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Electronics
Out of the Blue's electronics consist of two systems: power and drive systems, and sensor systems. The electronics were designed to be modular and easy to repair.
Sensor input and other and signals are routed to the controller used with the robot, the TINAH board, via a battery harness. Every sensor input and motor output plugged into the battery harness before being routed to the TINAH board, to make switching TINAH boards easier, and to facilitate using battery power, as opposed to the TINAH board's limited power supply.
To navigate the arena, reflective and touch sensors were used. Touch sensors on the sides of the robot determined whether or not the robot was in contact with a wall, and QRD 1114 reflectance sensors placed at regular intervals on the bottom of the chassis determined whether or not the robot was on top of the electrical tape laid on the white-painted arena. Given that these sensors were placed near the front of the robot, and the TINAH board near the back, these sensors plugged into a small board which output the signals via a ribbon cable.
The reflectance sensors output an analog signal, as opposed to a digital one. The routing board featured four comparator circuits, from which it draws its name. The voltage to which the signals are compared can be adjusted by turning a knob.
Sinusoidal infrared signals with varying frequencies indicated the presence of targets or the collection area. These were detected with filter circuits. To promote ease of debugging and repair, the circuit was composed of several, smaller, circuits.
- Infrared detection
- DC filter
- Amplification
- Frequency filtering
- Peak detection
These circuits were encased in grounded metal containers to reduce noise in the circuit. Two were used: one to detect the 10kHz signal of the target collection area, and one to detect the 1kHz signal of the targets.
Out of the Blue ran off of one 16V and 2 8V lithium-polymer batteries. The 8V batteries were used exclusively for sensors: powering circuits and providing threshold voltages. The 16V battery was used to power the motors and servos used to move the robot. When it was important that voltages stay constant (threshold voltages, etc.) voltage regulators were used. In order to produce the positive and negative 5V signals needed for the filter circuits, heat-dissipation voltage regulators were used. However, for the 5V signal required for the servo outputs, a PWM regulator was used: regulating from 16V to 5V using a heat-dissipation regulator was inefficient, and outside of the operating range of the regulators provided.
Out of the Blue used four motors and three servos: one motor for firing, one motor for ball collection, one servo for lifting balls to firing, and two servos and two motors for the drive system. The TINAH board provided motor output signals in the form of PWM signals. The motors used for firing and collection were only required to run in one direction, so MOSFETs were used to control them. The drive motors, however, were required to run in two directions, so H-Bridge circuits were manufactured. Taking in power from the batteries and the signal from the TINAH board, the H-Bridge circuits allowed the motor to rotate clockwise and counter-clockwise, driving the robot backwards and forwards.