QUIZ PREP

Have Quiz sheet ready. Title = QUIZ 8
Lab
Day/Time Section
Section
Lab Day/Time
Number
» Name (L, F, MI),
Number
Mon. 1:00
8
» Today’s date 10/9/12, Mon.
1:00
8
Mon. 3:00
9
Mon.
3:00
9
» Lab day , time
Wed. 1:00
10
Tue. 2:00
36
» section number
Wed. 3:00
11
Lab Day/Time
Section
Number
Monday, 1:00
8
Monday, 3:00
9
Wed., 1:00
10
Wed, 3:00
11
Friday, 1:00
Wed.
1:00
Thu. 2:00
12
10
29
Wed.
3:00
Fri. 1:00
11
12
Thu. 2:00
35
Fri. 1:00
12
1
Announcements
First professional memo due today in
lecture. Submit when called for.
 The preliminary design report is due at the
beginning of your Week 10 lab mtg.
 The final design report is due at the
beginning of Week 13 lab.

2
Design Reports: Audience
Design reports: Target audience is a busy
technical manager, not …
 Dr. Roppel
 Your GTA
 Mom
 Team members
 General public

3
Design Reports: Audience
Characteristics of your target audience:
 Very limited time to comprehend your
results. Can’t / won’t dig through fluff.
Make results jump off the page.
 Technically savvy, but not familiar with
your project details (you must suspend
reality here to get it right – role playing).
4
Scores on Canvas
Check your scores on Canvas
 If they are not right or not posted after two
weeks, check with your GTA.
 If you still need help, email me or see me in
person.
 All memos graded at same time, even if you
submitted early.

5
Announcements

Format and grading rubric for the Design
Reports are on the class website and
syllabus.
6
Announcements

Each TEAM bring the following to lab this
week:
» Motor control board
» Transmitter/receiver pair (check batteries –
voltage should be above 10.0 V).
» Two motors
» R1 and R2 that will give you 10 to 12 V.
7
Resistors
Can use resistors in lab for this week’s
experiment.
 You need to obtain your own for your car.

» Science supply store (best option)
» Radio Shack
» Online (shipping cost!)
8
Pulse Position Modulation - PPM
“Regular” or “Differential” PPM
 Used for simplicity
 Inexpensive, lightweight RX
 Fine for R/C; not great for general
communications

9
“Regular” PPM
10
Differential PPM
Six Channels, all zero (center stick) except Channel 3 (right stick).
1
2
3
4
5
6
time
Easier to decode – just need to detect time between two pulses.
Differential PPM is what our setup uses.
11
Servos and Op-Amps
Servos are special motors that include
control circuitry. Used for precise control of
position or velocity
 DC servos are used in R/C and robots. AC
servos are common in industry.
 Op-Amps are important analog circuits.
Used for amplifying, filtering, isolation, and
motor control.

12
DC Servos
Web link
13
Servos
Purchase servos locally at Hobbytown USA
14
Servos Position vs. Pulse Width

Input is a PWM signal; motor responds by
turning to a fixed position. Example:
15
Servo Control Signal Example
16
Other Servo Types
Continuous Rotation (control speed and
direction)
 Digital
 AC

17
Continuous Rotation Servos
Can be purchased or can modify traditional
servos.
 “Neutral” signal (e.g. 1.5 ms) yields no
movement.
 PW >1.5 ms yields CW rotation. PW < 1.5
ms yields CCW rotation.
 Great for driving robots.

18
Digital Servos
Use a microprocessor to analyze incoming
signal and perform motor control.
 Higher pulse rate (300 Hz vs. 50 Hz) yields
faster response, less deadband, more
holding power.
 ‘After flying digital servos, analogue
versions are like controlling custard’
 Tradeoff: use more power.

19
AC Servo Motors

Typically used for factory automation
20
Op-Amps
Operational Amplifier
 Developed circa 1940 by Bell Labs for
telephone amplification.
 Used for artillery aiming in WWII.
 Analog computers
 Now: input “pretreatment” and output
buffering for DSP.

21
Example Op-Amp Circuit
Inverting
Amplifier
Vout  
Rf
Rin
Vin
22
Op-Amp Circuit Analysis
Vout  A(0  VX )
VX
0
Gain = A
Very large
Vout  VX VX  Vin

Rf
Rin
Vout  0 0  Vin

Rf
Rin
Vout
 VX
A
A    VX  0
Vout Vin

Rf
Rin
Vout  
Rf
Rin
Vin
23
QUIZ PREP

Have Quiz sheet ready. Title = QUIZ 8
Lab
Day/Time Section
Section
Lab Day/Time
Number
» Name (L, F, MI),
Number
Mon. 1:00
8
» Today’s date 10/9/12, Mon.
1:00
8
Mon. 3:00
9
Mon.
3:00
9
» Lab day , time
Wed. 1:00
10
Tue. 2:00
36
» section number
Wed. 3:00
11
Lab Day/Time
Section
Number
Monday, 1:00
8
Monday, 3:00
9
Wed., 1:00
10
Wed, 3:00
11
Friday, 1:00
Wed.
1:00
Thu. 2:00
12
10
29
Wed.
3:00
Fri. 1:00
11
12
Thu. 2:00
35
Fri. 1:00
12
24
Quiz 8: Page 1 of 2
Write the correct answers on your Quiz sheet.
1. For a technical report, the use of lists, bullets,
and headers should be avoided. TRUE /
FALSE
2. The appropriate reader for whom you should
target your design reports is: Dr. Roppel / Busy
Manager / Mom
3. Differential PPM encodes joystick position as:
Absolute pulse position / Space between
pulses / Pulse width
Quiz 8: page 2 of 2
4. For standard servos, position is determined
by: Absolute pulse position / Space
between pulses / Pulse width
5. Operational amplifiers are used primarily
to: Calculate trajectories / Perform signal
processing
6. Op-amps have internal voltage gain that is:
Very small / Very large
26