8. ROBOTIC COMPUTERSYSTEMS AND

PROGRAMMING

DES IGN AND APPL ICAT IONS OF INDUSTRIAL ROBOTSSABARIG IR IVASAN.RISBN 978-81-908268-0-8

8. ROBOTIC COMPUTERSYSTEMS AND

PROGRAMMING

DESIGN AND APPLICATIONS OF INDUSTRIAL ROBOTSSABARIGIRIVASAN.RISBN 978-81-908268-0-8

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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) Microprocessor for data processing and controlling

b) Temporary memory unit

c) Permanent storage unit

d) Display unit

e) 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 witha) 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 ComputerHierarchy of Robot Computer

JC1, JC2, JC3, JC4, JC5, JC6 – Joint controllersGC – Gripper controller

Communicationperipherals

Communication line

JC1 JC2 JC6JC5JC4JC3 GC

To other computer systems

Program input MonitorMaster

ControllerCPU

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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 unitsa) 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 ControllerMaster Controller

CPU

Teach pendant

Key board

Input unit

Monitor

Communicationperipherals

Permanent storagememory

Microprocessor

External RAM

Output unit

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MicroprocessorMicroprocessor

I/O ports

ALU

Registers

Control unitTimer

RAM(cache)

System clock

System Bus

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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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MicrocontrollerMicrocontroller

Programmemory

I/Oports

Datamemory

Flash memory

ALU

Registers

Controlunit Timer 1 Timer 2

CCPmodule

ADC

USARTRAMSystemclock

System Bus

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Communication Systems

1. Communication between two units is needed for exchanging data and control signals.

2. Communication typesa) Serial communication

b) Parallel communication

3. Data transmission modesa) Simplex mode

b) Duplex mode• Half duplex mode• Full duplex mode

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Serial CommunicationSerial Communication

TX/RX

TX/RX – Transmitter/Receiver

TX/RX

Direction of transmissionMSB LSB

Stop bit 2 Stop bit 1 Start bit

B0B1B2B3B4B7 B5B6

101000 01

Data communication line

(a) Serial communication system

(b) Serial data transmission format D E S I G N A N D A P P L I C A T I O N S O F I N D U S T R I A L R O B O T S

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Parallel CommunicationParallel Communication

TX/RX

TX/RX – Transmitter/Receiver

TX/RX

Individual data lines for each bit

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Data Transmission ModesData Transmission Modes

TX/RX – Transmitter/Receiver

TX RX

TX/RX TX/RX

TXRXTX

RX

(a) Simplex mode(b) Half Duplex mode(c) Full Duplex mode

(a)

(b)

(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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USARTMasterclock

Transmitterclock

Receiverclock

Transmitter Receiver

Transmitter Receiver

Clock line

Data line

Data line

(a) Synchronous transmission

(b) Asynchronous transmission

USART

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CANCAN

. . . .

Node 1 Node 2 Node n

Microcontroller

CAN_H

CAN_L CAN Bus

CAN module

Microcontroller

CAN module

Microcontroller

CAN module

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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 ConverterAnalog to Digital Converter

Analog Input

Sampleand

Hold circuitADC

MSB

LSB

DigitalOutput

Start End of Conversion (EOC)

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Reference voltage

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Digital to Analog ConverterDigital to Analog Converter

MSB

Analog Output

DAC

LSB

DigitalInput

FinalOutputvoltage

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�ܨ� (Reference voltage)ܥܥ�

� �

� � +�– �

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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 area) 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 typesa) 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 languagea) First generation language – Limited capabilities

b) Second generation language – Advanced features

c) Future generation languages – World modeling

2. Some programming languagesa) AL

b) AML

c) RAIL

d) RPL

e) 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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4. It needs a computer with very large storage and computing power.

5. Features of an AI enabled machinea) Problem solving

b) Learning

c) Video and audio based recognition

Artificial Intelligence

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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 AIa) Logical interpretation – Boolean algebra

b) Artificial Neural Networks

c) Frames

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