What is needed for Fault Tolerance

      Awareness of:

• when a sensor is not functioning
• when a sensor is malfunctioning and to what extent
• environmental changes which cause sensors to give inaccurate percepts
• environmental changes which cause motors or other effectors to malfunction
• environmental changes which cause errant expectations, i.e. missing navigational cues
• when a motor or other effecter is not functioning
• when a motor or other effecter is malfunctioning and to what extent

      Under all conditions the ability to:

• identify the source of the problem to a level of granularity which affords the correct solution
• maintain this information on-line
• use this information on-line to find solutions to the problem
• inform operators of problems which will noticeably affect the robot’s performance

What is needed for Health Monitoring

      Awareness of:

• communications, i.e. operator to robot or robot to robot
  • drop outs
  • signal strength
• energy requirements of components
• battery level
• shock force, i.e. of an impact
• shock force tolerance of components
• processor utilization
• the relative CPU load and update rate for each schema
• temperature
  • motor
  • electronics (CPU, motor controller)
  • batteries
  • ambient
• temperature tolerance of components

      The ability to:

• use this information to select more appropriate behaviors or to adjust the parameters of behaviors so the robot’s resources are not exceeded
• activate corrective behaviors
  • modeled on negative-feedback behaviors used by animals to maintain homeostasis, i.e. moving to a cooler area before overheating
  • only used when the health problem is serious enough to jeopardize the robot's mission
• inform operators of impending problems
• allow operators to override health-aware decisions, force the robot to put itself at risk if necessary