ME 2110 – Studio II 1 of 12

Georgia Institute of Technology George W. Woodruff School of Mechanical Engineering

ME 2110 - Creative Decisions and Design

Spring 2012

STUDIO II

MACHINING & MECHACTRONICS PROJECT: ANGRY BIRDS© LAUNCHER

In order to successfully design and build a product, you must understand the capabilities of the tools and supplies at your disposal. For example, you must understand how motors and sensors work. Furthermore, you must have knowledge of manufacturing processes, such as machining with milling machines and lathes. This project will help you develop an understanding of the supplies and manufacturing processes available to you in ME 2110. Your goal is to build a pneumatic-powered launcher that shoots Angry Birds to knock down pigs that have stolen their eggs. The launcher will be controlled by the ME 2110 controller box. You will be assigned a group that will share the supply kit. Due to this and the fact that there are a limited number of machine tools available in the lab, your section will be split into two sub-groups, Group A and Group B. This studio is pass/fail. You must complete the assigned tasks to pass the course.

Week 4 in Studio (1/31-2/3) Group A:

In Week 4 of the semester, Group A will learn how to program the controller box, as well as use the sensors and actuators in the supply kit. You will have to connect and program the mechatronics to complete the tasks found in Mechatronics Lab Tasks: Group A in the Mechatronics Section of this document. You will have to demonstrate proper execution of the tasks to your Studio Instructor or TA. They will sign your assignment sheet, indicating the tasks have been completed.

Group B: In Week 4 of the semester, Group B will learn how to use the tools in the machine shop. An instructional seminar will take place in the lab in which the TA will instruct the group on proper lab safety, tool checkout procedures, and proper use of all of the lab tools. You will then begin to construct a pneumatic launcher. To do this, you are provided a detailed process plan and mechanical drawings for the device, located in the Manual Machining Section of this document, and you will receive plastic (Delrin) workpieces from which you will construct your launcher.

Week 5 in Studio (2/7-2/10) Group A:

In Week 5 of the semester, Group A will move on to the machining section of the project. They will undergo the same machining seminar as Group B and receive their own plastic workpieces.

Group B: In Week 5 of the semester, Group B will learn how to use the supply kit. They will complete the Mechatronics Lab Tasks: Group B found in the Mechatronics Section of this document.

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Week 6 in Studio (2/14-2/17) In Week 6 of the semester, you will work on whichever parts of the project that you need to complete. You will also need to use the ME computer cluster to create a drawing for a nametag for your final competition machine. This task is detailed in the Automated Machining Section of this document.

Outside of Studio (1/31-2/24) In addition to doing work inside your scheduled studio time, the lab will be open for other periods of time throughout the week. These are known as “Open Lab.” Any ME 2110 student may use either of the ME 2110 rooms during Open Lab. The Open Lab schedule is posted on the ME 2110 website. Due to limited time during scheduled studio, you will need to utilize Open Lab to complete your deliverables.

Week 7 in Studio (2/21-2/24) By Week 7 of the semester, you will have completed your pneumatic-powered Angry Birds launcher and gained sufficient knowledge of the supply kit to compete against other students in your studio to determine who can score the most points with the best combination of accuracy and distance. Figure 1 shows a schematic diagram of the competition setup. You will get three Angry Birds to shoot at pig targets whose distances range from 15-24 feet away. You must secure your device using the provided vice with adjustable launch angle. The vise is designed to fit into the channels on your launcher Baseblock. Note that you must share your computer controller and the pneumatic supplies with the other members of your team. The objective is to knock the pigs from their foam blocks such that they hit or are touching the ground. Each successful pig destruction is worth 10 pts. You get three shots at the same setup. The pigs are not reset in between shots.

Figure 1 – Angry Birds© Competition Setup (not to scale)1,2

Controller Box

Air Tank

Valve

15’

10  pt.  each  

12’’

Vice (provided)

Individual Launcher

19’

24’ 20’

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Deliverables Table 1 shows the deliverable schedule for this project.

Table 1 - Deliverables for Each Individual for Next Three Weeks of Studio Group A Group B

Deliverables due at the Beginning of Studio in Week 5

(2/7-2/10)

- 3 completed and signed Mechatronics Lab Tasks: Group A - 1 machined plastic component

Deliverables due at the Beginning of studio in Week 6

(2/14-2/17)

- All 5 completed and signed Mechatronics Lab Tasks: Group A

- 1 machined plastic components

- 3 completed and signed Mechatronics Lab Tasks: Group B

- Both machined plastic components

Deliverables due at the Beginning of studio in Week 7

(2/21-2/24)

- All 5 completed and signed Mechatronics Lab Tasks: Group A

- Both machined plastic components - 1 Drawing for a Nametag

- All 5 completed and signed Mechatronics Lab Tasks: Group B

- Both machined plastic components - 1 Drawing for a Nametag

References 1. “Enemy Behind the Sticks and Stones”. Angry Birds Online. http://www.angrybirds-

online.info/category/angry-birds-information/. Accessed 1/11/2012. 2. “Angry Birds Pig Who Likes Them?”. Angry Birds Online – We ♥ Angry Birds Rio & Seasons.

http://www.angry-birds-luv.com/angry-birds-pig-who-likes-them/. Accessed 1/11/2012.

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Mechatronics Section This lab will provide experience with integrating electrical, mechanical, and pneumatic systems. The lab is broken down into two weeks. During the first week, Group A of your team will complete part of the lab; the second part will be completed by Group B during the second week. Although the programming style will not be graded, the code written during these two labs should be helpful in developing the code for the final project. Therefore, it is important to program using a standard structure and adequately comment the code so the program will be easy to follow when referred to later on. The suggested format for your code is: • Constants Table • Program Variables • Main Program • Subroutines Before attempting to perform these programming tasks, it is helpful to read through the Mechatronics Kit Manual and Pneumatics Manual which are available on the website. These should provide a good background to the layout of the controller box and how to implement the electro-mechanical-pneumatic components in a design. This project has two checkpoints: at the beginnings of Week 3 and Week 4. At that time, each student is responsible for showing progress through the assignment as indicated by a signed task checklist. The task checklists for Group A and Group B are provided in the subsequent pages. After each task is completed, have the professor or TA initial the checklist to verify that the program works. Remember that each individual needs separately signed checklist. Feel free to ask the professor, TA, or peers for help in completion of this assignment.

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Mechatronics Lab Tasks: Group A, Name:__________________________________________ 1. Have the DC Motor run for 2 seconds, stop for 2 seconds, run for 2 seconds, etc. 2. Connect a microswitch to P0 (START) and have the DC motor run at full speed when the switch is held down and turn off when the lever is released.

Hint: Connect the microswitch to P0, read in the value of P0 when the lever is pressed and the value of P0 when the lever is released. The variable name corresponding to P0 is IN0 (it does not have to be defined).

Note: This is what will happen during the competition. The machines will begin when the circuit on P0 is shorted (lever is pressed) and will stop when the circuit is opened (lever is released).

These couple lines of code will be very important in your final design project.

3. Connect two microswitches and the pneumatics. The program starts with the cylinder retracted. When one switch is pressed, the cylinder should extend and remain extended after the switch is released. When the other switch is pressed, the cylinder should retract and remain retracted. This process should run indefinitely. 4. Connect two solenoids and two microswitches. When one microswitch is pressed, one solenoid is activated for 2 seconds and then release. When the other microswitch is pressed, the other solenoid is activated for 500 ms and then release. When one actuator is active the other cannot be activated. 5. Same as #4, only now the other actuator can be activated when the other is active.

Hint: Put a short pause in the program loop and assume that the time through the loop is equal to the length of the pause. You’ll know when to turn off the actuator by counting the number of times through the loop.

Checklist for Group A: 1. __________

2. __________

3. __________

4. __________

5. __________

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Mechatronics Lab Tasks: Group B, Name:__________________________________________ 1. Connect the stepper motor and the DC motor. Make them run clockwise for five seconds, stop for 2.5 seconds, run counter-clockwise for five seconds, and then stop for 2.5 seconds. Repeat this sequence five times. 2. Perform the same act as #1, but always have the stepper motor and the DC motor rotating in opposite directions. 3. Connect the IR distance sensor and one stepper motor. Have the motor run if the reading > 128 and have the motor stop if the reading <127. Put a two-second pause between distance sensor readings. 4. Connect the encoder and have the DC motor run at full speed when the encoder is being rotated and stopped when it is not being rotated. 5. Connect the encoder and the pneumatics. When the encoder is rotated 5 complete revolutions, the actuator should extend and remain extended until the encoder is rotated 3 complete revolutions. The cylinder should only extend 4 times and then remain retracted regardless of how many times the encoder is rotated. Checklist for Group B: 1. __________

2. __________

3. __________

4. __________

5. __________

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Manual Machining Section Pneumatic Angry Birds© Launcher In the machining section of this project, you will build the components for your pneumatic launcher. A sketch of the launcher assembly is shown in Figure 2. Detailed step-by-step directions along with mechanical drawings for the components are given on the last few pages of this handout. It is suggested that you use both to correctly machine your parts.

Figure 2 – Isometric Exploded and Assembled Views of Pneumatic Launcher

Fitting from Pneumatic Actuator

Barrel

Baseblock

Barrel screws into Baseblock

Adapter screws into Baseblock

Channel in Baseblock for Vise

Arm

Slot for Nametag

Attachment

ME 2110 – Studio II 8 of 12

Automated Machining Section Acrylic Nameplate In addition to machining the plastic parts for your pneumatic launcher, you will also create a drawing for an acrylic nameplate that you can mount on your final competition device. This nameplate will be cut out of acrylic sheet using the laser-cutting machine. Here are some tips and suggestions on constructing your drawing:

Drawing a Nameplate for Laser Cutting: 1. This task is most easily done by creating a 2-D drawing in AutoCAD of the nameplate profile. 2. The outline of your nameplate does not have to be rectangular, but the design must fit inside a

2”x1” rectangle. 3. For lines that you want to cut completely through the material, the color of the line should be

changed to red, and the thickness of the line should be changed to 0 mm. 4. For areas that you want to etch (cut only part-way through the material), the fill color should be

black. The area outline color should also be black. 5. Once your nameplate is finished, save it as a .dxf file. Make sure the file name includes your full

name and you section letter. Email the file to your TA to complete the deliverable. 6. Figure 3 shows a 2-dimensional nameplate designed in AutoCAD, and the resulting acrylic

nameplate that will be produced on the laser cutter.

Figure 3 – Nameplate AutoCAD Drawing and Resulting Acrylic Product

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Suggested Process Plan for Pneumatic Launcher Barrel: 1. Obtain nominal 3.2” length of round 1” diameter Delrin stock.

2. Face one end on the lathe to make it perpendicular to the axis of rotation.

3. Flip the piece over and face the other end, leaving the final length of 3.00”.

4. Turn down 0.40” length of the stock on one end to a diameter of 0.50”. Use multiple axial paths with

approximately 0.05” radial depths of cut per pass.

5. Mount the tailstock onto the lathe. Chuck the small center drill into the tailstock Jacobs chuck. Use

the center drill to start a centered hole in the end of the workpiece.

6. Replace the center drill in the tailstock chuck with the 19/64” drill bit. Use the tailstock and drill bit

to drill a 0.297” diameter hole through the entire workpiece. The drill may need to be advanced and

retracted multiple times to clear machining chips from the drill flutes.

7. Use the ½-20 UNF die to cut external threads on the 0.5” cylinder of the workpiece. The shared die

is located on the drill press bench and has red-taped handles. Use the vice located on the same bench

to hold the workpiece. Be sure to apply constant downward pressure on the die handles as you turn

it. Ask the TA for assistance since this is not trivial.  

8. Use the 1/8” endmill to cut a slot 0.125” deep along the axis of the barrel. The slot needs to start

from the bore end and have a total length of 2.40”.  

Suggested Process Plan for Pneumatic Launcher Baseblock: 1. Obtain the nominal 2.4” piece of square 1” Delrin stock.

2. Using the mill, endmill one end of the workpiece to make its face perpendicular to the longitudinal

axis of the block.

3. Then, endmill the other end of the block to a total length of 2.00”.

4. Next, facemill channels on opposite sides of the block. The channels should be centered along the

length of the block and should be 1.00” wide. Machine the first channel to be 0.125” deep, flip the

block over, and machine the other channel such that the thickness between the channels is 0.75”.

5. Now clamp the workpiece on end. Use a center drill to start a hole in the center of one end face.

6. Next, use an 8.50mm drill bit to drill a centered hole the full length through the block. Do this on the

large drill press. Use a backing material under the workpiece to avoid drilling into the vise itself.

7. Next, use a 29/64” drill bit to drill a centered hole 0.70” deep into one end of the block.

8. Using the large tap wrench and ½-20 UNF plug tap, cut internal threads on the inside of the 29/64”

hole.

9. On the other end of the block, use the large tap wrench and M10x1 plug tap to cut internal threads

on the inside of the 8.50 mm hole.

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MACHINE SHOP SAFETY

ALWAYS WEAR SAFETY GLASSES • Even when you are not working on a machine, you must wear safety glasses. A chip from a machine someone else is working on could fly into your eye. MACHINING • Follow directions. If you don’t know how to do something, ask. • Before you start the machine:

• Study the machine. Know which parts move, which are stationary, and which are sharp. • Double check that your workpiece is securely held. • Remove chuck keys and wrenches.

• Do not leave machines running unattended. • Clean up machines after you use them: a dirty machine is unsafe and uncomfortable to work on. • Do not use compressed air to blow machines clean. This endangers people's eyes and can force dirt into machine bearings. • Report all broken or non-working machines. CLOTHING, JEWELRY, AND HAIR • Wear long pants (to your shoes). • Wear short sleeves or roll up sleeves. • Wear closed toe shoes and socks. • Remove all jewelry - watches, bracelets, rings, necklaces, dangling earrings. • Long hair or beards must be tied back. • If your hair is caught in spinning machinery, it will be pulled out if you're lucky. If you are unlucky, you will be pulled into the machine. • No ties, scarves, and dangling clothes. SAFE CONDUCT IN THE MACHINE SHOP • Be aware of what's going on around you. • For example, be careful not to bump into someone while they're cutting with the bandsaw (they could lose a finger!). • Concentrate on what you're doing. If you get tired, leave. • Don't hurry. If you catch yourself rushing, slow down. • Don't rush speeds and feeds. You'll end up damaging your part, the tools, and maybe the machine itself. • Listen to the machine. If something doesn't sound right, turn the machine off. • Don't let someone else talk you into doing something dangerous. • Don't attempt to measure a part that's moving. • No fooling around. VIOLATIONS OF THESE RULES WILL RESULT IN IMMEDIATE EJECTION FROM THE MACHINE SHOP.