01-03-2013, 01:06 PM
Embedded Robotics
[attachment=52305]
ROBOTS CONTROLLERS
Robotics has come a long way. Especially for mobile robots, a similar
trend is happening as we have seen for computer systems: the transition
from mainframe computing via workstations to PCs, which will
probably continue with handheld devices for many applications. In the past,
mobile robots were controlled by heavy, large, and expensive computer systems
that could not be carried and had to be linked via cable or wireless
devices. Today, however, we can build small mobile robots with numerous
actuators and sensors that are controlled by inexpensive, small, and light
embedded computer systems that are carried on-board the robot.
There has been a tremendous increase of interest in mobile robots. Not just
as interesting toys or inspired by science fiction stories or movies [Asimov
1950], but as a perfect tool for engineering education, mobile robots are used
today at almost all universities in undergraduate and graduate courses in Computer
Science/Computer Engineering, Information Technology, Cybernetics,
Electrical Engineering, Mechanical Engineering, and Mechatronics.
Mobile Robots
Since the foundation of the Mobile Robot Lab by the author at The University
of Western Australia in 1998, we have developed a number of mobile robots,
including wheeled, tracked, legged, flying, and underwater robots. We call
these robots the “EyeBot family” of mobile robots (Figure 1.1), because they
are all using the same embedded controller “EyeCon” (EyeBot controller, see
the following section).
Interfaces
A number of interfaces are available on most embedded systems. These are
digital inputs, digital outputs, and analog inputs. Analog outputs are not
always required and would also need additional amplifiers to drive any actuators.
Instead, DC motors are usually driven by using a digital output line and a
pulsing technique called “pulse width modulation” (PWM).
Operating System
Embedded systems can have anything between a complex real-time operating
system, such as Linux, or just the application program with no operating system,
whatsoever. It all depends on the intended application area. For the Eye-
Con controller, we developed our own operating system RoBIOS (Robot Basic
Input Output System), which is a very lean real-time operating system that
provides a monitor program as user interface, system functions (including
multithreading, semaphores, timers), plus a comprehensive device driver
library for all kinds of robotics and embedded systems applications. This
includes serial/parallel communication, DC motors, servos, various sensors,
graphics/text output, and input buttons. Details are listed in Appendix B.5.
SENSORS
There are a vast number of different sensors being used in robotics,
applying different measurement techniques, and using different interfaces
to a controller. This, unfortunately, makes sensors a difficult subject
to cover. We will, however, select a number of typical sensor systems and
discuss their details in hardware and software. The scope of this chapter is
more on interfacing sensors to controllers than on understanding the internal
construction of sensors themselves.
What is important is to find the right sensor for a particular application.
This involves the right measurement technique, the right size and weight, the
right operating temperature range and power consumption, and of course the
right price range.
Data transfer from the sensor to the CPU can be either CPU-initiated (polling)
or sensor-initiated (via interrupt). In case it is CPU-initiated, the CPU has
to keep checking whether the sensor is ready by reading a status line in a loop.
This is much more time consuming than the alternative of a sensor-initiated
data transfer, which requires the availability of an interrupt line. The sensor
signals via an interrupt that data is ready, and the CPU can react immediately
to this request.
[attachment=52305]
ROBOTS CONTROLLERS
Robotics has come a long way. Especially for mobile robots, a similar
trend is happening as we have seen for computer systems: the transition
from mainframe computing via workstations to PCs, which will
probably continue with handheld devices for many applications. In the past,
mobile robots were controlled by heavy, large, and expensive computer systems
that could not be carried and had to be linked via cable or wireless
devices. Today, however, we can build small mobile robots with numerous
actuators and sensors that are controlled by inexpensive, small, and light
embedded computer systems that are carried on-board the robot.
There has been a tremendous increase of interest in mobile robots. Not just
as interesting toys or inspired by science fiction stories or movies [Asimov
1950], but as a perfect tool for engineering education, mobile robots are used
today at almost all universities in undergraduate and graduate courses in Computer
Science/Computer Engineering, Information Technology, Cybernetics,
Electrical Engineering, Mechanical Engineering, and Mechatronics.
Mobile Robots
Since the foundation of the Mobile Robot Lab by the author at The University
of Western Australia in 1998, we have developed a number of mobile robots,
including wheeled, tracked, legged, flying, and underwater robots. We call
these robots the “EyeBot family” of mobile robots (Figure 1.1), because they
are all using the same embedded controller “EyeCon” (EyeBot controller, see
the following section).
Interfaces
A number of interfaces are available on most embedded systems. These are
digital inputs, digital outputs, and analog inputs. Analog outputs are not
always required and would also need additional amplifiers to drive any actuators.
Instead, DC motors are usually driven by using a digital output line and a
pulsing technique called “pulse width modulation” (PWM).
Operating System
Embedded systems can have anything between a complex real-time operating
system, such as Linux, or just the application program with no operating system,
whatsoever. It all depends on the intended application area. For the Eye-
Con controller, we developed our own operating system RoBIOS (Robot Basic
Input Output System), which is a very lean real-time operating system that
provides a monitor program as user interface, system functions (including
multithreading, semaphores, timers), plus a comprehensive device driver
library for all kinds of robotics and embedded systems applications. This
includes serial/parallel communication, DC motors, servos, various sensors,
graphics/text output, and input buttons. Details are listed in Appendix B.5.
SENSORS
There are a vast number of different sensors being used in robotics,
applying different measurement techniques, and using different interfaces
to a controller. This, unfortunately, makes sensors a difficult subject
to cover. We will, however, select a number of typical sensor systems and
discuss their details in hardware and software. The scope of this chapter is
more on interfacing sensors to controllers than on understanding the internal
construction of sensors themselves.
What is important is to find the right sensor for a particular application.
This involves the right measurement technique, the right size and weight, the
right operating temperature range and power consumption, and of course the
right price range.
Data transfer from the sensor to the CPU can be either CPU-initiated (polling)
or sensor-initiated (via interrupt). In case it is CPU-initiated, the CPU has
to keep checking whether the sensor is ready by reading a status line in a loop.
This is much more time consuming than the alternative of a sensor-initiated
data transfer, which requires the availability of an interrupt line. The sensor
signals via an interrupt that data is ready, and the CPU can react immediately
to this request.