CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures Step-by-step procedures 1. In this lesson, you will learn the basics of pneumatics by constructing a simple

testbed. Note that this testbed will be used with a bicycle air pump as a pressure generator. It can be used with a powered generator by removing the tire pump fitting (lower left in the picture), and attaching the powered generator directly to the on off switch. Materials Needed: 1.An air pressure regulator 2.An InnovationFirst Pneumatics Kit 1, currently (5/2008) available at http:// www.vexrobotics.com/vex-robotics-pneumatic-parts.shtml. (Other parts may be substituted.) 3.A bicycle pump or other air pressure generator. 4.A Vex microntroller 5.Vex remote control (with frequency crystal matching the crystal in the Vex controller in the testbed) 2. Open ROBOTC

Select File/Open Program. Browse to Curriculum Programs. Open pneumatic_control.c Click the Download Program button to download the program.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 3. Begin with a blank testboard.

4. Place the tire pump fitting.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 5. Place the on/off Switch.

6. Place the air pressure regulator.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 7. Place the reservoir.

8. Place the “T” fitting.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 9. Place the first solenoid.

10. Place the first air push, spring return cylinder.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 11. Place the second solenoid.

12. Place the second air push, spring return cylinder.

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CURRICULUM ADVANCED APPLICATIONS / Pneumatics / Procedures

STUDENT

Pneumatics Procedures 13. Place the Vex microcontroller, receiver, battery pack, and transmitter.Attach the

solenoid drivers (the wires attached to the solenoids) to analog/digital ports 3 and 4. Finally, attach a tire pump to the tire pump fitting. You will want to get the gauge up to at least 20 PSI or so, then turn the blue knob on the on/off switch to horizontal to keep the pressure in the system. Click “Pneumatics Operation Video” under Lesson/Multimedia to view a video showing how to operate the testbed. After turning both the remote control transmitter and the Vex controller on, you should now be able to make each of the two cylinder arms extend by pressing on the two highest yellow buttons (channel 6 and channel 5) on the back of the remote control transmitter. 14. Answer the questions below on the “Checking for Understanding” quiz. Assume

the area of a cylinder arm in contact with compressed air is a circle 2” in diameter, and ignore the effect of frictional forces. 1.If the air pressure is 30 PSI, how much force will the extending cylinder arm have in pounds? 2.How much is 30 PSI in Newton/(meter)2 3.How much is 30 PSI in bars? 4.How much is 30 PSI in millibars? 5.How much force will the extending cylinder arm described above have in Newtons? 6.If the air pressure is increased by 50%, by what fraction will the force of the cylinder arm be increased? 7.If an extending cylinder arm exerts 2/5 less force than the cylinder arm in question 1, how much less air pressure will there be in this system? What is the name of the law that determines this answer? 8.How much pressure will the system in question 7 have in millibars? 9.If the temperature of the air in the system described in question 1, above, were to increase by 12.5%, by what fraction would the pressure increase or decrease? (Specify whether it would increase or decrease). What is the name of the law that determines this answer? 10.If you multiplied the pressure and volume of any system, then divided it by temperature, would it equal the pressure and volume of any other system divided by the temperature, assuming you used the same units? What is name of the law that determines this answer? 11.If you want the cylinder arm described in question 1 to exert a force of 300 pounds, how much pressure in PSI would have to be in the system? 12.If a pneumatics system has a pressure of 50 millibar, how much force would the cylinder arm described above produce in Newtons? How much in pounds? 13.If you substituted a cylinder arm with a pressured surface that was circular and 1” in diameter for the cylinder arm described above and kept the pressure the same, what would be the ratio of the the force exerted by the extension of the two cylinder arms?

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