The Micro Harmonic Drive~reg;: A high precision gear system miniaturized by Direct-LIG

摘要

Micro gear systems have to adapt the high rotational speed of up to 100.000 rpm and the low output torque in a range of some μNm provided by current micro motors to the requirements of many different applications. In addition to their miniaturized size and low weight micro gear systems must also feature zero backlash and precise angular transmission characteristics if they are to be used in micro positioning applications, e.g. in medical equipment, micro robotics, fiber communicational equipment and aerospace applications. At Micromotion GmbH in Mainz the principle of operation of a Harmonic Drive~® gear system has been applied to a micro gear system of only 1 mm axial length and 8 mm diameter using the LIGA technique. In addition to its small size the Micro Harmonic Drive~® achieves a very high reduction ratio between 160:1 and 1000 :1 in a single stage and transmits an output torque up to 40 mNm with a minimal torque loss of less than 16 μNm. The individual gear components of the Micro Harmonic Drive~® are manufactured from NiFe alloy using the Direct LIG process. This process is a modification of the LIGA technique, so as to allow the cost-effective production of micro gear components. With a repeatability and lost motion of less than 10 arc seconds the Micro Harmonic Drive~® is ideally suited for applications in high precision micro positioning drive systems. This unique micro gear is also the basis for the world's smallest backlash-free servo actuator, developed in cooperation with Maxon Motor AG of Switzerland. In the past two years the micro Harmonic Drive~® has successfully made the transition from laboratory into industrial applications.