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Team Status Report for 4/12

Validations Done

  • We conducted five in-vehicle tests to confirm that the car cigarette lighter reliably powers the unit for 30-minute sessions.
  • In real-world testing, we deployed the dash cam in a vehicle for a 30-minute drive, during which the driver continuously called out the license plate numbers observed. During the 30-minute session, the driver identified 25 license plates while driving. All 25 were correctly detected by the dash cam system. In addition, the dash cam detected an extra 117 license plates that the driver was unable to observe while driving.
  • To evaluate end-to-end system latency, we conducted 10 field tests and record timestamps at key stages. Average on-board detection latency is 123ms, OCR latency is 134ms, watchlist query latency is 469ms, and image upload latency is 7332ms.

Validations To Do

  • In the lab, we will verify that the unit’s weight is less than 1.5lbs using a scale.
  • We will time the initial setup process with five participants, ensuring that the average setup time is under 10 minutes.
  • We will verify that the system’s startup and shutdown scripts execute within 30s of a power change through five simulated tests and five field tests, ensuring that no file corruption occurs during the process.
  • We will test the opt-in switch functionality through 10 separate activation/deactivation cycles to confirm that the system reliably transitions its ALPR setting within 1s.
  • We will verify that data at rest on the dash cam is erased upon shutdown, that non-match data on the server is deleted immediately, and that matched data is retained for 21 days.

Risks

  • Since we are now in the testing phase, we find calculating our performance data quite challenging. It involves a lot of manual work as we need to look through footage to identify additional license plates that the dash cam caught.

Changes

  • We modified the image uploading pipeline due to a hardware limitation with I2C bandwidth. Initially, we planned for two parallel threads on the dash cam: one for uploading chunked images upon server request and another for ongoing inference and license plate number queries. However, our hardware supports only one active I2C communication at a time, preventing simultaneous uploads. To address this, we now pause inference and plate number query during image uploads, resuming them afterward. With an average upload time of 500ms, the impact on real-time detection is minimal. This approach also makes sure we prioritize plates on watchlists, as the chance of detecting another watchlist plate immediately after is very low.
  • We removed loop recording since it’s not the main focus of the project and it’s challenging for development and testing. Similarly, we decided to remove text formatting as current performance metrics looks good and it’s not the main focus of the project.
  • For security compliance, we’ve added an API key to the dash cam communication APIs. This ensures only authorized devices can access the system (send detection query / upload images). We can implement rate limiting to prevent API abuse. If necessary, we can trace back activities to specific dash cams.
  • Since we have limited bandwidth, we decided to cut the server load testing to conserve both budget and effort. This allows us to better focus on the integration and presentation.

Schedule

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Andy’s Status Report for 4/12

Verification and Validation Update:

As we transition into the verification and validation phase, we are aligning our testing approach with our core engineering design and use case requirements. I am mainly in charge of the dashcam circuit components so my individual testing are more oriented with the dash cam power supply system.

Our dashcam power system is designed to draw power from the car’s cigarette lighter, which is converted by an adaptor to 8.4V 2A for the UPS(Uninteruptable Power Supply). The UPS then regulates this input to provide a stable 5V 5A output to the Raspberry Pi, while also managing seamless switching to its internal battery when the car is turned off—ensuring a safe shutdown process for the RPi.

Tests Completed:

  • Power Regulation Test: Verified that the adaptor consistently provides stable output (8.4V ± 0.3V and 2A ± 0.2A) under both nominal and surge input conditions to the RPi UPS module.
  • UPS Power Supply Test: Verified that the UPS consistently provides stable output (5V ± 0.3V and 5A ± 0.4A) under both nominal and surge input conditions from the simulated power supply from car. Also I tested and verified that the UPS consistently provides stable output when the power supply simulated from the car is off, which means the UPS switched to its battery for backup power supply.

After verified the system works during simulation test in the lab, I tested the system on a car with actual car cigarette lighter.

  • In-Vehicle Test: Validated system stability in a real car environment with varying RPMs and load conditions. Continously measured the voltage for 5 min while another driver is driving the car under normal driving condition.

Verification Approach:

  • Instrumentation: Use multimeters, current clamps to monitor real-time voltage and current waveforms.
  • Simulation: Use voltage generator from ECE labs

Planned Tests:

  • Endurance Test: Run the complete system for an extended period to test long-term reliability, focusing on consistent voltage and system uptime.
  • Integration Test: Connect with RPi to conduct end-to-end testing for the entire system while continously measure the voltage and current to check for abnormal circuit behaviors.

Summary of Work This Week:

  • Cigarette Lighter to Adaptor Simulation Testing:
    • Used a wire-to-car-cigarette-lighter converter to simulate a car’s power source.
    • Connected our adaptor to a breadboard to measure voltage and current under standard conditions.
    • Confirmed that the adaptor correctly regulated the voltage from the car cigarette lighter.
    • Simulated transient input spikes ranging from 10V to 20V, which can occur due to vehicle alternator behavior or load switching.
    • Verified that our adaptor provided clean, regulated power even during input fluctuations.
  • Raspberry Pi UPS Power Test:
    • Used the stabilized adaptor to power a Raspberry Pi UPS HAT.
    • Disassembled the RPI and UPS HAT for isolated testing.

Next Steps and Schedule:

  • Continue full integration testing with the RPI in-vehicle.
  • Monitor long-term stability under varying driving conditions.
  • Begin logging power behavior during startup and shutdown phases.

Progress:

This week, I made progress by completing the majority of the circuit-level testing. I verified the power regulation behavior of our adaptor and UPS module, both in simulation and in a real vehicle environment. With these components confirmed to be working, we are ready to move forward with full system integration using the car cigarette lighter as the actual power source.

Additional tests, including endurance and thermal testing, are planned to further ensure reliability under extended and realistic conditions.