Senior Design: Recycling Robot
Purpose:
In order to graduate from engineering, an FSU student must pass a two semester long senior design class. This course allows the student to apply all the knowledge acquired during their degree into building something functional. The student also gains managerial, systems design, and presentation skills.
My team and I built an autonomous robot, as stated by the IEE SouthEast Con 2009 rules. The purpose was to locate, sort and appropriately store five aluminum cans, three plastic bottles, and two glass bottles. The robot was to travel on an Astroturf playing field, with a modulated RF signal representing an invisible fence. The robot had to navigate the field with the help of sensors, a microcontroller, and a drive system.
After completion, each of the 8 groups in the class competed against each other, with my team placing 3rd. I was the team manager, in charge of delegating tasks among each member, and also in charge of all the sensors on the robot.
Design:
- • The collection device was designed to resembled a hand to offer more grip on the object.
- • To avoid wiring faults, we designed and etched our own PCBs (printed circuit boards) instead of using breadboards.
- • The data from the motor encoders was used to tell the MCU exactly how far each wheel had been displaced.
- • Our ideas were kept simple to diminish the amount of error.
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Construction:
The body kit was pre-made out of aluminum and lexan panels. The arm, adopted from a smaller gripper model, was made out of plexiglass and nylon standoffs. Custom made plastic bags were used to store the containers being collected.
System Breakdown:
Power: The MCU is powered by one custom-built 14V Li-Ion battery pack. Two 9V batteries power the RF detector, while two 7.2V Nickel-Metal Hydride batteries power the rest of the robot.
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Drive: Two 7.2VDC, 30:1, 291 rpm (6mm shaft) gear head motor were used in the front. A sabertooth motor controller allowed for independent speed and direction operating modes.
Sensors: Four FRS05 ultrasonic sensors were placed around the robot to detect objects. Two FSR (force sensing resistor) sensors were used to determine the object type. Two RF detectors were used to detect the modulated signal designating the robot's peimeter.
Lifting Mechanism: The humanoid gripper was constructed with three degrees of freedom. It's opening and closing motion was controlled by a servo.
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Microcontroller: The Wytec miniDragon+ Freescale HCS12-based development board was used to implement the robot's functions.
Conclusion:
Building a robot for the first time was fun and rewarding. During test runs, the robot picked up about 75% of the objects on the field, and appropriately sorted them 67% of the time.
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