2021 EPAL Design
EPAL, or External Panels and Lights, encompasses the Dashboard, Cockpit Panel, the Side Panels on the exterior of the car, along with external lights stated within the rules. Below are all of the designs outlined through the use of various wiring diagrams, PCB assemblies, and inventor models.
2021 EPAL Documents:
Design Reviews: (Link)
Inventor Downloads: (Side Panel Inventor Models 1/27)
Front Dash Software Block Diagram: (PDF)
EPAL Current Inventory (Posted 3/4/21)
1. Front Dashboard
The Front Dashboard acts as the main source of information about car for the driver. This assembly consists of a Raspberry Pi 5″ display that displays information such as the speed, battery life, and other warnings not expressed on the LED indicators. The PCB within the Front Dash (created on KiCAD) encompasses the safety loop LEDs as well as fault LEDs required in the rules. These include: IMD Fault, AMS Fault, High Voltage (HV), Grounded Low Voltage (GLV), General Fault, Safety (SAFE), and AIRS. The fault lights will be red to indicate an error and the safety loop lights will be green to indicate that the safety loop is operating properly. Below are the current designs for the Front Dashboard.
Each “LED” is really 7 smaller LEDs arranged in a hexagonal pattern. The LEDs are all labeled on the PCB with AMS in the top left and the AIRs in the bottom right. These LEDs all have a 2V voltage drop, combined being 14V for each set of LEDs. As each LED set is receiving 24V from GLV, the last 10V is used by the LED controllers. Again, each set has one LED controller to limit the GLV signal to 20mA for the LEDs. The 10 pin header receives the signals from CarMan to distribute them over all of the LEDs.
The PCB also sends a 24V GLV signal through a 24V-5V voltage converter seen on the right side of the PCB. This 2 pin header is spliced with a USB connector to power the RPi screen on the dashboard. There are two capacitors in the current path, recommended by the voltage converter datasheet.
Notes for Next Year:
The space in the middle of the PCB can be used for whatever you like! The PCB manufacturer (JLCPCB) will charge you for it regardless of if they cut it off or not so we made some tiny cards to reflect our senior year on the project.
The LEDs did not pass the visibility test, where the LEDs while on must be visible in direct sunlight. This must be remedied through a higher current design whether through different LEDs or LED controllers. The overall design should work fine. Calculations should probably be done regarding the luminous exitance of the LEDs compared to the sun. I updated the PCB to V1.1 with some smaller changes regarding the rotation of the voltage converter and placement of the wire headers. V1 is being used in the lab.
Contact me if you have any questions: ThStranick@gmail.com
Front Dash Software Design
2. Cockpit Panel
The Cockpit Panel includes the drive button, reset button, and the emergency stop button. These are wired to CarMan who can then process the inputs and apply them to the safety loop. The drive button is LED illuminated when it is pressed to indicate the car is ready to drive.
Button Array + Driver Display Inventor Models
2020-2021 End of Year Files( Dashboard For Website)
user manual(Dashboard User Manual)
Notes For Next Year:
3D printing the driver display housing is quite difficult. It needs to be facing the build plate, rotated about 30-32 degrees and care must be taken to make sure that material doesn’t run off of the print bed. One time I tried support blockers, the easiest option is to wedge a thin(1 or 2 layer) piece of 3D printed material between the magnetic print bed and the print base so that excess material doesn’t drip off.
Consider shortening the wire from the flange to the PCB of the driver display. The wire is jammed in there tightly. There are a couple file versions but housing6forHDMI.ipt is the best and will be installed on the car on the first day of classes in Fall 2021.
housing5.ipt had problems where the screws wouldn’t stay in place.
The item titled screen2.ipt is the plexiglass semicircle though which light shines. We did basic testing with the GLV battery and found that the led’s inside did not shine bright enough to overcome daylight without the visor.ipt installed. We encourage you to test the version with the visor.ipt in the daylight but that probably still won’t shine bright enough. The plexiglass has an engravement IMS which needs to be changed to IMD in order to achieve rules compliance.
Cockpit Panel Electronics
The buttons housed within the button array include the E-Stop, Cockpit Reset, and Drive Button. Below is the wiring of the safety loop, showing the interconnectivity of the Cockpit Reset and E-Stop. The Cockpit Reset has a Relay that is required for operation that is also housed within the cockpit panel. The drive button is connected separately and sends a signal to CarMan to indicate that the car should move into drive mode. The button contains an LED that will let the driver know when the car is in “Ready to Drive Mode”.
The front metal panel holds all of the buttons while the enclosure holds the relay and wire connectors. This panel can be removed along with all of the buttons by disconnecting the quick connects. This allows work to be done inside the enclosure or on the panel without both pieces. The two wire connectors are for the safety loop and the driver button individually.
Notes for Next Year:
The enclosure design for the cockpit panel is sleek, however is very hard to use when wiring. There is only one side which you can access the inside and it makes it frustrating when trying to unhook the front panel or work inside the enclosure. A better more accessible design would be ideal.
The cockpit panel in the lab has a broken driver’s button, thus an LED is soldered to the outside. There is a new driver button part that was ordered that can be used to replace it. There were also more normally open switches that were ordered that can be used with the respective housing for the master reset.
Contact me if you have any questions: ThStranick@gmail.com
3. Side Panels
The two side panels contain the two master switches for the operation of the car, all three reset buttons listed on the safety loop, both side mounted emergency stops, and both side mounted Safety System Okay lights. These panels are mounted in the top of the rear triangle, at the driver’s head level when seated in the car.
3.1 Side Panel Inventor Models
Right Side Panel design, placed in the full car model w/ all components and dimensions updated 2/7/21
Left Side Panel design, placed in the full car model w/ all components and dimensions updated 2/7/21
3.2 Side Panel Part Drawings
Part drawings for manufacture of side panels, updated and approved 2/11/21
3.3 Side Panel Manufacturing Documents
Manufacturing Files used to waterjet cut the side panels, created 2/11/21
3.4 Side Panel Wiring Diagrams
Wiring Diagrams last updated 5/16/21
All Wiring is completed in hardware using 14 gauge copper wire and nylon coated quick disconnect joints when necessary. Wiring has been verified through testing with GLV power.
Right Side Panel Wiring Diagram
Left Side Panel Wiring Diagram
Errata/Notes for Next Year
First off, thank you for taking up where I left off last year! I would say that the side panels should be low on your list of concerns to remake and fix from the 2020-2021 design. For all testing purposes these panels did their job, and are ready to be mounted on the car after being labeled with the included vinyl labels I made. That being said, they can be improved in some notable ways.
- Remake the metal sheets that make up the panels themselves.
- Use thicker sheet steel to avoid flexing.
- Polish or brush any markings before mounting components.
- Redesign/correct the anti-rotation measures for each button and switch.
- Double check each button rather than copying what last year did.
- Use a normally open button for the IMD reset.
- There is probably one in the lab, but also feel free to order new matching buttons for both panels, just make sure you check the size.
- Test mount the panels in the car before wiring.
- Measure the distance and direction that the hardwired cables need to go.
- Mark down which sides of the panels are flush with frame tubes, and note any wiggle room you might have once they are finalized.
- Look at how long the screws you’re using for mounting are, and see how they’ll impact the wiring on the back of the panels.
- This also includes the screw holding the master relay that protrudes out the front of the right panel.
Brake Light Mount
The slots that hold in the brake light had to be filed to be wider to fit the key on the actual brake light.
Visit the Dashboard Design Archive for past designs: Here