Transcript Automated Precision Machines

Automated Precision Machines
Team 2
Nicholas Neumann
Ralph Prewett
Jonathan Brouker
Li Tian
Felix Adisaputra
November 5th, 2010
Contents
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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
• 7.5o to 15o step angles
• 48-24 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
• 3.6o to 0.9o step angles
• 100-400 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 Motor
Stepper Motor
Drive Circuit
Complicated. Difficult for user
to fabricate it.
Simple. User can fabricate it.
Noise and Vibration
Very little
Significant
Speed
Faster (3000-5000rpm max.)
Slow (1000-2000rpm max.)
Out-of-Step Condition
Not Possible (Heavy load
Still Run)
Possible (Heavy load
Control Method
Closed-Loop (uses an encoder) Open-Loop (no encoder)
Resolution
0.36° (1,000 ppr) to
0.036° (10,000 ppr)
ppr = pulses per
revolution
Stop)
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 RL >> (R1 and R2),
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
Gray Code
Analog/Digital Code
 Types:
• Absolute Rotary Encoder
• Incremental Rotary Encoder
Sensors for Precision Control
 Rotary Encoder
 Gray Code
Sector
Contact 1
Contact 2
Contact 3
Angle
1
off
off
off
0° to 45°
2
off
off
ON
45° to 90°
3
off
ON
ON
90° to
135°
4
off
ON
off
135° to
180°
5
ON
ON
off
180° to
225°
6
ON
ON
ON
225° to
270°
7
ON
off
ON
270° to
315°
8
ON
off
off
315° to
360°
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
Robotic Programming Languages
 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
Robotic Programming Languages
 Which Language to pick?
 Previous Experience
 How much time and effort you intend to invest
 Your goals
 Availability
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