Turtle
On the right, a 3D-image of the 2008 TURTLE (Tech United Robocup Team Limited Edition) is placed. When moving with your mouse across the picture various parts of the robot will be highlighted. When clicked, more information will be given concerning that specific part of the TURTLE.
Camera
On top of the TURTLE, a camera is placed to be able to see the world around it. The camera is pointing towards a parabolic mirror, thus creating a 360º view of its surroundings. Using this image, the robot is able to determine its position. To make a distinction between its own goal and the goal of its opponents, an electronic compass is placed on top of the mirror.
Mini PC Beckhoff
For data-acquisition and motion control, the TURTLE is equipped with Beckhoff EtherCAT devices, which are connected to a mini-pc via Ethernet. This mini-pc is running RTAI-Linux, in combination with MATLAB/Simulink/RTW, which provides a huge amount of toolboxes and a modular framework for development.
Platform
As can be seen in the top-view, three so-called omniwheels are placed under an angle of 120º. These omniwheels enable the possibility to move in every direction, forward, reverse, sideways and of course turning is possible. The wheels are driven by 150 W Maxon electro motors. Power is supplied by two Makita 24 V, 3.3 Ah batteries.
Ball handling
A feature that distinguishes Tech United Eindhoven from other mid-size RoboCup teams is the active ball-handling mechanism. The main part of the ball mechanism consists of two levers. At the end of each lever a wheel is mounted. These wheels can be actuated by DC motors and the velocities of these wheels are measured with tachos. The levers can rotate around fixed points of the TURTLE and the angles of the levers are measured by potentiometers. A preferred distance form the ball to the front of the TURTLE can be defined, which results in preferred angles of the two levers. If the levers are bending forward an error is introduced which is controlled towards zero by adjusting the velocities of the wheels. If the levers are bending backwards the wheels will be adjusted such that the ball is more or less pushed away from the TURTLE, and vice-versa. A short demonstration can be seen here.
Shooting
The kicking mechanism device is based on an electromechanical solenoid, in which a metallic plunjer is moved via a magnetic field generated by a current flowing through a coil. The plunjer of the solenoid is pushed against a metiallic leg to kick the ball. The leg consists of two parts, an inner and an outer leg. The inner leg produces a straight, flat shot. By turning the plunjer, the outer, foot-shaped leg can be used, producing a lob shot. The solenoid is powered by a 450 V, 4.7 mF capacitor.
