Smarter than ever
A new robotics innovation called the intelligent assist device (IAD) allows humans and computers to work together
By Richard O. Aichele

Intelligent assist devices (IADs) are just starting to emerge as a superior way to handle heavy, bulky manufactured items. They are not autonomous robots but instead function as an extension of an operator's arms and hands. As such, the emerging IAD technology will not replace robots on assembly lines, but will carve out a new niche in manufacturing technology.

Just as Henry Ford's automobile production line in 1913 changed the face of manufacturing, computerized robotics changed production lines during the 1980s. Robotic devices in varying degrees of technical sophistication have since spread to all industries, performing a broad range of repetitive tasks.

For intricate operations, Arrick Robotics in Hurst, Texas, produces small mobile robots and motorized positioning tables. The devices can be used for anything from applying PC board adhesives to drilling holes, according to company president Roger Arrick. At the other end of the size spectrum, robots have taken over many of the body welding and painting tasks in the automobile industry.

But robot technologies have not proved useful in the main areas of the automobile assembly lines, where dashboards, electrical system subassemblies, power components and interior items are installed into car bodies. "People have very good 3-D perception. They see, they hear and they touch. We use that very well," said Tom Pearson, an automation systems specialists with Ford Motor Co. in Redford, Mich. The lift assists that are currently used for magnifying human strength and moving large subassemblies into the automobile are complex to operate.

"It can have as many as six to eight buttons that people have to actuate at specific time periods," said Pearson. "They are slow and don't follow a person's movements naturally." Dr. Edward Colgate at Northwestern University in Evanston, Ill., concurs, calling the existing devices "very unsophisticated tools." The challenge has been to develop sophisticated automation that will help workers lift and maneuver large parts at assembly stations.

Creating a new technology
A collaborative effort started more than three years ago between General Motors and Ford to meet this challenge. The University of California at Berkeley and Northwestern University (through a grant from the General Motors Foundation) also got involved. The goal, according to Michael Peshkin, a professor of mechanical engineering at Northwestern, was to create a new type of production lift assist device -- one in which operating control would be shared by a human and a computer.

The IAD concept that evolved at Northwestern was a human-controlled robotic device employing very small electric motors for movement. It is controlled by a computerized guidance arrangement that includes virtual walls and virtual guideway paths. "The idea we started with led to our concept of the Cobot," said Colgate. The Cobot, or collaborative robot, is intended to work with a human operator and provide guidance for lift assist operations.

Colgate and Peshkin struck a deal with Northwestern University to license the intellectual property rights known as Cobot. In April 1997, they formed a new company, Collaborative Motion Control (CoMoCo), in Evanston, Ill., with a business strategy of "developing into a core component supplier and manufacturer of Cobot technology," said Colgate.

CoMoCo will create new Cobot software and mechanical components and sell them to larger equipment system integrators. The company, which currently has four employees, has set up shop in a small business incubator operated jointly by Northwestern and the city of Evanston.

A U.S. patent application for the Cobot technology was filed last year. According to Peshkin, the technology "produces haptic effects like virtual walls, artificial potential, guiding surfaces and following a path. It produces them and steers a non-holonomic device." The Cobot technology uses wheels and continuously variable transmissions that guide motion through certain steering actions.

Programming intelligence
At the heart of a Cobot is the computerized software and hardware. Cobot technology is built around a C++ platform running a PC-based system. Colgate notes that while "current software isn't yet as far along as robots," it is already very programmable. That versatility will help increase its value as a production tool on fast-paced assembly lines.

Guidance technology is the key to the new IADs and Cobots. As the human operator twists the handle or moves it forward or backward, the IAD carrying the part follows the operator's movements in a natural way. Cobot's virtual walls and virtual guides provide the path and direct the motions.

"If you have a large object like an instrument panel, you want to get it into the body without hitting any Class A surfaces. For automakers, Class A surfaces are those perceptible to a customer. In essence, you have a guide rail that the instrument panel will follow," Colgate said. The benefit of virtual walls is that a part being moved won't just hit the wall and stop. Instead, said Peshkin, "it would be like hitting a slick surface, and you would slide in the right direction."

Pearson is optimistic that Ford's Cobot prototype is "not a dumb device but a very smart device." But the technology is not quite there yet, he cautions. One current problem: "You are putting something into an engine block, you miss and it slams into the block. That needs to be smoothed out," he said. Pearson also noted that the virtual walls are only two-dimensional. "We need full-blown three-dimensional virtual walls," he said.

Colgate said the Cobot can use different sensors to detect its movements and signal the computer. Typically, the joints on the operating arms will be fitted with optical encoders. Force sensors are used at the point of human interface to detect what the human is trying to do. Based on the programming of virtual walls and virtual paths, the machine will then decide how to obey the force sensor's command.

As with other robotic devices, IAD and Cobot generally use electric motors or hydraulics for powering actuating arms or for movement. In the case of the Ford and General Motors prototype Cobots, NEMA 23 frame size 24 VDC motors provide the power to move the Cobot. The small motors are practical with the Cobot because of its free rolling and easy maneuverability.

The General Motors Cobot prototype has a footprint about the size of a desktop and weighs about 300 pounds, which is "heavier than we want it to be," said Colgate. The prototype at Ford is an overhead rail version that provides both guidance and power assist features.

Virtual walls
General Motors will have a new generation of intelligent lift assist devices installed on general assembly lines by December. "We expect to be using the [virtual] walls," said Dr. Prasad Akella, senior engineer at the GM Controls, Robotics & Welding Center in Warren, Mich. The walls are designed for both safety and ease of use. For instance, an operator of the IAD could push a device too hard and lose control. "So you put up a virtual wall and let him glide along the wall," Akella said.

For auto manufacturers, the new IAD will be coming on-line at the right time. IADs are expected to start moving parts on production floors next year, and may be in general use within five years. At the same time, automobile assembly is moving towards larger and bulkier subassembly modules. A front end module could have the radiator, lights, fog lights and bumper as a single integrated unit.

Without precision control of the large modules as they are installed on the automobile, accidental bumping and scratching of Class A surfaces becomes more likely. "We cannot afford that type of marring," said Pearson. The advances planned for the Cobot's guidance software should minimize those concerns.

The applications for IADs go beyond automobiles. IAD developers at Oak Ridge Laboratories in Oak Ridge, Tenn., have developed initial designs for the handling of heavy weapon systems during loading onto attack aircraft. Dr. Francois Pin, robotics scientist at Oak Ridge, said that during a recent test with Air Force personnel who had never seen the computerized automation systems before, the operator smoothly directed the prototype IAD to load a 2,000-pound weapon onto an aircraft pylon.

The Oak Ridge IAD is a self-contained unit with a diesel engine driving the IAD hydraulic operating system. Hydraulics were chosen to maintain compatibility with other Air Force equipment, Pin said, but IAD development for the Navy's aircraft carriers will use electric actuation. As with other IADs, the brains of the unit are the electronic controls, which Pin describes as "extremely sophisticated." Combined with many off-the-shelf components and sensors, the self-contained IAD is "a working system that can achieve sub-millimeter accuracy with payloads up to 5,000 pounds," he said.

When humans need help
IAD development could get a boost as the technology's benefits become more widely known. For lightweight objects that must be repetitively handled, Pearson said, the assist devices could help prevent injuries. And on the heavier end of the spectrum, IADs assist workers by amplifying human strength for the manipulation of objects over 50 pounds. Through the use of an IAD, heavy, bulky objects become simply bulky objects like an empty box.

The new IAD can also solve a common assembly line problem caused by mass variations in parts. For instance, Akella points out, prop shafts can vary from 17 to 34 pounds on truck assembly lines that are running several different models simultaneously. Existing pneumatic assists are generally set at a midpoint, which means they provide either overcompensation or undercompensation. The new generation of IADs compensate out the variations using both gravitational and inertial factors. "That's the really big benefit of the device," Akella said.

IAD technology offers promising growth for new and existing businesses. Says Akella, "The more people who come in, the better off the industry will be because things will go forward much faster." The market for these devices has barely been explored. Within a few years, the IAD industry could revolutionize many areas of production and material handling -- areas where robots are unsuitable but humans need help.

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