PICK AND PLACE ASSEMBLY

PRIORITY CLAIM

This Application claims the benefit of U.S. Provisional Patent Application Serial Number 61/790,139 filed March 15, 2013.

GOVERNMENT FUNDING

The invention described herein was made with government support under grant number W911NF-11-1 -0093, awarded by the Defense Advanced Research Projects Agency (DARPA). The United States Government has certain rights in the invention.

FIELD OF THE INVENTION

The invention relates generally to pick and place system and methods in which objects are picked from one location, transferred to another location, and placed in a precise position. More specifically, the invention relates to system and methods for object manipulation that utilizes electroadhesion in order to easily, carefully, and quickly pick and place objects, including micron sized objects, with precision.

BACKGROUND OF THE INVENTION

Automated manufacturing processes often include a mechanism that picks or selects an object and transfers it from one location to another in order for the object to be placed in a precise position.

There have been a number of devices invented in order to move hundreds of small objects. Some look at pick and place robotics to individually grasp and move each piece quickly, while others rely on self-assembly through energy minima. From suction to magnets to tweezers, numerous products attempt to quickly move large amounts of small objects efficiently and carefully. However, there is a limitation on size. Once objects get too small, for example, around the range of a millimeter and smaller, it becomes more difficult to handle these delicate objects and to quickly arrange the objects in a desired accurate configuration. Furthermore, most inventions use single end effectors to pick up objects - greatly increasing the time to move objects - when two or more objects could be moved in parallel and in any configuration or pattern if properly controlled.

There is a demand for a pick and place system that easily, carefully, and quickly manipulates objects including micron sized objects such as picking and placing objects individually and in parallel as well as in any configuration or pattern.

The invention satisfies this demand.

SUMMARY OF THE INVENTION

The invention is directed to a system and methods that utilizes electroadhesion to manipulate one or more objects including micron sized objects. For purposes of this application, a micron sized object is a very small object, for example, an object with a size around, about, or less than one thousandth of a meter

(millimeter) or one-millionth of a meter (micrometer).

Electroadhesion is a dry adhesion achieved by the virtue of electrostatic force of attraction between electrodes and an adjacent object where the electrostatic force is a result of interaction between the electrodes and the charge it induces on the object. This force is very similar to one observed between the two parallel plates of a charged capacitor. A typical electroadhesion based system can achieve a force as high as 2 N/m ² such that a special microstructure or wet agent is not needed to achieve adhesion.

The most attractive attribute of electroadhesion is its easy and fast switching - manipulating the power supply can instantly switch the adhesion on or off. In addition, electroadhesion is a versatile adhesion method independent of the material property of an object.

In one embodiment, the system comprises a power source component and an assembler component including electrically controlled elements. Electrically controlled elements include at least one pair of electrodes coated with a dielectric element. The dielectric element enhances adhesion force by increasing the net capacitance between each electrode of the pair. In addition, the dielectric element prevents any sort of short circuit, for example, when a conducting object is picked and placed such as on a metallic material. Certain embodiments of the invention may also include a switch component to control pairs of electrodes individually or in combination.

Specifically, the electrically controlled elements retain a charged force that is opposite from the charge force retained by the object such that the object can be picked up. Similarly, the electrically controlled elements display a charged force that is the same as the charge force retained by the object such that the object can be placed. In one embodiment, the electrically controlled elements may have negatively charged forces to pick up objects retaining positively charged forces. In another embodiment, the electrically controlled elements may have positively charged forces to pick up objects retaining negatively charged forces. In yet another embodiment, the electrically controlled elements may have negatively charged forces or positively charged forces to place or drop objects retaining negatively charged forces or positively charged forces, respectively.

The object to be manipulated obtains its charge from the electrodes. This is done by inducing a charge by the electrodes opposite in polarity to the object to be picked up. Inducing a charge on the object may be accomplished by maintaining a high voltage by the electrodes received from the power source component. When a high DC voltage is applied to the electrodes, the object nearby is polarized by the electrodes. Again, to pick up the object, it is polarized with a charge opposite from that retained by the electrodes. Inducing a charge by the electrodes to the object also occurs when the system drops or places the object. This is accomplished by turning off the power source component, or backing off the high voltage received from the power source component.

According to the invention, objects can be selected and placed with micro scale precision. It is contemplated that the invention may assist three-dimensional (3D) printers as well as be used to pick and place heavy objects. Thus, it is contemplated that the invention may assemble objects of all sizes including micron sized objects.

Another advantage of the invention is that assembly of objects including micron sized object can be performed in high-volumes. Furthermore, any size and any shape object may be manipulated to assemble components.

Another advantage of the invention is that the system is easier to maintain than existing systems since there are no complicated parts such as vacuums and tool heads.

Yet another advantage of the invention is that the system has the ability to control millions of micron sized objects including the ability to control each object independently from another.

Yet another advantage of the invention is the low power requirement of the system. For example, double A (AA) batteries are sufficient to operate the system.

Yet another advantage of the invention is its adaptability to various applications such as surface mounting applications and digital manufacturing applications.

The invention and its attributes and advantages may be further understood and appreciated with reference to the detailed description below of contemplated embodiments, taken in conjunction with the accompanying drawing.

DESCRIPTION OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the invention and, together with the description, serve to explain the advantages and principles of the invention:

FIG. 1 is a block diagram illustrating the system according to one embodiment of the invention.

FIG. 2 illustrates an assembler component according to one embodiment of the invention along with an exemplary object.

FIG. 3 illustrates electrically controlled elements of the assembler component according to one embodiment of the invention.

FIG. 4 is a diagram illustrating electrostatic actuated force according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram illustrating the system 50 according to one embodiment of the invention. The system 50 requires low power and is portable. As shown in FIG. 1 , the system 50 includes an assembler component 100 and a power source component 200. According to the invention, the power source component may be a DC-DC low to high voltage converter. The DC-DC low to high voltage converter contemplated requires low power such that AA batteries may be used to operate it. Certain embodiments of the invention may also include a switch component 300, which may be used to control electrodes individually or in combination.

Specifically, the system of the invention includes an assembler component 100 that includes electrically controlled elements in the form of at least one pair of electrodes 115, 116 coated with a dielectric element 120 as shown in FIG. 2. In one embodiment, a grid 112 of electrodes 115, 116 is printed on top of a printed circuit board (PCB) 110 by methods known to those skilled in the art of PCB fabrication. As shown in FIG. 2, a pair of electrodes 115, 116 are positioned at every intersection of the grid 112. Although it is contemplated that electrodes may 115, 116 be positioned in any arrangement including, for example, at every other intersection. Each electrode 115, 116 of the pair are activated to induce charge on an object.

The PCB 110 is coated with a dielectric element 120 which serves two fold; it enhances the adhesion force by increasing the net capacitance between the electrodes 115, 116, and prevents any possible short circuit that may result due to picking a conducting object. In one embodiment, a Parylene C dielectric coating is vapor deposited on the PCB 110. Specifically, the Parylene C dielectric is deposited in a 3μτη thick layer. Parylene C has a high dielectric strength (6800 Volts/mil), making it suitable for high voltage applications.

Each electrode 115, 116 retains a charge and induces an opposite charge on an object 130 in order for the assembler component 100 to pick up the object 130. The electrostatic force between two charges is given by:

6ne where, Q is the first charge, Q ₂ is the second charge, e is the permittivity of medium in between and d is the distance between the charges. The force F is highly sensitive to the distance d and it decreasesd sharply as one moves away from the charge.

According to the invention, an object to be picked up must retain a charge opposite in polarity from the electrodes. Similarly, the object must retain a charge the same in polarity from the electrodes in order to be repelled or placed.

Electrodes 115, 116 are shown more specifically in FIG. 3. One electrode 115 comes from top side of the PCB 110 through via 1 17 and another electrode 1 16 is in form of a concentric annulus around the via padding 1 18. The circumferential distance between two electrodes is a critical parameter and depends on the voltage output by the power source component, which in return is dependent on the weight of an object to be manipulated. In one embodiment, the system picks an object weighing .1 gm and with a voltage in the range of 100s of volt to pick it up. To drop or place the object, the voltage from the power source component is reduced or turned off.

FrG. 4 is a diagram illustrating electroadhesion according to one embodiment of the invention. As shown in FIG. 4, electrodes 310 with dielectric element 320 are maintained at a high voltage to induce charge opposite their own polarity at the object 330 nearby, resulting in an electrostatic force of attraction between the electrodes 310 and the object 330.

The described embodiments are to be considered in all respects only as illustrative and not restrictive, and the scope of the invention is not limited to the foregoing description. Those of skill in the art may recognize changes, substitutions, adaptations and other modifications that may nonetheless come within the scope of the invention and range of the invention.