For assembly and testing purposes, for example, assembly or testing of hybrid circuit modules, millimeter and smaller size objects need to be transported over distances on the order of several object diameters. In order to handle these sub-millimeter size mechanical or electronic components, a miniature manipulator system has been developed. There are many advantages to shrinking robots and mechanical actuators to the same size as the parts to be manipulated. Extremely delicate forces can be applied, robots can be readily parallelizable, and the relative accuracy required can be markedly reduced. One of the major difficulties in building millimeter scale micro-robots is overcoming forces due to friction and wiring. Friction forces can be reduced by using levitation or using fluid lubrication, such as an air-bearing. Here are some initial steps towards implementing a miniature robotic system using magnetically driven platforms about 7 mm square on a 35 mm square workspace. The position of the platform is sensed using an array-type capacitive proximity sensor. The system should be scalable to one tenth the present size. The mobile platforms will be used in cooperation to grab and position small objects.
Generic model of miniature planar robotic workcell. The goal is to build a system on which miniature parts can be transported, tested, and assembled.a
1995 version with squeeze film air bearing, magnet array, and integrated capacitor sensing.
Planar milli-robot system block diagram. Positions of robots and parts are detected using capacitive sensing, and robots are driven magnetically. The servo rate is 120 Hz, limited by sensor electronics scan time. The sensor is an 8 by 8 array, and the electromagnets are a 6 by 6 array.
Overall construction of the credit card robot system. Magnet and sensor layers are laminated together on to a rigid base. A squeeze-film air-bearing is formed by the 20KHz vertical vibration of the piezo-electric driver. Typical air-bearing thickness is 5 to 10 microns.