Covid-19 Stalls Progress

Over the weekend, electrical team has begun researching the motor and motor controller left by the last year's team. The motor is a SOFN model from a company called XOFO. We will learn its mechanisms by reading any information from the manufacturer or the reports of last year. The motor controller is a Kelly Controls that can handle up to 48V motors. There are datasheets online for this controller and its interface. The problem will be in distinguishing the wires of the controllers interface and assembling a suitable housing for them. The mechanical team continued 3D printing shoe containers to perfect the CAD. We are planning to use a type of acrylic for the final containers, so the CAD must conform to those properties. The third rails will be almost fully assembled by next week, so the pictures below are only an update on what they look like this week.
During the weekdays of this blog, SJSU announced that the risk of contracting and spreading Covid-19 at school was too high, so they cancelled all classes for the week to prepare for the transition to fully online classes beginning next week. As a result, we did not meet in-person on Wednesday, but continued to work remotely. The 4 in. linear actuators that we ordered arrived, but they may be too large so we are debating on whether to go down to 2 in. The third rail is almost complete; they just need some more screws. The T-slot idea is still in the works. We need to find the materials that would make it possible.

Current state of third rails

XOFO's SOFN Drawings

Third rail update and shoe enclosure design update.

This last week has been very busy with the wayside power team. The team decided to order two 4" linear actuators with brackets that will be attached to the current collector shoe. Designs were finalized for the third rail assembly and brought to a welding shop in San Carlos, A & D Welding, so the aluminum and steel rails could be laid out and the holes drilled in them. On Saturday the holes were drilled in the rails by Shane. Further work on the rails includes countersinging the holes for the hardware after the hardware is provided and then assembly.
Further design work was done on the shoe encloser to add rigidity. The sharp corners were filleted, and side walls were added. End tabs with holes were also added for the lid attachment.
Work in the future includes final shoe mount fitting into the shoe enclosure, shoe lid design and fitment, design of the attachment method from the shoe to linear actuator to the bogie, and third rail assembly.

Drawing of the aluminum rail 

Drawing of the stainless steel rail

Image of the rendered shoe enclosure

Written by Shane Sharp

The First Spring 2020 Presentation and Updated CAD

On Wednesday (02/26), the Spartan Superway Wayside Power Team were doing the first presentation of the ME 195B. After the presentation finished, the mechanical team and the electrical team are continuing to develop their works. The electrical team were working on the problem that they had last week which were not able sent current to the motor. Apparently, they found at that it was the wire issue. For the mechanical team, we were continuing on our work with the CAD design on the current collector.

They are working to integrate the arm mechanism to the bogie design from the last year team. The figures above are our work in progress assembly of our current collector. We are still determining the best linear actuator that we are going to use. The above figures of the linear actuator are just a CAD that we pull up from the actual McMaster shelves.

Written By,
Reynaldo Jahja

Meeting with VTA and Continued Development of Shoe Mechanism

Wayside Power Team has continued to increase the work completed each week. In the most recent week the team was able to send Chuong, Ryan, Shane, and Alex to meet with VTA to learn about application and industry standards. The team was able to talk with Sr. Systems Design Engineer Alan Ng and Jr. Transportation Engineer Francisco Alolong, Jr.. Much of the meeting covered industry standards, application, technologies, and how the simple technologies were usually the easiest to maintain.

While some members met with VTA, the other members were able to spend some time working on the shoe mechanism. The team was able to produce a 3D print of the desired shoe clip shape with the recently acquired shoes. 

Unfortunately the shoe clip is not to the exact desired specification, so the team will have to revise the design to better fit some of the unforeseen problems in the current shoe clip design. A lot of design needs to be tested before completion as such the wayside power mechanism has much work before completion.

Written by:
Alex Ng

Development of Electrical and Mechanical Systems

On Thursday (02/06), Waylon and Melody discussed how to hook up a 24V power supply to a motor driver. They also discussed how to test the power transfer from the rails to the motor. Waylon looked for parts to buy for a voltage converter. Shane and Reynaldo went over designs, drawings, and parts. They redrew the existing platform to represent the actual track. They discussed possible designs for the conductor shoe mechanisms. Reynaldo modeled the track, adding insulators and aluminum rails. Shane assisted Reynaldo in specs of the drawings and looked up current sensors from Pololu that may be useful in the project to gather electrical current data.

On Sunday the team met and discussed what needs to be purchased for the electrical system. Two linear actuators, hall effect sensors, strain gauges, and voltage sensors need to be ordered. For the measuring system, the team will be using a Hall Effect Current Sensor ACS758 (50B Version) and LCD display. Melody and Waylon used draw.io to make the electrical schematic below (Figure 1).

Figure 1. Electrical Schematic

The mechanical team discussed the shoe arm mechanism. A single pivot point connection to the linear actuator will be used. The linear actuator stroke length will be 2”-6”. There will be one strain gauge on the center sliding shoe contact. The necessary force for the spring will be calculated. It was estimated that 6 PSI is required for the shoe. Next up the team will be assembling the steel cap and ramps.

Written by,
Melody (A. Bake)

Enhancing our designs

We are continuing to improve our electrical test station, track design, and actuator design. The electrical test station required some new wires and terminals to reach the power supply. We are using a power supply that can output more than 20V to account for voltage drop through the rail. The test shoe wooden bar was given another wooden block that provides a snug fit on the test rails. Shane found some aluminum in the engineering yard at school. We will be able to use this aluminum for the large portion of the track. Steel can be capped onto the aluminum to improve wear resistance. However, our order of conductor shoes were lost in delivery. We will have to hunt down those shoes for now. The shoe container material has not been determined yet, but it must be flexible and an insulator. Design of the linear actuators includes how to attach them onto the bogie. We are in the process of CADing the attachment and deciding on its material. The linear actuators do not need to be large, we are thinking about 2-6 inches, but they have to be strong enough to hold the forces we want and be able to compensate for changes in the track.

Electrical Test Station

Aluminum bar resting on Insulator (missing brackets under insulator and the middle layer is wood which is acting as a placeholder)

Spring 2020; Hitting the ground running!

The new semester has begun and our team has some serious work to do. Over the winter break, we were able to finish the 30-foot track and dismantle the battery pack from last year's project. This way we can use the bogie to mount our current collector mechanisms. Today we purchased Helwig elctrographite brushes from eBay. They are a lot cheaper compared to the supplier. Helwig's price is $58.20 each, however, we found an eight pack for $90 on eBay. These brushes are grade H51 which provide 3200 PSI in strength, low resistivity, and an 80 amp current rating. Electrographite brushes are commonly used in high-speed motor applications with high current densities. Our current specs are approximately 33.4 amps, so these brushes will meet the requirements. Additionally, we designed brackets that hold the brushes in the collector shoe. Our next steps include researching appropriately rated springs that will provide pressure on the brushes to contact the third rail, designing an enclosure for the multiple brushes, and 3D printing the bracket and enclosure to ensure the design will work. Also, we are working on testing the current transfer from the third rail to a 12-volt motor using an Arduino and motor driver. This will be done using the brushes from last year's projects and a 12-volt power supply. After this is successfully tested, the team will scale up to 36 volts and test a bigger motor.

Helwig Elctrographite brush. https://www.helwigcarbon.com/shop/70-622091/

30-foot track complete

Bogie stripped of the battery pack and ready for the current collector