According to NHTSA Traffic Safety Facts, bicyclist deaths and injuries in 2013 are recorded as 732 and 48,000, respectively. In the State of Florida the safety of bicyclists is of particular concern as the bicycle fatality rates are nearly triple the national average. Further Florida ranks #1 on bicycle fatality rate in the nation for several years. To determine the cause of near-misses and crashes, a detailed study of bicyclist behavior and environmental conditions is needed. In a Florida Department of Transport (FDOT) funded project, USF CUTR has proposed naturalistic bicycle study based on ride data collected from 100 bicyclists for 3000 hrs. To this end, Bicycle Data Acquisition System (BDAS) is being researched and developed.
The main objective of this thesis work is to design and implement low power video and audio subsystems of BDAS as specified by domain experts (USF CUTR researchers). This work also involves design of graphical user interface (Windows application) to visualize the data in a synchronized manner. Selection of appropriate hardware to capture and store data is critical as it should meet several criteria like low power consumption, low cost, and small form factor. Several Camera controllers were evaluated in terms of their performance and cost. The major challenges in this design are synchronization between collected data, storage of the video and sensor data, and design of low power embedded subsystems.
REAL-TIME VIDEO RECORDING SYSTEM
The image processor in VC0706 can generate JPEG images at 640 x 480 pixel resolution. Using this module, we can achieve the required frame rate of 15 fps. It supports both SPI and UART interfaces for data collection and communication with the device respectively. Support for composite video output is also available in this module using which we can adjust the focus of the lens. All communication with camera is done using UART (frame length, resume, and stop) but actual frame data is received through SPI interface. This module works in the master mode when it uses SPI interface. Figure 3 shows the image of the VC0706 Camera Controller.
In this microcontroller we have two SPI interfaces: one can be used in slave mode and the other in master mode. So a frame from camera can be received simultaneously while writing another frame to SD card. MBED RTOS is easy to implement and takes less time. The read and write operations can be run in two concurrent threads. Figure 8 shows the image of MBED LPC1768 Prototype Board.
DATA COLLECTION, SYNCHRONIZATION, AND VISUALIZATION
Synchronization between the collected data and its visualization are the main challenges in the naturalistic bicycle study. Therefore, a graphical user interface is designed for data visualization. This chapter discusses how the tasks are optimized with time and data is stored.
SYSTEM OPERATION AND POWER MANAGEMENT
Ultra-low Power Accelerometer ADXL362 is used to detect the presence of a motion. This accelerometer can be configured in such a way that it generates INT1 (output logic high) and maintains this logic even in absence of motion until INT1 is cleared by microcontroller (Arduino Due). Therefore, there will be no abnormal power shutdown when there is no motion.
Audio and video systems were continuously tested for 48 hours to test the stability. The results obtained from the test are accurate. Figure 13 shows BDAS installed on the bicycle. The front and back module are powered by a 12 Volts 10 Ampere-hour battery. Both modules communicate with each other through UART for synchronization of data.
We can observe that voltage drops from 12V to 10V over 48 hours. Figure 17 shows the current profile. We have used MCR-4V, a multi-channel voltage data logger for power profiling the system. Immediate on-the-spot checking of continually-changing data is possible with this data logger.
CONCLUSION AND FUTURE WORK
The same system can also be used for motorcycle study. The Intel Edison can be the potential tool for further development and the upside in the usage of that specific module can be the IOT connectivity, HD video synchronization, etc. Cycling data can be used to implement new protective measures/traffic rules to increase the safety of the bicyclists.
We have more Platform development options for Intel Edison because it uses Yocto Linux. Custom Linux-based systems for embedded products can be created using Yocto project regardless of the hardware architecture.
Source: University of South Florida
Author: Janardhan Bhima Reddy Karri