 mm), rectangle is 0.5 in / 0.874 in. This work is still in progress for it turns out to be very challenging to edit the drawing above. We might have to do it over entirely.

We also tried to power on the motor and could not. The data sheet is almost non existent and there is little you can find about it online. After reviewing the "datasheet", a lab aide pointed out we might be using the wrong current setting ( we were using 12 V - 1 A). We made another test and used a 12 V - 5 A and the motor started working. Switching the leads changes the direction of the rotation. As the motor was spinning, we realized we did not know how it was working. A lab aide held the screw and we were able to see how the pivot and the motor were supposed to work. This also helped us realize that the idea is to create a kit that should make any power wheel autonomous. We should verify if the arduino used has Bluetooth or a WiFi feature.

We are also working on how to attach the motor and pivot to the car. Finally, we are considering using at least two 12 V battery for the entire electronics.

Next week, we will continue working with the team with Arduino code and on the pivot. We will also work on a mock-up for our sub-system and the entire system. We will also finish the pivot design, print it. A teammate pointed out an interesting point about the head of the pivot that might slip during operation. The more we think about it, the more we think we might just made a flat head for it or have a reversed cone head like this:

As both the pedal and the pivot will be made of plastic, it is a possibility to consider.

https://en.wikiversity.org/wiki/User:Medelen8/ENES100/APW_Design_C#The_initial_design

https://en.wikiversity.org/wiki/User:Medelen8/ENES100/APW_Design_C#Experimental_prototypes_and_testing_conducted_during_design

Week 3 Narrative
This week, after consulting with our teacher, we decided to just change the holes' dimensions of the pivot. We worked with the original designer but were not successful. We met with the teacher who suggested that we make a new design and showed us how we could it. We made several attempts and finally were able to do it. The teacher approved it and it was printed:

The pictures above show that the hole for the screw should be adjusted. The width will increase from 0.5 to 0.7 in. The pivot was also tested with the motor. Another test will be conducted once a new pivot will be printed.

We also looked at the code to see how to improve it so we can run the gear motor and the linear actuator off the same Arduino and monster motor shield. We will need to run some tests to know how to modify it.

Finally, we are looking at ways to simulate a pedal for our mock-up. We considered using a spring between two plates. The previous team determined that 5 pounds will be enough to depress the pedal by putting weights on it. 5 pounds is about 22.2 N. We will keep looking for other ideas

https://en.wikiversity.org/wiki/User:Medelen8/ENES100/APW_Design_C#Experimental_prototypes_and_testing_conducted_during_design

https://en.wikiversity.org/wiki/User:Medelen8/ENES100/APW_Design_C#Appropriate_optimization_in_the_presence_of_constraints

Week 4 Narrative
This week, we made several tests for our projects and did a lot of modifications of the pedal pusher design.

We had printed three models this week. The first one was printed with twice its size. We set to figure out why we needed to scale and how to do it. We found a video on this website (copying and past the url video led us to a series of youtube videos that are tutorials for solidEdge cad software). We tested the solution right away but with a different design whose objective was to keep the pivot from spinning by 'trapping' the pedal:

Unfortunately the hole for the knot was small, as well as the U shape for the pedal. We thought about increasing the size of the beams. Finally, our teacher improved his initial design to save printing time:

The printer was damaged on Thursday and we will print and test this new design as soon as it is fixed.

We were finally able to test the gear motor with the Arduino and the monster moto shield. Our first problem was that the Arduino was not recognized by the PC so we had to restart it. Then the shield was not getting powered by the ammeter. There were two reasons for that: first, we were using the wrong setting (5V/5A instead of 5V/1A) and also the ground and power were switched when connecting the alligator clips to the shield. Once we tested it, we ran into a third problem, the voltage is dropping as soon as the gear motor is plugged, keeping it from spinning. We tested the linear actuator and confirmed that indeed the current was too low. We decided to use an old ammeter stored in the back of the engineering room that was used before and worked with the gear motor. The idea was to run both the linear actuator and the gear motor off it and start modifying this code. There was also one final problem: how to activate the second set of pins that we could not use for this test.

We made some research to figure out what was wrong with the second set of pins but could find anything useful or particular so we went back to the code we thought might be the issue. For that we needed to make sure the new ammeter was able to fully power the gear motor and it worked. We tested the linear actuator to make sure there won't be any current setting we needed to adjust and it worked. So we returned to the code to figure out how to power both motors. We did not see any problem with it but we made some modifications. Unfortunately, the motors were not working anymore. We asked for help from an instructor. He took a look at the code and confirm that all pins were activated and both motors should run at the same time. He suggested to switch the wires from the set that is working to the set that is not working. It worked so he gave us a new set of wires and both motors were running off the Arduino duomilanove and the sparkfun monster moto shield. We played with the delay command to figure out how to correctly synchronize the motors. What we need to do now is to figure out how to distinguish them and how to modify the code so they can move in a certain sequence

We also tested if the gear motor can lift 5 pounds. We wanted to print a spring with the stiffness corresponding to the force that we needed to depress the pedal but our teacher suggested that we just lift 5 pounds which is a little less that 3 kg. Since we had the code working we tried using the new pedal (that does not spin as long as it 'holds' a non-moving object, we used a PC mouse to test it). Unfortunately, since the knot was not fitting it would spin when lifting so it would not move very far. We went back to the over-sized and old model. We cut the cone part and tested like the one before, 2 kgs, then 3kgs (we taped both weight together for security and practical reasons). Our teacher pointed out that the motor was operating at a lower speed and we realized that it was operating at a low voltage. We increased the voltage and it ran faster and the current increased as well.

We finally worked on our cdio report for this project. Though the frame and the steering wheel were not fully developed. We were able to figure out how the electronics for this system will work.