Inside DARwIn the Humanoid Robot

By alexjc | March 23, 2007

DARwIn Dribbling

DARwIn is a humanoid robot that plays soccer, set to take on other candidates from around the world in the 2007 Robocup competition. It was developed by a group of mechanical engineering students from Virginia Tech, in the Robotics & Mechanisms Laboratory.

DARwIn’s measurements: 48 cm high, 4.2 kg and an autonomy of a few hours. It’s capable of getting up off the floor unassisted, walking around without falling, and kicking balls around. Not quite up to standard with the professionals in European football leagues, but it doesn’t cost as much!

Find out more technical details behind DARwIn, and watch a video of the robot in action after the jump…

There have been multiple iterations during the development of this humanoid. Two of the existing robots form a soccer team, DARwIn I stands as the goal keeper and DARwIn IIa plays up front as the striker. Version 2 of the robot is a bit more flexible with two extra actuators, and has a better power-to-weight ratio. The next prototype IIb, described here and currently under development, will have a wider variety of actuators.

The Hardware

The majority of the actuators, used to control the joints of the robot, are Dynamixel DX-117. These are worth about $200 each, and there are over twenty of them in DARwIn I for example. The servomotors are high-torque motors, as most joints won’t do much high speed rotation! Through the serial connection, it’s also possible to get basic sensory information such as position and voltages, etc. The Dynamixel RX range of servo-motors is used on the latter prototypes to provide better performance. (These are harder to find for hobbyists).

As for separate sensors, the early versions of the robots only include small cameras, useful for finding the location of the ball. These are like standard firewire web cameras, available from UniBrain among others. The more recent prototypes of DARwIn include other proprio-sensors that can detect the global orientation of the skeleton. A gyroscope sensor can do this, like those available from XSens.

All the information is processed by an onboard computer, based on a battery-powered Pentium M configuration. This isn’t the fastest available, only 1.4 Ghz, but given enough optimisations it seems to provide the best ratio of computation vs. power consumption. The computer can gather the information from each of the sensors, and control each of the actuators depending on the current situations and internal goals.

The Software

LabVIEW runs as the operating system of the onboard computer, and provides a host of facilities for gathering, processing and analysing large quantities of data. A lot of time during development is spent on debugging both hardware and software, so having a robust set of tools readily available significantly helps the process.

LabVIEW also simplifies the process of developing the software, providing a higher-level of abstraction to work on rather than accessing the interface devices directly in a low-level language like C or C++. The programming methodology itself is visual rather than syntactical. The developer simply creates boxes and connects them together to model the flow of information in the robot.

Further Research

The DARwIn humanoids are part of a whole group of robots developed at RoMeLa, the robotics department at Virginia Tech. Their current research covers half a dozen prototypes based on the same technology as the Robocup team.

Among their publications there are a few interesting papers to read, but one in particular applicable to DARwIn’s technology:

Biologically Inspired Locomotion Strategies: Novel Ground Control Robots at RoMeLa (5.2 Mb PDF)

For mainstream media coverage of DARwIn, see the following articles:

Students develop soccer bot
Robot designed by students successful at international competition

More information about the DARwIn robots visit their site.

Tags: humanoid, labview, robocup, robot, romela
Category: analysis |