An Integral System for Assisted Mobility

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An Integral System for Assisted Mobility

• Manuel Mazo the Research group of the SIAMO
  Project

Yuchi Ming, IC LAB
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Contents

• Overview.
• System Architecture
• HMI(Human-Machine Interface).
• Environment Perception.
• Navigation and Control.

• Summary

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Overview

• The SIAMO(Spanish acronym for Integral System for
  Assisted Mobility) project began at the end of
  1996.
• Motivation Design autonomous wheelchairs as an
  assistance device for the disabled or the
  elderly.
• Goal Safety, Comfort and Modularity.

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System Architecture
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Human-Machine Interface

• Breath expulsion
• Head Movements.
• Electro-oculography(EOG).
• User-dependent voice recognition.
• Joystick.
• Display voice synthesizer.

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Guidance by Breath Expulsion

• A differential air-flow sensor with a linear
  output is used, so it is possible to detect both
  strength and direction of breathing.
• With an easy-to use breath code it is possible
  to obtain the references of linear and angular
  velocities and to stop the chair in case of
  trouble.
• This driving aid allows commanding the chair in
  broad corridors and halls as well as crossing
  through doors of 1.5m wide without any other
  assistance or sensory system.

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Guidance Head Movements.
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Guidance by Electro-Oculography

• This method allows one to generate simple coder
  for controlling the wheelchair using eye
  placement.
• Several biopotential skin electrodes are placed
  on the users face to detect eye movement.

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Guidance by Voice Commands

• Instead of a computer, a commercial isolated word
  recognition chip has been used.
• A set of nine voice commands are developed. Each
  command has an associated driving function Stop,
  Forward, Back, Left, Right, Plus, Minus, Password
  and Track.
• Plus and Minus means increase or decrease the
  speed.
• Password allows switch between the voice
  control and normal conversation.
• Track allows switch between voice control and
  Autonomous control.

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Environment Perception

• Ultrasonic sensors.
• Infrared sensors.
• Active laser sensors.
• Passive vision system based on artificial
  landmarks.

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Ultrasonic Sensors.
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Infrared Sensors

• The role of the infrared sensors is to detect
  floor unevenness.
• The sensor makes distance reading up to a point
  marked on the floor 2m in front of the wheelchair

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Active Laser Sensors

• This sensor module obtains 3-D positions of
  obstacles.
• A laser emitter projects a plane-form bean over
  the scene. From the image captured by the CCD
  camera, the points belonging to that bean are
  segmented.
• Expensive.

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Passive Vision System

• The landmarks are simple A4 paper sheet with a
  black-white pattern printed on them.
• Positioning is performed by measuring the
  landmark distortion in the captured image.
• Landmarks must be located at heights over
  1.5m(height of the camera, and each entrance door
  must be signaled with one landmark right over it.

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Navigation and Control

• Automatic Navigation strategy is incorporated in
  the wheelchair so that the user only need to
  indicate the destination point.
• Automatic Navigation need a full mapping of of
  the environment.

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• One contactless node, equipped with a wireless
  drive, can be placed on the main doors and loaded
  with a full description of room identification,
  landmark location, and routing inside the
  building.
• The wheelchair need not to store all the maps.

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Summary

• The system has the characteristic of being
  modular, which allows it to be easily adapted to
  each users specific requirements, depending on
  the type and degree of disability.