Automatic pick-and-place of 40 microns objects using a robotic platform.

International audienceRobotic micro-assembly is one way to manufacture new generation of out of plane and/or hybrid microsystems. This approach requires the study of micromanipulation strategies adapted to the microworld and especially to the surface and adhesion forces. We are focusing our works on the study of robotic assembly methods applied to objects whose size is below 100 micrometers. The handling strategy used is based on a two fingered gripper. In order to reduce the adhesion between the gripper and the manipulated objects specific end-effectors have been developed. Moreover, to improve the release reliability we are using a polymer substrate which induces high adhesion with the objet. Some automatic pick-and-places on objects whose typical size is 40 micrometers have been done (cycle time of 1.8 second). There show the reliability of the proposed approach

Development of a micromanipulation system with force sensing

This article provides in-depth knowledge about our undergoing effort to develop an open architecture micromanipulation system with force sensing capabilities. The major requirement to perform any micromanipulation task effectively is to ensure the controlled motion of actuators within nanometer accuracy with low overshoot even under the influence of disturbances. Moreover, to achieve high dexterity in manipulation, control of the interaction forces is required. In micromanipulation, control of interaction forces necessitates force sensing in milli-Newton range with nano-Newton resolution. In this paper, we present a position controller based on a discrete time sliding mode control architecture along with a disturbance observer. Experimental verifications for this controller are demonstrated for 100, 50 and 10 nanometer step inputs applied to PZT stages. Our results indicate that position tracking accuracies up to 10 nanometers, without any overshoot and low steady state error are achievable. Furthermore, the paper includes experimental verification of force sensing within nano-Newton resolution using a piezoresistive cantilever endeffector. Experimental results are compared to the theoretical estimates of the change in attractive forces as a function of decreasing distance and of the pull off force between a silicon tip and a glass surface, respectively. Good agreement among the experimental data and the theoretical estimates has been demonstrated

Adhesion state detection by vision and its application to automatic micro manipulation

In our previous paper, we proposed a method for reducing adhesion forces by oscillation. However, the following problems have not been still resolved: (1) Since adhesion state was checked by analyzing the data obtained by laser displacement meter, this method is available in only limited situations. (2) Automatic checking system for adhesion state was not developed. (3) Automatic micro manipulation system was not developed. Considering the above, in this paper, we propose a method to automatically check adhesion state by vision. Firstly, we develop a method to estimate the amplitude of the oscillation using the blur resulted from the oscillation. We call the estimated amplitude AIV (amplitude indicating value). Then, we develop a method for checking adhesion state by AIV. Based on the checking method, we develop a automatic micro manipulation system for pick and place operation. The validity of our method is shown by experiments. ©2008 IEEE

Micromanipulation using squeeze effect

In this paper, we proposed a novel strategy for pick and place operation in a micro range, by using a squeeze effect In a micro range, the attracting forces such as the van der Waals, capillary, and electrostatic forces are dominate due to the scaling effect. The attracting forces make a release of an object difficult. In this paper, by vibrating the finger, we generate the gas film (the squeeze effect) between the object and the finger and relax the attracting forces. Some experimental results are shown to verify our approach

Study on Adhesion Force Reduction and State Estimation by Piezo-transducer

Our previous paper presented a method for reducing adhesion forces by oscillation and showed the adhesion state can be checked by analyzing the data obtained by laser displacement meter. However, there are several problems in this method. 1)The end-effector must be located at the specific point where laser displacement meter can measure oscillation. 2)The adhesion state can not be checked if something blocks the light/laser or the target leaves the measuring point. 3)The total system becomes very large. To resolve these problems, this paper firstly presents a method for checking the adhesion state by piezo-transducer. Next, to achieve more precise manipulation, we propose a method to deform the end-effector by adding DC input to the piezo actuator which is also oscillated simultaneously to reduce adhesion forces. Furthermore, we find that the first mode resonance frequency shifts with the increase of the pushing force applied to the object by the end-effector. Using the shift amount, we develop a method for checking the adhesion state. © 2009 IEEE

Mechanism of Micro Manipulation using Oscillation

In this paper, we analyze the mechanism of the phenomenon between an endeffector, a micro object and a substrate during a micro manipulation. In a micro range, the attracting forces such as the van der Waals, capillary, and electrostatic forces dominate and course adhesion between the object and the endeffector. The adhesion makes the manipulation of an object difficult. Recently, we developed a method to reduce the attracting/adhesion effect. When bringing an oscillating endeffector close to a micro object on a substrate, the attracting force between the object and the endeffector is reduced, attracting the object to the substrate. Then, it becomes easy to remove the endeffector from the object. Using this method, a micro object can be easily manipulated. However, the mechanism of the phenomenon is still unclear. In this paper, we develop the theoretical model of the system to analyze the phenomenon, and simulate the dynamical motion of the system. Comparing the experimental results, we show the validity of our approach. Using simulation and experiment, we show that the oscillation of the endeffector can reduce the adhesion effect between the endeffector and the object, attracting the object to the substrate. © 2006 IEEE