Application in a New Micro-Scara-Robot
The trend to miniaturization in the field of consumer and investment goods is leading to increasing interest in the field of precision assembly of small components. Until now most machines for precision assembly have been many orders of magnitude larger than the workpieces to be handled or the necessary workspace. The Institute of Machine Tools and Production Technology of the Technical University of Braunschweig, represented by Arne Burisch, and Micromotion GmbH are now working together to develop a small-scale SCARA robot featuring a parallel hybrid kinematic structure. This new robot, with a base area of less than 150 x 150 mm2 will position small workpieces with a mass of up to 50 g with a repeatability of better than 1 µm.
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TU Braunschweig Institut für Werkzeugmaschinen und Fertigungstechnik Langer Kamp 19 B 38106 Braunschweig www.iwf.ing.tu-bs.de
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| Micro-Robot | Arne Burisch from IWF with the robot | FEM Analysis of Robot Arm Segment |
The parallel structure achieves sub-µm accuracy over almost the complete workspace and also has a symmetrical resolution map. The parallel structure should offer a significantly better dynamic performance, because only the gear motor for the fourth (rotational) axes is carried by the moving arm. Furthermore the passive joints of the parallel structure are easier to miniaturize than active joints. For these reasons the parallel SCARA structure was chosen as the basic structure for further development. By providing an angular repeatability of 10 arc seconds, the Micro Harmonic Drive® gear is the only micro gear currently available that provides sufficient accuracy for a micro robot of this kind.
| Criterion | Value | Unit | ||
| Workspace (rectangular) | 60 x 40 x 20 | mm³ | ||
| Workspace (primary) | 40 x 30 x 20 | mm³ | ||
| Footprint (area of robot base) | < 150 x 150 | mm² | ||
| Repeatability | < 1 | µm | ||
| Linear speed (X,Y,Z directions) | > 100 | mm/s | ||
| Angular resolution | 0.0028 | ° | ||
| Rotational speed (Ψ axis) | 187 | rpm | ||
| Angular resolution (Ψ axis) | 0.022 | ° | ||
| Payload | 50 | g | ||
