Page 234 - Designing Autonomous Mobile Robots : Inside the Mindo f an Intellegent Machine

Becoming Unstuck in Time

Some years later I was notified that the patent had been granted, but by then our robots
were sporting the very capable LMS lidar systems. The story of robot development is one
of continuous improvement in the enabling technologies, and therefore continuous change
in the robots that use these technologies.

Managing the time dimension

We have seen that the time dimension can work for or against us. We must constantly
think of the effects of other things that may be occurring concurrently. We must also
ensure that data has been appropriately compensated for latency and collection times.
The consideration of latency is not limited to navigation; for example, a security robot
will tend to use its camera in many ways in order to maximize its coverage. When the
robot is performing routine patrols, the camera will often be given coordinates to
watch. Similarly, if an intruder is sensed it will be directed to track the suspect. There are
several latency issues here. For example, the sensor data is always a bit old due to
processing, the communications system will require time to relay the control message to
the camera, and the camera will require a finite time to move to the requested
position. To compensate for these delays, the robot must dynamically calculate a
“lead” from the current position command according to the target’s apparent motion. If
this is not done, the camera will be largely ineffective.

If we try to ignore tiny time delays, and the things that can happen during these
delays, we may pay dearly in the performance of the robot. On the other hand, if we
imagine that we have data from multiple robot time-places available, we can imply a
rich amount of information from relatively sparse data. The trick is to begin to think
in terms of time and to learn to avoid static and sequential problem solving. We must
become unstuck in time.

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