What you are about to read is a foundational document created by me, Noah Hickman, the Longhorn Racing Solar Fergo System Lead for the 2024-2025 competition season. I have chosen to create this document to make a referenceable database for any new and future ergonomics subsystem members. Though I made this documentation purely off my knowledge and research of solar car ergonomics construction, this is a universal document that includes useful information for ergonomics design in general, which means any and every team, LHR Combustion, Electric, Solar, or even teams beyond UT Austin can hopefully utilize this document. I hope for this document to aid in the design, procurement, and manufacture of any and every piece of a competition car's ergonomics design.

This document or rather my experiences and knowledge gained from my time in LHR is not accurately portrayed or represented without acknowledging those who helped me along the way. From Solar’s team captain, to chief engineer and mechanical lead, as well as members and leads of both the Combustion and Electric team, I cannot thank those enough for the impact they have had on my development as an engineer, and therefore the creation of this document and information therein.

Goals of the Ergonomics Subsystem (subject to change):

Consider all and every component that the driver touches and uses during normal driving operations:
- This includes and is not limited to:
  - Driver model
  - Pedal box
  - Driver Communications system
  - Driver harness/seatbelt configuration
  - Belly pan
  - Driver seat
  - Driver cooling
  - Steering wheel
  - Brakes (brake lines, proportioning valve, etc.)
  - Parking/Handbrake
Additionally consider items that shield the driver and that are specific to each driver (I say this as ASC requires multiple drivers)
- This includes and is not limited to:
  - Ballast Box
  - Frame cushioning/padding
  - Driver shielding
Take in any design considerations or concerns from systems such as Controls (Dashboard), Electromechanical (Cooling), and Dynamics (Brakes, Steering Wheel) to ensure smooth integration and that all design cases are met
To meet ASC guidelines (which directly affect the ballast box, steering wheel, braking system, seatbelt setup, etc.), design each component to meet standards
Utilize topology optimization and prototyping to refine each design, maximizing the weight to stiffness ratio, and upholding high DFM (design for manufacturing) standards
Perform FEA simulation via SolidWorks or ANSYS (preferably ANSYS) in order to once validate FOS of at least 1.1+ and ensure parts are optimal for their average use/load cases
Manufacture each necessary part via manual milling, lathing, CNC, TIG/MIG welding, etc. etc.
Integrate with the frame and other systems

TLDR: One big subsystem, many smaller (but highly significant) projects

Disclaimer before we start: I have been previously a Frame member and Frame lead, with no role or real experience pertaining to Ergonomics. With that being said, I have a base level knowledge from my own research and prior intuition into car design as a whole. Please do not take anything I say as the absolute final word, this is merely meant to try and guide you in the right direction and give you a jumping point to go off of. Throughout the guide, I will do my best to cover everything as it pertains directly to Ergonomics but again, don't just go off of what I say. Be skeptical, do your own research, and create your own knowledge base and decisions.

Foundational Documentation/Good Reads (in a good reading order):

Fergo ASC and VR3 Documentation Break Down → This is a non-negotiable must read for all members, as it specifically lays out the guidelines and regulations we must follow to ensure we meet ASC and FSGP standards.
Ergonomics Lead Summary by Rachel Dong → Though this summarizes the lead role, this is a defacto exit summary from a previous Combustion lead and guide on what the Ergo subsystem does, what to consider, what sort of deadlines you'll have, and primary concerns for the subsystem.
Cockpit Design of a Formula Student Race Car: An Ergonomics Study → Though based on FSAE, this provides a good overview onto the design methodology of the cockpit of a car, regarding what considerations to take in, what you are designing for, and how those can be affected by the design.
TIG Welding Topics - Miller Welds → (Unlike Frame, there can/will be significantly less or no welding required for Ergo but it's possible) Just trust me on this one, welding is fun and fairly simple to learn, but not so simple to master and get good at. Use the resources available here and any mentors around, you WILL need it.
The entire “To Win” series by Carroll Smith is a great series written on motorsport racing and race car development as a whole. These are great reads as a whole if you like cars, motorsport, and automotive engineering in general.

Necessary Fundamental Knowledge

To be successful with your many ergonomics projects, one must be knowledgeable in the realms of many foundational engineering principles, being primarily Solids, Statics, Materials, and even Fluid Mechanics.

DISCLAIMER:I never completed any of these classes upon first drafting this work, but these are continuously updated as a I venture into the topics in class, on my own, and as I encounter them in LHRS as a whole. 👍

Statics

Start here → Statics Lecture.pdf

Pictured here is an explanation of moment as it pertains to the example of a brake pedal. The force at A causes a moment around B with the distances of 240mm and 100mm.

Moment

Firstly, many different static and dynamics ergonomics parts will experience various forces and moments when in use on the car.

For example, you have the driver putting force (causing a moment) on the brake and throttle pedals with his legs, while applying a grip force on the steering wheel, all while the equal and opposite contact forces from the seat and harness keep the driver at equilibrium and safe within the occupant cell.

Force → load applied at a point, causes pressure and by extension stress (force over an area), displacement, work, etc.
Moment → measure of a force times a perpendicular distance from a point (I.e. tendency of a force to rotate around an axis of an arbitrary point)

Takeaways from this → Each part takes on different loads and moments that we must tailor each design and mechanism for to take on

Inside each part, internal forces are present, which can cause different effects (i.e. compression → buckling, shear force → shearing, bending moment →bending stress, etc.)

When designing a part, especially when FEA and additional analysis is required, one must consider the different types of forces acting on the part, and how each one can affect the overall part (i.e. where are the weakest points in the structure based on the loads placed on it?). Some parts may experience only one of these cases (think of a seat only experiencing shear forces caused by the gravity of the occupant), while some parts may experience multiple at the same time (think of a brake pedal with both compression and bending moment caused by the force of the driver's foot).

Axial Forces

Axial forces (forces parallel to the center axis of the part) can cause compression or tension in a part, which can essentially be broken down into squeezing or stretching
Too much of either tension or compression can lead to either plastic deformation or buckling
Most parts are resistant to axial forces as compared to shear forces or bending moments (this can vary on the material, shape, and size of the part however)
Buckling is more common in longer, less stiff parts (I.e. shorter, stiffer part → less chance of buckling)

Shear Forces

Shear forces (forces perpendicular to the center axis of the part) can cause the shearing of a part
Think of it as a cutting force, like scissors cutting paper, a force perpendicular to the part can sort of “cut” the part in half

Bending Moments

Bending moments (forces that cause a rotation around a fixed point, causing bending) can cause bending stress (this is the root of most all problems in a lot of design)
You can think of bending moments as the worst case scenario, not only are you getting normal stress loads, but you are getting transverse shear stress as well
Bending moments have a lot to do with load pathing (i.e. if your load path is a straight line, no bending moment is caused (forces are only axial), but as soon as you introduce an angled path, bending moments are caused)

Torsional Forces

Torsional (or twisting) forces occur when torque is applied about the longitudinal axis of a part
A good way to visualize this would be when the driver continually tries to turn the steering wheel after they have reached the steering stops
- No more allowed rotation → torque is opposed → torsion (albeit not that much unless our driver is Bruce Banner or something) occurs

Supports will come in later when you take Statics/are introduced to FEA.

Supports assume infinite stiffness in specific degrees of freedom. Some supports (like fixed) have reactionary forces and moments in all DOF, some like (roller and pinned) have reactionary forces and moments in only specific DOF
All that matters is that different types of supports resist different types of forces/moments, which you can use to solve/isolate forces and understand the reactions happening in a system
Supports are integral to setting up a simulation right. If you have too many constraints, your sim will be too stiff and you will have inaccurate results. Too little constraints, same problem, inaccurate results, that can cause you to falsely presume your part is safe/effective.

Friction is also present in some capacities within the Ergonomics system, with the main part being the braking system.

Friction is the force that resists or opposes either
- a) relative motion → Kinetic Friction (although relative motion can be at rest so potentially Static Friction)
- b) impending motion → Static Friction
Friction is made up of the coefficient of friction which is determined by the surfaces and materials you are working with and the normal force, the force pressing the contacting surfaces together.
Friction is also most often associated with heat energy, meaning that when friction occurs, heat dissipation is likely to follow. Think of this as when you rub your hands together → friction occurs → heat follows shortly after
As an example, friction is present in the braking system as when the driver pushes the brake pedal and shifts the braking fluid, which sends hydraulic pressure to the brake caliper, which cause the brake pads to contact the brake rotor, thereby causing friction, which then slows down the rotor and wheels, while also releasing some of the transferring kinetic energy as heat to the atmosphere.

Two Force Members

A two force member in our case would be a tube with forces only acting in two locations, with the forces being equal opposite and colinear.

Topology Optimization

Useful Tidbits

Ergo Idea dump :

Wet layup carbon fiber molded seat, starts from foam CNCed mold that is then overlayed with carbon fiber, resin, etc.
Composite, fully 3d printed steering wheel???? ( with 3d printed grips )
Top-opped pedal box with lightweight materials

Ergo 101: A Guide to the Ergonomics Subsystem