Automated Precision Machines Team 2 Nicholas Neumann Ralph Prewett Jonathan Brouker Li Tian Felix Adisaputra November 5 th, 2010

Contents  Servo Motor  Stepper Motor  Sensors for Precision Control  Robotic Programming Languages  Automated Machines

What is a Servo Motor? Closed-Loop System Precise position control

Servo Motor  Servo Mechanism  1: Position Sensor  2: Electric Motor  3: Reduction Gears

Servo Motor  Closed-Loop System

Servo Motor  Example  No Control  No Feedbacks

Servo Motor  Proportional-Integral-Derivative Control  Overshoot = 0  Rise Time  Settling Time  Steady-State Error = 0

Servo Motor  Applications  Labelling Machine

Stepper Motor Brushless, Synchronous Electric Motor Open-Loop System (No Feedback) Full Rotation Divided into Large Number of Steps Torque Decreases as Speed Increases.

Stepper Motor  Permanent Magnet Stepper Motor “Tin-Can” or “Canstock” Low Cost Low Resolution 7.5 o to 15 o step angles steps/revolution Rotor Magnetized with Alternating Poles More Magnetic Flux Provides More Torque

Stepper Motor  Hybrid Stepper Motor  More Expensive  Better Performance Torque Speed  Higher Resolution 3.6 o to 0.9 o step angles steps/revolution  Rotor Multi-Toothed Axially Magnetized Concentric Magnet

Stepper Motor  Two-Phase Stepper Motor  Bipolar Drive Single Winding per Phase Half the Power Loss  Unipolar Drive Two Windings per Phase One for Each Magnetic Field Direction Fewer Switches

Stepper Motor  Applications  Film-Advance

Stepper Motor  Applications  Conveyor

Servo Motor vs Stepper Motor Servo MotorStepper Motor Drive CircuitComplicated. Difficult for user to fabricate it. Simple. User can fabricate it. Noise and VibrationVery littleSignificant SpeedFaster ( rpm max.)Slow ( rpm max.) Out-of-Step ConditionNot Possible (Heavy load Still Run) Possible (Heavy load Stop) Control MethodClosed-Loop (uses an encoder)Open-Loop (no encoder) Resolution ppr = pulses per revolution 0.36° (1,000 ppr) to 0.036° (10,000 ppr) 2-phase PM model: 7.5° (48 ppr) 2-phase HB model: 1.8° (200 ppr) or 0.9° (400 ppr) 5-phase HB model: 0.72° (500 ppr) or 0.36° (1,000 ppr)

Sensors for Precision Control  Hall Effect Sensor  Voltage Transducer  Response to Changes in Magnetic Field  Applications: Switching, Positioning, Speed Detection, Current Sensing

Sensors for Precision Control Advantage:  They are immune to dirt, dust and water,  They are capable of switching at high frequencies.  They can be used for a wide variety of applications.

Sensors for Precision Control  Rotary Potentiometer  Position Transducer  Three-Terminal Resistor  Adjustable Voltage Divider

Sensors for Precision Control  Potentiometer If R L >> (R 1 and R 2 ),

Sensors for Precision Control  Linear Potentiometer  Displacement Transducer  Voltage Division Hybrid Conductive Film

Sensors for Precision Control  Rotary Encoder  Electromechanical Device  Angle Transducer  Angular Position Analog/Digital Code  Types: Absolute Rotary Encoder Incremental Rotary Encoder Gray Code

Sensors for Precision Control  Rotary Encoder  Gray Code

Robotic Programming Languages  C Language  Pros: Speed of Resulting Application Application in Firmware Programming Compatible with Many Other Languages Code is Compacted into Executable Instruction  Cons: No Runtime Checking No Strict Type Checking –Can Pass Integer Value for Floating Data Type Very Difficult to Fix Bugs as Program Extends

Robotic Programming Languages  RobotC Language  Pros: More Functions than Regular Graphical Language Easy to Navigate Through Program Suitable for More Complicated Programs  Cons: Text-Based Language –Hard for Beginners Must be Bought Separately from Kit

Robotic Programming Languages  Ladder Logic  Pros: Familiar Programming Language –Relay Logic (Widely Used) Cost-Effective Equipment Reliable Parts –Simple Circuits  Cons: Difficult Integration with Third Party Software

 BASIC  Pros: User Friendly and Interactive Simple and Easy Rapid Development Powerful Front-End Tool Multiple Vendor Support  Cons: Memory Leakage Passing Value by Reference Only for Windows Sluggish Performance Robotic Programming Languages

 LabVIEW  Pros: User Friendly Graphical Interface Universal Platform for Numerous Applications Compatible with Other Languages Execution Highlighting Feature  Cons: Expandability Problem –Depends on How Well the Original Program was Written Memory Management –Difficult Memory Allocation Expensive

Robotic Programming Languages  LEGO Mindstroms NXT  Pros: Icon-Based Drag and Drop –Graphical Language Easy Maintenance –Simple Programs  Cons: Lack of Complex Features in the Compiler

 Which Language to pick?  Previous Experience  How much time and effort you intend to invest  Your goals  Availability Robotic Programming Languages

Automated Machines  Control Systems  Information Technologies  Reduce Human Work

Automated Machines  Programmable Logic Controller (PLC)  Digital Computer  Automation of Electromechanical Processes  Multiple Input-Output Arrangements  Armored for Severe Conditions  User Interface

Automated Machines  Supervisory Control and Data Acquisition (SCADA) Centralized Systems Monitor and Control Human-Machine Interface (HMI) Alarm Conditions

Automated Machines  Main Advantages  Replacing Human Operators in Monotonous Work  Performing Tasks that are Beyond Human Capabilities Size, Weight, Speed  Dangerous Environment Space, Underwater, Nuclear Facilities  Economy Improvement

Automated Machines  Main Disadvantages  Technology Limits Unable to Automate All Desired Tasks  High Initial Cost  Unpredictable Development Costs

Questions