Overview

Overview

Hello all who are reading this. If you see this, then you are most likely an intern for summer of 2016.  We are a group of Engineering students at San Jose State University working to develop the Spartan superway, a solar powered podcar automated transportation network. This document  is simply a summary of the Spring 2016 final report for the Spartan Superway project.

Navigating this summary is very simple. Each of the subteam’s work is divided into individual blog posts, with a roman numeral indicating the order. Furthermore, each of the organizational sections are underlined like this. Notes taken on each problem have a * in front of them, with lower case roman numerals (such as i and ii) signaling further notes and individual numbers (like 1 and 2) signal even further notes.

Here is an example with a made up sub-team named “Cold fusion wayside”

XIV. Cold fusion wayside

Testing and analysis

• We tested our energy system at Lawrence Livermore national laboratory

i. We used a tank to bring over all of the materials

1. The tank was a an M8, provided by the United states national guard

ii. There was a bump in the road that nearly destroyed our system, but thanks to duct tape we were able to fix it

• Our results gave us a 99% efficiency rating

Introduction

Abstract

• Superway team mostly Mechanical, some electrical, few masters from other departments in addition to the International Institute of Sustainable Transportation (INIST) and various other industry partners
• 4 year legacy project, earlier years developed 1/12 scale model with working software and control system for single car, full scale length model of an intersection of a track, as well as shows manner of steering
• Largest year yet, 50 students in total [42 ME, 3 EE, 1 MME (Wade), 1 MUP (Jie), 2 MSE (Anirudh, Madhur), 1 Isaac = 50]
• Increased academic expectations
• Goals for year:

i. Increase size of 1/12 scale by 4 and add software features to control multiple        simultaneous cars

ii. Intermediate scale design team → Complete loop + add slopes to tracks and      active suspensions  

• Intermediate scale = success
• Biggest issue: getting propulsion, steering, active suspension, and braking to work
• 1/12th scale = success
• Project in total was a success

Executive summary

• Traffic congestion major problem for urban areas, increased inefficiency and pollution
• Superway here to help
• Personal Rapid Transport System (PRT) uses automated solar powered pod cars to transport passengers with no stops to their destination
• Superway team making installable solar cell array so system can self-generate energy (No fossil fuels)
• Superway intended for Silicon Valley

I (Intermediate) Guideway

I Intermediate scale guideway

Background and context

• Guideway important because cabin/bogie must travel between two points

• This year, guideway team demonstrated straight, switch, and sloped path
• Guideway has two pathways

i. Travel to destination

ii. Arrival to station

• These 2 pathways only accessible through fork split

i. Path to destination → long 70-foot path of straight rail suspended 10                    feet

ii. Path to station → turn out followed by a drop of a 17-degree slope

Objectives

• Show that bogie/cabin can travel turns and elevations.
• This year’s goal: To show that Bogie can travel up/down 17 degree angle path to simulate patron pickup
• Switching in guideway shows that sloped track entering to the right
• Direct design from full-scale (except for fib)
• Angle of the bottom of the posts are now 45-45-90 to provide more stability
• Objectives for this year's guideway

i. Design a complete loop guideway

ii. Provide the bogie the required pathway to travel across

iii. Design the guideway to be able to carry the load of the cabin, bogie,                                     suspension and the electronic interfaces for the EE team

iv. Design the supports to be able to carry the load of the 5 solar panels                                                    across the straight path

v. Provide adequate room for wayside to mount their designs

Design requirements and specifications

• Guideway Design requirements

i. Design sections come apart into smaller 8’9” inch sections

ii. Support Structures: 1 per every 17’ 6” of track, end of turning section and end of lowest point of track

iii. Desired elevation change with a slope of 17 degrees to demonstrate declination to station followed by inclination back to track

iv. An allowance of four degrees per second to allow suspensions actuators to level cabin

v. Complete closed loop guideway to allow cabin to complete path and     return to initial position

• Guideway assembled into 8’9” sections (to put in small truck)
• Longest piece was sloped section at 16 feet (for smoother travel)
• Actuators moved at 4.0 degrees specified,  if curved sections too sharp, then the actuators would not level in time and cabin would dip forward

Description of design

• Length of guideway shortened to accommodate for maker faire,
• Guideway rails/support ribs made from A513 steel
• Support posts A36 steel
• Length of track = 70’
• The straight portion of the track was assembled using cut to length 8'9" pieces of straight ¼"-thick rectangular tube of cross-section 1"x3" and 1"x2", lower and the upper rail, respectively.
• Rib supports made to length using ¼’ thick 1” x 1” square tubes
• Posts were made up of ¼” thick 3”x3” post → Cut into 10’ long pieces→ Tack welded on with ¼” thick flat bar→ flat bar was tack welded to the bottom of posts → 45 degree angle supports were welded between them → Conn
• Posts were first thing that were done during fabrication.
• After rib supports were ready/aligned with rail they were tack welded on

Analysis/testing

• Maximum deflection is 0.39mm
• Rails can support over 300 lbs of force

Money Spent on Project

• Overall cost: $1907.07

Results and discussions

• Outcome was partially incomplete
• Importance of slope → be able to pick up people at different heights to make traffic safer
• Idea needed to make rails where the posts meet more aligned.
• Clamps could be used and weld brackets to keep them fixed
• Errors in posts due to inexperience with welding

What to do differently

• Get started right away
• Have more people in on it early on
• Stop building track when we run out of room at design center

II (Intermediate) Bogey

II Intermediate Bogey

Background and context for the work of the sub-team

• Interconnects all different intermediate design teams
• Accounts for 17 degree slope
• Design fail safe mechanisms
• This year’s focus: adress failure situations focused on wheels

Description of the subteam and objectives

• Works on half-scale bogie
• Objectives:

i. Redesign for traversing +- 17 degree guideway

ii. Design of fail-safe mechanism in case of falling

iii. Re-design the bogie and h-bar to integrate all supporting teams             (propulsion, steering, braking, guideway, suspension, wayside power, and cabin)

Design Requirements and Specifications for the Sub-team’ s Work Products

• Bogie must have multiple fail-safe mechanisms for the following situations: Falling straight down/Falling to the left or right
• Fail-safe mechanisms must be mechanical and operate without the usage of sensors and/or power
• -Each fail-safe mechanism must be able to hold 300lbs(weight of whole bogie and cabin)
• -Bogie must be able to traverse up and down a guideway sloped at ±17° (30% grade)
• Bogie must have at least a safety factor of 2

State-of-the-Art/Literature Review for the Sub-team’ s Sphere of Work

• Fail-safe mechanisms for project were analyzed based on roller coaster designs (only designs that deal with suspended transport)
• Chain dog used as fail safe mechanism (consists of Ratchet and Pawl)
• This design concept was not implemented since the braking system was not enough to keep it from moving backwards
• Friction wheels also used
• Able to stay on track from all directions, allowing for complete fail-safe
• Stabilizes incline and decline

Description of Your Design

• Fully mechanical safety system (No need for external systems that could be subject to power loss)
• Upstop wheel placed on static portion of bogie (stabilizes bogie during incline/decline)
• The solid catches are fastened on to the top and bottom of the bogie
• If the object falls vertically, then the bottom catch will hit the bottom track
• Cutches are not too long to interfere with the guideway
• Since the guideway now has a slope of 17 degrees, superway H-bar now must require 2 degrees of freedom
• U-joints were designed to allow for horizontal and vertical travel between bogies
• Bogie now like 4 bar mechanism
• U-joints allow for incline, decline, and turns
• Hub motor moved between half-bogies
• H-bar constructed using 1”x1” 11 GA A36 steel square tubing
• 90° angle bar was cut and welded in for additional support
• Total length of H-bar is now 30” to accommodate for space needed for actuators
• Bogies were fabricated using ǩ” thick A36 steel
• 1”x1” 11GA A36 steel square tubing was usedfor structure of the frame of the bogie
• The six square tubes provide support for the bogie as well as mounting holes for the eight wheels needed
• All structures were MIG welded together

Analysis/Validation/Testing

• Every part simulated with load of 300 lbs (maximum load)
• A36 steel was chosen as material
• Upper catches suggest that materials and dimensions would produce a safety factor of 3.5
• U-joints tested by connecting both half-bogies/connecting bars→ simulating movement that would be experienced while traveling in slops and turns
• U-joints + Bogie were able to fully support load conditions without failing

Money Spent on Project

• Overall cost: $43.75

Results and Discussion

• All designs satisfied requirements
• Failsafe mechanism prevented bogie from falling
• Bogie able to traverse +-  17 degree slope
• Upstop assembly stabilizes bogie + locks it down to bottom plate of guideway
• Traversing slope smoother and safer
• Bogie protected from all possible directions
• Each bogie has:

i. load wheel on top of the lower rail on the guideway

ii. 6 inner wheels that roll on inner sides of guideway rails

iii. 2 upstop wheels that roll underneath guideway

iv. Steering mechanism that rolls on outer sides of upper rail of the guideway (Locking Bogie in all directions)

     - If any of these wheels fail, then the upper/lower catches will prevent bogie from falling/derailing

     

Conclusions and Suggestions for Future Work

• Build failsafe mechanism for bogie for track switching