Robot Arm Employing Slave-Master Control System
To the left is the playing field used in the robot arm competition during the 2016-2017 school year. Note that an additional stack of 10 pennies is in the upper right hand corner of the field, but is hidden here behind my partner, who did not help me build the robot, but helped me control it during the state competition. The goal of the competition is to create an apparatus that moves stacks of pennies, initial heads-side up, as closely consolidated to the center of an archery target as possible. One receives the most points for placing pennies in the center, and fewer points for each annulus radiating outward. One also receives double the points for each penny flipped to tails, but no points for any overlapped pennies.
Early Stages
This is one of the first times I tested the robot's control system. The mechanism that I am moving is an "avatar," or the "master" part of the "slave-master" system. Its skeleton is made of wood, and each joint is a 10k ohm potentiometer. Note this is very early in the fabrication process; the range of motion for the servos does not exactly correlate to that of the pots.
Vacuum Wand End-Effector
Here is one of many attempted end effectors: the vacuum wand. It is shown here picking up a penny. Though I loved the elegance of this design, it was far too slow to process all 50 pennies in 3 minutes. I am controlling the vacuum force using a single-pull double-throw switch which actuates two solenoids. One solenoid controls the flow of a vacuum from an accumulator and vacuum pump; the other opens to the air, which acts as a vent.
Vacuum Control Board
The picture to the right shows the board used to control the vacuum end effector. A single pull double throw switch (not pictured) was used to control the vent and vacuum solenoids (2 and 5, respectively).
1. Vacuum power (7.2 V at 3000 mAh)
2. Vent Solenoid (corresponds to NO)
3. Vacuum pump
4. Accumulator
5. Vacuum solenoid (corresponds to NC)
6. Lead that connects to vacuum tube which runs up the side of the robot arm to the end effector. This split in the tubing was put in place in order to make transportation of the entire device easier.
Robot with Vacuum Wand
Depicted is the entire robot with the vacuum wand end effector. The white circle points out the wand itself.
Clamshell with Penny Ejector End Effector
The right picture depicts one of my many designs for the end effector of my robot. However, reliability was a problem, and it could not place the pennies close enough together to position them in the target area. I did not end up using this design for my final robot; it was far too intricate and volatile.
1. Steel clamshell to encapsulate pennies
2. Clamshell servo, which opens and closes the clamshell
3. Microservo which serves to eject pennies one by one
4. Servo which serves to turn the entire mechanism 180 degrees in order to flip the pennies from heads to tails and receive bonus points.
5. Wrist servo, which is not a part of the mechanism, but rather is used to make slight adjustments to the position of the end effector to optimize the precision in depositing the pennies onto the playing field. A short video of this mechanism working is included next in the portfolio.
Functioning Clamshell/Penny Ejector End Effector
Shown here is the clamshell and penny ejector end effector working.
Simple Clamshell with Ring End Effector
This end effector is the final product and was used on my robot for my last competition at state. The clamshell was used to encapsulate and flip over the stacks of pennies, then dump them over the center of the target. The ring was used to smooth over and consolidate the pennies around the center of the target so that none are overlapping and as many points as possible are received. The simplicity of this design made it by far superior to the others. This is because its elegance made it efficient and easy to work with. Moreover, there was less work needed to maintain this design. This was especially helpful in eliminating stress on competition day.
1. Plastic clamshell
2. Clamshell servo
3. Flipping servo
4. Plastic ring with weight, which made functionality easier
State Competition Using Simple Clamshell with Ring End Effector (2017)
This video shows my run from the state competition for Robot Arm for my junior year. The last week before the competition, I found I would move faster if I had someone to help me operate the robot. I recruited by friend Jenna to control the clamshell pot, which made her responsible for encapsulating and releasing the penny stacks. I controlled every other aspect of the robot. The clamshell first encapsulates a stack of pennies, moves it over the center of the target, and then dumps them out, leaving them tails and worthy of bonus points. The ring is then used to smooth out the pennies so that none overlap (if they do, no points are received for either pennies). It is also used to consolidate the pennies around the center of target in order to receive maximum points. This run placed me second in the state.
Robot with Claw End Effector (2015)
Included are some segments from a competition from my Sophmore year. The goal for this competition was to move lego bricks, pencils, and ping pong balls into egg cartons; moreover, we were to flip dice to an even number. The easiest way to complete these tasks was to use a claw that simply opened, closed, and could be tilted slightly up and down.