At the beginning of the track, our robot has to pass through an armed door, that indicates whether it is armed or disarmed through the use of an IR signal at different frequencies. An IR signal at 10kHz indicates that the door is disarmed, thus allowing the robot to pass through without triggering an alarm. Any other frequency denotes the door is armed. While it would be very simple to feed the signal from a QSD (IR signal detector) sensor into the TINAH board and allow the microprocessor to determine whether or not a 10kHz is available, we had a limited number of analog input pins. Therefore, we constructed an IR signal filter and detection circuit to provide either a logical high signal for a 10kHz signal and a low signal for all other frequencies

The circuit consisted of the following components

1. Signal amplifier - since the signal source is far away, we would need a strong signal to process. We used a differential amplifier with a negative feedback loop to achieve this.
2. Signal filter - using a band pass filter constructed of both a high pass filter and a low pass filter, we ensured that the range over which the dB/dec roll off was narrow enough to only recognize a 10kHz signal as an input.
3. Peak detector - Based on the signal of the output wave, we designed a peak detector to generate a digital signal from an analog sine wave that could be fed into the TINAH board as indication of a 10kHz sine wave.

QRD1114 Sensors were used to detect the black tape placed along the track. They provided guidance for the robot. Four QRD sensors were closely integrated together to assist in the PID control system. They indicated if the robot was just to the left, just to the right, far to the left or far to the right of the track based on what the QRD sensors had detected and the state of the QRD readings in the previous sampling.

The QRD sensors were placed facing down on a sled at the front of the robot. Because the center of mass of the robot was located near the back of the robot, this made it easy for the robot to identify when it needed to turn at junctures along the track.

Our microcprocessor, the TINAH board is loosely based off the Wiring board and uses Arduino (.ino) and C++ coding. Naturally, we utilized the Arduino IDE along with GitHub for source code control.

The main source of our code is divided into two components - one that handles tape following based events, such as identifying the location of the tracks as well as identifying where the agents are placed, and a second component that handles other robot actions, such as diverting attention to the signals from the beacons, operating the claw and driving to the zipline. All of the source code is located in this repository

The TINAH board was the main processing head for our robot that controlled the functions of driving, arm maneuvering, QRD analyzing, and QSD monitoring. Some of the key features of the TINAH board were

1. The TINAH had 6 analog pins while the rest of the pins were used for digital signals
2. Has the capacity to drive motors that do not require as much torque or power
3. Has dedicated inputs to operate servo motors
4. Is tolerant to being powered by sources ranging from 9-16V

Among other things, further details about the TINAH board can be found here

The implemented drive system used by our robot was based on PID control in C++. The QRD1114 sensors provided the input data that would determine the position of the robot with respect to the taped line, and state memory was conserved to identify the location of the robot with respect to the line in the prior sampling. THe QRD's were sampled frequently to determine an "error" between where the robot was supposed to be and where it was. This would then gradually alert the motors to turn back onto the line of the tracks.

The drive system was also used to identify the location of the agents in the containment. Each of the agents were situated on a platform inside a circular containment filled with the water. Normal to the tangent line of where the agents were located was a vertical taped mark. These taped markings were wider than the regular track tape, thus indicated that an agent was located at that point. Determining this point and ensuring the arm (located at an offset from the QRD sensors) could reach the agents was an intended function of the drive system.

Drive system code can be found located in this repository file