Electrical

Electrical Schematics

SEAL utilizes two PIC32s, where one acts as the leader (PIC 1), and the other acts as a follower (PIC 2).

Leader/Driver PIC32 (PIC 1)

The Leader PIC32 operates as the brain of the robot, controlling the two wheel motor drivers, getting input from encoders, ultrasonic sensors and button, and an on/off indicator LED.

It also connects to the Follower PIC via SPI, for inter-microprocessor communication. It sends servo and trigger motor commands and switches on the IR sensor in the follower.

Follower PIC32 (PIC 2)

The Follower PIC32 gets inputs from reflectance (tape) sensors, IR sensor and limit switch, and controls the servo motor and launch/trigger motor.

It also connects to the Leader PIC via SPI. It sends information from its sensors and switches to the leader.

One encoder for each driver motor helped in precise control of the motors.

There are 2 Servo motors connected to the Follower PIC. The yard servo shows what YARD the robot is in (Karl or Ed). The arm servo controls the arm.

TLE 5206s and the PCB boards were used to drive the motors. Output was directly connected to the DC motors and the input signals were controlled by Driver PIC32 with output compare (PWM) and directional information (digital). The third motor is the launch motor, which triggers the launch mechanism.

Two ultrasonic sensors attached to the front of the robot help it to align with the wall. One trigger pin sends a pulse to each sensor, which is received by each Echo pin. A voltage divider helps to reduce the output voltage from 5V to 3.3V.

Three reflectance sensors are attached to the front-right, front-left and right of the robot's base to detect black tape on the ground. It is used to keep our robot aligned with the tape during the robot's translation and lane change phases.

Universal Signal Conditioning Board

The beacon signal conditioning circuit consists of a photo-transistor to detect IR light emitted from the four beacon towers. The signal will go through two amplification stages, a high pass filter as well as a low pass filter to create a band-pass filter. This filter accepts all 4 frequencies of the beacons in the challenge.

The signal will then go through a comparator circuit with hysteresis to convert it into a clean digital signal.

The voltage reference generator is within the signal conditioning board. It provides a 2.5V reference voltage for the comparator in IR circuit.

The button, when pressed, starts the robot. The LED, which is built-in, lights up when the robot is on, and switches off when the 2min 18s game timer ends.

The limit switch helps to control the launch motor with the help of the cam. It switches on when the launch trigger is ready, and then switches off when an ACORN is pushed.

Pin Management

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