Discontinuity in Event Triggering Time of Dynamic Vision Sensors under Dim Light Conditions

Conceitos Básicos

The dynamic vision sensor (DVS) exhibits a discontinuity in event triggering time, which becomes more prominent under dim light conditions due to the slow changing speed of light intensity.

Resumo

This paper analyzes the typical DVS circuit and finds that there exists a discontinuity in the event triggering time, which is one of the main factors contributing to the unsatisfactory behavior of DVS under dim light conditions.
The analysis shows that the discontinuity is caused by the charge and discharge of the parasitic capacitor of the photodiode in the DVS circuit. This time delay between consecutive triggering events follows a non-first-order system behavior, unlike the usual first-order response of DVS.
The time delay is inversely proportional to the changing speed of light intensity. In dim light conditions, the difference in light intensity is generally small, leading to a slow changing speed and thus a more prominent discontinuity in the event triggering time distribution.
Experimental results on real DVS data validate the analysis and the existence of the discontinuity, which reveals the non-first-order behaviors of DVS under dim light conditions. This understanding can help improve the design of DVS and event simulators.

Estatísticas

Ipd(t1 + Δt) - Ipd(t1) ∝ L(t1 + Δt) - L(t1)
ΔVd(t1) = -A · ΔVsf = -A · VT · κsf/κfb (ln Ipd(t1 + Δt) - ln Ipd(t1))
ΔQ = ΔVpd · CJ = ΔIpd · Δt
Δte ∝ 1/ΔIpd ∝ 1/(μ · T)

Citações

"The time delay Δte is inversely proportion to the changing speed of light intensity μ."
"In the dim light conditions, the changing speed of light is slow because the absolute difference of light is small. As a result, the time delay Δte is more significant."

Principais Insights Extraídos De

Charaterization of dim light response in DVS pixel: Discontinuity of event triggering time

by Xiao Jiang,F... às arxiv.org 04-30-2024

https://arxiv.org/pdf/2404.17771.pdf

Perguntas Mais Profundas

How can the discontinuity in event triggering time be mitigated or compensated for in the design of DVS circuits?

In order to address the discontinuity in event triggering time in DVS circuits, several design considerations can be implemented:

Optimizing Parasitic Capacitance: Since the charge and discharge of the parasitic capacitor of the photodiode contribute significantly to the time delay, reducing the effects of this parasitic capacitance can help mitigate the discontinuity. Designing the circuit to minimize the impact of parasitic capacitance or implementing compensation techniques can be beneficial.

Improved Signal Processing Algorithms: Developing advanced signal processing algorithms that can predict or compensate for the time delay caused by the parasitic capacitor can help in reducing the discontinuity. These algorithms can adjust the event triggering time based on the expected delay, improving the overall performance of the DVS.

Feedback Mechanisms: Introducing feedback mechanisms in the circuit design can help in stabilizing the event triggering time by compensating for the delays caused by the parasitic capacitance. Feedback loops can adjust the circuit response based on the detected delays, ensuring more consistent event triggering.

Calibration Techniques: Implementing calibration techniques that account for the inherent delays in event triggering can help in minimizing the impact of discontinuities. By calibrating the circuit parameters based on the observed delays, the circuit can be optimized to reduce the discontinuity in event triggering time.

By incorporating these design strategies, DVS circuits can be optimized to mitigate the discontinuity in event triggering time, improving their performance in dim light conditions.

What are the potential implications of the non-first-order behavior of DVS under dim light conditions on applications that rely on event-based vision?

The non-first-order behavior of DVS under dim light conditions can have significant implications for applications that rely on event-based vision. Some potential implications include:

Accuracy and Reliability: The non-first-order behavior can introduce uncertainties and inconsistencies in event triggering times, affecting the accuracy and reliability of event-based vision systems. This can lead to errors in event detection and processing, impacting the overall performance of the system.

Response Time: The non-linear response of DVS under dim light conditions can result in varying response times to changes in light intensity. This can affect the real-time processing capabilities of event-based vision systems, potentially causing delays in detecting critical events.

Dynamic Range: The non-linear behavior may limit the dynamic range of DVS in dim light conditions, affecting the system's ability to capture a wide range of light intensities accurately. This limitation can impact the system's performance in environments with varying lighting conditions.

Calibration Challenges: The non-first-order behavior may introduce challenges in calibrating and optimizing DVS systems for dim light conditions. Calibration procedures may need to account for the non-linear response characteristics, requiring more sophisticated calibration techniques.

Overall, the non-first-order behavior of DVS under dim light conditions can pose challenges for applications that rely on event-based vision, impacting their performance, accuracy, and reliability.

What other factors, beyond the changing speed of light intensity, might contribute to the discontinuity in event triggering time in DVS?

In addition to the changing speed of light intensity, several other factors can contribute to the discontinuity in event triggering time in DVS:

Temperature Variations: Fluctuations in temperature can affect the performance of DVS circuits, leading to variations in the event triggering time. Temperature changes can impact the characteristics of the photodiode and other components, influencing the overall response of the circuit.

Noise Sources: Various noise sources, such as shot noise, dark current, and junction leak noise, can introduce disturbances in the circuit operation, affecting the event triggering time. These noise sources can contribute to the unpredictability and discontinuity in event detection.

Component Variability: Variations in component characteristics, such as capacitance values, transistor parameters, and circuit layout, can introduce inconsistencies in the circuit response. Variability in component properties can lead to differences in the time delay between triggering events, contributing to the discontinuity.

Power Supply Stability: Instabilities in the power supply voltage can impact the operation of the DVS circuit, influencing the event triggering time. Fluctuations in the power supply can introduce variations in the circuit's response, potentially causing discontinuities in event detection.

By considering these additional factors along with the changing speed of light intensity, designers can better understand and address the discontinuity in event triggering time in DVS circuits, improving their overall performance and reliability.