Maddie’s research and notes on the accel and brake pedal sensors we’ll be using.

Preliminary Notes

Purpose of sensors

In the 2024-2026 car, Controls will need to detect the position of the accel pedal for movement, as well as the position of the brake pedal for fault conditions and telemetry. While the position of the acceleration pedal is necessary, the position of the brake is technically optional- all Controls needs is to enable the brake lights. However, for the purpose of analysis and additional features, we want to measure the position of the brake pedal and the pressure in the brake fluid line to

Send measurements to Data Aq for analysis
Detect and display a fault when there are discrepancies between the brake pedal position and brake fluid line
[ Possibly adjust the brake light brightness ]

and these sensors will be under Controls since we require it for the car state and therefore would like to receive this data as fast as possible (in short, we need it more/sooner than Data Aq).

What did we do in Daybreak?

In the 2024-2026 cycle, we used a linear potentiometer for the accelerator pedal, and a button for the brake pedal (since entering brake state is a binary decision).

Linear potentiometer

50mm Stroke (measuring length)
Cost: $144
SKU: SLPC 50 A 2K 1M (621400)
Compact linear displacement transducer with rod end bearings
2KΩ resistor value
18mm diameter (housing)
IP65 Rating
Connector: plug type w/mating connector included / Cable: 1 m length (3 wire)
Intended for industrial applications

Notes:

IP (Ingress Protection) Environmental Rating: Standard for the resistance of the part to environmental conditions like dust and moisture.

How to read the rating:

IP[Protection from solid objects][Protection from liquids]

Protection from solid objects: 0 (none) - 6 (no ingress)

Protection from liquids: 0 (none) - 9 (high-pressure hot water from different angles)

Why did we choose this sensor?

“linear was a relatively arbitrary choice made by me bc it was the first one I found with a good mechanical rating” - Sid

Sensor Research

Key Parameters

Mechanical Rating
Accuracy
Type (angular potentiometers, brake line pressure sensor)
Output (ideally supports digital protocol we use)
Cost (to some extent)
Size

Name	Description	Cost
SLP Linear Potentiometer	Used on Daybreak
HoneywellMLH		$288

References

https://www.reddit.com/r/FSAE/comments/ab3gs3/brake_pressure_sensors/

https://www.summitracing.com/parts/sum-890004
Industrial wet pressure transducer from Mouser or Allied
Honeywell MLH200
pressure switch rated for hydraulics
https://www.aim-sportline.com/en/products/sensors/index.htm#pressuresensors
For brake pedal (not line): load cell to measure force

https://www.fsae.com/forums/showthread.php?751-Brake-line-pressure-sensor&s=24ff250b660f943588ee776b1167bec7

Digikey MSI, 0-1000ish psi
https://www.digikey.com/en/products/detail/honeywell-sensing-and-productivity-solutions/MLH02KPSB06A/1248869?s=N4IgTCBcDaICwA4AMBaMBWAzHFA5AIiALoC%2BQA

https://www.fsae.com/forums/showthread.php?12194-EV-Car-brake-pressure-sensor

Linear potentiometer may be cheaper?
Can call to see if company will give a discount
Radio volume potentiometers have been used with suspension measurements- cheaper but less precise
Ebay

https://fsaeparts.com/collections/for-the-car