Wednesday, October 26, 2016

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.

Tuesday, October 18, 2016

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.

Tuesday, October 11, 2016

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.