Transcript No Slide Title

Group Lab Assignment (50
Points)
• Robot starts behind line, delivers Ping-pong
ball to destination and returns to behind line
• 10 Point bonus – first group to succeed
• 10 Point bonus – each ball consecutively
delivered
• Any mechanical modification
• Autonomous
Design Axioms
• Main Entry: ax·i·om
Pronunciation: 'ak-sE-&m
Function: noun
1 : a maxim widely accepted on its intrinsic merit
2 : a statement accepted as true as the basis for argument or
inference : POSTULATE 1
3 : an established rule or principle or a self-evident truth
Wikipedia: …The method gets its name from its use of
design principles or design Axioms (i.e., given without
proof) governing the analysis and decision making process
in developing high quality product or system designs.
Robotics Design Axioms
• Software cannot overcome weak
mechanical design
• A machine cannot control what it cannot
sense
Lego Robotics Design Axioms
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Lighter is better than heavier
Smaller is better than larger
Solutions requiring the least travel are better
Direct actuation is better than relying on Gravity
Fewer parts is better than many parts
Constrained objects behave better than unconstrained
Active sensing of location is better than deducing from navigation
Self-aligning is better than requiring careful aim
Reaching low is better than reaching high
Reaching near is better than reaching far
Mechanical solutions are better than robotic solutions
Solutions that allow easy return or retrieval are better
Solutions with fewer causes of failure are better
Design project
• Milestone 1 Friday 12th.
• Make the iStamp play a song of your
choosing,e.g. Mary had a little lamb or
Stairway to heaven, see detailed description
• Example lab0701.bsp – read manual for
Piezo output
Introduction to Mechatronics
ENGR450 Presentation
Matthew Stein
Mecha-what?
The word itself is a portmanteau of 'Mechanics' and
'Electronics'.
Main Entry:
1
port·man·teau
Pronunciation:
\pȯrt-ˈman-(ˌ)tō\
Function:
noun
Etymology:
Middle French portemanteau, from porter to carry + manteau mantle, from Latin
mantellum
Date:
1579
1 : a large suitcase 2 : a word or morpheme whose form and meaning are derived
from a blending of two or more distinct forms (as smog from smoke and fog)
Basics of Mechatronics
Always described as a
combination of
mechanical and
electronic devices
Figure courtesy of Kevin Craig
Marquette University
Like what?
Formerly mechanical
control system replaced
Performance improved
by digital control
Figure courtesy of Kevin Craig
Marquette University
How is it done?
Mechanism
Actuator
Sensor
Electronic
Device
A little more detail
Power
Physical Signal
Mechanism
Physical Signal
Power
Actuator
Sensor
Mechanical
Electronic
Electronic signal
Electronic
Device
Electronic signal
For Example:
From:
Howstuffworks.
com
Anti-lock brakes
Hydraulics
Physical Signal
Hydraulic
cylinder on
brakes
Solenoid pulse
on hydraulic
line
Mechanical
Physics of car
Wheel speed
sensor
Electronic
Wires
ABS
Control Unit
Wires
This class
Mechanism
Actuator
Sensor
Electronic
Device
Signals
• Arrows in the diagram are signals
• Signals are either mechanical
– Pneumatic/Hydraulic pressure or flow
– Position/velocity/acceleration/rotation
– Deformation/deflection/pressure
• Or electrical
– Voltage/current/charge
– Analog or digital
• Mechatronics always has both
What’s the difference
• A digital signal is a voltage
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–
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–
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Either 5V or 0V (logical 1 or logical 0)
In between is undefined
Chosen for convenience
Konrad Zuse, Eckerd&Mauchley (1940’s)
Represented in binary
Lab Exercise (10 minutes)
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Hook a DVM to port 0
Write a simple program to toggle ON/OFF
What is the reading on the DVM?
Mechatronics makes use of the physical
implementation of digital logic
– Makes electrical use of 0V to 5V transition
Analog signals
• An analog signal is also voltage
– Range chosen for convenience
– Any value in a given range
• 0V-5V
• -5V – 5V
• 0 V– 10V
– All physical signals are inherently analog
How to handle
• Digital computer cannot handle directly
– 3.7V not immediately usable by a computer
• Convert between Analog and Digital
– Analog to digital conversion (A/D)
– Digital to Analog conversion (D/A)
– Produce a voltage to represent the value of a
signal relative to its range
How’s it done?
• Start with D/A:
• Lab exercise (Start now, complete by Friday)
• Build this circuit
• Any resistor > 1K
will do
• Get 13 identical
resistors
• Wire them up like
this Output ports 0-3
Probe
Digital Range
• 4-Bit number
• Range 0-15
• Represents in volts 0 to VREF in
increments of 1/15th
• If VREF = +5V
• Every bit is 5/15V or 1/3V
Possible Representations
• 4-Bit number representing 0V – 5V
Binary
Number
Voltage
Binary Number
Voltage
0000
0V
1000
2.6V
0001
.33V
1001
3VV
0010
.66V
1010
3.33V
0011
1V
1011
3.66V
0100
1.33V
1100
4V
0101
1.66V
1101
4.33V
0110
2V
1110
4.66V
0111
2.33V
1111
5V
Possible Representations
• 4-Bit number representing 0V – 5V
Binary
Number
Voltage
Binary Number
Voltage
0000
0V
1000
2.5V
0001
.3125V
1001
2.8125V
0010
.625V
1010
3.125V
0011
.9375V
1011
3.4375V
0100
1.25V
1100
3.75V
0101
1.5625V
1101
4.0625V
0110
1.875V
1110
4.375V
0111
2.1875V
1111
4.6875V
Voltage Equivalents
• B0 “Bit Zero” The Least Significant Bit
(LSB)
• B0 = 0.3125V (1/16 VREF)
• B1 = 0.625V (2/16 VREF)
• B2 = 1.25V (4/16 VREF)
• B3 = 2.5V (8/16 VREF)
Easy conversion
• If each bit is a 5V/0V signal
• This circuit effectively adds bits together
Easy conversion
Wikipedia Thevenin Example: R-2R Ladder
D/A Conversion
• D/A works by a relatively straightforward
resistor network.
• 4 bit nibble represents 16 distinct voltages
scaled by VREF
• More bits more distinct voltages
• Conversion instantaneous (i.e speed of
light)
Simple A/D Conversion
• Uses D/A and successive approximation.
• Counter increases binary number until
voltages match
• Once matched,
signal the end of A/D
More complex schemes are faster
but not that different
A/D Conversion
• Result is a n-bit binary number representing
voltage (percentage of VREF)
• More bits more precision
• 8 bits = 256 distinct voltages
• 10 bits = 1024 voltages (2 10 )
From izeBot Manual
Since the i-stamp or Basic Stamp 2SX, which is the main
micro-controller in the iZEBOT Stamp-BOX, does not
have an analog to digital converter module (A/D
converter), an external converter must be connected in
order to communicate with components that send out
voltage signals, such as Module GP2D120. Therefore, IC
QP410 will be used to convert and send digital signals to
the main micro-controller. (pg 35)
Program to read the ADC
Notes from manual
(1) Pauses or delays for 1 second so that the IC QP410 is ready to
operate.
(2) Sends a pulse signal so that the IC QP410 can acknowledge and
get ready to communicate with the Stamp-BOX
(3) The i-Stamp sends the value of the channel to be read to the IC
QP410. From Listing A12-1, the value is 1 which means that it will
be communicate with ANALOG1
(4) The i-Stamp reads the value from channel ANALOG1 of the IC
QP410 and stores it in the variable ADC. The variable is defined as
type word, which can store up to 16 bits of data, therefore easily
storing the 10 bit data from the IC QP410.
(5) i-stamp sends the value that it reads to be displayed on the Debug
Terminal.
Lab Exercise (20 minutes)
• Build the structure to attach the GP2D120
to the ezbot
• Use the program to determine basic
functionality
How does it work?
• Figure from manual
• “Array of
photransistors” will
be discussed later
Group Lab Assignment 1 (30
minutes, 20 Points)
• Use the relationship given in the manual
• Calibrate the GPD
• Write a program that displays distance in
CM
• Instructor will test +/1 2cm for credit