COMPACT AND COST-EFFECTIVE MOBILE 2.4 GHZ RADAR SYSTEM FOR OBJECT DETECTION AND TRACKING
thesisposted on 17.01.2019, 00:45 by Seongha Park
Various types of small mobile objects such as recreational unmanned vehicles have become easily approachable devices to the public because of technology advancements. The technology advancements make it possible to manufacture small, light, and easy to control unmanned vehicles, therefore the public are able to handily access those unmanned vehicles. As the accessibility to unmanned vehicles for recreational purposes, accidents or attacks to threat a person using those the unmanned vehicles have been arising and growing rapidly. A specific person could be a target of a threat using an unmanned vehicle in open public places due to its small volume and mobility. Even though an unmanned vehicle approaches to a person, it could be difficult to detect the unmanned vehicle before the person encounters because of the compact size and maneuverability.
This research is to develop a radar system that is able to operate in open public areas to detect and track unmanned vehicles. It is not capable using existing radar systems such as for navigation, aviation, national defense, air traffic control, or weather forecasting to monitor and scan public places because of large volume, high operation cost, and danger to human health of the radar systems. For example, if electromagnetic fields emitted from high-power radar penetrate exposed skin surface or eyes, the energy from the electromagnetic fields can cause skin burns, eye cataracts, or more (Zamanian & Hardiman, 2005). Therefore, a radar system that can perform at the public place is necessary for monitoring and surveillance the area.
The hardware of this proposed radar system is composed of three parts: 1) radio frequency transmission and receiver part which we will call RF part; 2) transmitting radio frequency control and amplifying reflected signal part which we will call electric part; and 3) data collection, data processing, and visualization part which we will call post-processing part. A transmitting radio frequency control and an amplifying reflected signal part are based on a research performed at a lecture and labs designed by researchers at Massachusetts Institute of Technology (MIT) Lincoln Lab, Charvat et al. (2012) and another lecture and labs designed by a professor at University of California at Davis, Liu (2013). The radar system designed at University of California at Davis is based on the system designed at MIT Lincoln Lab that proposed a design of a small, low cost, and low power consuming radar. The low power radar proposed by MIT Lincoln Lab is suitable to operate in any public places without any restrictions for human health because of it low power transmission, however surveillance area is relatively short and limited. To expand monitoring area with this proposed low power radar system, the transmit power of the radar system proposed in this study is enhanced comparing to the radar proposed by MIT Lincoln Lab. Additionally, the radar system is designed and fabricated on printed circuit boards (PCBs) to make the system compact and easy to access for use of various purposed of research fields. For instance, the radar system can be utilized for mapping, localization, or imaging.
The first part of post-processing is data collection. The raw data received and amplified through the electric part in the hardware is collected through a compact computer, a Raspberry Pi 3, that is directly connected to the radar. The data collected every second and the collected data is transferred to the post-processing devices, which is a laptop computer in this research. The post-processing device processes data to estimate range of the object, applies filters for tracking, and visualizes the results. In the study, a variant of the Advanced Message Queuing Protocol (AMQP) called RabbitMQ, also called as RMQ (Richardson, 2012; Videla & Williams, 2012) is utilized for real-time data transfer between the Raspberry Pi 3 and a post-processing device. Because each of the data collection, post-processing scripts, and visualization processing have to be performed continuously and sequentially, the RMQ has been used for data exchange between the processes to assist parallel data collection and processing. The processed data show an estimated distance of the object from the radar system in real-time, so that the system can support to monitor a certain area in a remote place if the two distant places are connected through a network.
This proposed radar system performed successfully to detect and track an object that was in the sight of the radar. Although further study to improve the system is required, the system will be highly suitable and applicable for research areas requiring sensors for exploration, monitoring, or surveillance because of its accessibility and flexibility. Users who will adopt this radar system for research purposes can develop their own applications that match their research environment for example to support robots for obstacle avoidance or localization and mapping.