Selected results on microhandling of the Micro- and Nanorobotics group
Hybrid handling combining robotic micromanipulation with droplet self-alignment
We have studied novel methods for assembling microparts of different shapes, to well defined positions and orientations. Such task is a fundamental operation in a typical microassembly application. Our approach combines robotic micromanipulation for coarse positioning and droplet self-alignment for fine positioning. We call such methods as hybrid microhandling methods.
To study the feasibility of hybrid microhandling, an apparatus has been setup composed of a robotic microgripper, three dimensional micropositioning system, a droplet dispenser and a microscopic vision system. The handling technique was tested with block-shaped SU-8 microparts, ranging from 50 µm x 50 µm x 40 µm to 300 µm x 300 µm x 70 µm.
The handling sequence is illustrated below. The robotic microgripper picks a micropart (top part) from a reservoir of microparts and carries it near another part (bottom part), which is fixed to a substrate. The dispenser dispenses a droplet of water on the bottom part. The robot carries the top part over the bottom part so that the droplet wets the surfaces of both parts and a meniscus is formed. After this, the microgripper quickly opens, releasing the top part from its grasp. The surface tension of the droplet aligns the top part to the bottom part. Finally, all water evaporates, leaving the two parts aligned to each other.
- hybrid2.wmv 300 µm x 300 µm parts are aligned to each other using the method
- hybrid3.wmv The droplet self-alignment overcomes the adhesion force between the part and the tool
The method can adapt not only to parts of similar sizes, but also parts of different sizes. By using robotic positioning, the initial position of the top part can be controlled that leads to deterministic self-alignment, which is not possible using purely stochastic self-assembly.
- hybrid4.wmv The method can be used to align parts of different sizes, by starting the process with the top part outside the bottom part. The top part is 100 µm x 100 µm.
- hybrid5.mpg Another example of aligning parts of different sizes. The bottom part is 300 µm x 300 µm
The method can also be used to realise dexterous manipulation. By dispensing water in specific location, the capillary forces can be used e.g. to flip part by 90 degrees.
- hybrid_flipping.wmv Using capillary forces to flip part by 90 degrees.
- hybrid_cascade.wmv Stacking multiple parts using temporary fixing by capillary forces and adhesion.
- hybrid_cantilever.wmv Building cantilever structures using hybrid methods to align parts of different sizes.
- Sariola, V., Zhou, Q., Koivo, H.N. “Hybrid microhandling: a unified view of robotic manipulation and self-assembly”, Journal of Micro-Nano Mechatronics, 2008.
- Sariola, V., Zhou, Q., Koivo, H.N., “Three Dimensional Hybrid Microassembly Combining Robotic Microhandling and Self-Assembly”, to be published in 2009 IEEE International Conference on Robotics and Automation, Kobe, ICRA’09, Japan, 2009.
- Sariola, V., Zhou, Q., Lass, R., Koivo, H.N., “Experimental study on droplet based hybrid microhandling using high speed camera”, to be published in 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS’2008, Nice, France, 2008.
- Zhou, Q., Chang, B., “Microhandling using robotic manipulation and capillary self-alignment”, 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS’2006, October 10-13, Beijing, pp. 5883-5888, 2006.
Automatically controlled 6 DOF dexterous microgripper
We have designed and build a fully sensorized and automated 6-DOF microgripper. The gripper is part of a microhandling system designed for handling and inspection of small (10 µm - 500 µm) micro components in 6 DOF in a workspace of approximately 180 x 180 x 30 µm. The microhandling system aligns components in 3D to the field-of-views of two microscopes for uniform focus. The gripper is implemented by a novel mechanical structure utilizing 2D piezoelectric bender actuators and piezoelectric stack actuators to achieve the 6 DOF. 10 strain gauge sensors are used for closed loop control. The gripper has a compact structure, modular design, as well as an advanced automation system. The microgripper with its main components are shown below.
- 6dof_testing.wmv 300 µm x 300 µm parts manipulated by the gripper
To demonstrate the performance of the system, firstly automatic manipulation of micro component is tested, then a pick, alignment, inspection and placement cycle of a micro component was performed fully automatically. In both tests, 300 µm x 300 µm x 100 µm commercial optoelectronics components were used.
- 6dof_automation.wmv Fully automated quality inspection of optoelectronic components using 6 DOF gripper. Cycle time 7 seconds.
- Zhou, Q., Korhonen, P., Laitinen, J., Sjövall, S. “Automatic dextrous microhandling based on a 6 DOF microgripper”, Journal of Micromechatronics, Vol. 3, No. 3-4, pp. 359-387, 2006.
- Zhou, Q., Korhonen, P., Chang, B., Sariola, V., “6 DOF dextrous microhandling system for inspection of microparts”, Proceeding of 2005 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM'05, pp. 534-539, Montery, USA, July 24-26, 2005.
- Korhonen, P., Zhou, Q., Laittinen, J., Sjövall, S., “Automatic dextrous handling of micro components using a 6 DOF microgripper”, Proceedings of 6th IEEE International Symposium on Computational Intelligence in Robotics and Automation, CIRA'05, pp. 125-131, Espoo, Finland, June 27-30, 2005.
Environment controlled microassembly
We have developed a microassembly system with controlled environment, which consists of an environmental control system and a microassembly platform. The environmental control system controls the environmental conditions including temperature and humidity in a closed chamber, providing a clean and vibration isolated environment for microassembly. The temperature can be controlled in the range of -10 – 40°C and relative humidity in the range of 5 – 80%RH. The microassembly platform, which is installed in the environmental control system, has microrobotic instruments such as microgrippers, micromanipulator, positioning stages, microdispenser, ultraviolet light source, microscopes, etc. Experimental results of the influences of environmental conditions on microassembly instruments and pick-and-place operations are reported.
We have experimentally studied the various effects of ambient environment on microassembly, including humidity effects on adhesion forces and temperature and humidity effects on piezoelectric actuators and pick-and-place operations.
- Zhou, Q., Chang, B., Koivo, H.N., “Temperature and Humidity Effects on Micro/nano Handling”, Materials Science Forum, Vols. 532-533, pp. 681-684, 2006.
- Zhou, Q., Aurelian, A., Chang, B., del Corral, C., Koivo, H.N., “Microassembly System with Controlled Environment”, Journal of Micromechatronics, 2004, Vol. 2, Issue 3, pp. 227-248, 2004.
- Zhou, Q., del Corral. C., Esteban, P.J., Albut, A. and Koivo, H.N. “Environmental Influences on Microassembly”, Proceedings of the 2002 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS’02, EPFL, Lausanne, Switzerland, October 2002, pp. 1760 - 1765, 2002.
- Chang, B., Zhou, Q., Koivo, H. N., “Experimental Study of Microforces in a Controlled Environment”, Proceedings of 2nd VDE World Microtechnologies Congress, MICRO.tec 2003, Munich, Germany, pp. 89-94, October 13-15, 2003.