11/9-11/16

Throughout this week the finalization of what will be our design took place. Overall, all design for steering was finalize and deadline was met as planned. All parts necessary are clear and will be ready to be listed as previously mentioned. As the design is finalize I began to double check any calculations made to ensure that the correct decisions were made accordingly. Checking the design more the once will ensure that any minimal mistakes made will be fix as soon as possible before any manufacturing is done. Even though the design is for the most part in its final stages, steering for my case, there maybe other solutions that can be implemented to the design. A thing to consider for the gears implemented is stress in the teeth. When designing the steering, there was small consideration of stress as the main importance of the system was to work correctly and ensuring safety. The gear sizes may change to reduce stress and also to ensure a longer gear life which will improve reliability, safety and reduce the maintenance cost. As the semester ends, I began working in the final report to ensure that there will be enough time to correctly explain and implement all information on the design of the bogie, failsafe and steering.

11/2-11/9

During this week, my main focus is finalizing all design for the steering. All gears and pulleys necessary for the system are finalized. The only thing necessary for the steering is the housing where the gears will be placed. The main difficulty is to design such housing so that it does not interfere with the other subsystems. Another thing to consider this week is the listing of parts necessary. Finalizing the list as soon as possible will be essential as it takes time for the parts to be delivered. The sooner the order is placed the more time we will be able to work on the fully assembly part thus adjustments can be made accordingly. Also, constant communication with the propulsion/breaking team has been made from my part as their system goes directly inside the bogie which will limit the design of the housing for the gears. The more spacing it is available in the finalize assemble, the better as it will facilitate maintenance when required. Ultimately, the week has been busy as there is an essay to be due on November 9 for the class which takes some time from working on the mechanical steering. Overall, the steering complete design and cad should be done before the major deadline on  November 16(part list should be finalized).

10/19-10/26

During this week, the I continued to work on the steering as well as the presentation in the upcoming weeks. After finalizing and sharing the idea of steering with my sub-team, the CAD design begin to take form. The finalize gears and gear ratios required for the system were determine according to the safety factor of 3. The gears were chosen accordingly and in a way where the parts can be obtained by purchasing from the shelf rather than customizing. By choosing the parts in such of way, the cost will be maintained relatively low. In conjunction with my partner, we began a prototyping to better visualize and understand if the changes we are making will work as we expected. The prototype will consist of wood which can easily be remade and adjusted as required. Although the work and progress of the project continues, the main focus of this week is presentation number two of the semester where all the progress will be explained to all sub-teams. From this presentation, there is expected to be feedback and critical opinions from our peers which may lead us to see any problems that may arise from our design thus adjustments can be made. Also, continuing to communicate with remains of great importance thus certain meetings occur when necessary.

10/12-10/19

During this week, many implementation of ideas took place as our current design comes together. The space provided by merging most ideas is very limited and once again I was forced to provide a different idea which deviate it from the previous solution. The previous solution consisted of a pulley system which provided useful and accurate movement for the mechanical steering. The new steering mechanism will consist of a set of gears which will take a small space in the bogie and will provide other groups with more space to fit their design. Another advantage of using the gears is that by using different gear ratios, the motor can provide a greater holding torque which in turn will provide a better safety. The only concern is the speed in which the steering will take to provide the movement desire. The bigger the torque I provide, the slower the system will be. In the current design, the force needed is of approximately 33.45 lbf when the cart travels at approximately 3.6 ft/sec. The current stepper motor we currently are working with, provides a holding torque of 106 lb-in. Using the specifications provided by the manufacturer I was able to design a gear system with a factor of safety of 3. The gearing system will now provide a torque of 318 lb-in at a speet of 16.6 RPM compared to the manufacturing torque of 106 lb-in and speed of 50 RPM. This design will provide reliability to the mechanical steering system.

10/5-10/12

During this week, some changes in our design took place. I began redesigning our steering system as a meeting with Bengt pointed out the flaws of our current system. The previous steering system contains two different motors working independent of each other. It was said to cause many problems as there is a higher chance for the system to fail. If one motor fails, the entire bogie will fall from the rails thus predicting or preventing any failure with two motors is very difficult. The new system consists of only one motor. The second motors task will be replaced by a pulley system connected to the main motor. The pulleys will be placed accordingly to fit the limited space in the bogie. We will be using a two face timing belt as when the top steering linkage rotates clockwise, the bottom steering linkage will be rotating counterclockwise. Thus a complex pulley system is necessary. I have yet to finalize the length of the links, radius of the pulleys and length of the timing belt as it the space for the other components is yet defined. During this week a finalized design for the new steering system will be made.

Week 4

During this week, the design and calculation process has continue as we enter the first presentation of the week. The presentation is of upmost importance as it will communicate and give important info to the rest of the sub-teams and will enable us to continue working and communicating in such a way which will enable good team work. My role this week was to finalize the kinematic calculations  for the steering. Once the calculations were done, I began to implement all formulas obtained into an excel sheet which will iterate all calculations in a simple manner. This will save time which can be used for testing or the designing of other components. The excel sheet is ready to used and it relies a great amount of freedom to the position of the motors used. Also, ideas for the failsafe system were discussed, but we will implemented as soon as the rest of our design is finalized. Such thing is necessary as the fail safe system is more lenient in comparison to other components thus the shape and its placement can be determined once most of the components are finalized. Finally, during this week I attended the Paseo Public Prototyping Challenged located at the Hammer Theatre on Wednesday September 21. The event was conducted by various professors and professionals which encouraged students at SJSU to make a difference and enter the challenge to better our city. Inventions and ideas can be entered in the contest and will get funding to make them a realization. The topics are based in problems experienced in san jose, thus solutions to those problems are necessary. Below, a picture is illustrated of myself in attendance to the event.

Week 3

During week three we begin by communicating with the sub-teams conforming the half scale design. This was of importance this week as we begin to really plan our future deadlines and it what manner we want to achieve the best results. When communicated with the rest of our peers, the ideas of each one come into light. By knowing the ideas and different prospective design ideas of each member, we can design the parts accordingly thus avoiding future parts which may not fit the final design. After, the planification and scheduling of what task will be taking place was determined. From, designing to testing was planed in order to obtain the best scope and also to have deadlines that will help us plan better our tasks. Once those details were finalized, we began working a little more in depth in the project. In my specific sub-team, bogie and steering, we began analyzing our ideas and computing some numbers to see which feature will be more reliable and the best to implement in the design. Personally, I started working in the steering motion and the linkage that we would like to use. I noticed that a four bar linkage can be implemented in order to move the steering accordingly. As such, the derivation for the linkage was done with variables involved. An excel sheet was crated to plug in values which will describe the behavior of mechanism which will lead to the best design for steering as well as the location of such mechanism. This week became of high productivity and as such, the communication and designing of the project will continue.