One important parameter in robotics, one that can raise serious problems when trying to make things smaller, is the size of the parts you are using in building your robot. Because some indispensable pieces of hardware, like motors or batteries, have their sizes and even the smallest ones can be too big to use effectively, it is difficult to build a really small robot that incorporates all of these necesary elements. One solution to the problem could be to place these components outside of the robot.
This tiny robot uses an 18x Picaxe microcontroller from Sparkfun, a micro serial servo controller, 2 high torque servos and 2 standard servos from Polulu and 2- 1/8″ x 1/16″ and 1- 1″x1″x1″ neodymium magnets (a detailed parts list is available in the link). The case of the robot is built from 3 metal cases made of .oo5″ thick phosphor bronze sheet metal and the volume of the robot measures less than 1/20 of a cubic inch. The robot only uses non-magnetic materials in its construction, including the glass bead wheels which are attached to brass pins on the bottom of the robot.
The reason for this is that the robot is activated using a rotating and spinning magnetic field. Two magnets are attached to an internal vertical pole that is bent to form one arm of the gripper. The robot can move forward and back, turn left or right, move the gripper, open or close it. The magnetic field is mounted on a CNC type machine and it can be moved and rotated horizontally or vertically. The four servo motors actuate the magnet which the robot follows. The serial servo controller receives commands from the Picaxe microcontroller and sets the speed and direction of the motors.
Additional upgrades to the robot can include all kinds of sensors, like temperature or light sensors. An ingenious solution to a difficult problem, the Minuscule Gripper Robot could prove to be one step to microscopic robots of the future.