References
The design concerns referenced here are mainly paraphrased/pulled from these sources:
Please reference these for the actual comments made on PDR.
Blindspot Sensor
As far as driver safety is concerned, two side cameras may make more sense than blindspot sensors (or perhaps a combination of both!)
If planning to still do blindspot sensors, do not consider cost a factor at all (since this is a pretty safety critical element)
Testing will need to be done in different light conditions + glare – be careful about infrared
Perhaps even upgrading the backup camera will help with this
Lights
Make sure that light power isn't supplied by the peripheral boards – they're only capable of 1W maximum and are mainly meant for sensors
As long as the power itself comes from an external source (e.g. supplemental battery) and is only driven by the peripheral boards, it would be fine
Power Draw
I'd like to try to limit power draw as much as possible on this new design, and our previous power draw (measured 2/17/24) was ~18.5W
If we can stay in this range or maybe even get lower than this, it would be good. 1W is provided as an upper bound on each SOM, but with smart firmware we can lower this further
This may be tough especially considering blindspot sensors, new display, and possibly even side cameras.
Motor Consideration
Investigate https://www.h3x.tech/#hpdm-30 as a possible motor/MC alternative since we have a partnership with them
No, too much power
Steering Wheel Buttons
@Nathan Lee 100% does not like the idea of using the quick disconnect again due to integration issues, so we may have to come up with something else
Consider a peripheral board on the steering wheel to interface with the buttons, that just spits shit out over CAN to leader. This makes # of wires to steering wheel go from like 8 to like 4
Button placement and steering wheel design needs to be ironed out with ergo as soon as possible (i.e. whenever ergo is done with current gen stuff)
Horn button needs to be considered & integrated
chase car radio button placement needs to be considered (communicate with dataacq). this should be a completely independent circuit since it's just a button that clips onto the steering wheel and plugs into the walkie talkie
Display
Define display requirements such as:
Minimum brightness
Viewing angle
Glare
Our definite requirements for right now are probably:
7 inch
Not much more power draw than the Nextion (which was 1.25W)
The Waveshare + RPI display was ~3.1W total and the Riverdi display was ~4.05W iirc
A lot of displays exist that could be less power draw in that they have their own internal control unit
Instead of leader → RPI → display, it could be leader → display where the display does all the control of pixels and stuff on its own (think Nextion)
Another bit of reasoning for this is that the RPI runs full linux, whereas we only need an embedded RTOS really if we're just using it as an interface for the display (full linux is unnecessary)
Options (communication via SPI):
Horn
Find horn that's low power draw THAT MEETS REGULATION REQUIREMENTS
The regs requirements are our main constraining factor on limiting power draw of this. We need a certain volume level of sound iirc
Lakshay's horn: https://www.amazon.com/SoundOriginal-Universal-Motorcycle-Electric-Waterproof/dp/B072QBNTSM
Backup Camera
Verify our current backup camera is viable
The regs require a way for the driver to always view behind the car. We accomplish this with a backup camera, so this is critical requirement.
Tested on 3/2/2024 and it does work but the display is not good at all viewing angles. Need to check with ergo on how this might look in reality.
Data Acq Optimal Speed
Originally, data acquisition was going to send us an optimal speed to go at a regular interval. Controls was going to add this information to the display for the driver to use.
Idea is no longer feasible due to data acq processing their information on the cloud and not on a board in the car.
Array Precharge
Array does need precharge!
Mostly a power systems problem
Peripheral Board Voltage Drop
See 2024 Controls Post-PDR Review: Peripheral Board CAN Voltage Drop.
Design Decisions
Using side cameras instead of blind spot sensors - Aiden again! (Thank u)
Auxiliary Display
Decided on separate display that will switch inputs when blinkers are pressed
Peripheral Board required - same peripheral SOM, different daughter, DISPLAY DAUGHTER
Communication protocol – interfacing with HW
Are we able to display the video?
Third display for side cameras
Power draw concerns
Integration of side camera into main display requires less power draw
More research on camera
Noise tolerant video!
Main Display
500 nits, 3.15W: https://www.buydisplay.com/spi-1280x400-7-84-inch-ips-tft-lcd-module-optl-capacitive-touch - long boi display
Will also show backup camera on one side permanently - same camera as side cameras (3 of the same)
Peripheral Board required
Steering Wheel
Peripheral Board required
Takes all the buttons in and outputs onto CAN
Peripheral Boards
4 Peripheral SOMS
2x normal peripheral daughter - steering wheel & lights
2x display daughters - one for each display
Horn
Electronic brake and regen still needs to be revisited
Requires significant testing with functional car!!
Would regen/blended braking all the time be beneficial?
CAN Topology
Option 1
Pedal hardware issue detection
Sense pins
Use Pull Down Resistor