ABOUT THE PROJECT

The goal of this project was to develop a cheap, reliable, localization system capable of accurately locating a tagged object with minimal error. The system is intended to function in an outdoor environment where line of sight can not be guaranteed, and should maintain reliability over a range of 100 meters. While many localization technologies currently exist, they are often bulky, expensive, require professional installation, and are not capable of centimeter level accuracy. A prototype system has been developed that can determine the location of a tagged object reliably with an accuracy that is typically within 20 centimeters. The maximum distance from the farthest transceiver has been tested to be 150 meters, but there exists significant room for improvement to achieve even greater ranges with an even greater level of accuracy. The localization was achieved and tested in two dimensions, but the system could be extrapolated to three dimensions with relative ease. This prototype system is very competitively priced compared to other technologies on the market and is also more compact and more accurate than existing systems.

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PROJECT TECHNIQUE

We used a technique call double-sided two-way ranging (DS-TWR). This approach calculates the distance by using two round trip times between two receivers. These round trip times are combined to give a time of flight that has reduced error in most situations. In this topology, each device must act as both a receiver and a transceiver. The figure below is from the DW1000 user manual and illustrates the basic transmission scheme of each message in a DS-TWR setup.

Using the figure above as a reference, the estimate for the time of flight, T_propcan be calculated as:

(₁ × ₂ − ₁ × ₂)

= ————————————-

(₁ + ₂ + ₁ +₂)

The distance is then simply the time of flight times the speed of light.

At least four nodes are necessary to determine an object’s relative position in three dimensions. Once the distance to each of the four reference points is measured, the position can be pinpointed using a localization algorithm.

PROJECT DOCUMENTS

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DWM1000 is an IEEE802.15.4-2011 UWB compliant wireless transceiver module based on DecaWave’s DW1000 IC. DWM1000 enables the location of objects in real time location systems (RTLS) to a precision of 10 cm indoors, high data rate communications, up to 6.8 Mb/s, and has excellent communications range of up to 300 m thanks to coherent receiver techniques.

We initially tried to use the MSP430 launchpad to interface with the chip, but the Application Programming Interface (API) provided by DecaWave was not designed to work with this type of controller. We then selected the STM32F103RB, which is a controller in the same family as the one the API was written around.

To interface with the chip, we initially soldered wires directly to the chip and ran these to the microcontroller, but it was very difficult to establish reliable connections and the fragility of the connections made testing nearly impossible. For this reason, we designed a simple PCB that we could solder the module to that would give us access to all of the pins on the device without having to worry about harming the chip or severing a connection.

Since we are not really using any of the peripherals on the microcontroller board we chose, for an end product we would integrate the microcontroller chip and LEDs onto a single PCB with associated power regulating circuitry. This would allow every transceiver to be a self contained unit that could operate on battery power if necessary.

PROJECT GALLERY

OUR TEAM

David Alan Gilbert

Manager

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Caelan Zakari Fields

Presentation Preparation

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Zihao Wang

Webmaster

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Hanqing Wang

Document Preparation

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Christopher Adam Huber

Lab Coordinator & Document Preparation

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OUR SPONSOR

Eaton Corporation Plc is a multinational power management company, founded in the United States with corporate headquarters in Dublin, Ireland. Eaton provides solutions to its customers to manage electrical, hydraulic and mechanical power efficiently, safely and sustainably. Eaton acquired Cooper Industries in November 2012. The 2014 revenue of the combined companies was $22.6 billion. Eaton has approximately 97,000 employees and sells products to customers in more than 175 countries.

CONTACT US

Hello,

We are glad that you can contact us and learn more about our project if you are interested in our design. And, If you have specific questions or concerns, please do not hesitate to contact us.

Thank you!

Team 13