Progress Update After Presentation #1

For the meeting on September 30, my sub-team conducted the first presentation on the steering/braking mechanism and guideway. The goal of the first presentation was for us to introduce the objectives of the team, what challenges are ahead of us, and what responsibilities and tasks we need to take to progress. Although we had relatively enough content for the presentation, our style did not meet the format for the most part. Following the presentation, I observed the presentations of the other groups and looked more into the assertive presentation style online in order for us to learn from our mistakes and improve on our next presentation.        

For the following days after the presentation, time was spent to conduct more research on different types of actuators and their specifications. I also looked into how servos work and how to size them. Furthermore, more sketches were made for the switching mechanism since we have not concluded on how our final design of the switching mechanism will look like. For inspiration, I tried not to only look at previous years' reports but also from other sources.

Update on Blog Assignment #2

Prior to our meeting last week, the team decided to disregard the current Bogie mechanism and start designing a new one from scratch. Thus, each team member spent time to come up and sketch a new design for the Bogie mechanism that would seem viable. However, during last week’s meeting, it was decided to make modifications to the current Bogie mechanism instead of designing an entirely new one.

After the meeting, I spent more time to do research by reading more into detail about the steering mechanism from the 2014-2015 project report. I thought of several shortcomings the previous design had. From last year’s report, the specifications that last year’s team had was to design switching mechanisms for top and bottom rail to keep the bogie securely engaged to the guide rail and have the switching mechanism actuate automatically. Furthermore, the critical points where the steering mechanism will experience the most stress were taken into consideration. Because the Bogie will experience a moment at the bottom wheels which will rotate the bogie off the track, the moment must be counteracted by another force.

I propose to utilize a hydraulic actuator system to generate enough force to counteract the moment to keep the Bogie on the guideway and prevent it from falling off. However, this is just an initial thought and much more research needs to be conducted. Also, additional force analysis calculations need to be done in order to determine how much force is needed to counteract the moment.

Steering Mechanism Sketch

This is a sketch of the steering mechanism for the bogie mechanism. The design of the steering mechanism is simplified and more compact compared to last year's model and consists of two arms that have a guiding wheel attached to each of them. The arm is a link mechanism that is able to move 90 degrees to allow the rotatable guide wheel to engage against the third rail. The purpose of having the third rail is for one of the guide wheels to readjust to it to determine what direction the podcar will travel. Furthermore, there are two more wheels that are attached to the enclosed track which simply roll at the inside of the track to propel the podcar and provide stability. At both sides of the track, ball bearings are engaged against the top and bottom of the track to reduce friction and provide smoother travel.

Bogie Mechanism: Possible Solutions

I decided to be part of the Bogie mechanism team due to some critical flaws the current design has and I am looking forward to what could be improved on it. I decided to read further into the 2014-2015 project report and from what I have read, the Bogie mechanism is engaged to the guideway by switching mechanisms that are installed on the top and bottom rail. Although the design worked, it did so sluggishly. Because many podcars will be travelling on the same track in the real world, the current design proves to be time inefficient and will cause delays.

One problem with the current Bogie mechanism is that it generates a lot of vibration and noise which hampers the smooth ride passengers expect. Because the Bogie mechanism will be subject to many types of forces (i.e. friction, rolling resistance), a possible solution is to come up with a damper mechanism that can be mounted between the wheels and guideway to reduce the effects of the forces the passengers will experience.

Also, the thing that is bothering me is that only one side of the bottom outer wheels is engaged to the guideway while the other side is freehanging. A solution needs to be thought of to have both sides engage to the guideway.

Below is an image of the Bogie mechanism designed by the 2014-2015 project team:

September 2, 2015 Meeting

The meeting on September 2, 2015 was spent to introduce ourselves and give a brief presentation of what we have learned from reading the previous Spartan Superway reports. Afterwards, time was spent to observe and study the full scale model of the ATN to get an idea of how the system as a whole functions. While observing the full scale model, I thought of several shortcomings the current model had and what possible improvements need to be made. The component that stood out the most to me was the Bogie mechanism because it was one of the most critical components of the whole model which involves switching the direction that the podcar will be heading. Due to the many forces, stresses, and deformations that will act on the system in the real world, the Bogie mechanism must be supported safely and efficiently by the guideway.

After demonstration of the full scale model, students were broken up into sub-teams which have their own focus on one specific part of the ATN. I decided to be part of the team that will work on the Bogie mechanism and fail & safe system. During our group meeting, we have decided to modify the Bogie mechanism by simplifying it to reduce cost and make it more reliable. Furthermore, due to the slow and sluggish operation of the current Bogie mechanism, we plan to redesign the Bogie mechanism so that it operates more smoothly and faster.

This week I have delved further into reading the Spartan Superway reports from the last 2 years to get an idea of what work was put in by other students to design various components of the ATN. 

Introduction

My name is Chin Ming Lui and I am a senior pursuing a Bachelor’s Degree in Mechanical Engineering with a focus on mechanical design. I joined SMSSV because of my big interest in vehicles and find it to be a great opportunity to explore new transportation concepts to help improve the current infrastructure. Having a previous internship at Zeta Instruments, a company specialized in designing and building optical profilers, I have acquired invaluable hands-on experience in assembling and calibrating systems, and modifying parts. The SMSSV project will provide an exciting opportunity for me to utilize my skills gained from academics and internship to the fullest. Furthermore, being part of SMSSV allows me to improve my networking with other people and gain more experience in design and machining. During my free time, I enjoy bowling, listening to music, keeping up with the latest car news, and spending time with family and friends.