Laboratory 4: Hardware Analysis & Synthesis
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Transcript of Laboratory 4: Hardware Analysis & Synthesis
Laboratory 4:Hardware
Analysis & SynthesisGeneral Engineering
Polytechnic University
OVERVIEW
Objectives Review Reverse Engineering Forces Gears Gear Trains Materials for Lab
Procedure Written Assignment Recitation Topics Closing
OBJECTIVES
Review the concept of sketchingUnderstand the concept of “reverse
engineering”Learn about the importance of torque & gears Use your new knowledge to find out how a
device works
REVIEW
Orthographic vs. Isometric ViewsSketching Rules
REVERSE ENGINEERING
Begins with the intact product– Works through the design process in the
opposite direction
Used to understand: – How products are made by other companies– The quality of the product
FORCESForce = m * a
Torque - French for “twist” - A twisting force = F * l
l1 l2
F1 F2
m = mass (lbs. or kg.)a = acceleration (ft/s2 or m/s2)F = Force (lbs. or Newtons)l = Distance from force to
point of rotation (ft. or m) = Torque (ft-lbs. or newton
meters)
If F1=F2, but l1<l2, the right side of the beam will tip down, due to unbalanced torque.
Equilibrium: 1= 2 F1*l1 = F2* l2
TORQUE OUTPUT OF GEARS
Small force (F1) used to lift large weight (F2)
Penalty for increased torque– small gear turns
through larger angle than large gear
F1
F2
R1 R2
– indicated in ratio of revolutions/second (gear speed) in equation: F1 * R1 = F2 * R2 (1 = 2)
GEARSUsed to increase/decrease torque or speedTorque and speed inversely proportionalVelocity ratio equals inverse of gear ratio
Output = the destination of the rotation
(e.g. a wheel)Input = the source of the rotation
(e.g. a motor)Velocity Ratio =Input
Output
Gear Ratio =OutputInput
TYPES OF GEARS
SPUR GEAR: gear wheel having radial teeth parallel to axle
CROWN GEAR: gear wheel with teeth set in rim perpendicular to its plane
crown gear
TYPES OF GEARS
IDLER GEAR: gear between two other gears to transmit motion from one to other– Changes direction of rotation – No effect on ratios– ODD number of gears
First & last gear rotate in same direction
– EVEN number of gearsFirst & last gear rotate in different direction
idler gear
SIMPLE GEAR TRAIN
Output
Input
Velocity Ratio
1” 2” 4”
n1
n2n3
2
1
4
2
4
1 *
n
n
n
n
n
n *
1
2
2
3
1
3
Gears with the same size teeth, ratio equal to ratio of number of teeth (n) on each gear.
COMPOUND GEAR TRAIN
Output
InputVelocity Ratio
n
n*
n
n
n
n1
2
3
4
5
6* n
n 7
8*
n1
n2 n5
n6
n3n4 n7
n8
Angular velocities of all gears are equal to that of the shaft on which they are mounted
MATERIALS FOR LAB
WAO II Robot– Model MV-961
– OWI Incorporated
– 2 Portions• Mechanical /
Electrical
• Computer
Toolbox with 17 tools
PROCEDUREExamining the Robot
– Inspect the intact robot
– Record the appearance of the robot
– Include sketches of the robot, complete with the outside dimensions
– Hypothesize how the robot works (Try not to look at the bottom of the WAO II)
Examining
Disassembling
Understanding
Reassembling
PROCEDUREDisassembling the Robot
– After you instructor signs your hypothesis & sketches, obtain a toolbox, complete with tools
– Take apart the robot. Do NOT break it
– Record what you see as you take the robot apart
– Sketch the inside of the robot including the gear train. Be sure to label
Examining
Disassembling
Understanding
Reassembling
PROCEDUREUnderstanding the Robot
– Describe the different components that make up the whole device
– Record the functions of the individual major parts
– Learn how the Power Gear Linkages allow:• Rotation on the axis located in the center of the
robot
• Turning (rotation outside the axis)
• Translation (movement in a straight line)
– Determine the Gear Ratio for the train of gears that link the motor to the wheels
Examining
Disassembling
Understanding
Reassembling
PROCEDUREReassembling the Robot
– Reassemble the device to working order
– Refer to the WAO II manual for assistance (disregard the sensor portion of the manual)
– Return the assembled WAO II to the box and give it to you instructor
– Record any further observations, including improvements to the robot and assembly instructions
Examining
Disassembling
Understanding
Reassembling
WRITTEN ASSIGNMENT
Use the form report on Page 55 to complete the lab report (Be sure to type out your answers on a different piece of paper)
Include original sketches with the instructor’s initials
Remember to create a title page
RECITATION TOPICS
Explain how the device works Discuss components of the WAO II and their
functions How do the parts fit together? Discuss the overall construction of the device Discuss the assembly instructions for the WAO II.
Are they clear? If so, explain what is clear. If not, what changes would you make to the assembly instructions?
Discuss you findings for the gear ratio.
CLOSING
Be sure to label your sketchesAvoid breaking partsKeep track of the pieces