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- •1. TABLE OF CONTENTS
- •2. OVERVIEW
- •3. PROCESS CONTROL
- •3.1 INTRODUCTION
- •3.2 CONTROL SYSTEM CHARACTERISTICS
- •3.3 CONTROLLER TYPES
- •3.4 PROCESS DIAGRAMS AND SYMBOLS
- •3.5 PRACTICE QUESTIONS
- •4. DISCRETE CONTROLLER DESIGN
- •4.1 POSITIONING CONTROLLERS
- •4.1.1 Dead Beat Control
- •4.1.2 Programming Examples
- •4.1.2.1 - BASIC
- •4.1.2.3 - Pascal
- •4.1.2.4 - 6811 Assembler
- •4.1.3 First Order Response
- •4.2 TRACKING
- •4.2.1 Minimum Error
- •4.3 DISTURBANCE RESISTANT
- •4.3.1 Disturbance Minimization
- •4.4 MULTI-CONTROLLER SYSTEMS
- •4.4.1 Disturbance Feedforward
- •4.4.2 Command Feedforward
- •4.4.3 Cascade
- •4.5 SAMPLE TIME
- •4.6 SUMMARY
- •4.7 PRACTICE PROBLEMS
- •5. DISCRETE SYSTEMS
- •5.1 DISCRETE SYSTEM MODELLING WITH EQUATIONS
- •5.1.1 Getting a Discrete Equation
- •5.1.2 First Order System Example
- •5.1.3 Second Order System Example
- •5.1.4 Example of Dead (Delay) Time
- •5.2 DISCRETE CONTROLLERS
- •5.2.1 A Proportional Controller
- •5.2.2 Integral Control
- •5.2.3 Differential Control
- •5.2.4 Proportional, Integral, Derivative (PID) Control
- •5.3 BLOCK DIAGRAMS AND TRANSFER FUNCTIONS
- •5.3.1 The Backward-Shift ‘B’ Operator
- •5.3.2 Reducing Block Diagrams
- •5.3.3 Back-Shift Transform Table
- •5.3.3.1 - A Summary of Differential Equation Solutions
- •5.3.4 Stability
- •5.4 SAMPLING FUNCTIONS
- •5.5 SYSTEM RESPONSE
- •5.6 STEADY STATE ERROR
- •5.7 PRACTICE PROBLEMS
- •6. PETRI NETS
- •6.1 INTRODUCTION
- •6.2 IMPLEMENTATION FOR A PLC
- •6.3 PRACTICE PROBLEMS
- •7. CONTINUOUS CONTROL SYSTEMS
- •7.1 CONTROL SYSTEMS
- •7.1.1 PID Control Systems
- •7.1.2 Analysis of PID Controlled Systems With Laplace Transforms
- •7.1.3 Manipulating Block Diagrams
- •7.1.3.1 - Commercial PID Tuners
- •7.1.4 Finding The System Response To An Input
- •7.1.5 System Response
- •7.1.6 A Motor Control System Example
- •7.1.7 System Error
- •7.1.8 Controller Transfer Functions
- •7.2 ROOT-LOCUS PLOTS
- •7.2.1 Approximate Plotting Techniques
- •7.2.2 State Variable Control Systems
- •7.3 DESIGN OF CONTINUOUS CONTROLLERS
- •7.4 PRACTICE PROBLEMS
- •8. FUZZY LOGIC
- •8.1 COMMERCIAL CONTROLLERS
- •8.2 REFERENCES
- •8.3 PRACTICE PROBLEMS
- •9. MECHATRONICS CIRCUITS
- •9.1 POWER SWITCHING
- •9.2 USER INPUT/OUTPUT
- •9.2.1 Multiplexing
- •10. HARDWARE BASED CONTROLLERS
- •10.1 CIRCUITS
- •10.2 FLUIDICS
- •10.3 PNEUMATICS
- •10.4 PRACTICE PROBLEMS
- •11. EMBEDDED CONTROLLERS
- •11.1 TYPES
- •11.1.1 Micro Controllers
- •11.1.2 DSPs
- •11.1.3 CPUs
- •11.2 CONTROLLER DESIGN EXAMPLE
- •11.3 PRACTICE PROBLEMS
- •12. DISCRETE SENSORS
- •12.1 INTRODUCTION
- •12.2 SENSOR WIRING
- •12.2.1 Switches
- •12.2.2 Transistor Transistor Logic (TTL)
- •12.2.3 Sinking/Sourcing
- •12.2.4 Solid State Relays
- •12.3 CONTACT DETECTION
- •12.3.1 Contact Switches
- •12.3.2 Reed Switches
- •12.4 PROXIMITY DETECTION
- •12.4.1 Optical (Photoelectric) Sensors
- •12.4.2 Capacitive Sensors
- •12.4.3 Inductive Sensors
- •12.4.4 Ultrasonic
- •12.4.5 Hall Effect
- •12.4.6 Fluid Flow
- •12.4.7 Other Types
- •12.5 PRACTICE PROBLEMS
- •13. CONTINUOUS SENSORS
- •13.1 INPUT ISSUES
- •13.2 SENSOR TYPES
- •13.3 ANGULAR POSITION
- •13.3.1 Potentiometers
- •13.3.2 Encoders
- •13.3.3 Resolvers
- •13.3.4 Practice Problems
- •13.4 LINEAR POSITION
- •13.4.1 Potentiometers
- •13.4.2 Linear Variable Differential Transformers (LVDT)
- •13.4.3 Moire Fringes
- •13.4.4 Interferometers
- •13.5 VELOCITY
- •13.5.1 Velocity Pickups
- •13.5.2 Tachometers
- •13.6 ACCELERATION
- •13.6.1 Accelerometers
- •13.7 FORCE/MOMENT
- •13.7.1 Strain Gages
- •13.7.2 Piezoelectric
- •13.8 FLOW RATE
- •13.8.1 Venturi
- •13.9 TEMPERATURE
- •13.9.1 Resistive Temperature Detectors (RTDs)
- •13.9.2 Thermocouples
- •13.9.3 Thermistors
- •13.10 SOUND
- •13.10.1 Microphones
- •13.11 LIGHT INTENSITY
- •13.11.1 Light Dependant Resistors (LDR)
- •13.12 PRESSURE
- •13.12.1 Bourdon Tubes
- •13.13 PRACTICE PROBLEMS
- •13.14 REFERENCES
- •14. ACTUATORS
- •14.1 ACTUATOR TYPES
- •15. DISCRETE ACTUATORS
- •15.1 INTRODUCTION
- •15.1.1 Interfacing
- •15.1.1.1 - Relays
- •15.1.1.2 - Transistors
- •15.1.1.3 - Triacs
- •15.2 TYPES
- •15.2.1 Solenoids
- •15.2.2 Hydraulic
- •15.2.3 Hydraulics
- •15.2.4 Electric
- •15.2.5 Pneumatic
- •15.2.6 Others
- •15.3 PRACTICE PROBLEMS
- •16. CONTINUOUS ACTUATORS
- •16.1 ACTUATOR CONTROL
- •16.1.1 Block Diagrams
- •16.1.2 Linear Control Systems
- •16.1.3 Motor Controllers
- •16.1.3.1 - DC Motors
- •16.1.3.2 - Stepper Motors
- •16.1.3.3 - Separately Excited DC Motor
- •16.1.3.4 - AC Motors
- •16.1.3.4.1 - Synchronous
- •16.1.4 Hydraulic
- •16.2 PRACTICE PROBLEMS
- •17. PROGRAMMABLE LOGIC CONTROLLERS
- •17.1 BASIC PLCs
- •17.1.1 PLC Connections
- •17.1.2 Ladder Logic
- •17.1.3 Ladder Logic Outputs
- •17.1.4 Ladder Logic Inputs
- •17.2 A SIMPLE EXAMPLE
- •17.3 PRACTICE PROBLEMS
- •18. PLC CONNECTION
- •18.1 SWITCHED INPUTS AND OUTPUTS
- •18.1.1 Input Modules
- •18.1.2 Output Modules
- •18.1.2.1 - Relays
- •18.2 PRACTICE PROBLEMS
- •19. PLC OPERATION
- •19.1 PLC ORGANIZATION
- •19.2 PLC STATUS
- •19.3 MEMORY TYPES
- •19.4 SOFTWARE BASED PLCS
- •19.5 PROGRAMMING STANDARDS
- •19.5.2 The Future of Open Architecture Controllers
- •19.6 PRACTICE PROBLEMS
- •20. SWITCHING LOGIC
- •20.1 BOOLEAN ALGEBRA
- •20.2 DISCRETE LOGIC
- •20.2.1 Boolean Algebra for Circuit and Ladder Logic Design
- •20.2.2 Boolean Forms
- •20.3 SIMPLIFYING BOOLEAN EQUATIONS
- •20.3.1 Karnaugh Maps for Combinatorial Design
- •20.4 ADDITIONAL TOPICS
- •20.4.1 Negative Logic
- •20.4.2 Common Logic Forms
- •20.4.2.1 - NAND/NOR Forms
- •20.4.2.2 - Multiplexers
- •20.4.2.3 - Seal-in Circuits
- •20.5 DESIGN CASES
- •20.5.1 Logic Functions
- •20.5.2 Car Safety System
- •20.5.3 Motor Forward/Reverse
- •20.6 PRACTICE PROBLEMS
- •21. NUMBERING
- •21.1 INTRODUCTION
- •21.2 DATA VALUES
- •21.2.1 Binary
- •21.2.2 Boolean Operations
- •21.2.3 Binary Mathematics
- •21.2.4 BCD (Binary Coded Decimal)
- •21.2.5 Number Conversions
- •21.2.6 ASCII (American Standard Code for Information Interchange)
- •21.3 DATA CHARACTERIZATION
- •21.3.1 Parity
- •21.3.2 Gray Code
- •21.3.3 Checksums
- •21.4 PRACTICE PROBLEMS
- •22. EVENT BASED LOGIC
- •22.1 INTRODUCTION
- •22.2 TIMERS, COUNTERS, FLIP-FLOPS, LATCHES
- •22.2.1 Latches
- •22.2.2 Flip-Flops
- •22.2.3 Timers
- •22.2.4 Counters
- •22.3 PROGRAM DESIGN METHODS
- •22.3.1 Process Sequence Bits
- •22.3.2 Timing Diagrams
- •22.4 DESIGN CASES
- •22.4.1 Counters And Timers
- •22.4.2 More Timers And Counters
- •22.4.3 Oscillator
- •22.4.4 More Timers
- •22.4.5 Cascaded Timers
- •22.4.6 Deadman Switch
- •22.4.7 Conveyor
- •22.4.8 Accept/Reject Sorting
- •22.4.9 Shear Press
- •22.4.10 Actuator Failure
- •22.4.11 Palm Button Detection
- •22.5 PRACTICE PROBLEMS
- •23. SEQUENTIAL LOGIC DESIGN
- •23.1 SCRIPTS
- •23.2 FLOW CHARTS
- •23.3 STATE BASED MODELLING
- •23.3.1 State Diagrams Example
- •23.3.1.1 - Block Logic Conversion
- •23.3.1.2 - Single State Equations
- •23.3.1.3 - Entry and Exit State Equations
- •23.3.1.4 - State Transition Equations
- •23.4 PARALLEL PROCESS FLOWCHARTS
- •23.4.1 Implementation with Microcontroller
- •23.5 SEQUENTIAL LOGIC CIRCUITS
- •23.5.1 Latches and Seal-in
- •23.5.2 Shift Registers
- •23.6 PRACTICE PROBLEMS
- •24. ADVANCED LADDER LOGIC FUNCTIONS
- •24.1 ADDRESSING
- •24.1.1 Data Files
- •24.1.1.1 - Inputs and Outputs
- •24.1.1.2 - User Bit Memory
- •24.1.1.3 - Timer Counter Memory
- •24.1.1.4 - PLC Status Bits (for PLC-5s and Micrologix)
- •24.1.1.5 - User Function Control Memory
- •24.1.1.6 - Integer Memory
- •24.1.1.7 - Floating Point Memory
- •24.2 INSTRUCTION TYPES
- •24.2.1 Basic Data Handling
- •24.2.1.1 - Move Functions
- •24.2.1.2 - Mathematical Functions
- •24.2.2 Logical Functions
- •24.2.2.1 - Comparison of Values
- •24.2.2.2 - Binary Functions
- •24.2.3 Boolean Operations
- •24.2.4 Binary Mathematics
- •24.2.5 BCD (Binary Coded Decimal)
- •24.2.6 Advanced Data Handling
- •24.2.6.1 - Multiple Data Value Functions
- •24.2.7 Complex Functions
- •24.2.7.1 - Shift Registers
- •24.2.7.2 - Stacks
- •24.2.7.3 - Sequencers
- •24.2.8 Program Control Structures
- •24.2.8.1 - Branching and Looping
- •24.2.8.2 - Immediate I/O Instructions
- •24.2.8.3 - Fault Detection and Interrupts
- •24.2.9 Block Transfer Functions
- •24.3 DESIGN TECHNIQUES
- •24.3.1 State Diagrams
- •24.4 DESIGN CASES
- •24.4.1 If-Then
- •24.4.2 For-Next
- •24.4.3 Conveyor
- •24.5 FUNCTION REFERENCE
- •24.6 PRACTICE PROBLEMS
- •25. PLC PROGRAMMING
- •25.1 PROGRAMMING STANDARDS
- •25.1.2 The Future of Open Architecture Controllers
- •25.2 PRACTICE PROBLEMS
- •26. STRUCTURED TEXT PROGRAMMING
- •26.1 INTRODUCTION
- •26.2 THE LANGUAGE
- •26.3 PRACTICE PROBLEMS
- •27. INSTRUCTION LIST PROGRAMMING
- •27.1 INTRODUCTION
- •27.2 PRACTICE PROBLEMS
- •28. FUNCTION BLOCK PROGRAMMING
- •28.1 INTRODUCTION
- •28.2 PRACTICE PROBLEMS
- •29. ANALOG INPUTS AND OUTPUTS
- •29.1 ANALOG INPUTS
- •29.1.1 Analog To Digital Conversions
- •29.1.2 Analog Inputs With a PLC
- •29.2 ANALOG OUTPUTS
- •29.2.1 Analog Outputs With A PLC
- •29.3 DESIGN CASES
- •29.3.1 Oven Temperature Control
- •29.3.2 Statistical Process Control (SPC)
- •29.4 PRACTICE PROBLEMS
- •30. CONTINUOUS CONTROL
- •30.1 CONTROLLING CONTINUOUS SYSTEMS
- •30.2 CONTROLLING DISCRETE SYSTEMS
- •30.3 CONTROL SYSTEMS
- •30.3.1 PID Control Systems
- •30.3.1.1 - PID Control With a PLC
- •30.4 DESIGN CASES
- •30.4.1 Temperature Controller
- •30.5 PRACTICE PROBLEMS
- •31. PLC DATA COMMUNICATION
- •31.1 COMPUTER COMMUNICATIONS CATEGORIES
- •31.2 THE HISTORY
- •31.3 WITH PLCs
- •31.4 SERIAL COMMUNICATIONS
- •31.4.1.1 - ASCII Functions
- •31.4.2 ASCII (American Standard Code for Information Interchange)
- •31.5 PARALLEL
- •31.6 NETWORKS
- •31.6.1 Introduction
- •31.6.2 OSI Network Model
- •31.6.2.1 - Physical Layer
- •31.6.2.2 - Data Link Layer
- •31.6.2.3 - Network Layer
- •31.6.2.4 - Transport Layer
- •31.6.2.5 - Session Layer
- •31.6.2.6 - Presentation Layer
- •31.6.2.7 - Application Layer
- •31.6.2.8 - Open Systems
- •31.6.2.9 - Networking Hardware
- •31.7 BUS TYPES
- •31.7.1 Devicenet
- •31.7.2 CANbus
- •31.7.3 Controlnet
- •31.7.4 Profibus
- •31.7.5 Ethernet
- •31.7.6 Proprietary Networks
- •31.7.6.1 - Data Highway
- •31.7.7 Other Network Types
- •31.8 DESIGN CASES
- •31.8.1 PLC Interface To Robots And NC Machines
- •31.9 PRACTICE PROBLEMS
- •32. HUMAN MACHINE INTERFACES (HMI)
- •32.1 INTRODUCTION
- •32.2 HMI/MMI DESIGN
- •32.3 DESIGN CASES
- •32.4 PRACTICE PROBLEMS
- •33. DESIGNING LARGE SYSTEMS
- •33.1 PROGRAMMING
- •33.2 DOCUMENTATION
- •33.3 PLC PROGRAM DESIGN FORMS
- •33.4 PRACTICE PROBLEMS
- •34. IMPLEMENTATION
- •34.1 ELECTRICAL
- •34.1.1 Electrical Wiring Diagrams
- •34.1.1.1 - JIC Wiring Symbols
- •34.1.2 Wiring
- •34.1.3 Shielding and Grounding
- •34.2 SAFETY
- •34.2.1 Troubleshooting
- •34.2.2 Forcing Outputs
- •34.2.3 PLC Environment
- •34.2.3.1 - Enclosures
- •35. PROCESS MODELLING
- •35.1 REFERENCES
- •35.2 PRACTICE PROBLEMS
- •36. SELECTING A PLC
- •36.1 SPECIAL I/O MODULES
- •36.2 PLC PROGRAMMING LANGUAGES
- •36.3 ISSUES
- •36.4 PRACTICE PROBLEMS
- •37. PLC REFERENCES
- •37.1 SUPPLIERS
- •37.2 PROFESSIONAL INTEREST GROUPS
- •37.3 PLC/DISCRETE CONTROL REFERENCES
- •38. USING THE OMRON DEMO PACKAGE
- •38.1 OVERVIEW
- •38.1.1 Installation
- •38.1.2 Basic Use
- •38.1.3 Connecting to the PLC
- •38.2 REFERENCE GUIDE FOR OMRON PLC DEMO SOFTWARE
- •39. INDUSTRIAL ROBOTICS
- •39.1 INTRODUCTION
- •39.1.1 Basic Terms
- •39.1.2 Positioning Concepts
- •39.1.2.1 - Accuracy and Repeatability
- •39.1.2.2 - Control Resolution
- •39.1.2.3 - Payload
- •39.2 ROBOT TYPES
- •39.2.1 Basic Robotic Systems
- •39.2.2 Types of Robots
- •39.2.2.1 - Robotic Arms
- •39.2.2.2 - Autonomous/Mobile Robots
- •39.2.2.2.1 - Automatic Guided Vehicles (AGVs)
- •39.2.3 Commercial Robots
- •39.2.3.1 - Seiko RT 3000 Manipulator
- •39.2.3.2 - DARL Programs
- •39.2.3.2.1 - Language Examples
- •39.2.3.2.2 - Commands Summary
- •39.2.3.3 - Mitsubishi RV-M1 Manipulator
- •39.2.3.4 - Movemaster Programs
- •39.2.3.4.1 - Language Examples
- •39.2.3.4.2 - Command Summary
- •39.2.3.5 - IBM 7535 Manipulator
- •39.2.3.6 - AML Programs
- •39.2.3.7 - ASEA IRB-1000
- •39.2.4 Unimation Puma (360, 550, 560 Series)
- •39.3 ROBOT APPLICATIONS
- •39.3.1 Overview
- •39.3.2 Spray Painting and Finishing
- •39.3.3 Welding
- •39.3.4 Assembly
- •39.3.5 Belt Based Material Transfer
- •39.4 END OF ARM TOOLING (EOAT)
- •39.4.1 EOAT Design
- •39.4.2 Gripper Mechanisms
- •39.4.2.1 - Vacuum grippers
- •39.4.3 Magnetic Grippers
- •39.4.3.1 - Adhesive Grippers
- •39.4.4 Expanding Grippers
- •39.4.5 Other Types Of Grippers
- •39.5 ADVANCED TOPICS
- •39.5.1 Simulation/Off-line Programming
- •39.6 PRACTICE PROBLEMS
- •40. ROBOTIC PATH PLANNING METHODS
- •40.1 INTRODUCTION:
- •40.1.1 ROBOT APPLICATIONS
- •40.1.2 ROBOTIC CONSTRAINTS
- •40.1.3 THE OPTIMIZATION PROBLEM OF PATH PLANNERS
- •40.1.4 EVALUATION OF PATH PLANNERS
- •40.2 GENERAL REQUIREMENTS
- •40.2.1 PROBLEM DIMENSIONALITY
- •40.2.2 2D MOBILITY PROBLEM
- •40.2.2.1 - 2.5D HEIGHT PROBLEM
- •40.2.2.2 - 3D SPACE PROBLEM
- •40.2.3 COLLISION AVOIDANCE
- •40.2.4 MULTILINK
- •40.2.5 ROTATIONS
- •40.2.6 OBSTACLE MOTION PROBLEM
- •40.2.7 ROBOT COORDINATION
- •40.2.8 INTERACTIVE PROGRAMMING
- •40.3 SETUP EVALUATION CRITERIA
- •40.3.1 INFORMATION SOURCE
- •40.3.1.1 - KNOWLEDGE BASED PLANNING (A PRIORI)
- •40.3.1.2 - SENSOR BASED PLANNING (A POSTIERI)
- •40.3.2 WORLD MODELLING
- •40.4 METHOD EVALUATION CRITERIA
- •40.4.1 PATH PLANNING STRATEGIES
- •40.4.1.1 - BASIC PATH PLANNERS (A PRIORI)
- •40.4.1.2 - HYBRID PATH PLANNERS (A PRIORI)
- •40.4.1.3 - TRAJECTORY PATH PLANNING (A POSTIERI)
- •40.4.1.4 - HIERARCHICAL PLANNERS (A PRIORI & A POSTIERI)
- •40.4.1.5 - DYNAMIC PLANNERS (A PRIORI & A POSTIERI)
- •40.4.1.6 - OFF-LINE PROGRAMMING
- •40.4.1.7 - ON-LINE PROGRAMMING
- •40.4.2 PATH PLANNING METHODS
- •40.4.3 OPTIMIZATION TECHNIQUES
- •40.4.3.1 - SPATIAL PLANNING
- •40.4.3.2 - TRANSFORMED SPACE
- •40.4.3.3 - FIELD METHODS
- •40.4.3.4 - NEW AND ADVANCED TOPICS
- •40.4.4 INTERNAL REPRESENTATIONS
- •40.4.5 MINIMIZATION OF PATH COSTS
- •40.4.6 LIMITATIONS IN PATH PLANNING
- •40.4.7 RESULTS FROM PATH PLANNERS
- •40.5 IMPLEMENTATION EVALUATION CRITERIA
- •40.5.1 COMPUTATIONAL TIME
- •40.5.2 TESTING OF PATH PLANNERS
- •40.6 OTHER AREAS OF INTEREST
- •40.6.1 ERRORS
- •40.6.2 RESOLUTION OF ENVIRONMENT REPRESENTAION
- •40.7 COMPARISONS
- •40.8 CONCLUSIONS
- •40.9 APPENDIX A - OPTIMIZATION TECHNIQUES
- •40.9.1 OPTIMIZATION : VELOCITY
- •40.9.2 OPTIMIZATION : GEOMETRICAL
- •40.9.3 OPTIMIZATION : PATH REFINEMENT
- •40.9.4 OPTIMIZATION : MOVING OBSTACLES
- •40.9.5 OPTIMIZATION : SENSOR BASED
- •40.9.6 OPTIMIZATION : ENERGY
- •40.10 APPENDIX B - SPATIAL PLANNING
- •40.10.1 SPATIAL PLANNING : SWEPT VOLUME
- •40.10.2 SPATIAL PLANNING : OPTIMIZATION
- •40.10.3 SPATIAL PLANNING : GENERALIZED CONES
- •40.10.4 SPATIAL PLANNING : FREEWAYS
- •40.10.5 SPATIAL PLANNING : OCT-TREE
- •40.10.6 SPATIAL PLANNING : VORONOI DIAGRAMS
- •40.10.7 SPATIAL PLANNING : GENERAL INTEREST
- •40.10.8 SPATIAL PLANNING - VGRAPHS
- •40.11 APPENDIX C - TRANSFORMED SPACE
- •40.11.1 TRANSFORMED SPACE : CARTESIAN CONFIGURATION SPACE
- •40.11.1.1 - TRANSFORMED SPACE :
- •40.11.2 TRANSFORMED SPACE : JOINT CONFIGURATION SPACE
- •40.11.3 TRANSFORMED SPACE : OCT-TREES
- •40.11.4 TRANSFORMED SPACE : CONSTRAINT SPACE
- •40.11.5 TRANSFORMED SPACE : VISION BASED
- •40.11.6 TRANSFORMED SPACE : GENERAL INTEREST
- •40.12 APPENDIX D - FIELD METHODS
- •40.12.1 SPATIAL PLANNING : STEEPEST DESCENT
- •40.12.2 SPATIAL PLANNING : POTENTIAL FIELD METHOD
- •40.13 APPENDIX E - NEW AND ADVANCED TOPICS
- •40.13.1 ADVANCED TOPICS : DUAL MANIPULATOR COOPERATION
- •40.13.2 ADVANCED TOPICS : A POSTIERI PATH PLANNER
- •40.13.3 NEW TOPICS - SLACK VARIABLES
- •40.14 REFERENCES:
- •41. ROBOTIC MECHANISMS
- •41.1 KINEMATICS
- •41.1.1 Basic Terms
- •41.1.2 Kinematics
- •41.1.2.1 - Geometry Methods for Forward Kinematics
- •41.1.2.2 - Geometry Methods for Inverse Kinematics
- •41.2 MECHANISMS
- •41.3 ACTUATORS
- •41.3.1 Modeling the Robot
- •41.4 PATH PLANNING
- •41.4.1 Slew Motion
- •41.4.1.1 - Joint Interpolated Motion
- •41.4.1.2 - Straight-line motion
- •41.4.2 Computer Control of Robot Paths (Incremental Interpolation)
- •41.5 PRACTICE PROBLEMS
- •42. MOTION PLANNING AND TRAJECTORY CONTROL
- •42.1 TRAJECTORY CONTROL
- •42.1.1 Resolved Rate Motion Control
- •42.1.2 Cartesian Motion System
- •42.1.3 Model Reference Adaptive Control (MRAC)
- •42.1.4 Digital Control System
- •42.2 PATH PLANNING
- •42.2.1 Slew Motion
- •42.2.1.1 - Joint Interpolated Motion
- •42.2.1.2 - Straight-line motion
- •42.3 MOTION CONTROLLERS
- •42.3.1 Computer Control of Robot Paths (Incremental Interpolation)
- •42.4 SPECIAL ISSUES
- •42.4.1 Optimal Motion
- •42.4.2 Singularities
- •42.5 PRACTICE PROBLEMS
- •42.6 MICROBOT OVERVIEW
- •42.7 CRS PLUS ROBOT OVERVIEW
- •42.8 BASIC DEMONSTRATION STEPS
- •43. CNC MACHINES
- •43.1 MACHINE AXES
- •43.2 NUMERICAL CONTROL (NC)
- •43.2.1 NC Tapes
- •43.2.2 Computer Numerical Control (CNC)
- •43.2.3 Direct/Distributed Numerical Control (DNC)
- •43.3 EXAMPLES OF EQUIPMENT
- •43.3.1 EMCO PC Turn 50
- •43.3.2 Light Machines Corp. proLIGHT Mill
- •43.4 PRACTICE PROBLEMS
- •44. CNC PROGRAMMING
- •44.1 G-CODES
- •44.3 PROPRIETARY NC CODES
- •44.4 GRAPHICAL PART PROGRAMMING
- •44.5 NC CUTTER PATHS
- •44.6 NC CONTROLLERS
- •44.7 PRACTICE PROBLEMS
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Figure C.4 Grid Representation of Space
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This map only indicates an objects presence, the remainder of the information is kept in a concurrent list. By finding and using a series of holes and walls within the grid an A* search is applied to find the best path. The cost function of the search is based on the path length and the number of turns made. The performance of this method is not stated, and thus no basis for comparison is available. This method provides straight line path segments. The mapping to configuration space could be convenient for the first pass of a path planner for general path finding.
40.12 APPENDIX D - FIELD METHODS
In an attempt to model ’natural flow’, there have been attempts to use gradients and potentials to choose natural path choices. These methods use the equivalent of field representations to provide a direction of travel that is ’down hill’. These methods have long setup times, and they can get caught. These techniques will benefit the most as more powerful computer hardware becomes available.
40.12.1 SPATIAL PLANNING : STEEPEST DESCENT
In an attempt to find a fast path planning method, the steepest descent method was proposed by P.W.Verbeek, L.Dorst, B.J.H. Verwer, and F.C.A. Groen [1987]. Their method is an array based method which will take the workspace represented polygons. This array is a two dimension representation of space in which the goal position is represented with a zero value, and the objects are represented with a value of infinity. Each element of the array is considered in a series of iterations over the array. The result of these iterations is a map of a ’height’ with respect to the goal state. The method then just follows the steepest gradient, down to the goal state.
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Figure D.1 Steepest Descent Representation and Path
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A Distance Map
This method has been implemented for a 2D multilink manipulator, but it uses 4 Mbytes of memory for a workspace resolution of 32 by 32 by 32. On a 12 MHz, 68000 VME computer system the whole process takes about 12 seconds. This is broken up into a 6 seconds for detection and labelling of forbidden states, a 6 second generation of distance landscape, and less than a second for finding the shortest path by steepest descent.
40.12.2 SPATIAL PLANNING : POTENTIAL FIELD METHOD
When considering that the basic thrust of the path planning methods is to avoid obstacles, it is easy to compare this avoidance to repulsion. The basic concept of repulsion is based on potential fields, as thus the potential field method of W.T.Park [1984]. In particular, the method was directed towards a workcell with multiple manipulators. In this setting there is a problem with potential manipulator collisions, which must be considered when path planning. To do this a planar view of the work cell is created, and the arms are given a potential. The potential repulsion of the manipulators is mapped for a number of various joint and slider positions. In the work of Park, a manipulator with two revolute joints, and a Stanford manipulator is used. Both of the manipulators have two degrees of freedom, thus a number of two dimensional arrays are necessary to fully describe the work space. This memory requirement is very large, and thus is one of the drawbacks of this technique. The Even with the use of compression techniques, the arrays still consume over 100 KBytes each. In the experimental implementation, the computer used was a VAX 750. The problem was constrained to 4 d.o.f., which used 2 MBytes of memory, and took 8 hours of computation time, to calculate about a million combinations. This method may also get caught in cul-de-sacs. The bottom line on this method is it highly oriented to batch and workcell operations, but too staggering to consider for use in a practical system.
In a more complex vein, Y.K.Hwang and N.Ahuja [1988] have developed a method using polygons and polyhedra to represent objects, from which a potential field is generated. First
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