Frame Design for Autonomous Robotic Vehicle (ARV) Team

Sep 2019 - Mar 2020 for Autonomous Robotic Vehicle Team. Robotic frame for Intelligent Ground Vehicle Competition

Background

Our engineering project team aims to compete at the annual Intelligent Ground Vehicle Competition (IGVC) typically held in June. In order to do so, the team must have a functional robotic platform to compete. This robot must house various sensors to traverse a grass track autonomously and be able to do so while carrying a 20lb. payload.

Design Goals

• Structurally sound frame to be able to support 20lb payload, 2 large 12V batteries (positions in final design shown in above image on right), and provide space for all necessary electrical and mechanical components

• Improve battery constraint designs from previous year iteration

• Meet competition specifications including a minimum length of 3ft, minimum width of 2ft, and maximum height of 6ft.

• Support a 6-wheeled drop center drive train

Reflection

The team was not able to complete manufacturing of the total robotic platform due to COVID restrictions taking place in March of 2020. Attempts were made to continue work but University restrictions made it difficult and the work was transferred over to the students taking over the mechanical team after I graduated undergrad.

A large amount of work towards this robot iteration was completed however. Design iterations following the competition specifications were deliberated on with the team. I was pushed to consider and work with components and manufacturing processes I did not have experience with. Prototyping was extensive and began with a wooden frame to understand the 6-wheeled drop center drive train approach. Calculations were completed to estimate the center of mass of the design and the loads certain pieces of the frame would endure. Material choices were made and eventually a CAD model of the design was created and managed followed by manufacturing of approved parts. The majority of the frame of the robot was complete by the March of 2020 and shelves for electrical components were to be completed for initial testing of the robot while components such as a cover for the robot had not been produced yet.

Reflecting on the design, there were areas where the team could have improved for ease of manufacturing and assembly, and reduce the number of machined parts.

Areas of improvement:

• The design iteration used rivets for the primary fastener. This became frustrating to work with at times and were time consuming to install and remove. I would most likely consider returning to screws for future iterations.

• There was an intention for wires to be routed through the center struts of the frame, but the holes allotted ended up being too small and large burrs from manufacturing were difficult to remove so larger pieces of aluminum tubing should have been considered.

• The payload support was overly complicated with too many pieces and brackets included in the support. The number of pieces in the support provided for greater points of potential failure and made assembly a pain. In a future iteration I would simplify the design, potentially outsourcing custom parts if needed.