Miller Robotic Interface II Manual de usuario descargar pdf (Pagina 28)

camera is used to detect heat signatures and help find victims that may be covered in dust as well

as in darkened areas. We did some work trying to fuse the infrared video image with the live

regular video stream, so a user does not have to toggle between the two camera views, as they

had to in some other robot systems that were studied [Hestand and Yanco, 2004]. We originally

mounted the Raytheon Nightdriver camera, a low resolution, black and white image that was

intended to be mounted to an automobile. This camera was large and heavy, so we were not

able to have it pan and tilt with the regular color camera as we originally wanted to. We later

moved to a color FLIR camera. The new camera was much smaller and much lighter, which left

open the option to have it mimic the pan/tilt of the primary video camera, which could make

overlaying the infrared image much easier.

4.2 Control Protocol

The overall system architecture is shown in figure 7. Most of the sensor information is sent

from the robot to the interface via User Datagram Protocol (UDP) sockets. We chose UDP

over Transmission Control Protocol (TCP) for two main reasons. The first reason is that in a

crowded network, TCP will throttle its bandwidth back to try to improve connectivity for all

users. It will also queue up packets to be sent when connectivity improves. However, in the

type of situations we are dealing with, we want to be selfish. We do not want the driving

commands that are sent to the robot to be throttled back or held in a queue. If we need to stop

the robot in an emergency, we need that message to get there as quickly as possible. Also, the

queuing problem can be devastating in a fragile environment. If the user gets frustrated that the

robot isn’t responding due to dropped packets or slow connection, every command that they

sent while the connection is slow will quickly get executed as soon as a good status is restored.

This can result in very erratic and extremely dangerous behavior. Therefore, we want to make

sure that any packets that aren’t received in a timely fashion are just ignored and not queued up.

We want the most current data to be received and acted upon. We do not want old data.

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Miller Robotic Interface II Manual de usuario Pagina 28