The objective of the Multiple Robot Network was to design, develop, and simulate a wireless, real-time system that would monitor and track the movements of objects (robots) in a specified, confined area. The objects were monitored using sensors, a radar device, and a computer that communicates with the objects (robots).

While there were no major hardware or software problems associated with the project, the group did run into obstacles. Namely, the original intent of the project was to determine the exact location of the object (robot) within the specified area in addition to monitoring movement. However, after initial tests were conducted, the group realized that such a single radar device was not capable of determining location. Given more funding, the group could have determined exact locations with additional radar devices. Due to this constraint, the project was altered in that a database application was created that would determine whether an object (robot) entered a field, the identification of the object, and the time at which it entered. Other obstacles that were solved are also discussed throughout the paper.

The creation of a database would allow security personnel, nurses, and doctors to keep a record of their respective moving objects. For example, nurses would be able to determine behavioral patterns based on previous data of patients. The vicinity of patients experiencing Alzheimer's could be immediately determined under such a system. While the project objective (in terms of exact location was altered), the group still accomplished its goal in terms of monitoring and tracking movement in specified area. In addition, the group created a database application to assist users such as nurses and security personal to receive real-time information into the whereabouts of moving objects.

The database application was created using Java. The extensive code is attached for reference. It demonstrates numerous functionalities and error checks which are discussed throughout the paper. The testing methodology for the entire project involved making sure the information was passed error-free, the data was recorded and presented in an organized, user friendly manner, and that the information was delivered in a real-time environment.

I-1. Acknowledgement

The Multiple Robot Network was successfully implemented and built with the help of Mr. Leigh H. Hickcox from AWID. Mr. Hickcox provided the group with guidelines and information regarding the hardware components. Also, with the help of professor Tewksbury, our group was able to locate and use a linear power supply which was necessary according to design specifications. Our budget was not considered an issue because there was no sponsorship for this project. Lastly, Professor Tureli and Professor Bruno assisted the group by providing advices and alternative feedback when faced with difficulty.

II. Implemented Prototype
II-1. Introduction

Prior to implementing this system, many technologies were explored. The one that was chosen is Radio Frequency Identification (RFID). This technology was chosen to develop a solution for an indoor human tracking application for use in confined facilities such as a nursing home.

Knowing that some other tracking designs exist such as the implanted miniaturize chip in humans (to process human's movement), Multiple Robot Network is implemented in a number of different methods and for different purposes. By using the tags, radar, and a central computer, it can process human's movement or any other obstacles. In the Multiple Robot Network, robots are used to model a large-scale facility that requires the tracking of patients or objects (where the patient/object movement is simulated by the movement of robots) by a using wireless protocol. This implemented prototype sounds simple nevertheless there were technical problems that were encountered.
The problems that the prototype addresses are:

- The radar cannot keep track of the time duration (what time the tags entered and what time the tags left)
- Inconsistencies in read range occurred during the powering
- The radar is limited to any communication devices using similar frequencies - wireless phones, scanners, wrist radios and personal locators that can interfere with transmission

The first problem was resolved by creating a database application using the system clock to display the time when the tags entered. The second problem was resolved by using regulated power supply, where a plug-in transformer capable of providing 1 amp of linear, regulated power with excellent dynamic loading characteristics. The third problem was overcome by keeping the radar away from any communication devices.

Key parameters of RFID technology include a low frequency band of 100-500 kHz. While this results in a low reading speed, it is a more cost efficient method. In addition, a power level of 100 - 500mW was used to correspond with the Wiegand/RS-232 set up at a 9600-baud rate. As a rule of thumb, higher supply voltage results in longer read range (not to exceed 12V) but at the expense of higher power consumption.

II-2. Prototype Specification
MR1824 has an internal micro-controller, a transmitter, a receiver, and a shared transmit/receive antenna. It has a transmitting frequency of 125 kHz. MR-1824 has the ability to operate under temperature of 31 to 150 degree Fahrenheit and humidity of 0 to 95 %. The tags are passive in nature. The following diagram indicates the prototype specification.

Shown above is the block diagram for Multiple Robot Network. MR-1824 is connected to the laptop through RS 232. MR-1824 requires a linear power supply. It can operate at a voltage of 5 to 12 volts. Higher voltage will result in higher range. The MR1824 used in the project has a range of about 18 to 24 inches. It has a read range of 18 inch with 250mA at 5VDC or 24 inch with 600mA at 12VDC. The following two graphs show the read range vs. the power supply with access control panel at 300ft and 500 ft respectively.
Read Range VS. Wire Gauge and Supply Voltage (300 ft)

A - 20 ft AWG
C - 300 ft AWG
B - 300 ft AWG
D - 300 ft AWG

Read Range VS. Wire Gauge and Supply Voltage (500 ft)

A - 20 ft AWG
C - 500 ft AWG
B - 500 ft AWG
D - 500 ft AWG

MR 1824 works simultaneously with serial and parallel but the final information sent to central computer is serial. The used ID is coded in the form of bits. The tags are programmed with between 26 and 56 bits binary code, in a variety of bit formats. The binary bit format may contain 2 or more parity bits and 2 or more data fields. The binary bit in each field runs from most significant bit to leash significant bit. An example of bit format is shown below:

1 2 3 4 5
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
E S S S S S S S S I I I I I I I I I I I I I I I I O

Parity bit information:

E E E E E E E E E E E E
O O O O O O O O O O O O

S = Site/Facility Code
I = ID. Number
E = Even Parity
O = Odd Parity

The RS-232 out put for each card is a string of 20 ASCII characters. The MR1824 transmits the card's code through RS-232 Transmit Data (TD) line. In RS-232 data format each byte contains 1 start bit, 8 data bits,1 stop bit and no parity bit. The data range is 9600 bits per second.

The circuit diagram explaining the connection of RS-232 and MR1824 is shown below.

The orange wire of MR1824 receives data and is connected to pin 3 of RS-232 which transmits data. Violet wire of MR1824 transmits data and is connected to pin 2, receives data, of RS-232. The black wire is connected to pin 5, ground, of RS-232. The red wire is connected to power supply to gain voltage.

II-3 Prototype Performance and Evaluation

Performance:

The testing of the prototype was performed in two stages during the second semester of the project. First, it was done by testing the transmission between the tags and the radars by using the hyperterminal. After hyperterminal testing was completely successful, the prototype was further develop by applying the java program associated with database application. The second stage was tested and proved that the prototype can perform multiple functions at the same time.

Performance was measured in terms of the capabilities of the hardware and the written software. Because the Multiple Robot Network is a design to implement an automatic identification and data transmission in an access control, the radar must be able to read and identify the identification code bound back by the tags. The radar must communicate to a central computer informing it of which identification number is present. The identification code was implemented by utilizing a database application. This database application can display the time of the tags entered and extended to perform more tasks such as:
- Load and store tags information to a file
- Display a lists of all tag user names
- Mark three tags as active user names
- Customize display of user name such as first last or last, first
- Identify which tag user entered
- How many times the user entered
- Display errors when invalid user names entered

Operating Environment:

The operating environment for the human tracking system should be indoors. The system's wiring should be at least 12 inches away from all other wiring. Temperature range of operation is expected to be approximately between 31 -150 degrees Fahrenheit.
Do not operate the reader within 36 inches of a computer CRT terminal.