Good Vibrations Help Move Objects





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Imagine a machine that enables you to rearrange all the furniture in your home with the simple lift of just one finger - the one finger needed to click a mouse button.

This might become a reality years from now thanks to an invention by UC Berkeley computer science graduate student Dan Reznik. Reznik's vibrating machine may one day allow you to tell your living room to shake the coffee table from one precise spot to another.

Over the last four years, Reznik, a computer science doctoral candidate, has been working in his Robotics Laboratory office in Soda Hall to redesign and improve the universal planar manipulator machine he designed.

In his lab, Reznik, the principal architect of the gadget, uses his machine to move around poker chips, pennies, wine bottles, screwdrivers and just about anything he can fit onto the table.

Applied to the physical world, the convention could one day eliminate the difficulty and energy demands required of moving heavy objects, making it possible for anyone to literally barely lift a finger to do strenuous work.

"If you want to move objects around or to relocate furniture, you can say 'OK room, shift the couch to that place,'" Reznik said. "If we're able to extend the model to three dimensional manipulation, you can then think about manipulating objects and beds just by shaking the walls of the volume."

In his research at UC Berkeley, Reznik searches for ways to manipulate - move - objects with as much efficiency as possible.

Manipulation is the moving of something in a controlled fashion, and comes from the word "mano," which means "hand."

The universal manipulator is a horizontal vibrating tray that shakes objects that sit upon the plate and moves them without the need for any robotic arms or grippers.

"The goal of the system is to manipulate parts," Reznik said. "These parts can be pennies, wine bottles, many things."

Like all machines, Reznik's machine is designed to produce the greatest amount of work through the least amount of work applied.

Efficiency is increased when a gadget can move object in a number dimensions of space with the least number of what Reznik calls degrees of manipulation. In his designs, he always strives for the ultimate goal of efficiency, or minimalism.

"I wanted to show that you can do a lot with a little," he said. "The plate has three degrees of freedom in which the direction is free to move."

Most people, Reznik said, do not realize that they are already immersed in a world filled with devices that have been designed by engineers to reduce the amount of mechanical work that needs to be done - to use small numbers of degrees of freedom to manipulate systems of many degrees of freedom.

"(The manipulator) has the ability to amplify degrees of freedom," he said.

Reznik likens the efficiency goal of his projects to a juggling clown or a car driving down the street.

The car, for example, is a mechanically efficient device that has the ability to move something in a three dimensional world through only two degrees of manipulation.

During a drive, the car moves itself and its passengers in a three dimensional world - up and down, side to side and in rotation. To achieve this three dimensional movement, however, the driver needs only to master two dimensions of work. The driver must only turn the steering wheel and step on the gas pedal.

"A car lies in a three degree of freedom world and yet you only use two controls to move it in that world," Reznik said.

The motivation behind Reznik's project came from everyday occurrences such as playing his water tic-tac-toe game, watching a circus clown juggle and driving a car.

"This is kind of a juggling task because the system we're using only has three degrees of freedom, yet the system I'm trying to manipulate has four - two times the two degrees of pennies," he said.

The tic-tac-toe game is an example of controlling many degrees of freedom with a one-dimensional mechanism. As Reznik sits in his laboratory office, he often picks up the toy and is mesmerized by the reduced mechanics of the system - the fact that he can move so many of the colored balls around in the water with the simple push of his thumb, which requires only one degree of freedom.

In juggling, a clown uses two degrees of freedom - the movement of his two hands - to juggle a number of balls. The better suited the clown to amplifying the degrees of freedom, the more balls he can juggle at once, and the more efficient that system.

"A juggler has only two hands and the number of juggling objects is what you're trying to control," Reznik said. "The juggler is able to juggle many more balls than he has hands."

Creating a device that can manipulate objects of many degrees of freedom pays off greatly because it reduces the need for mechanics, which often comes with high costs, Reznik said.

"Mechanics is hard," he said. "It's hard to build a system and the cost involved in mechanical design is harder. (My work) helps shift the costs from mechanical into control."

The universal manipulator takes advantage of currents applied to motors to vibrate a flat surface.

Objects on the table move in response to the specific vibrations.

"You're able to rotate objects in tandem and we're also able to move things around (separately)," Reznik said.

In addition to its ability to move a number of things in the same direction, the machine, which is connected to a computer program, is also designed for the independent manipulation of a number of objects.

"It's a very programmable device," he said. "You can also draw a path for an object to follow."

In choosing the material for the table, the engineers tried to maximize the stiffness and minimize the weight of the table. Reznik chose to use tiles of a composite material called honeycomb, which is also used in commercial airlines as well as in the fuselage of space shuttles.

"Honeycomb paneling is the technology which achieves the highest stiff to weight ratio," he said. "That's what they use for the floors of airlines. Airplanes don't want a lot of weight and they have to be rigid. You're trying to optimize the ratio of stiffness by weight."

Possible applications that Reznik sees in the future involve humans in the physical world. During a meeting, for example, a vibrating table can move your cup of coffee from one end of a large conference table to your seat without the need for any pushing or robots.

"(It helps) if you're sitting at a table and you want to move the coffee toward you," he said. "In the physical world, you want the system to help you neatly organize things."

Reznik has also been thinking about various industrial applications, such as using the manipulator to lessen the mechanics involved in building a car.

Currently, a car assembly line consists of robotic hand grippers that latch onto a door in order to attach it to the car. Using vibration-based manipulation would eliminate the need for costly machines designed specifically for each part, Reznik said.

"Instead of pick and place, you can use vibration to move several things," Reznik said. "Using a surface as the driving mechanism eliminates the need for clutter that might be associated (with hands). It's a very unobstructed type of actuation. You want a simple device and bringing in actuators like arms would be obstructive. (The manipulator can help) put part A in B instead of using an arm or a gripper."

But, before any of Reznik's applications can come to fruition, the invention has to be constantly modified, he said. Invention entails as much frustration and defeat as it does success.

"I've been working on it for four years and it went through major generations of designs," he said. "Everything failed except for the very last one."

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