Transcript 8. ROBOTIC COMPUTER SYSTEMS AND PROGRAMMING

8. ROBOTIC COMPUTER
SYSTEMS AND
PROGRAMMING
D E S I G N A N D A P P L I C AT I O N S O F I N D U S T R I A L R O B OT S
S A B A R I G I R I VA S A N . R
I S B N 978-81-908268-0-8
Computer System of a Robot
1. A robot is programmable hence it should
have adequate computing facilities.
2. Main components of a computing system are
broadly classified into two types, they are
a) Hardware
b) Software
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Hardware
1. All electronic devices forming the physical
components of the computing system are
known as Hardware.
2. Hardware components
a)
b)
c)
d)
e)
Microprocessor for data processing and controlling
Temporary memory unit
Permanent storage unit
Display unit
Communication peripherals
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Hierarchy of Robot Computer
1. Processors in the robot computer system is
arranged in a hierarchical manner.
2. The robot computer is configured with
a) Master controller
b) Slave controller
3. Master controller communicates with all
slave controller for sending and receiving
control and data signals.
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Hierarchy of Robot Computer
Hierarchy of Robot Computer
Master
Controller
CPU
Program input
Monitor
Communication To other computer systems
peripherals
Communication line
JC1
JC2
JC3
JC4
JC5
JC6
GC
JC1, JC2, JC3, JC4, JC5, JC6 – Joint controllers
GC – Gripper controller
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Master Controller
1. Master controller has its architecture and
operating principles similar to a personal
computer.
2. It has three main units
a) Input unit
• Key board, Teach pendant
b) Central Processing Unit (CPU)
• 32 bit microprocessor
• RAM, Permanent storage memory
c) Display unit
• CRT or LCD Monitor
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Master Controller
Master Controller
Permanent
storage
memory
Communication
peripherals
Teach pendant
Microprocessor
Key board
Monitor
Output unit
Input unit
External RAM
CPU
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Microprocessor
RAM
(cache)
ALU
System Bus
Registers
I/O ports
Control unit
Timer
System clock
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Slave Controller
1. The individual joint controller provided for
each joint is referred as slave controller.
2. 8 bit or 16 bit microcontrollers are used.
3. A microcontroller is a microprocessor with
low computing power but with additional
circuits like integrated ADC, CCP module,
PWM module, USART module.
4. It has two types of onboard memory.
a) RAM – Used to store temporary data.
b) ROM – Used to store program instructions.
• OTPROM and Flash memory are widely used.
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Microcontroller
Flash memory
ALU
System
clock
RAM
Program Data
memory memory
USART
I/O
ports
Registers
System Bus
Control
unit
Timer 1
Timer 2
CCP
module
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ADC
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Communication Systems
1. Communication between two units is needed
for exchanging data and control signals.
2. Communication types
a) Serial communication
b) Parallel communication
3. Data transmission modes
a) Simplex mode
b) Duplex mode
• Half duplex mode
• Full duplex mode
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Serial
Communication
Serial Communication
Data communication line
TX/RX
TX/RX
TX/RX – Transmitter/Receiver
(a) Serial communication system
Direction of transmission
MSB
LSB
B7 B6 B5 B4 B3 B2 B1 B0
0
Stop bit 2
1
0
0
0
1
0
1
Stop bit 1
Start bit
(b) Serial data transmission format
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Parallel Communication
Individual data lines for each bit
TX/RX
TX/RX
TX/RX – Transmitter/Receiver
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Data Transmission Modes
RX
TX
(a)
TX/RX
TX/RX
(b)
TX
RX
TX/RX – Transmitter/Receiver
RX
TX
(a) Simplex mode
(b) Half Duplex mode
(c) Full Duplex mode
(c)
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Communication Interface and Protocols
1. RS232 – 20Kbps over 15m
2. Universal Synchronous Asynchronous
Receiver Transmitter (USART)
3. Universal Serial Bus (USB)
a) USB 1.0 – 1.5 Mbps
b) USB 1.1 – 12 Mbps
c) USB 2.0 – 480 Mbps
4. Controller Area Network (CAN) – 1 Mbps
over 40 m
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USART
USART
Master
clock
Clock line
Transmitter
Data line
Receiver
(a) Synchronous transmission
Transmitter
clock
Transmitter
Receiver
clock
Data line
Receiver
(b) Asynchronous transmission
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CAN
Node 1
Node 2
Microcontroller
Microcontroller
CAN module
CAN module
Node n
....
Microcontroller
CAN module
CAN_H
CAN_L
CAN Bus
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Additional Peripherals
1. Additional I/O channels are provided for
interfacing additional sensors and
controllers
2. Analog to Digital Converter (ADC)
Used to convert an analog signal to digital
format.
3. Digital to Analog Converter (DAC)
Used to convert digital codes into its
proportional analog signal.
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Analog to Digital Converter
Start Reference voltage
End of Conversion (EOC)
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Analog
Input
Sample
and
Hold circuit
ADC
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MSB
Digital
Output
LSB
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Digital
to
Analog
Converter
Digital to Analog Converter
(Reference voltage)
MSB
Digital
Input
LSB
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+
DAC
Analog
Output
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–
Final
Output
voltage
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Software
1. Software is the set of instructions fed in a
specific format to the hardware to perform
certain task in the required sequence.
2. Software is broadly classified into two
types they are
a) Operating system
b) Application programs
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Operating System
1. Operating system is the computer program
that supervises and coordinates the
functions of various hardware components
inter connected in the computer system.
2. It accepts the robot program written in
high level language and converts it into
machine language.
3. Compiler or Interpreter is used for this
purpose.
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Operating System
4. Machine language is the assembly language
program that has opcodes in binary form.
5. Each opcode has a specific function to do
for a specific kind of microprocessor.
6. The operating system provides three main
operating modes for organizing a program,
a) Monitor mode
b) Run mode
c) Edit mode
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Application Programs
1. They are the actual robot program fed to the
computer for controlling the robot motion.
2. They are created individually for each kind
of application.
3. They are actually compiled by human
programmers using any one of the
programming methods.
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Robot Programming
1. Programming is the process of loading a set
of instructions in a specific format so that
the robot controller can process them to
move the arm and the endeffector.
2. The set of instructions that drives the robot
is known as robot program.
3. Robot programming is of two types
a) Lead through programming
b) Textual programming
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Lead through Programming
1. In lead through programming the robot is
moved along the required path to the
required destination and the joint angles
and positions generated during this motion
are recorded in the controllers memory.
2. These set of points recorded during the
motion constitute the program for the path
generated.
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Lead through Programming
1. It is of two types,
a) Manual lead through programming
• Robot is moved manually by the operator using a
special handle.
b) Powered lead through programming
• Robot is moved by powering its own actuators.
• Teach pendant is used to move the robot while
programming.
• Joint motions, motion along xyz coordinates and
tool point coordinate motions are employed to
define points on the required path.
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Textual Programming
1. Instructions that are required to drive the
robot are compiled using a high level
language that has human readable words.
2. The program in the high level language is
converted into machine language with the
help of a compiler or interpreter.
3. The controller can thus process the
machine code to drive the robot.
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Programming Languages
1. Generations of language
a) First generation language – Limited capabilities
b) Second generation language – Advanced features
c) Future generation languages – World modeling
2. Some programming languages
a)
b)
c)
d)
e)
AL
AML
RAIL
RPL
VAL
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Artificial Intelligence
1. Artificial intelligence (AI) is the
intelligence capability built into a machine
to function and make decision of their own
in response to their environmental
stimulants.
2. AI enabled machine can behave just like
humans or other natural animals do.
3. AI for a machine can be achieved by
processing vast amounts of data in a
sequential manner.
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Artificial Intelligence
4. It needs a computer with very large storage
and computing power.
5. Features of an AI enabled machine
a) Problem solving
b) Learning
c) Video and audio based recognition
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Methods to achieve Artificial Intelligence
1. Decision making using AI is achieved by
analyzing vast amount of data representing
the characteristic properties of a problem
or situation.
2. Techniques to achieve AI
a) Logical interpretation – Boolean algebra
b) Artificial Neural Networks
c) Frames
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