September 2021 - June 2022
PROJECT PURPOSE | Create a platform for autonomous vehicle research by converting a go-kart’s steering and braking systems to be controlled electronically.
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DELIVERABLES | Steering system, Braking system, Emergency Stop system

Project Timeline

2021

September
October
November


2022

January
February



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March


April

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May



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Initial Project Conception
Scope of Work
The scope of work highlights our important project details, establishes our plan moving forward, and describes the high-level management within our team.
Preliminary Design Review (PDR)
Our team implemented ideation strategies, decision tools, engineering analysis and supplemental research to develop a preliminary design. In our concept design, the steering system will have a parallel-mounted DC motor driving the steering column with spur gears. For the braking system, we will use an electric linear actuator to push against the existing brake pedal to operate the original braking system. In the case of an emergency, a radio-controlled power-cut system will cut all power to the motor and activate the automated braking system. For motor control, a microcontroller will be used to output voltages between 0V and 5V directly to the throttle ECU signal pin.
 
 
Interim Design Review (IDR)
Critical Design Review (CDR)
Our team presented the final design for each our systems in order to get approval to move forward with manufacturing. I focused on the design and analysis of the steering subsystem by designing a custom 2:1 gearbox to integrate the provided motor into our go-kart steering design. 
Manufacturing
We worked in the Cal Poly Machine shops to manufacture our prototype based off the designs. I led the team through the manufacturing while working on the manual mill, manual lathe, TIG welder, and CNC mill. 
Testing
We tested the basic functionality of each of the systems to verify that our specifications were met. For the steering system we had two specifications: the first is to maintain the original go-kart steering range of motion and the second is to achieve full steering range of motion in two seconds or less. 
Final Design Review (FDR)

Final Design

Manufacturing

CNC Mill
I machined the gearbox case using the Haas VF3 and the Haas Minimill. The machining process was done in three operations: the first machined the outside of the case and roughed the inside of the bearing bores, the second operation machined the inside of the gearbox case, and the final operation finished the bearing bore and the locating features. This was done to eliminate custom tooling and produce the required tolerances for the bearing fits. I expected the extruded stock to warp as material was removed so I finished the inside of the bearing bores in the final operation. 
TIG Welder
All of the gearbox mounting tabs and tube are 5000 series aluminum so that they could be easily welded to the provided chromoly tube frame. We used a TIG welder in the Cal Poly Machine shops to weld the tabs and mounts to the frame of the cart. The aluminum gearbox case was used to ensure proper mount spacing to eliminate required welding fixtures and reduce manufacturing time. 
Assembly Fit Check
Prior to each major stage along the design and manufacturing process, I conducted a 3D printed assembly fit check. This helped reduce the time required for the design process by allowing me to physically inspect the design and review any details that were overlooked before beginning final manufacturing. For example during the first fit check, I discovered that the motor key was incorrectly sized because the edge of the keyway was rounded. This reduced the available keyway length I could use because we had purchased square keys. With a larger budget and timeline, I would have re-ordered rounded keys; however, I was able to grind down the purchased keys to produce a sufficient prototype. 

Preliminary Design