Robotic Arm Project Presentation

1
Robotic Arm ProjectPresentation

• This presentation will probably involve audience
  discussion, which will create action items. Use
  PowerPoint to keep track of these action items
  during your presentation
• In Slide Show, click on the right mouse button
• Select Meeting Minder
• Select the Action Items tab
• Type in action items as they come up
• Click OK to dismiss this box
• This will automatically create an Action Item
  slide at the end of your presentation with your
  points entered.

Project Leader Gregg Sutton
Education Lead Alyssa Anglin
Programming Lead Rachael Voss
Mechanical Design Team Zachary Wood and Sarah
Furrow
2
Robotic Arm
3
Presentation Outline

• Project Overview
• Task Descriptions
• Status

4
Robotic Arm Overview

• Assists students in learning educational
  concepts.
• Simulates the human arm.
• Controlled using a SiLabs C8051F310
  microcontroller.
• Software developed in C (or assembly) using
  Silicon Laboratories software.

5
The Robotic Arm Shall

• be cost effective.
• model a human arm.
• have the ability to lift a tennis ball or full
  soft drink can.
• be as safe as possible!

6
Robotic Arm Overview

• Overall schematic showing signal flow between the
  microcontroller, the h-bridge motor drivers, the
  motors, and the input controller.

M
Input Controller
M
M
Dual H-Bridge
Microcontroller SiLabs C8051F310
Dual H-Bridge
M
Dual H-Bridge
M
M
7
Educational Objectives

• The robotic arm will teach students
• mechanics of the human arm and its movement.
• control of the human arm.
• about robotics and engineering.
• basic circuitry.

8
Educational Outline

• Human Arm Mechanics
• Interaction between muscles and bones
• Range of motion
• Robotic Arm Mechanics
• Sliders as individual inputs
• Range of motion (more limited)
• Gears and motors
• Robotic Arm Engineering
• Design Process
• Basic Circuitry
• Potentiometers (inputs)
• Microcontrollers (brain)

9
Educational Activity

• Task Students will be required to move the
  Robotic Arm to a specified location and pick up
  small object.
• Outcome Students will learn about complexity of
  human arm movement.

10
Mechanical Design

• The arm is constructed
• Mounting of H-bridge drivers and micro in
  progress
• Debugging mechanical operation
• Elbow joint
• Shoulder rotation servo
• Forearm servo
• Shoulder lift servo

11
Analysis of Mechanical System

• Analyzed torque required to lift a one pound
  load.
• Determined additional requirements for servomotor
  selection.
• Strain and Stress analysis was not performed due
  to the fact that the arm will only move light
  loads.

12
Gripper

• The selected gripper is
• constructed of
• lightweight
• aluminum.
• able to open to
• four inches.
• able to lift a full
• soft drink can or tennis ball.
• donated last fall by www.stampbuilder.com .

13
Arm Movement
14
2D view of shoulder
15
Shoulder Lift and Pivot Joint
16
Forearm Rotation Joint
17
Elbow Joint
18
Electromechanical Design

• Determined interface of microcontroller, H-bridge
  drivers and servomotors
• Selection of servomotors
• Designing of electromechanical assemblies
• Designing of input controller

19
Electromechanical Interaction

• The microcontroller will output direction and
  speed signals for each motor that will be sent to
  the H-Bridges, which in turn will be sent to the
  motors.
  
• The position of the motors, supplied by internal
  potentiometers, will be sent back to the
  microcontroller to control the automatic power
  off of the motors when the limit of a joint is
  reached.

20
Electromechanical Interaction
21
Selection of Microcontroller

• SiLabs C8051F310 Microcontroller
• Has 29 I/O ports
• 20 ports can be used for Analog to Digital
  conversion (we need 12 for all of the inputs)
• 16Kb of non-volatile flash memory
• UART interface for future
• projects to program
• movement, even possibly
• through LAN
• On chip hardware debugger
• with step through capabilities.
• Cheap!

22
Selection of Servomotors

• The servomotors
• purchased from HiTec RCD, USA, Inc.
• are sized for each joint based on torque
  requirements.
• include built-in circuitry (this was removed for
  control purposes)

23
Selection of H-Bridge Drivers

• The H-Bridge Drivers
• Purchased from Lynxmotion
• Voltage
• 4.8v - 12vdc
• Peak Current
• 2.0 amp (motors
• draw 50 mA)
• Each can drive two motors

24
Designing of Input Controller

• provides students with an interface to
  controlling the arm.
• uses potentiometers to provide voltage input
  signals for
• each motor.
• is safe for
• students to use.

25
Input controller operation

• Input controller will control the direction of
  the servomotor rotation.
• The middle of the controller will be a null
  zone corresponding to no movement
• Above the null zone will correspond to clockwise
  movement
• Below the null zone will correspond to
  counterclockwise movement

26
Input Controller Operation
INPUT CONTROLLER SLIDER DIAGRAM GREGGS
RESPONSIBILITY
27
Electronic Control System Design

• Determine control software strategy
• Inputs feedback potentiometers and input
  controller
• Outputs Speed and direction
• Safe shutdown procedure

28
Robotic Arm Status

• Mechanical construction completed
• Electromechanical design completed
• Preliminary wiring completed
• Educational material for students completed

29
Robotic Arm Next Steps

• Mechanical debugging
• Finalizing software
• Professionalize wiring
• User manual
• Educational lesson plan approval

Estimated delivery date April 2005