Pioneer 2 / PeopleBot - Manual (Page 35)

ActivMedia Robotics
Pioneer 2 Operating System
Chapter 6
Figure 19. ActivMedia Robotics client-
server control architecture
All ActivMedia robots use a client-server
mobile robot-control architecture
developed by Dr. Kurt Konolige and others
at SRI International. In the model, the
robot’s controller servers—the Pioneer 2
Operating System (P2OS)—work to
manage all the low-level details of the
mobile robot’s systems. These include
operating the motors, firing the sonar,
collecting sonar and wheel encoder data,
and so onall on command from and
reporting to a separate client application,
such as ARIA or Saphira.
With this client/server architecture, robotics
applications developers do not need to
know many details about a particular robot
server, because the client insulates them
from this lowest level of control. Some of
you, however, may want to write your own
robotics control and reactive planning
programs, or just would like to have a
closer programming relationship with your
robot. This chapter explains how to
communicate with and control your
ActivMedia robot via the P2OS client-server
interface. The same P2OS functions and
commands are supported in the various
client-programming environments that
accompany your robot or are available for
separate license.
Experienced Pioneer users can be assured that P2OS is upwardly compatible with PSOS,
implementing all the same commands and information packets. P2OS, of course,
extends the servers to add new functionality, improve performance, and provide
additional information about the robot's state and sensing. Hence, P2OS-specific
programs may not operate on original Pioneers.
Communication Packet Protocol
Table 2. Main elements of PSOS/P2OS communication packet protocol
Component Bytes Value Description
Header 2 0xFA, 0xFB Packet header; same for client and server
Byte Count 1 N + 2 Number of subsequent data bytes, including
the Checksum word, but not the Byte Count.
Maximum 200 bytes.
Data N command
or SIP
Client command or server information
packet (SIP)
Checksum 2 computed Packet integrity checksum
P2OS communicates with a client application using a special packet protocol for both
command packets from client to server and server information packets (SIPs) from the
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