The project’s goal
Making the robot independently approach to a ball and
kick it
The project’s main tasks
• Creating an API for embedded robot’s controller in C,
which will allow controlling the robot on higher level
• Creating an image processing mechanism for the robot’s
camera in C++
• Creating a protocol for communication between the image
processing unit on PC and the robot
• Creating the decision making controller – the “brain”
The Bioloid Robot
(Premium Upgrade Kit ++)
2-Axis
Accelerometer
CM-510 controller
based on Atmel
ATmega1281 8-bit AVR
microcontroller
Dynamixel AX-12
motor x 20
Robotis Wireless
CMOS Camera
230x240, 30 FPS
DMS – Distance
Measurement
Sensor (IR)
ZigBee Zig-110
Wireless Module
The general idea
Peripheral
Devices
The Robot
Sensors
Camera
Camera
Receiver
The Controller PC
USB
Main Controller
Motion Controller
Dynamixels
Wireless connection
Image Processing
Unit
ZigBee
ZigBee
UART
Wireless Data
Processing Unit
Motion Controller structure
Motion control
Indicators
Head
Body
Robot’s body
movement
management
Robot’s body
movement
management
Main
All modules initialization
The main procedure
SW Utilities
Memory
Sensors
Analog port data
processing
DMS
Robot’s distance
measurement data
processing
ATmega1281
memory management
Robot’s CM-510
buttons handling
Errors
Accelerometer
Accelerometer
data processing
Robot’s CM-510
LEDs handling
Communication
ZigBee
Failures handling
Buttons
Robot’s sound
management
LEDs
Motion
Dynamixels
management
ADC
Buzzer
Utilities
General helper
functions
Wireless
communication
controller
Motion control
Terminology
• Dynamixel’s Offset – a dynamixel’s absolute angle
• Dynamixel’s Speed – a dynamixel’s speed of rotating
Motion control
Terminology
• Pose – a set of dynamixels’ offsets (except for the head)
• Page – a set of poses to be played sequentially
Except for the poses, page also holds an information about: play time, delays, next
page to play etc.
Motion control
Terminology
• Memory program space – the memory space, where the
code resides
• Memory data space – the memory space, where the data
resides
The user can’t access the program space directly due to AVR processor’s Harvard
architecture, but using special functions
Motion control
Terminology
• Robot’s Head – the robot’s head is an add-on of 2
dynamixels and a camera to the original Premium Upgrade
Kit
The head has 2 degrees of freedom: tilt and pan
Motion control
Memory management
• To avoid spending time on teaching the robot new poses, the poses
provided by manufacturer are used
• The manufacturer (ROBOTIS) places all the motion data in the program
space
• Original pages of poses are copied from program space to data space
• The data space is to small to hold all the pages, so a sort of caching
mechanism was implemented, based on the random replacing policy
Motion control
Pose playing
• The challenge is setting the robot’s pose, such as all the dynamixels will
start and end their motion simultaneously.
• This is performed by the next means:
• Calculating the correct speed for each dynamixel to move with, according to
the offset to be performed.
• Sending a broadcast message on the Dynamixel’s bus, such as all off it get
the moving command at the same time
Motion control
Page playing
• When playing a page of poses, there are defined speeds and delays for
each pose, so the dynamixel’s speeds are adjusted accordingly
• After reaching the end of page, there is a jump to the Next Page (one of
the page’s properties).
• Also there is a Stop Page pointer to jump there if something’s wrong
Motion control
Motion cycle
ZigBee
command
arrived?
No
Play the initial
pose
Yes
Preload relevant
pages into the cache
Body
What kind of
command?
Management
Any sensors
changed?
Yes
Correct the
pose(s)
Play the pose(s)
No
Perform management
operations such as:
update default
dynamixels offsets
Head
Move head
Motion control
Motion cycle
• Some explanations to the previous slide:
• During the motion play, the sensors are sampled and some corrections to
the motion can be made. For example:
• If accelerometer detects falling, the appropriate dynamixels are moved to avoid it
• If DMS detects close object while walking, the robot will try to avoid the obstacle
by walking around it
• If a button is pressed, robot returns to its initial pose
• As a result of ZigBee command the relevant page sequence is being played,
but after each pose there is a check if the ZigBee command has changed, so
another sequence will be played
Image processing
General principles
• The general principles of the tracking:
• Choosing the object’s color, which should be different from the background color
• The image processor calculates the average geometrical location of the chosen color
on the screen.
• The command to move robot’s head is sent to the robot, such as the average
geometrical location will be at the center of the screen (in infinite loop).
Wireless communication
General principles
• Wireless communication between Main Controller and robot is performed
using ZigBee protocol (not talking about video data, only the commands)
• The commands are generated (and can be received) by the Wireless Data
Processing unit and are sent to the robot.
• With correct ZigBee devices configuration the command generation from RC-
100 (remote controller) is also supported
Main Controller
(not implemented yet )
General principles
• The Main Controller is responsible for making a decision about a command to
be sent to the robot according to results received from the Image Processing
unit.
• The Image Processing unit provides the Main Controller with data about the
object’s (ball) location, such as:
• The relative angle in horizontal plane
• Estimated distance
• The Main Controller sends the movement commands to the robot
• The above actions are done in the loop until the robot finally is in the ball-kick
position
• The kick command is sent
Future development
possible directions
• Placing the main controller on the robot (some lite weight, but strong computing device),
to make the robot completely independent
• Upgrading the accelerometers (called “gyro” by the manufacturer) with the real gyros, to
improve robot’s stability (falling prevention)
• Improving the motion algorithms and flows by the principle:
•
Efficiency in cost of modularity
• Upgrading the camera for better performance
• Improving image processing for new features to be possible, such as:
•
Easy obstacle overcoming instead of avoiding
• Adding some device to the robot, which will allow:
•
Navigation
•
Shortest path finding
• ...
The End