Semi-Autonomous Control of Mobile Robotic Field Agents: The Algorithm, Interface, and Implementation Results

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Semi-Autonomous Control of Mobile Robotic Field
Agents The Algorithm, Interface, and
Implementation Results

• Mr. John M. Kuperavage
• Mr. John Haughery
• Dr. John R. Wright, Jr., CSIT
• Department of Industry Technology
• Millersville University of Pennsylvania

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The Need for Education

• Advances in the field of robotics have resulted
  in dependable robots that are extremely accurate
  and repeatable while becoming affordable. In the
  last decade the prices for robots have fallen
  nearly 40. During the same period robots have
  become faster and more versatile. Analysts expect
  the use of robots in the electronics industry to
  grow at an average rate of 35 annually during
  the next four years (Dunham, 2001).

• It has been cited by the RIA Robotics
  International Association, that only 12 of the
  American companies that could use a robot, are
  presently using one. Therefore, 88 of the market
  is still untapped. There are many reasons for
  this. But the predominant reason is the lack of a
  trained workforce that understands how to
  implement the technology. We need more engineers
  to develop a hands-on understanding of what
  constitutes a good application (Harris, 2003).

www.rixan.com
3
The Need for Education

• Recent advances in the development of robotics
  combined with significant reduction of their
  costs have made the implementation of such
  devices in todays smaller and midsize companies
  increasingly necessary and feasible.
• According to Peter Cavallo, head of U.S. sales
  for Denso Robotics, its well within the means
  of any size company to use robots. Its no longer
  just the realm of large or dollar-intensive
  companies (Spencer, 2003).

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Overview of Robotic Control

• Industrial Robots
• Bang-Bang
• Point-to-Point
• Controlled Path
• Continuous Path
• Mobile Robots
• Hard Wired
• Tele-operation
• Semi-Autonomous
• Autonomous
• Known versus Unknown

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Sectors of Society that Employ Mobile Robots

• 1) Manufacturing
• Automatic Guided Vehicles (AGVs)
• 2) Medical
• Hospital Food Delivery
• 3) Military (Urbie)
• Recognizance
• 4) Research/Exploration
• Space, Hazardous Environments, etc.

http//robotics.jpl.nasa.gov/tasks/tmr/picts/Stair
Photo.jpg
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Progression of Semi-Autonomous Research

• Students began with general Basic Stamp II
  tutorial books which included programs to run
  servo motors and various sensors.
• Whats a Microcontroller
• and
• Robotics with the BOE Bot

• Once familiar with the basics, the students were
  able to start applying this knowledge to begin
  operating speed controllers and steering servos
  to move a mobile robotic vehicle.
• Independent research was performed on more
  advanced sensors and wireless Bluetooth
  technology.

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SA-1s Development

• SA-1 was first introduced using only
  tele-operated control but was designed to have an
  autonomous function integrated into it. This was
  done while the team members were being introduced
  to the technology in various classes.
• Independent Studies and Independent Research
  expanded our technical capability in the use of
  infrared sensors and wireless Bluetooth
  communications.
• The original SA-1, which was built for the 2004
  NAIT conference employed semi-autonomous control
  (tele-operation and autonomous modes).
• SA-1 was modified for the 2005 National Robotics
  Challenge. The autonomous function was expanded
  to include a search pattern that could be
  activated to find an object and then grab it.
  This advanced our autonomous mode, leaving the
  tele-operation the same.

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Motor Control

• Many tele-operated vehicle motors are controlled
  by speed controllers.
• Research was preformed on to how to control a
  hobbyist level speed controller via a
  microcontroller.
• We found that the control is similar to that of a
  servo motor. A pulse out range of 500 to 1000
  milliseconds will drive the speed controller from
  full reverse to full forward (750 being neutral).

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Infrared (IR) Sensors

• To detect objects, two Parallax S.S.I.R infrared
  sensors were used. These required no integration
  other then connecting them to the proper pins.
• These were placed inside of the
• gripper to detect the object and
• then center the robot on it.
• The sensors used one pin on the Microcontroller
  to both send and receive signals.
• Certain kinds of light sometimes cause erroneous
  signals with this type of sensor. The code had to
  be modified to filter out these stray signals,
  which allowed for more accurate detection. This
  code will be explained later.

Sensors
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Bluetooth Communication

• To allow an operator to initiate the automation
  and monitor the status of the robot, a wireless
  communication link needed to be established.

• This was done using a Parallax EmbeddedBlue
  transceiver and a USB Bluetooth adapter for the
  PC.
• The Bluetooth adapter simply plugs into a PC USB
  port. The EmbeddedBlue transceiver plugs directly
  into the AppMod Header on the BASIC Stamp II.

AppMod Header VSS Pins

• Code was written to allow communications between
  the EmbeddedBlue transceiver and the PC adapter.
  The user would first open a HyperTerminal window
  on the PC screen where he could see a prompt
  which was sent from the microprocessor. Then he
  could input a value that could be used in the
  code to do things such as start an automated
  process.

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Tele-Operated to Autonomous Control

• SA-1s control was transferred from the remote
  control to the Basic Stamp through the wireless
  Bluetooth connection.
• The user would drive the robot to a position
  where the object would be within a certain range
  of the gripper.
• At this point, the user would initiate the
  automated function from the HyperTerminal prompt
  on the laptop screen.
• This sent a start signal to the microprocessor,
  which began the automated process. During this
  process, the microprocessor takes precedence over
  the remote controller, temporarily disabling it.
• To transfer control of the robot back to the
  remote controller, the microprocessor activated a
  control relay which temporarily shorted out the
  BASIC Stamp reset. This reset the program and the
  process.

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Integrating the Technologies

• Once the students had the knowledge base and more
  advanced technologies had been explored, the next
  step was to integrate the research into one
  working system.
• Many code adaptations were necessary to allow all
  of the systems to function together.
• Our teams task was to develop a semi-autonomous
  system to allow an operator drive an unknown
  course and engage an automatic mode that searches
  for an object and then picks it up.
• This process was automated to allow the pick up
  to be done quicker and more reliably then if it
  were done through manual control.
• We will now go through an overview of the logic
  algorithm which was formed to develop the code
  for the automated portion of the robots control.

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Complete Algorithm
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Starting the Automation Process

• SEROUT 1,84,CR,"Press 1 to start the Automation
  process",CR
• SERIN 0,84,DEC1 CmdData
• BRANCH CmdData,Open_Shell
• GOTO Main

• SEROUT puts a display on the computer screen
  prompt and SERIN waits for the user to give a
  response.
• A zero on the keyboard starts the automation
  process by directing the program to an open shell
  subroutine.
• No input re-loops the code until an input is
  given.

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Complete Algorithm
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Opening/Closing the Shell

• Open_Shell
• IF IN4 0 THEN Manipulator
• PULSOUT Motor,870
• PAUSE 20
• GOTO Open_Shell

• This is a loop to open the shell. Once inside,
  the program will remain in the loop until a limit
  switch indicating fully open is depressed. That
  limit corresponds to IN4 0 and the THEN
  goes to code to open the manipulator.
• If the limit switch is not depressed, the program
  will continue to run through the loop pulsing out
  to Motor which controls the speed controller
  for the hinge motor.
• This is the exact same process for closing the
  shell, except you pulse out to the speed
  controller in the opposite direction.

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Complete Algorithm
Grab Object
Start Automation
Object Search
Open/Close Shell
Open/Close Shell
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Opening the Manipulator

• Manipulator
• FOR a 1 TO 10
• PULSOUT Servo1, Backwards
• PULSOUT Servo2, Fwd
• PAUSE 20
• NEXT

• The code to open the manipulator is simply a set
  number of passes through a loop. (Notice, no
  feedback.) Each time through the loop, a pulse is
  sent to two servos on both sides of the
  manipulator to open the two doors.
• The program then proceeds to a search pattern.
  This is a left, then right zigzag pattern,
  checking the sensors for an object 8 times each
  cycle.

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The Search Pattern

• Each time through the search, the cycle yields
  four pulses to the left and four to the right.
  This is done by always pulsing to Motor2, which
  is a drive motor speed controller. The zigzag
  motion is accomplished by pulsing out forward or
  reverse to Pin 10, which is the steering servo.
• You can also again see a SEROUT which gives a
  prompt indicating the status of the search.
• The GOSUB is a subroutine to check the sensors
  for object detection each after each pulse.

• Search
• FOR x 1 TO 4
• PULSOUT 10, 1000
• PULSOUT Motor2, 815
• SEROUT 1,84,CR,"The SA-1 is Searching", CR
• GOSUB sensor_check
• NEXT
• PAUSE 250
• FOR x 1 TO 4
• PULSOUT 10, 500
• PULSOUT Motor2, 815
• SEROUT 1,84,CR,"The SA-1 is Searching", CR
• GOSUB sensor_check
• NEXT
• PAUSE 250

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Checking the Sensors

• sensor_check
• CountUp 0
• tally 0
• FOR freqSelect 0 TO 6
• LOOKUP freqSelect,37500,38000,38500,39000,3950
  0,40000,40500, irFrequency
• FREQOUT 1,1, irFrequency
• IF IN1 0 THEN CountUp (Countup 1)
• NEXT
• IF (CountUp gt 1 )THEN tally (tally 1)
• IF tally 2 THEN found
• Bolded code is for detection using two sensors

• If the reliability is high enough (enough
  instances of detection are seen), the a variable
  tally is incremented.
• This code is for one sensor. Setting up another
  sensor the same way would have the same result.
• To align the mobile robot on the object, all
  sensors must detect something reliably. In this
  case two sensors must set the variable tally to
  two before continuing to the object found
  section of the code.

• The LOOKUP Command checks the sensor at
  different frequencies (different sensitivities).
• FREQOUT sends and receives the signal through
  Pin 1 or IN1.
• CountUp records how many times the something is
  detected.

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Object Found!

• Found
• FOR x 1 TO 8
• PULSOUT Servo3, 750
• PAUSE 300
• NEXT

• Once the robot searches and finds the object, it
  must straighten its wheels before proceeding to
  pick the object up.
• This is done by pulsing a centering value to a
  servo a set number of times to overcome the
  resistance of the ground.

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Complete Algorithm
Grab Object
Start Automation
Object Search
Open/Close Shell
Open/Close Shell
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Grabbing the Object

• Within the MOVE loop, the code pulses to the
  drive motor speed controller until the object is
  in the gripper. This is indicated by a depressed
  limit switch IN3.
• Notice again that SEROUT is used to prompt the
  user of the status of the robot.
• Once the object is in the gripper the two servos
  on both sides of the gripper close the doors by
  receiving a set number of pulses.

• MOVE
• PULSOUT Motor2, 815
• SEROUT 1,84,CR,"The SA-1 is now in motion",
  CR
• IF IN3 0 THEN SERVO_CLOSE
• PAUSE 20
• GOTO MOVE
• SERVO_CLOSE
• FOR b 1 TO 5
• PULSOUT Servo2, Fwd
• PULSOUT Servo1, Backwards
• PAUSE 20
• NEXT

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Complete Algorithm
Grab Object
Start Automation
Object Search
Open/Close Shell
Open/Close Shell
25
What the Process Looks Like!

• The algorithm
• in motion!

The operators view
Video taken at the 2005 National Robotics
Challenge, Marion Ohio
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Seems Simple?

• Developing this algorithm may seem easy or
  difficult to some, but there is more to creating
  a working Semi-Autonomous system.
• So far, we have acquired the necessary knowledge,
  developed key technologies, and integrated them
  by forming a logic algorithm for the autonomous
  mode.
• Even though everything works as bench tested, you
  still need to perform electromechanical
  integration to make all those components function
  together.
• SA-1 had two major electromechanical systems
• Opening and closing the shell and grabbing the
  object.

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Opening/Closing SA-1

• A hinging action was used to open/close SA-1s
  shell.
• This also lowered manipulator to ground level to
  allow the object to be grabbed.
• This hinging was performed by means of a motor
  and a screw.
• The chassis hinged at its center and its front
  end, which allowed it to fold up as it opened.

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Opened
Closed
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Hinging Motor Screw

• Function
• Lowered raised the manipulator.
• Provided a mechanical advantage for lifting a
  load.

Motor Screw Threaded Nut
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Hinging Motor Wiring Diagram
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Hinging Open Limit Switch(Mechanical Interface)
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Open
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Hinging Open Limit Switch(Mechanical interface)
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Hinging Closed Limit Switch(Mechanical interface)
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Closed
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Hinging Closed Limit Switch(Mechanical interface)
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Limit Switch Wiring Diagram
Note - The wiring diagrams for all limit switches
are the same except each is wired to a different
input.
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Gripping The Object

• SA-1 employed an encompassing gripper to grasp
  the object.
• A limit switch was used to indicate when the
  object was within the grippers grasp.
• The limit switch employed an active compliance
  system to reduce contact shock to the object.

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Gripper Limit Switch(Mechanical interface)
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Conclusions

• We discussed the need for robotic education and
  an overview of mobile robotics and control.
• The progression of research leads students from
  performing simple applications to developing
  complex algorithms, which can be used to automate
  portions of the robots function.
• Once an algorithm is developed, code can be
  written to perform the tasks within each section.
  
• Finally, electromechanical integration must take
  place to allow the code to control the mechanical
  components properly.

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Thank You!

• Any Questions?

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References

• Dunham, P. (2001). Robots provide automated
  soldering solution. Electronics Manufacture and
  Test. Accessed online (July, 2003)
  http//www.emtmagazine.co.uk/
• Harris, S. (2003). Stats for grant application.
  Email correspondence with Stephen Harris,
  President of Rixan Associates, Inc. Dayton, Ohio.
• Lindsay, A. (2004). Robotics with the Boe-Bot
  (VERSION 2.2). Parallax, Inc.
• Spencer, R., Ed. (2003). Robotic machine tending
  a mature application, but still has room to
  grow. Robotics World, 21(5). Accessed online
  (July, 2003) http//www.roboticsworld.com/featur
  es.asp
• Whats a Microcontroller. (VERSION 1.9). (1999).
  Parallax, Inc.