Electromechanical XY Programmable Gantry Positioning System

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Electromechanical X-Y Programmable Gantry
Positioning System

• Wojciech Indyk Slawomir Kielian

UNIVERSITY OF ILLINOIS-URBANA CHAMPAIGN
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Introduction

• XY Coordinate Positioning System
• Applications laser micromachining, plasma
  cutting applications, plotter heads, robotic
  grippers, microscope applications, etc.
• Low cost alternative to presently available
  linear positioning systems

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Objective

• Design and Implement a PC programmable XY
  positioning system
• Three modes of operation
• Single Step Mode
• Single Command Mode
• Programmable Mode
• Advanced traversal algorithms
• High Precision 15.875 ?m / step
• Cost efficiency

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Project Overview

• Mechanical Construction
• Light Weight Aluminum Design
• Control Software
• Graphical Users Interface
• Traversal Algorithms
• Control Hardware
• Stepper Motor Driver Circuit
• Limit Switches
• Software-Hardware Interface
• Parallel Port Connection

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Mechanical Construction

• 22 Machine Shop
• CAD drawings
• 46 Mechanical Parts
• 0.500-8 ACME
• Lead Screws

Overall Dimensions 50 x 59 Plot Region 39
x 49
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Control Software

• Control program implemented using Visual Basic
• Graphical User Interface
• Supports three modes of operation
• Intuitive Controls
• User-Friendly

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Graphical User Interface (GUI)
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Traversal Algorithms

• Single Step Function
• Enables single step in any given direction
• Basis for all traversal algorithms
• X-Y and Y-X Traversals
• Shortest Distance Traversal
• Finds the shortest distance between two input
  coordinates

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Traversal Algorithms (cont.)

• Circular Traversal
• CW or CCW (clock-wise or counter clock-wise)
  traversal direction
• Start and End Angle option
• Start and End Offset option with tool up or down
  option during offset execution
• Polar coordinate entry available (by product)

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Control Hardware

• Stepper Motor Driver Circuit
• Implemented using LMD18245 Stepper Motor Driver
  IC
• Provides Stepper Motors with Gray Code input bit
  sequences
• Limit Switches
• Monitor plotting boundary conditions

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Stepper Motor Driver Circuit
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Parallel Port I/O Interfacing
DB-25 Male Connector

8 Data Outputs 4 Misc. Outputs 5 Data Inputs
Data Reg. (0x0378) Status Reg. (0x0379) Control
Reg. (0x037A)
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Test and Verification

• Message Center Window
• - Parallel port register contents
• - Update user with program status info
• Debug Coordinate Window
• - Output coordinates for plotting (Mathematica
  plots generated)
• Post-Assembly Test
• - U of I sign generation

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Traversal Algorithm Simulation Results Part 1

• X-Y Traversal

• Y-X Traversal

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Traversal Algorithm Simulation Results Part 2

• Shortest Distance
• Traversal

• Circular Traversal

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Traversal Algorithm Simulation Results Part 3

• Circular Traversal Special Features

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U of I Sign Generation
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Successes

• Design was fabricated and tested
• All design specifications were met
• Educational Benefits
• Stepper motor principles and control
• GUI programming (Visual Basic)
• Team collaboration and communication with
  manufacturing personnel

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Future Development

• Research interrupt techniques for Windows NT and
  Windows 2K operating systems
• Investigate variable output frequency algorithms
• Improve crucial mechanical tolerances

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Questions ?